Showing 1–50 of 630 results for author: Young, D

Cluster-First Labelling: An Automated Pipeline for Segmentation and Morphological Clustering in Histology Whole Slide Images

Authors: Muhammad Haseeb Ahmad, Sharmila Rajendran, Damion Young, Jon Mason

Abstract: Labelling tissue components in histology whole slide images (WSIs) is prohibitively labour-intensive: a single slide may contain tens of thousands of structures--cells, nuclei, and other morphologically distinct objects--each requiring manual boundary delineation and classification. We present a cloudnative, end-to-end pipeline that automates this process through a cluster-first paradigm. Our syst… ▽ More Labelling tissue components in histology whole slide images (WSIs) is prohibitively labour-intensive: a single slide may contain tens of thousands of structures--cells, nuclei, and other morphologically distinct objects--each requiring manual boundary delineation and classification. We present a cloudnative, end-to-end pipeline that automates this process through a cluster-first paradigm. Our system tiles WSIs, filters out tiles deemed unlikely to contain valuable information, segments tissue components with Cellpose-SAM (including cells, nuclei, and other morphologically similar structures), extracts neural embeddings via a pretrained ResNet-50, reduces dimensionality with UMAP, and groups morphologically similar objects using DBSCAN clustering. Under this paradigm, a human annotator labels representative clusters rather than individual objects, reducing annotation effort by orders of magnitude. We evaluate the pipeline on 3,696 tissue components across 13 diverse tissue types from three species (human, rat, rabbit), measuring how well unsupervised clusters align with independent human labels via per-tile Hungarian-algorithm matching. Our system achieves a weighted cluster-label alignment accuracy of 96.8%, with 7 of 13 tissue types reaching perfect agreement. The pipeline, a companion labelling web application, and all evaluation code are released as open-source software. △ Less

Submitted 10 April, 2026; originally announced April 2026.

Comments: 7 pages, 4 figures

ATLAS100 -- I. A volume-limited sample of supernovae and related transients within 100 Mpc

Authors: Shubham Srivastav, Stephen J. Smartt, Thomas Moore, Kenneth W. Smith, David R. Young, Michael D. Fulton, Charlotte R. Angus, Matt Nicholl, Heloise F. Stevance, Ting-Wan Chen, Andrea Pastorello, Julian Sommer, Fiorenzo Stoppa, Jack W. Tweddle, Joseph P. Anderson, Mark E. Huber, Armin Rest, Lauren Rhodes, Luke J. Shingles, Aysha Aamer, Alejandro Clocchiatti, Alexander J. Cooper, Nicolas Erasmus, James H. Gillanders, Dylan Magill , et al. (7 additional authors not shown)

Abstract: We present ATLAS100 -- a sample of 1729 supernovae and other explosive optical transients within $\sim 100$ Mpc observed by the ATLAS survey over a span of 5.75 years from 2017 September 21 to 2023 June 21. The volume-limited sample includes transients associated with galaxies with a spectroscopic redshift of $z \leq 0.025$, and spectroscopically classified transients within this redshift threshol… ▽ More We present ATLAS100 -- a sample of 1729 supernovae and other explosive optical transients within $\sim 100$ Mpc observed by the ATLAS survey over a span of 5.75 years from 2017 September 21 to 2023 June 21. The volume-limited sample includes transients associated with galaxies with a spectroscopic redshift of $z \leq 0.025$, and spectroscopically classified transients within this redshift threshold where a host redshift was not available in existing catalogues. Our host galaxy list is constructed from aggregating all available galaxy redshift and distance catalogues. We carefully select all transients within a projected radius of 50\,kpc of these hosts. The ATLAS100 transient sample has a host galaxy redshift completeness fraction of $83$ per cent, consistent with expectations for the redshift completeness of local galaxy catalogues. Within this volume, the spectroscopic classifications are 87 per cent complete and we reclassify many ambiguous transients with joint light curve and spectroscopic considerations. Here, we release the catalogue together with compiled, binned and cleaned ATLAS photometry for all transients. We fit the light curve data to derive peak luminosity and characteristic timescales. We explore the sample characteristics, demographics and discuss completeness and purity of the sample. △ Less

Submitted 3 March, 2026; originally announced March 2026.

Comments: Submitted to MNRAS, data products available online

SN 2024abvb: a Type Ibn/Icn supernova with evidence of helium and an extreme offset from its host galaxy

Authors: Callum Aster, Cosimo Inserra, Andrea Pastorello, Joseph P Anderson, Franz Erik Bauer, K. Azalee Bostroem, Kenneth C. Chambers, Ting-Wan Chen, Joseph R. Farah, Morgan Fraser, Dino Pierluigi Fugazza, Mariusz Gromadzki, Claudia P. Gutiérrez, D. Andrew Howell, Erkki Kankare, Tom L. Killestein, Niilo Koivisto, Giorgos Leloudas, J. D. Lyman, Kyle Medler, Shane Moran, Tomás E. Müller-Bravo, Giuliano Pignata, Miika Pursiainen, Fabio Ragosta , et al. (5 additional authors not shown)

Abstract: We present spectroscopic and photometric observations and analysis of SN 2024abvb, a peculiar transitional Type Ibn/Icn supernova located at an unusually large projected distance from its host galaxy (21.5 kpc). SN 2024abvb displays an extended rise time in the $g$- and $o$-bands (10.1 and 10.6 days respectively), followed by a linear decline in all photometric bands. Comparisons with other supern… ▽ More We present spectroscopic and photometric observations and analysis of SN 2024abvb, a peculiar transitional Type Ibn/Icn supernova located at an unusually large projected distance from its host galaxy (21.5 kpc). SN 2024abvb displays an extended rise time in the $g$- and $o$-bands (10.1 and 10.6 days respectively), followed by a linear decline in all photometric bands. Comparisons with other supernova subclasses show that the photometric and spectroscopic evolution of SN 2024abvb are distinct from Type~Ibn and Type Icn events, with a higher peak $r$-band luminosity and lower blackbody temperatures. Spectra reveal an initial blue continuum and narrow P-Cygni profiles, with C {\sc ii} $λ$5890 dominating in emission, persisting at late phases, and showing a rapid decline in the expansion velocity. Weak He {\sc i} $λ$5876 features are tentatively detected at early times. Analysis of progenitor scenarios rules out thermonuclear origins based on incompatible light curve shapes and spectral signatures. A rare massive star progenitor appears unlikely given the low local star formation rate. The most plausible origin is an ultra-stripped supernova scenario involving a binary system; this best explains the observed separation from the host, the low circumstellar material mass, the fast photometric evolution and the low nickel production, although a discrepancy in model versus observed ejecta mass remains. These results reinforce the classification of SN 2024abvb as a distinctive Type Ibn/Icn event and highlight the diversity of progenitor channels for interacting supernovae. △ Less

Submitted 24 February, 2026; originally announced February 2026.

Comments: Accepted 2026 February 23. Received 2026 February 21; in original form 2026 January 05, 15 pages, 12 figures, 10 pages appendix

A nearby He-rich superluminous supernova at photospheric phases

Authors: A. Fiore, A. Kozyreva, L. Yan, S. Benetti, J. P. Anderson, P. Baklanov, Y. -Z. Cai, E. Cappellaro, T. -W. Chen, N. Elias-Rosa, A. Gal-Yam, M. J. Graham, M. Gromadzki, S. L. Groom, C. P. Gutiérrez, D. Hiramatsu, D. A. Howell, C. Inserra, M. M. Kasliwal, R. Könyves-Tóth, P. Lundqvist, C. McCully, A. Mironov, S. Moran, T. E. Müller-Bravo , et al. (19 additional authors not shown)

Abstract: Aim. We present and interpret the data of the nearby hydrogen-deficient but helium-rich superluminous supernova SN~2021bnw which reached a magnitude of -20.7 at maximum luminosity in g band. Methods. We discuss the light curves and spectra of SN 2021bnw based on its spectro-photometric follow up exploiting different observational facilities. We reproduce the NIR spectrum of SN 2021bnw with TARDIS… ▽ More Aim. We present and interpret the data of the nearby hydrogen-deficient but helium-rich superluminous supernova SN~2021bnw which reached a magnitude of -20.7 at maximum luminosity in g band. Methods. We discuss the light curves and spectra of SN 2021bnw based on its spectro-photometric follow up exploiting different observational facilities. We reproduce the NIR spectrum of SN 2021bnw with TARDIS to inspect the chemical composition at late photospheric phases and identify helium features. We also use a STELLA model coupling hydrodynamics and radiation transport to constrain the physical parameters of the explosion assmunig a 56Ni+CSM scenario. Results. We suggest that SN 2021bnw was mainly powered by the interaction of the ejecta with a previously lost He-rich circumstellar material, coupled with a central power source. Conclusions. This work expands the data sample of He-rich superluminous supernovae rich (SLSNe Ib) and, assuming a single progenitor scenario, can constrain the masses and the physics of their progenitors. △ Less

Submitted 13 February, 2026; originally announced February 2026.

Comments: 17 pages, 11 figures, submitted to A&A. Comments are welcome

Optimizing Chlorination in Water Distribution Systems via Surrogate-assisted Neuroevolution

Authors: Rivaaj Monsia, Daniel Young, Olivier Francon, Risto Miikkulainen

Abstract: Ensuring the microbiological safety of large, heterogeneous water distribution systems (WDS) typically requires managing appropriate levels of disinfectant residuals including chlorine. WDS include complex fluid interactions that are nonlinear and noisy, making such maintenance a challenging problem for traditional control algorithms. This paper proposes an evolutionary framework to this problem b… ▽ More Ensuring the microbiological safety of large, heterogeneous water distribution systems (WDS) typically requires managing appropriate levels of disinfectant residuals including chlorine. WDS include complex fluid interactions that are nonlinear and noisy, making such maintenance a challenging problem for traditional control algorithms. This paper proposes an evolutionary framework to this problem based on neuroevolution, multi-objective optimization, and surrogate modeling. Neural networks were evolved with NEAT to inject chlorine at strategic locations in the distribution network at select times. NSGA-II was employed to optimize four objectives: minimizing the total amount of chlorine injected, keeping chlorine concentrations homogeneous across the network, ensuring that maximum concentrations did not exceed safe bounds, and distributing the injections regularly over time. Each network was evaluated against a surrogate model, i.e.\ a neural network trained to emulate EPANET, an industry-level hydraulic WDS simulator that is accurate but infeasible in terms of computational cost to support machine learning. The evolved controllers produced a diverse range of Pareto-optimal policies that could be implemented in practice, outperforming PPO, a standard reinforcement learning method. The results thus suggest a pathway toward improving urban water systems, and highlight the potential of using evolution with surrogate modeling to optimize complex real-world systems. △ Less

Submitted 10 April, 2026; v1 submitted 6 February, 2026; originally announced February 2026.

Comments: 13 pages, 9 figures, GECCO '26

ACM Class: I.2.1

The Effects of Non-ideal Mixing in Planetary Magma Oceans and Atmospheres

Authors: Aaron Werlen, Edward D. Young, Hilke E. Schlichting, Caroline Dorn, Anat Shahar

Abstract: Sub-Neptunes with hydrogen-rich envelopes are expected to sustain long-lived magma oceans that continuously exchange volatiles with their overlying atmospheres. Capturing these interactions is key to understanding the chemical evolution and present-day diversity of sub-Neptunes, super-Earths, and terrestrial planets, particularly in light of new JWST observations and upcoming missions. Recent adva… ▽ More Sub-Neptunes with hydrogen-rich envelopes are expected to sustain long-lived magma oceans that continuously exchange volatiles with their overlying atmospheres. Capturing these interactions is key to understanding the chemical evolution and present-day diversity of sub-Neptunes, super-Earths, and terrestrial planets, particularly in light of new JWST observations and upcoming missions. Recent advances in both geochemistry and astrophysics now allow the integration of experimental constraints and thermodynamic models across melt, metal, and gas phases. Here we extend a global chemical equilibrium model to include non-ideal behavior in all three phases. Our framework combines fugacity corrections for gas species with activity coefficients for silicate and metal species, enabling a fully coupled description of volatile partitioning. We show that for planetary embryos (0.5 M$_\oplus$ at 2350 K), non-ideality introduces only modest corrections to atmosphere-magma ocean interface (AMOI) pressures, volatile inventories, and interior compositions. In contrast, for sub-Neptunes with higher temperatures ($\approx$ 3000 K) and pressures, non-ideal effects are more pronounced, though still modest in absolute terms$-$typically within 20% and at most a factor of two. Including activity and fugacity coefficients simultaneously increases the AMOI pressure, enhances water retention in the mantle and the envelope. Our results demonstrate that non-ideality must be treated globally: applying corrections to only one phase leads to incomplete or even misleading trends. These findings highlight the importance of self-consistent global thermodynamic treatments for interpreting atmospheric spectra and interior structures of sub-Neptunes and super-Earths. △ Less

Submitted 5 February, 2026; originally announced February 2026.

Comments: Accepted for publication in The Astrophysical Journal

Journal ref: ApJ 999 178 (2026)

Light-Curve and Spectral Properties of Type II Supernovae from the ATLAS survey

Authors: K. Ertini, J. P. Anderson, G. Folatelli, S. González-Gaitán, C. P. Gutiérrez, J. Sollerman, O. Rodríguez, A. Aryan, T. -W. Chen, E. Concepcion, S. P. Cosentino, M. Dennefeld, N. Erasmus, M. Fraser, L. Galbany, M. Gromadzki, C. Inserra, T. E. Müller-Bravo, P. J. Pessi, T. Pessi, T. Petrushevska, G. Pignata, F. Ragosta, S. Srivastav, D. R. Young

Abstract: Type II supernovae (SNe II) are the most common terminal stellar explosions in the Universe. With SNe now being detected within days after explosion, there is growing evidence that the majority of Type II SNe show signs of interaction with a confined, dense cirumstellar material (CSM) in the first few days post explosion. In this work we aim to bridge the gap between single SN studies showing earl… ▽ More Type II supernovae (SNe II) are the most common terminal stellar explosions in the Universe. With SNe now being detected within days after explosion, there is growing evidence that the majority of Type II SNe show signs of interaction with a confined, dense cirumstellar material (CSM) in the first few days post explosion. In this work we aim to bridge the gap between single SN studies showing early-time interaction in their spectra, and the statistical studies of early-time SN light curves, which imply the existence of CSM. We present a sample of 68 Type II SNe with both early photometric data, obtained with the ATLAS survey, and spectroscopic data, obtained with the ePESSTO+ collaboration. A subset of the sample is classified based on the presence or absence of narrow spectral features with electron-scattered broadened wings in the early spectra, indicative of interaction with CSM. We characterise the photometric and spectroscopic properties of the sample by measuring rise times to maximum light, peak magnitudes, decline rates and line velocities. Additionally, we measure the ratio of absorption to emission (a/e) of the H alpha P-Cygni profile. Our analysis reveals that SNe II showing early spectroscopic signs of interaction with CSM decline faster and are brighter than those without. However no difference is found in rise times between the two groups. A clear separation is observed in the a/e ratio: SNe with signs of interaction exhibit lower a/e ratios at all epochs compared to those without. Our results highlight that understanding SN II ejecta-CSM interaction requires large, uniform samples of photometric and spectroscopic data, such as the one presented in this work. △ Less

Submitted 3 February, 2026; originally announced February 2026.

Comments: Submitted to A&A

An interpretable data-driven approach to optimizing clinical fall risk assessment

Authors: Fardin Ganjkhanloo, Emmett Springer, Erik H. Hoyer, Daniel L. Young, Holley Farley, Kimia Ghobadi

Abstract: In this study, we aim to better align fall risk prediction from the Johns Hopkins Fall Risk Assessment Tool (JHFRAT) with additional clinically meaningful measures via a data-driven modelling approach. We conducted a retrospective cohort analysis of 54,209 inpatient admissions from three Johns Hopkins Health System hospitals between March 2022 and October 2023. A total of 20,208 admissions were in… ▽ More In this study, we aim to better align fall risk prediction from the Johns Hopkins Fall Risk Assessment Tool (JHFRAT) with additional clinically meaningful measures via a data-driven modelling approach. We conducted a retrospective cohort analysis of 54,209 inpatient admissions from three Johns Hopkins Health System hospitals between March 2022 and October 2023. A total of 20,208 admissions were included as high fall risk encounters, and 13,941 were included as low fall risk encounters. To incorporate clinical knowledge and maintain interpretability, we employed constrained score optimization (CSO) models to reweight the JHFRAT scoring weights, while preserving its additive structure and clinical thresholds. Recalibration refers to adjusting item weights so that the resulting score can order encounters more consistently by the study's risk labels, and without changing the tool's form factor or deployment workflow. The model demonstrated significant improvements in predictive performance over the current JHFRAT (CSO AUC-ROC=0.91, JHFRAT AUC-ROC=0.86). This performance improvement translates to protecting an additional 35 high-risk patients per week across the Johns Hopkins Health System. The constrained score optimization models performed similarly with and without the EHR variables. Although the benchmark black-box model (XGBoost), improves upon the performance metrics of the knowledge-based constrained logistic regression (AUC-ROC=0.94), the CSO demonstrates more robustness to variations in risk labeling. This evidence-based approach provides a robust foundation for health systems to systematically enhance inpatient fall prevention protocols and patient safety using data-driven optimization techniques, contributing to improved risk assessment and resource allocation in healthcare settings. △ Less

Submitted 28 January, 2026; v1 submitted 8 January, 2026; originally announced January 2026.

Comments: This work was intended as a replacement of arXiv:2510.20714 and any subsequent updates will appear there

AT2024wpp: An Extremely Luminous Fast Ultraviolet Transient Powered by Accretion onto a Black Hole

Authors: Daniel A. Perley, Anna Y. Q. Ho, Zoë McGrath, Michael Camilo, Cassie Sevilla, Ping Chen, Genevieve Schroeder, Taya Govreen-Segal, Aleksandra Bochenek, Yu-Jing Qin, James H. Gillanders, Benjamin Amend, Joseph P. Anderson, Igor Andreoni, Amar Aryan, Eric C. Bellm, Joshua S. Bloom, Thomas de Boer, Jonathan Carney, Ilaria Caiazzo, Ken C. Chambers, Panos Charalampopoulos, Ting-Wan Chen, Tracy X. Chen, Eric R. Coughlin , et al. (47 additional authors not shown)

Abstract: We present the discovery of AT 2024wpp ("Whippet"), a fast and luminous 18cow-like transient. At a redshift of z=0.0868, revealed by Keck Cosmic Web Imager spectroscopy of its faint and diffuse star-forming host, it is the fourth-nearest example of its class to date. Rapid identification of the source in the Zwicky Transient Facility data stream permitted ultraviolet-through-optical observations t… ▽ More We present the discovery of AT 2024wpp ("Whippet"), a fast and luminous 18cow-like transient. At a redshift of z=0.0868, revealed by Keck Cosmic Web Imager spectroscopy of its faint and diffuse star-forming host, it is the fourth-nearest example of its class to date. Rapid identification of the source in the Zwicky Transient Facility data stream permitted ultraviolet-through-optical observations to be obtained prior to peak, allowing the first determination of the peak bolometric luminosity (2x10^45 erg/s), maximum photospheric radius (10^15 cm), and total radiated energy (10^51 erg) of an 18cow-like object. We present results from a comprehensive multiwavelength observing campaign, including a far-UV spectrum from the Cosmic Origins Spectrograph on the Hubble Space Telescope and deep imaging extending >100 days post-explosion from the Very Large Telescope, Hubble Space Telescope, Very Large Array, and Atacama Large Millimetre Array. We interpret the observations under a model in which a powerful rapidly-accreting central engine blows a fast (~0.15c) wind into the surrounding medium and irradiates it with X-rays. The high Doppler velocities and intense ionization within this wind prevent any identifiable features from appearing in the ejecta or in the surrounding circumstellar material, even in the far-ultraviolet. Weak H and He signatures do emerge in the spectra after 35 days in the form of double-peaked narrow lines. Each peak is individually narrow (full width ~3000 km/s) but the two components are separated by ~6600 km/s, indicating stable structures of denser material, possibly representing streams of tidal ejecta or an ablated companion star. △ Less

Submitted 6 January, 2026; originally announced January 2026.

Comments: Submitted to MNRAS

Collective Hard Core Interactions Leave Multiscale Signatures in Number Fluctuation Spectra

Authors: Eleanor K. R. Mackay, Anna Drummond Young, Adam Carter, Sophie Marbach, Alice L. Thorneywork

Abstract: A full understanding of transport in dense, interacting suspensions requires analysis frameworks sensitive to self and collective dynamics across all relevant spatial and temporal scales. Here we introduce a trajectory-free approach to address this problem based on the power spectral density of particle number fluctuations (N-PSD). By combining colloidal experiments and theory we show that the N-P… ▽ More A full understanding of transport in dense, interacting suspensions requires analysis frameworks sensitive to self and collective dynamics across all relevant spatial and temporal scales. Here we introduce a trajectory-free approach to address this problem based on the power spectral density of particle number fluctuations (N-PSD). By combining colloidal experiments and theory we show that the N-PSD naturally probes behaviour across multiple important dynamic regimes and we fully uncover the mechanistic origins of characteristic spectral scalings and timescales. In particular, we demonstrate that while high-frequency scalings link to self-diffusion, low-frequency scalings sensitively capture long-lived correlations and collective dynamics. In this regime, interactions lead to non-trivial spectral signatures, governed by pairwise particle exchange at small length scales and collective rearrangements over large scales. Our findings thus provide important insight into the effect of interactions on microscopic dynamics and fluctuation phenomena and establish a powerful new tool with which to probe dynamics in complex systems. △ Less

Submitted 19 December, 2025; originally announced December 2025.

Improving the electromagnetic form factor of the pion at large $Q^2$ using the Feynman-Hellmann theorem

Authors: K. U. Can, J. A. Crawford, R. Horsley, J. J. McKee, P. E. L. Rakow, I. van Schalkwyk, G. Schierholz, H. Stüben, R. D. Young, J. M. Zanotti

Abstract: At large momentum transfer, it becomes increasingly difficult to access the form factor of the pion $F_π(Q^2)$ using lattice QCD simulations. Two of the limiting factors include the increased computational cost of adding more statistics to overcome gauge noise, as well as suppressed overlap with the ground state of the boosted pion. Here we apply two noise reduction techniques, all-mode averaging… ▽ More At large momentum transfer, it becomes increasingly difficult to access the form factor of the pion $F_π(Q^2)$ using lattice QCD simulations. Two of the limiting factors include the increased computational cost of adding more statistics to overcome gauge noise, as well as suppressed overlap with the ground state of the boosted pion. Here we apply two noise reduction techniques, all-mode averaging (AMA) and momentum smearing, to the computation of $F_π(Q^2)$ at high momentum transfers using the Feynman-Hellmann (FH) theorem. First, we show that all-mode averaging by itself produces good improvement compared to previous results, at an equal computational cost. We also implement a momentum smearing technique to further reduce statistical uncertainties. In contrast to conventional smearing approaches, our Feynman-Hellmann method requires combining back-to-back momentum states, and hence we adapt a version of smearing involving a superposition of back-to-back smearing operations. This method is then implemented to compute $F_π(Q^2)$ at $Q^2 = 6.6 \;\mathrm{GeV^2}$, demonstrating good improvement over the regular smeared counterpart. Finally both all-mode averaging and momentum smearing are combined to determine $F_π(Q^2)$ at $Q^2 = 6.6 \;\mathrm{GeV^2}$ showing an excellent preliminary improvement over previous calculations. △ Less

Submitted 15 December, 2025; originally announced December 2025.

Comments: 17 pages, 7 figures. Contribution to the the XVIth Quark Confinement and the Hadron Spectrum Conference (QCHSC24) 19-24 August, 2024 Cairns Convention Centre, Cairns, Queensland, Australia

Report number: ADP-25-31/T1293, LTH1412

Journal ref: PoS QCHSC24 (2025) 082

MALLORN: Many Artificial LSST Lightcurves based on Observations of Real Nuclear transients

Authors: Dylan Magill, Matt Nicholl, Vysakh Anilkumar, Sjoert van Velzen, Xinyue Sheng, Thai Son Mai, Hung Viet Tran, Ngoc Phu Doan, Thomas Moore, Shubham Srivastav, David R. Young, Charlotte R. Angus, Joshua Weston

Abstract: The Vera C. Rubin Observatory's 10-Year Legacy Survey of Space and Time (LSST) is expected to produce a hundredfold increase in the number of transients we observe. However, there are insufficient spectroscopic resources to follow up on all of the wealth of targets that LSST will provide. As such it is necessary to be able to prioritise objects for followup observations or inclusion in sample stud… ▽ More The Vera C. Rubin Observatory's 10-Year Legacy Survey of Space and Time (LSST) is expected to produce a hundredfold increase in the number of transients we observe. However, there are insufficient spectroscopic resources to follow up on all of the wealth of targets that LSST will provide. As such it is necessary to be able to prioritise objects for followup observations or inclusion in sample studies based purely on their LSST photometry. We are particularly keen to identify tidal disruption events (TDEs) with LSST. TDEs are immensely useful for determining black hole parameters and probing our understanding of accretion physics. To assist in these efforts, we present the Many Artificial LSST Lightcurves based on the Observations of Real Nuclear transients (MALLORN) data set and the corresponding classifier challenge for identifying TDEs. MALLORN comprises 10178 simulated LSST light curves, constructed from real Zwicky Transient Facility (ZTF) observations of 64 TDEs, 727 nuclear supernovae and 1407 AGN with spectroscopic labels using Gaussian process fitting, empirically-motivated spectral energy distributions from SNCosmo and the baseline from the Rubin Survey Simulator. Our novel approach can be easily adapted to simulate transients for any photometric survey using observations from another, requiring only the limiting magnitudes and an estimate of the cadence of observations. The MALLORN Astronomical Classification Challenge, launched on Kaggle on 15/10/2025, will allow competitors to test their photometric classifiers on simulated LSST data to find TDEs and improve upon their capabilities prior to the start of LSST. △ Less

Submitted 4 December, 2025; originally announced December 2025.

Identifying Transient Hosts in LSST's Deep Drilling Fields with Galaxy Catalogues

Authors: Josh G. Weston, David R. Young, Stephen J. Smartt, Matt Nicholl, Matt J. Jarvis, I. H. Whittam

Abstract: The upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will enable astronomers to discover rare and distant astrophysical transients. Host-galaxy association is crucial for selecting the most scientifically interesting transients for follow-up. LSST Deep Drilling Field observations will detect distant transients occurring in galaxies below the detection limits of most all-sk… ▽ More The upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will enable astronomers to discover rare and distant astrophysical transients. Host-galaxy association is crucial for selecting the most scientifically interesting transients for follow-up. LSST Deep Drilling Field observations will detect distant transients occurring in galaxies below the detection limits of most all-sky catalogues. Here we investigate the use of pre-existing smaller-scale, field-specific catalogues for host identification in the Deep Drilling Fields (DDFs) and a ranking of their usefulness. We have compiled a database of 70 deep catalogues that overlap with the Rubin DDFs and constructed thin catalogues to be homogenised and combined for transient-host matching. A systematic ranking of their utility is discussed and applied based on the inclusion of information such as spectroscopic redshifts and morphological information. Utilising this data against a Dark Energy Survey (DES) sample of supernovae with pre-identified hosts in the XMM-LSS and ECDFS fields, we evaluate different methods for transient-host association in terms of both accuracy and processing speed. We also apply light data-cleaning techniques to identify and remove contaminants within our associations, such as diffraction spikes and blended galaxies where the correct host cannot be determined with confidence. We use a lightweight machine learning approach in the form of extreme gradient boosting to generate confidence scores in our contaminant selections and associated metrics. Finally, we discuss the computational expense of implementation within the LSST transient alert brokers, which will require efficient, fast-paced processing to handle the large stream of survey data. △ Less

Submitted 27 November, 2025; originally announced November 2025.

Comments: Submitted to ApJ

Experiments reveal extreme water generation during planet formation

Authors: Francesca Miozzi, Anat Shahar, Edward D. Young, Jianhua Wang, Andrew Steele, Stephan Borensztajn, Suzy M. Vitale, Emma S. Bullock, Nicolas Wehr, James Badro

Abstract: The most abundant type of planet discovered in the Galaxy has no analogue in our Solar System and is believed to consist of a rocky interior with an overlying thick H2 dominated envelope. Models have predicted that the reaction between the atmospheric hydrogen and the underlying magma ocean can lead to the production of significant amounts of water. The models suffer however from the current lack… ▽ More The most abundant type of planet discovered in the Galaxy has no analogue in our Solar System and is believed to consist of a rocky interior with an overlying thick H2 dominated envelope. Models have predicted that the reaction between the atmospheric hydrogen and the underlying magma ocean can lead to the production of significant amounts of water. The models suffer however from the current lack of experimental data on the reaction between hydrogen and silicate melt at high pressures and temperatures. Here we present novel experimental results designed to investigate this interaction. Laser heating diamond anvil cell experiments were conducted between 16 and 60 GPa at temperatures above 4000 K. We find that copious amounts of hydrogen dissolve into the silicate melt with a large dependence on temperature rather than pressure. We also find that the reduction of iron oxide leads to the production of significant amounts of water along with the formation of iron-enriched blebs. Altogether, the results predict that the typical processes attending planet formation will result in significant water production with repercussions for the chemistry and structure of the planetary interior as well as the atmosphere. △ Less

Submitted 3 November, 2025; originally announced November 2025.

Comments: 3 main figures, 9 additional figures. This is the author-accepted version of a paper published in Nature (Accelerated Article Preview, 30th October 2025)

Subspace Ordering for Maximum Response Preservation in Sufficient Dimension Reduction

Authors: Derik T. Boonstra, Rakheon Kim, Dean M. Young

Abstract: Sufficient dimension reduction (SDR) methods aim to identify a dimension reduction subspace (DRS) that preserves all the information about the conditional distribution of a response given its predictor. Traditional SDR methods determine the DRS by solving a method-specific generalized eigenvalue problem and selecting the eigenvectors corresponding to the largest eigenvalues. In this article, we ar… ▽ More Sufficient dimension reduction (SDR) methods aim to identify a dimension reduction subspace (DRS) that preserves all the information about the conditional distribution of a response given its predictor. Traditional SDR methods determine the DRS by solving a method-specific generalized eigenvalue problem and selecting the eigenvectors corresponding to the largest eigenvalues. In this article, we argue against the long-standing convention of using eigenvalues as the measure of subspace importance and propose alternative ordering criteria that directly assess the predictive relevance of each subspace. For a binary response, we introduce a subspace ordering criterion based on the absolute value of the independent Student's T-statistic. Theoretically, our criterion identifies subspaces that achieve the local minimum Bayes' error rate and yields consistent ordering of directions under mild regularity conditions. Additionally, we employ an F-statistic to provide a framework that unifies categorical and continuous responses under a single subspace criterion. We evaluate our proposed criteria within multiple SDR methods through extensive simulation studies and applications to real data. Our empirical results demonstrate the efficacy of reordering subspaces using our proposed criteria, which generally improves classification accuracy and subspace estimation compared to ordering by eigenvalues. △ Less

Submitted 24 November, 2025; v1 submitted 31 October, 2025; originally announced October 2025.

Low-N Protein Activity Optimization with FolDE

Authors: Jacob B. Roberts, Catherine R. Ji, Isaac Donnell, Thomas D. Young, Allison N. Pearson, Graham A. Hudson, Leah S. Keiser, Mia Wesselkamper, Peter H. Winegar, Janik Ludwig, Sarah H. Klass, Isha V. Sheth, Ezechinyere C. Ukabiala, Maria C. T. Astolfi, Benjamin Eysenbach, Jay D. Keasling

Abstract: Proteins are traditionally optimized through the costly construction and measurement of many mutants. Active Learning-assisted Directed Evolution (ALDE) alleviates that cost by predicting the best improvements and iteratively testing mutants to inform predictions. However, existing ALDE methods face a critical limitation: selecting the highest-predicted mutants in each round yields homogeneous tra… ▽ More Proteins are traditionally optimized through the costly construction and measurement of many mutants. Active Learning-assisted Directed Evolution (ALDE) alleviates that cost by predicting the best improvements and iteratively testing mutants to inform predictions. However, existing ALDE methods face a critical limitation: selecting the highest-predicted mutants in each round yields homogeneous training data insufficient for accurate prediction models in subsequent rounds. Here we present FolDE, an ALDE method designed to maximize end-of-campaign success. In simulations across 20 protein targets, FolDE discovers 23% more top 10% mutants than the best baseline ALDE method (p=0.005) and is 55% more likely to find top 1% mutants. FolDE achieves this primarily through naturalness-based warm-starting, which augments limited activity measurements with protein language model outputs to improve activity prediction. We also introduce a constant-liar batch selector, which improves batch diversity; this is important in multi-mutation campaigns but had limited effect in our benchmarks. The complete workflow is freely available as open-source software, making efficient protein optimization accessible to any laboratory. △ Less

Submitted 28 October, 2025; originally announced October 2025.

Comments: 18 pages, 4 figures. Preprint. Open-source software available at https://github.com/JBEI/foldy

Joint Score-Threshold Optimization for Interpretable Risk Assessment

Authors: Fardin Gankhanloo, Emmett Springer, Erik H. Hoyer, Daniel L. Young, Kimia Ghobadi

Abstract: Risk assessment tools in healthcare commonly employ point-based scoring systems that map patients to ordinal risk categories via thresholds. While electronic health record (EHR) data presents opportunities for data-driven optimization of these tools, two fundamental challenges impede standard supervised learning: (1) labels are often available only for extreme risk categories due to intervention-c… ▽ More Risk assessment tools in healthcare commonly employ point-based scoring systems that map patients to ordinal risk categories via thresholds. While electronic health record (EHR) data presents opportunities for data-driven optimization of these tools, two fundamental challenges impede standard supervised learning: (1) labels are often available only for extreme risk categories due to intervention-censored outcomes, and (2) misclassification cost is asymmetric and increases with ordinal distance. We propose a mixed-integer programming (MIP) framework that jointly optimizes scoring weights and category thresholds in the face of these challenges. Our approach prevents label-scarce category collapse via threshold constraints, and utilizes an asymmetric, distance-aware objective. The MIP framework supports governance constraints, including sign restrictions, sparsity, and minimal modifications to incumbent tools, ensuring practical deployability in clinical workflows. We further develop a continuous relaxation of the MIP problem to provide warm-start solutions for more efficient MIP optimization. We apply the proposed score optimization framework to a case study of inpatient falls risk assessment using the Johns Hopkins Fall Risk Assessment Tool. △ Less

Submitted 20 January, 2026; v1 submitted 24 October, 2025; originally announced October 2025.

Smule Renaissance Small: Efficient General-Purpose Vocal Restoration

Authors: Yongyi Zang, Chris Manchester, David Young, Ivan Ivanov, Jeffrey Lufkin, Martin Vladimirov, PJ Solomon, Svetoslav Kepchelev, Fei Yueh Chen, Dongting Cai, Teodor Naydenov, Randal Leistikow

Abstract: Vocal recordings on consumer devices commonly suffer from multiple concurrent degradations: noise, reverberation, band-limiting, and clipping. We present Smule Renaissance Small (SRS), a compact single-stage model that performs end-to-end vocal restoration directly in the complex STFT domain. By incorporating phase-aware losses, SRS enables large analysis windows for improved frequency resolution… ▽ More Vocal recordings on consumer devices commonly suffer from multiple concurrent degradations: noise, reverberation, band-limiting, and clipping. We present Smule Renaissance Small (SRS), a compact single-stage model that performs end-to-end vocal restoration directly in the complex STFT domain. By incorporating phase-aware losses, SRS enables large analysis windows for improved frequency resolution while achieving 10.5x real-time inference on iPhone 12 CPU at 48 kHz. On the DNS 5 Challenge blind set, despite no speech training, SRS outperforms a strong GAN baseline and closely matches a computationally expensive flow-matching system. To enable evaluation under realistic multi-degradation scenarios, we introduce the Extreme Degradation Bench (EDB): 87 singing and speech recordings captured under severe acoustic conditions. On EDB, SRS surpasses all open-source baselines on singing and matches commercial systems, while remaining competitive on speech despite no speech-specific training. We release both SRS and EDB under the MIT License. △ Less

Submitted 24 October, 2025; originally announced October 2025.

Comments: Technical Report

An interpretable data-driven approach to optimizing clinical fall risk assessment

Authors: Fardin Ganjkhanloo, Emmett Springer, Erik H. Hoyer, Daniel L. Young, Kimia Ghobadi

Abstract: In this study we aim to better align fall risk prediction from the Johns Hopkins Fall Risk Assessment Tool (JHFRAT) with additional clinically meaningful measures via a data-driven modelling approach. We conducted a retrospective analysis of 54,209 inpatient admissions from three Johns Hopkins Health System hospitals between March 2022 and October 2023. A total of 20,208 admissions were included a… ▽ More In this study we aim to better align fall risk prediction from the Johns Hopkins Fall Risk Assessment Tool (JHFRAT) with additional clinically meaningful measures via a data-driven modelling approach. We conducted a retrospective analysis of 54,209 inpatient admissions from three Johns Hopkins Health System hospitals between March 2022 and October 2023. A total of 20,208 admissions were included as high fall risk encounters, and 13,941 were included as low fall risk encounters. To incorporate clinical knowledge and maintain interpretability, we employed constrained score optimization (CSO) models on JHFRAT assessment data and additional electronic health record (EHR) variables. The model demonstrated significant improvements in predictive performance over the current JHFRAT (CSO AUC-ROC=0.91, JHFRAT AUC-ROC=0.86). The constrained score optimization models performed similarly with and without the EHR variables. Although the benchmark black-box model (XGBoost), improves upon the performance metrics of the knowledge-based constrained logistic regression (AUC-ROC=0.94), the CSO demonstrates more robustness to variations in risk labelling. This evidence-based approach provides a robust foundation for health systems to systematically enhance inpatient fall prevention protocols and patient safety using data-driven optimization techniques, contributing to improved risk assessment and resource allocation in healthcare settings. △ Less

Submitted 5 February, 2026; v1 submitted 23 October, 2025; originally announced October 2025.

Magma ocean interactions can explain JWST observations of the sub-Neptune TOI-270 d

Authors: Matthew C. Nixon, R. Sander Somers, Arjun B. Savel, Jegug Ih, Eliza M. -R. Kempton, Edward D. Young, Hilke E. Schlichting, Tim Lichtenberg, Luis Welbanks, William Misener, Anjali A. A. Piette, Nicholas F. Wogan

Abstract: Sub-Neptunes with substantial atmospheres may possess magma oceans in contact with the overlying gas, with chemical interactions between the atmosphere and magma playing an important role in shaping atmospheric composition. Early JWST observations have found high abundances of carbon- and oxygen-bearing molecules in a number of sub-Neptune atmospheres, which may result from processes including acc… ▽ More Sub-Neptunes with substantial atmospheres may possess magma oceans in contact with the overlying gas, with chemical interactions between the atmosphere and magma playing an important role in shaping atmospheric composition. Early JWST observations have found high abundances of carbon- and oxygen-bearing molecules in a number of sub-Neptune atmospheres, which may result from processes including accretion of icy material at formation or magma-atmosphere interactions. Previous work examining the effects of magma-atmosphere interactions on sub-Neptunes has mostly been limited to studying conditions at the atmosphere-mantle boundary, without considering implications for the upper atmosphere which is probed by spectroscopic observations. In this work, we present a modeling architecture to determine observable signatures of magma-atmosphere interactions. We combine an equilibrium chemistry code which models reactions between the core, mantle and atmosphere with a radiative-convective model that determines the composition and structure of the observable upper atmosphere. We examine how different conditions at the atmosphere-mantle boundary and different core and mantle compositions impact the upper atmospheric composition. We compare our models to JWST NIRISS+NIRSpec observations of the sub-Neptune TOI-270~d, finding that our models can provide a good fit to the observed transmission spectrum with little fine-tuning. This suggests that magma-atmosphere interactions may be sufficient to explain high abundances of molecules such as H$_2$O, CH$_4$ and CO$_2$ in sub-Neptune atmospheres, without additional accretion of icy material from the protoplanetary disk. Although other processes could lead to similar compositions, our work highlights the need to consider magma-atmosphere interactions when interpreting the observed atmospheric composition of a sub-Neptune. △ Less

Submitted 24 February, 2026; v1 submitted 8 October, 2025; originally announced October 2025.

Comments: 19 pages, 8 figures. Updated to reflect published version in ApJ

Journal ref: The Astrophysical Journal, Volume 995, Issue 1, id.95, 2025

Pan-STARRS follow-up of the gravitational-wave event S250818k and the lightcurve of SN 2025ulz

Authors: J. H. Gillanders, M. E. Huber, M. Nicholl, S. J. Smartt, K. W. Smith, K. C. Chambers, D. R. Young, J. W. Tweddle, S. Srivastav, M. D. Fulton, F. Stoppa, G. S. H. Paek, A. Aamer, M. R. Alarcon, A. Andersson, A. Aryan, K. Auchettl, T. -W. Chen, T. de Boer, A. K. H. Kong, J. Licandro, T. Lowe, D. Magill, E. A. Magnier, P. Minguez , et al. (8 additional authors not shown)

Abstract: Kilonovae are the scientifically rich, but observationally elusive, optical transient phenomena associated with compact binary mergers. Only a handful of events have been discovered to date, all through multi-wavelength (gamma ray) and multi-messenger (gravitational wave) signals. Given their scarcity, it is important to maximise the discovery possibility of new kilonova events. To this end, we pr… ▽ More Kilonovae are the scientifically rich, but observationally elusive, optical transient phenomena associated with compact binary mergers. Only a handful of events have been discovered to date, all through multi-wavelength (gamma ray) and multi-messenger (gravitational wave) signals. Given their scarcity, it is important to maximise the discovery possibility of new kilonova events. To this end, we present our follow-up observations of the gravitational-wave signal, S250818k, a plausible binary neutron star merger at a distance of $237 \pm 62$ Mpc. Pan-STARRS tiled 286 and 318 square degrees (32% and 34% of the 90% sky localisation region) within 3 and 7 days of the GW signal, respectively. ATLAS covered 65% of the skymap within 3 days, but with lower sensitivity. These observations uncovered 47 new transients; however, none were deemed to be linked to S250818k. We undertook an expansive follow-up campaign of AT 2025ulz, the purported counterpart to S250818k. The griz-band lightcurve, combined with our redshift measurement ($z = 0.0849 \pm 0.0003$) all indicate that SN 2025ulz is a SN IIb, and thus not the counterpart to S250818k. We rule out the presence of a AT 2017gfo-like kilonova within $\approx 27$% of the distance posterior sampled by our Pan-STARRS pointings ($\approx 9.1$% across the total 90% three-dimensional sky localisation). We demonstrate that early observations are optimal for probing the distance posterior of the three-dimensional gravitational-wave skymap, and that SN 2025ulz was a plausible kilonova candidate for $\lesssim 5$ days, before ultimately being ruled out. △ Less

Submitted 18 November, 2025; v1 submitted 1 October, 2025; originally announced October 2025.

Comments: Updated to match the version accepted for publication in ApJL. Contains 24 pages, 8 figures and 2 tables

Redefining interiors and envelopes: hydrogen-silicate miscibility and its consequences for the structure and evolution of sub-Neptunes

Authors: James G. Rogers, Edward D. Young, Hilke E. Schlichting

Abstract: We present the first evolving interior structure model for sub-Neptunes that accounts for the miscibility between silicate magma and hydrogen. Silicate and hydrogen are miscible above $\sim 4000$K at pressures relevant to sub-Neptune interiors. Using the H$_2$-MgSiO$_3$ phase diagram, we self-consistently couple physics and chemistry to determine the radial extent of the fully miscible interior. A… ▽ More We present the first evolving interior structure model for sub-Neptunes that accounts for the miscibility between silicate magma and hydrogen. Silicate and hydrogen are miscible above $\sim 4000$K at pressures relevant to sub-Neptune interiors. Using the H$_2$-MgSiO$_3$ phase diagram, we self-consistently couple physics and chemistry to determine the radial extent of the fully miscible interior. Above this region lies the envelope, where hydrogen and silicates are immiscible and exist in both gaseous and melt phases. The binodal surface, representing a phase transition, provides a physically/chemically informed boundary between a planet's "interior" and "envelope". We find that young sub-Neptunes can store several tens of per cent of their hydrogen mass within their interiors. As the planet cools, its radius and the binodal surface contract, and the temperature at the binodal drops from $\sim 4000$K to $\sim 3000$K. Since the planet's interior stores hydrogen, its density is lower than that of pure-silicate. Gravitational contraction and thermal evolution lead to hydrogen exsolving from the interior into the envelope. This process slows planetary contraction compared to models without miscibility, potentially producing observable signatures in young sub-Neptune populations. At early times ($\sim 10$-$100$Myr), the high temperature at the binodal surface results in more silicate vapour in the envelope, increasing its mean molecular weight and enabling convection inhibition. After $\sim$Gyr of evolution, most hydrogen has exsolved, and the radii of miscible and immiscible models converge. However, the internal distribution of hydrogen and silicates remains distinct, with some hydrogen retained in the interior. △ Less

Submitted 16 September, 2025; originally announced September 2025.

Comments: 17 pages, 11 figures, resubmitted to MNRAS after revision

Journal ref: Mon Not R Astron Soc (2025) 3496-3511

Long-term evolution of the SN 2009ip-like transient SN 2016cvk

Authors: K. Matilainen, E. Kankare, S. Mattila, A. Reguitti, G. Pignata, J. Brimacombe, A. Pastorello, M. Fraser, S. J. Brennan, J. P. Anderson, B. Ayala-Inostroza, R. Cartier, P. Charalampopoulos, T. -W. Chen, M. Gromadzki, C. P. Gutierrez, C. Inserra, T. E. Müller-Bravo, M. Nicholl, J. L. Prieto, F. Ragosta, T. M. Reynolds, I. Salmaso, D. R. Young

Abstract: The interacting transient SN 2016cvk (ASASSN-16jt) is a member of the peculiar SN 2009ip-like events. We present our follow-up data and aim to draw conclusions about the physical nature of the progenitor system. Our spectrophotometric data set of SN 2016cvk covers the ultraviolet, optical, and near-infrared wavelength region extending to +1681 d from the light curve peak; the data is analysed and… ▽ More The interacting transient SN 2016cvk (ASASSN-16jt) is a member of the peculiar SN 2009ip-like events. We present our follow-up data and aim to draw conclusions about the physical nature of the progenitor system. Our spectrophotometric data set of SN 2016cvk covers the ultraviolet, optical, and near-infrared wavelength region extending to +1681 d from the light curve peak; the data is analysed and compared to other SN 2009ip-like transients. Archival data reveals pre-outbursts of the progenitor with the first detection at -1219 d. The light curve evolution of SN 2016cvk consists of two consecutive luminous events A and B with peak magnitudes of M_V < -15.6 and M_r = -18.3 mag, respectively. The spectra are dominated by Balmer emission lines that have a complex, multi-component evolution similar to other SN 2009ip-like targets. SN 2016cvk is among the first detected SN 2009ip-like events that show early `flash ionisation' features of C III, N III, and He II, lasting for 16 +/- 5 d. Our late-time +405 d spectrum shows forbidden [Ca II], [Fe II], and [O I] features with the latter detected particularly clearly for a SN 2009ip-like event. The evolution of SN 2016cvk is similar to other SN 2009ip-like transients, with some uncommon traits. The lack of a double-peaked structure in the Balmer lines is likely caused by differences in the circumstellar medium structure or viewing angle. The flash features in the early spectra propose abundances consistent with a red, yellow, or blue supergiant progenitor rather than for example a luminous blue variable. The detection of [O I] in the +405 d spectrum suggests possible evidence of nucleosynthesised material generated in a SN explosion. △ Less

Submitted 2 September, 2025; originally announced September 2025.

Comments: 25 pages, accepted for publication in A&A

Do White Dwarfs Sample Water-Rich Planetary Material?

Authors: Isabella L. Trierweiler, Carl Melis, Érika Le Bourdais, Patrick Dufour, Alycia J. Weinberger, Boris T. Gänsicke, Nicola Gentile-Fusillo, Siyi Xu, Jay Farihi, Andrew Swan, Malena Rice, Edward D. Young

Abstract: Polluted white dwarfs offer a unique way to directly probe the compositions of exoplanetary bodies. We examine the water content of accreted material using the oxygen abundances of 51 highly polluted white dwarfs. Within this sample, we present new abundances for three H-dominated atmosphere white dwarfs that showed promise for accreting water-rich material. Throughout, we explore the impact of th… ▽ More Polluted white dwarfs offer a unique way to directly probe the compositions of exoplanetary bodies. We examine the water content of accreted material using the oxygen abundances of 51 highly polluted white dwarfs. Within this sample, we present new abundances for three H-dominated atmosphere white dwarfs that showed promise for accreting water-rich material. Throughout, we explore the impact of the observed phase and lifetime of accretion disks on the inferred elemental abundances of the parent bodies that pollute each white dwarf. Our results indicate that white dwarfs sample a range of dry to water-rich material, with median uncertainties in water mass fractions of $\approx$15\%. Amongst the He-dominated white dwarfs, 35/39 water abundances are consistent with corresponding H abundances. While for any individual white dwarf it may be ambiguous as to whether or not water is present in the accreted parent body, when considered as a population the prevalence of water-rich bodies is statistically robust. The population as a whole has a median water mass fraction of $\approx$25\%, and enforcing chondritic parent body compositions, we find that 31/51 WDs are likely to have non-zero water concentrations. This conclusion is different from a similar previous analysis of white dwarf pollution and we discuss reasons why this might be the case. Pollution in H-dominated white dwarfs continues to be more water-poor than in their He-dominated cousins, although the sample size of H-dominated white dwarfs remains small and the two samples still suffer a disjunction in the range of host star temperatures being probed. △ Less

Submitted 27 August, 2025; originally announced August 2025.

Comments: 30 pages, 14 figures Accepted to ApJ

Leveraging Evolutionary Surrogate-Assisted Prescription in Multi-Objective Chlorination Control Systems

Authors: Rivaaj Monsia, Olivier Francon, Daniel Young, Risto Miikkulainen

Abstract: This short, written report introduces the idea of Evolutionary Surrogate-Assisted Prescription (ESP) and presents preliminary results on its potential use in training real-world agents as a part of the 1st AI for Drinking Water Chlorination Challenge at IJCAI-2025. This work was done by a team from Project Resilience, an organization interested in bridging AI to real-world problems. This short, written report introduces the idea of Evolutionary Surrogate-Assisted Prescription (ESP) and presents preliminary results on its potential use in training real-world agents as a part of the 1st AI for Drinking Water Chlorination Challenge at IJCAI-2025. This work was done by a team from Project Resilience, an organization interested in bridging AI to real-world problems. △ Less

Submitted 26 August, 2025; originally announced August 2025.

SN 2021aaev: a Hydrogen-Rich Superluminous Supernova with Early Flash and Long-Lived Circumstellar Interaction in an Unusual Host Environment

Authors: Yang Hu, Ragnhild Lunnan, Priscila J. Pessi, Alberto Saldana-Lopez, Anders Jerkstrand, Jesper Sollerman, Steve Schulze, Joseph P. Anderson, Seán J. Brennan, Stefano P. Cosentino, Anjasha Gangopadhyay, Anamaria Gkini, Mariusz Gromadzki, Matthew J. Hayes, Cosimo Inserra, Tomás E. Müller-Bravo, Matt Nicholl, Giuliano Pignata, Avinash Singh, Jacob L. Wise, Lin Yan, Judy Adler, Ting-Wan Chen, Tracy X. Chen, Mansi M. Kasliwal , et al. (3 additional authors not shown)

Abstract: We present photometric and spectroscopic observations of SN\,2021aaev, a hydrogen-rich, superluminous supernova with persistent (at least $\sim100$ days) narrow Balmer lines (SLSN-IIn) at redshift $z=0.1557$. We observed SN\,2021aaev to rise in $32.5 \pm 1.0$ days since first light and reach a peak absolute magnitude of $-21.46 \pm 0.01$ in the ATLAS $o$ band. The pre-peak spectra resemble those o… ▽ More We present photometric and spectroscopic observations of SN\,2021aaev, a hydrogen-rich, superluminous supernova with persistent (at least $\sim100$ days) narrow Balmer lines (SLSN-IIn) at redshift $z=0.1557$. We observed SN\,2021aaev to rise in $32.5 \pm 1.0$ days since first light and reach a peak absolute magnitude of $-21.46 \pm 0.01$ in the ATLAS $o$ band. The pre-peak spectra resemble those of typical SNe IIn with flash-ionization features arising from the interaction with a dense, confined circumstellar medium (CSM), albeit the flash timescale is longer than usual ($>20$ days). Post peak, the narrow emission lines evolve slowly, and the absence of ejecta features indicates strong deceleration by the CSM. The total radiated energy (about $1.41\times10^{51}$~ergs) is possible with a low-mass (1--$2\,M_{\odot}$) ejecta ploughing into a massive (9--$19\,M_{\odot}$), extended (outer radius $>1\times10^{16}$~cm) H-rich CSM, or alternatively, with magnetar-powered models. Interestingly, the host environment consists of a spiral galaxy with a red substructure in the south-eastern part, and the SN's exact location coincided with the quiescent red substructure (star-formation rate$=0.02^{+0.13}_{-0.02}\,M_{\odot}$~yr$^{-1}$). Given the atypical environment and the obscuring effect of the massive CSM, a thermonuclear (Type Ia-CSM) origin cannot be ruled out. Altogether, SN\,2021aaev is a compelling case to study the diversity of SLSN-IIn features and their host environment. △ Less

Submitted 15 August, 2025; originally announced August 2025.

Comments: Submitted to ApJ

A Roadmap for Climate-Relevant Robotics Research

Authors: Alan Papalia, Charles Dawson, Laurentiu L. Anton, Norhan Magdy Bayomi, Bianca Champenois, Jung-Hoon Cho, Levi Cai, Joseph DelPreto, Kristen Edwards, Bilha-Catherine Githinji, Cameron Hickert, Vindula Jayawardana, Matthew Kramer, Shreyaa Raghavan, David Russell, Shide Salimi, Jingnan Shi, Soumya Sudhakar, Yanwei Wang, Shouyi Wang, Luca Carlone, Vijay Kumar, Daniela Rus, John E. Fernandez, Cathy Wu , et al. (3 additional authors not shown)

Abstract: Climate change is one of the defining challenges of the 21st century, and many in the robotics community are looking for ways to contribute. This paper presents a roadmap for climate-relevant robotics research, identifying high-impact opportunities for collaboration between roboticists and experts across climate domains such as energy, the built environment, transportation, industry, land use, and… ▽ More Climate change is one of the defining challenges of the 21st century, and many in the robotics community are looking for ways to contribute. This paper presents a roadmap for climate-relevant robotics research, identifying high-impact opportunities for collaboration between roboticists and experts across climate domains such as energy, the built environment, transportation, industry, land use, and Earth sciences. These applications include problems such as energy systems optimization, construction, precision agriculture, building envelope retrofits, autonomous trucking, and large-scale environmental monitoring. Critically, we include opportunities to apply not only physical robots but also the broader robotics toolkit - including planning, perception, control, and estimation algorithms - to climate-relevant problems. A central goal of this roadmap is to inspire new research directions and collaboration by highlighting specific, actionable problems at the intersection of robotics and climate. This work represents a collaboration between robotics researchers and domain experts in various climate disciplines, and it serves as an invitation to the robotics community to bring their expertise to bear on urgent climate priorities. △ Less

Submitted 17 July, 2025; v1 submitted 15 July, 2025; originally announced July 2025.

Differentiation, the exception not the rule -- Evidence for full miscibility in sub-Neptune interiors

Authors: Edward D. Young, Aaron Werlen, Sarah P. Marcum, Lars Stixrude, Cornelis P. Dullemond

Abstract: We investigate the consequences of non-ideal mixing between silicate, iron metal, and hydrogen for the structures of the cores of sub-Neptunes with implications for super-Earths, warm Neptunes, and ice giants. A method of extrapolating what we know about the miscibility in the three bounding binary systems MgSiO$_3$-H$_2$, MgSiO$_3$-Fe, and Fe-H$_2$ to the ternary composition space is used to dedu… ▽ More We investigate the consequences of non-ideal mixing between silicate, iron metal, and hydrogen for the structures of the cores of sub-Neptunes with implications for super-Earths, warm Neptunes, and ice giants. A method of extrapolating what we know about the miscibility in the three bounding binary systems MgSiO$_3$-H$_2$, MgSiO$_3$-Fe, and Fe-H$_2$ to the ternary composition space is used to deduce the phase equilibria of this system at relevant temperature and pressure conditions. We find that while separate silicate and metal phases can exist at shallow depths, the phases become entirely miscible deeper in the cores, thus altering the density structure of the cores. The assumption that the interiors of large rocky planets, either with extant magma oceans beneath H$_2$-rich envelopes, or evolved from such bodies, are composed of a differentiated metal core overlain by a silicate mantle is inconsistent with our understanding of the phase equilibria of these bodies. △ Less

Submitted 3 October, 2025; v1 submitted 1 July, 2025; originally announced July 2025.

Comments: Paper now in Press in PSJ, updated description of the density effects of Fe

Sub-Neptunes Are Drier Than They Seem: Rethinking the Origins of Water-Rich Worlds

Authors: Aaron Werlen, Caroline Dorn, Remo Burn, Hilke E. Schlichting, Simon L. Grimm, Edward D. Young

Abstract: Recent claims of biosignature gases in sub-Neptune atmospheres have renewed interest in water-rich sub-Neptunes with surface oceans, often referred to as Hycean planets. These planets are hypothesized to form beyond the snow line, accreting large amounts of H$_2$O (>10 wt%) before migrating inward. However, current interior models often neglect chemical equilibration between primordial atmospheres… ▽ More Recent claims of biosignature gases in sub-Neptune atmospheres have renewed interest in water-rich sub-Neptunes with surface oceans, often referred to as Hycean planets. These planets are hypothesized to form beyond the snow line, accreting large amounts of H$_2$O (>10 wt%) before migrating inward. However, current interior models often neglect chemical equilibration between primordial atmospheres and molten interiors. Here, we compute global chemical equilibrium states for a synthetic population of sub-Neptunes with magma oceans. Although many initially accrete 5-30 wt% water, interior-atmosphere interactions destroy most of it, reducing final H$_2$O mass fractions to below 1.5 wt%. As a result, none meet the threshold for Hycean planets. Despite that, we find H$_2$O-dominated atmospheres exclusively on planets that accreted the least ice. These planets form inside the snow line, are depleted in carbon and hydrogen, and develop small envelopes with envelope mass fractions below 1%, dominated by endogenic water. In contrast, planets formed beyond the snow line accrete more volatiles, but their water is largely converted to H$_2$ gas or sequestered into the interior, resulting in low atmospheric H$_2$O mass fractions. Most H$_2$O-rich envelopes are also fully miscible with H$_2$, making a separate water layer unlikely. Our results topple the conventional link between ice accretion and water-rich atmospheres, showing instead that H$_2$O-dominated envelopes emerge through chemical equilibration in hydrogen-poor planets formed inside the snow line. △ Less

Submitted 29 August, 2025; v1 submitted 1 July, 2025; originally announced July 2025.

Comments: Accepted for publication in The Astrophysical Journal Letters

Journal ref: ApJL 991 L16 (2025)

Decoding Noise in Nanofluidic Systems: Adsorption versus Diffusion Signatures in Power Spectra

Authors: Anna Drummond Young, Alice L. Thorneywork, Sophie Marbach

Abstract: Adsorption processes play a fundamental role in molecular transport through nanofluidic systems, but their signatures in measured signals are often hard to distinguish from other processes like diffusion. In this paper, we derive an expression for the power spectral density (PSD) of particle number fluctuations in a channel, accounting for diffusion and adsorption/desorption to a wall. Our model,… ▽ More Adsorption processes play a fundamental role in molecular transport through nanofluidic systems, but their signatures in measured signals are often hard to distinguish from other processes like diffusion. In this paper, we derive an expression for the power spectral density (PSD) of particle number fluctuations in a channel, accounting for diffusion and adsorption/desorption to a wall. Our model, validated by Brownian dynamics simulations, is set in a minimal but adaptable geometry, allowing us to eliminate the effects of specific geometries. We identify distinct signatures in the PSD as a function of frequency $f$, including a $1/f^{3/2}$ scaling related to diffusive entrance/exit effects, and a $1/f^2$ scaling associated with adsorption. These scalings appear in key predicted quantities -- the total number of particles in the channel and the number of adsorbed or unadsorbed particles -- and can dominate or combine in non-trivial ways depending on parameter values. Notably, when there is a separation of timescales between diffusion inside the channel and adsorption/desorption times, the PSD can exhibit two distinct corners with well-separated slopes in some of the predicted quantities. We provide a strategy to identify adsorption and diffusion mechanisms in the shape of the PSD of experimental systems on the nano- and micro-scale, such as ion channels, nanopores, and electrochemical sensors, potentially offering insights into noisy experimental data. △ Less

Submitted 6 November, 2025; v1 submitted 30 June, 2025; originally announced June 2025.

Comments: The following article has been submitted to the Journal of Chemical Physics

Precision Matrix Regularization in Sufficient Dimension Reduction for Improved Quadratic Discriminant Classification

Authors: Derik T. Boonstra, Rakheon Kim, Dean M. Young

Abstract: Sufficient dimension reduction (SDR) methods, which often rely on class precision matrices, are widely used in supervised statistical classification problems. However, when class-specific sample sizes are small relative to the original feature-space dimension, precision matrix estimation becomes unstable and, as a result, increases the variability of the linear dimension reduction (LDR) matrix. Ul… ▽ More Sufficient dimension reduction (SDR) methods, which often rely on class precision matrices, are widely used in supervised statistical classification problems. However, when class-specific sample sizes are small relative to the original feature-space dimension, precision matrix estimation becomes unstable and, as a result, increases the variability of the linear dimension reduction (LDR) matrix. Ultimately, this fact causes suboptimal supervised classification. To address this problem, we develop a multiclass and distribution-free SDR method, stabilized SDR (SSDR), that employs user-specified precision matrix shrinkage estimators to stabilize the LDR projection matrix and supervised classifier. We establish this technique with the theoretical guarantee of preserving all classification information under the quadratic discriminant analysis (QDA) decision rule. We evaluate multiple precision matrix shrinkage estimators within our proposed SSDR framework through Monte Carlo simulations and applications to real datasets. Our empirical results demonstrate the efficacy of the SSDR method, which generally improves classification accuracy and frequently outperforms several well-established competing SDR methods. △ Less

Submitted 23 June, 2025; originally announced June 2025.

The ATLAS Virtual Research Assistant

Authors: H. F. Stevance, K. W. Smith, S. J. Smartt, S. J. Roberts, N. Erasmus, D. R. Young, A. Clocchiatti

Abstract: We present the Virtual Research Assistant (VRA) of the ATLAS sky survey which performs preliminary eyeballing on our clean transient data stream. The VRA uses Histogram Based Gradient Boosted Decision Tree Classifiers trained on real data to score incoming alerts on two axes: "Real" and "Galactic". The alerts are then ranked using a geometric distance such that the most "Real" and "Extra-galactic"… ▽ More We present the Virtual Research Assistant (VRA) of the ATLAS sky survey which performs preliminary eyeballing on our clean transient data stream. The VRA uses Histogram Based Gradient Boosted Decision Tree Classifiers trained on real data to score incoming alerts on two axes: "Real" and "Galactic". The alerts are then ranked using a geometric distance such that the most "Real" and "Extra-galactic" receive high scores; the scores are updated when new light curve data is obtained on subsequent visits. To assess the quality of the training we use the Recall at rank K, which is more informative to our science goal than general metrics such as accuracy or F1-Scores. We also establish benchmarks for our metric based on the pre-VRA eyeballing strategy, to ensure our models provide notable improvements before being added to the ATLAS pipeline. Finally, policies are defined on the ranked list to select the most promising alerts for humans to eyeball and to automatically remove the bogus alerts. In production the VRA method has resulted in a reduction in eyeballing workload by 85% with a loss of follow-up opportunity <0.08%. It also allows us to automatically trigger follow-up observations with the Lesedi telescope, paving the way to automated methods that will be required in the era of LSST. inally, this is a demonstration that feature-based methods remain extremely relevant in our field, being trainable on only a few thousand samples and highly interpretable; they also offer a direct way to inject expertise into models through feature engineering △ Less

Submitted 8 September, 2025; v1 submitted 11 June, 2025; originally announced June 2025.

Comments: 20 pages, 17 figures, 4 tables (+10 pages Appendices, 8 Figures). Published in ApJ (embargo lifts 10th September)

Journal ref: Astrophysical Journal, Sept. 2025, Volume 990, Issue 2, article 210

Dust production rates in Jupiter-family comets II: Trends and population insights from ATLAS photometry of 116 JFCs

Authors: A. Fraser Gillan, Alan Fitzsimmons, Larry Denneau, Robert J. Siverd, Ken W. Smith, John L. Tonry, David R. Young

Abstract: Jupiter-family comets (JFCs) have orbital periods of less than 20 years and therefore undergo more frequent sublimation compared to other comet populations. The JFCs therefore represent the ideal dynamical population for investigating the dust production rates at high-cadence. We analyzed observations by the Asteroid Terrestrial-impact Last Alert System (ATLAS) of 74 JFCs that reached perihelion i… ▽ More Jupiter-family comets (JFCs) have orbital periods of less than 20 years and therefore undergo more frequent sublimation compared to other comet populations. The JFCs therefore represent the ideal dynamical population for investigating the dust production rates at high-cadence. We analyzed observations by the Asteroid Terrestrial-impact Last Alert System (ATLAS) of 74 JFCs that reached perihelion in 2022 and 2023. The work contained in this study builds upon our previous work (Gillan et al. 2024), for a total of 116 JFCs over a four-year period. Using the Afrho parameter, we measured the dust production rates of each JFC as a function of heliocentric distance. We found that there remained a clear preference for JFCs to reach their maximum A(0)frho post-perihelion, with 170P/Christensen, 254P/McNaught and P/2020 WJ5 (Lemmon) reaching a maximum A(0)frho between 200-400 days after perihelion. However, all JFCs reached their maximum dust production within 10% of their orbital period relative to perihelion. Fitting A(0)fp as a function of Rh^n, we measured statistically significant differences in the distribution of pre-perihelion and post-perihelion activity index n, with average activity indices of -5.2 +/- 4.5 and -3.2 +/- 2.7 respectively. We derived upper limits for the nuclear radii of comets 444P/WISE-PANSTARRS and 459P/Catalina as Rn \leq 1.5 +/- 0.2 km and Rn \leq 1.7 +/- 0.1 km respectively. We measured six outbursts in comets 97P/Metcalf-Brewington, 99P/Kowal 1, 118P/Shoemaker-Levy 4, 285P/LINEAR and 382P/Larson. From our four years of observing JFC outbursts in the ATLAS data, the average increase in magnitude was - 1.3 +/- 0.8. △ Less

Submitted 10 June, 2025; originally announced June 2025.

Comments: Accepted for publication in The Planetary Science Journal (PSJ)

Results from the Pan-STARRS Search for Kilonovae: Contamination by Massive Stellar Outbursts

Authors: M. D. Fulton, S. J. Smartt, M. E. Huber, K. W. Smith, K. C. Chambers, M. Nicholl, S. Srivastav, D. R. Young, E. A. Magnier, C. -C. Lin, P. Minguez, T. de Boer, T. Lowe, R. Wainscoat

Abstract: We present results from the Pan-STARRS optical search for kilonovae without the aid of gravitational wave and gamma-ray burst triggers. The search was conducted from 26 October 2019 to 15 December 2022. During this time, we reported 29,740 transients observed by Pan-STARRS to the IAU Transient Name Server. Of these, 175 were Pan-STARRS credited discoveries that had a host galaxy within 200 Mpc and… ▽ More We present results from the Pan-STARRS optical search for kilonovae without the aid of gravitational wave and gamma-ray burst triggers. The search was conducted from 26 October 2019 to 15 December 2022. During this time, we reported 29,740 transients observed by Pan-STARRS to the IAU Transient Name Server. Of these, 175 were Pan-STARRS credited discoveries that had a host galaxy within 200 Mpc and had discovery absolute magnitudes M > -16.5. A subset of 11 transients was plausibly identified as kilonova candidates by our kilonova prediction algorithm. Through a combination of historical forced photometry, extensive follow-up, and aggregating observations from multiple sky surveys, we eliminated all as kilonova candidates. Rapidly evolving outbursts from massive stars (likely to be Luminous Blue Variable eruptions) accounted for 55% of the subset's contaminating sources. We estimate the rate of such eruptions using the ATLAS 100 Mpc volume-limited survey data. As these outbursts appear to be significant contaminants in kilonova searches, we estimate contaminating numbers when searching gravitational wave skymaps produced by the LIGO-Virgo-Kagra science collaboration during the Rubin era. The Legacy Survey of Space and time, reaching limiting magnitudes of m = 25, could detect 2-6 massive stellar outbursts per 500 deg^2 within a 4-day observing window, within the skymaps and volumes typical for binary neutron star mergers projected for Ligo-Virgo-Kagra Observing run 5. We conclude that while they may be a contaminant, they can be photometrically identified. △ Less

Submitted 8 June, 2025; originally announced June 2025.

Comments: Submitted to MNRAS Journal on 24th May 2025. The supplementary photometry file is proprietary until the Journal's acceptance. 19 pages, 15 figures, 2 tables

Journal ref: Mon Not R Astron Soc (2025) 541-559

Zero-Shot Tree Detection and Segmentation from Aerial Forest Imagery

Authors: Michelle Chen, David Russell, Amritha Pallavoor, Derek Young, Jane Wu

Abstract: Large-scale delineation of individual trees from remote sensing imagery is crucial to the advancement of ecological research, particularly as climate change and other environmental factors rapidly transform forest landscapes across the world. Current RGB tree segmentation methods rely on training specialized machine learning models with labeled tree datasets. While these learning-based approaches… ▽ More Large-scale delineation of individual trees from remote sensing imagery is crucial to the advancement of ecological research, particularly as climate change and other environmental factors rapidly transform forest landscapes across the world. Current RGB tree segmentation methods rely on training specialized machine learning models with labeled tree datasets. While these learning-based approaches can outperform manual data collection when accurate, the existing models still depend on training data that's hard to scale. In this paper, we investigate the efficacy of using a state-of-the-art image segmentation model, Segment Anything Model 2 (SAM2), in a zero-shot manner for individual tree detection and segmentation. We evaluate a pretrained SAM2 model on two tasks in this domain: (1) zero-shot segmentation and (2) zero-shot transfer by using predictions from an existing tree detection model as prompts. Our results suggest that SAM2 not only has impressive generalization capabilities, but also can form a natural synergy with specialized methods trained on in-domain labeled data. We find that applying large pretrained models to problems in remote sensing is a promising avenue for future progress. We make our code available at: https://github.com/open-forest-observatory/tree-detection-framework. △ Less

Submitted 3 June, 2025; originally announced June 2025.

Comments: Code: https://github.com/open-forest-observatory/tree-detection-framework

SN 2024bfu, SN 2025qe, and the early light curves of type Iax supernovae

Authors: M. R. Magee, T. L. Killestein, M. Pursiainen, B. Godson, D. Jarvis, C. Jiménez-Palau, J. D. Lyman, D. Steeghs, B. Warwick, J. P. Anderson, T. Butterley, T. -W. Chen, V. S. Dhillon, L. Galbany, S. González-Gaitán, M. Gromadzki, C. Inserra, L. Kelsey, A. Kumar, G. Leloudas, S. Mattila, S. Moran, T. E. Müller-Bravo, K. Noysena, G. Ramsay , et al. (17 additional authors not shown)

Abstract: Type Iax supernovae (SNe Iax) are one of the most common subclasses of thermonuclear supernova and yet their sample size, particularly those observed shortly after explosion, remains relatively small. In this paper we present photometric and spectroscopic observations of two SNe Iax discovered shortly after explosion, SN 2024bfu and SN 2025qe. Both SNe were observed by multiple all-sky surveys, en… ▽ More Type Iax supernovae (SNe Iax) are one of the most common subclasses of thermonuclear supernova and yet their sample size, particularly those observed shortly after explosion, remains relatively small. In this paper we present photometric and spectroscopic observations of two SNe Iax discovered shortly after explosion, SN 2024bfu and SN 2025qe. Both SNe were observed by multiple all-sky surveys, enabling tight constraints on the moment of first light and the shape of the early light curve. Our observations of SN 2025qe begin <2d after the estimated time of first light and represent some of the earliest observations of any SN Iax. Spectra show features consistent with carbon absorption throughout the evolution of SN 2025qe, potentially indicating the presence of unburned material throughout the ejecta. We gather a sample of SNe Iax observed by ATLAS, GOTO, and ZTF shortly after explosion and measure their rise times and early light curve power-law rise indices. We compare our results to a sample of normal SNe Ia and find indications that SNe Iax show systematically shorter rise times, consistent with previous work. We also find some indication that SNe Iax show systematically lower rise indices than normal SNe Ia. The low rise indices observed among SNe Iax are qualitatively consistent with extended $^{56}$Ni distributions and more thoroughly-mixed ejecta compared to normal SNe Ia, similar to predictions from pure deflagration explosions. △ Less

Submitted 30 September, 2025; v1 submitted 2 June, 2025; originally announced June 2025.

Comments: 26 pages, 4 appendices, 20 figures, 10 tables. Accepted by MNRAS

Journal ref: Mon Not R Astron Soc (2025) 3731-3753

Towards nucleon structure function moments and parton momentum fractions from lattice QCD

Authors: K. U. Can, R. Horsley, P. E. L. Rakow, G. Schierholz, H. Stüben, R. D. Young, J. M. Zanotti

Abstract: We calculate the lowest even isovector moment of the $F_2$ structure function in $2+1$-flavour lattice QCD with varying quark masses corresponding to $m_π\approx [410, 360, 300] \; {\rm MeV}$, at a fixed volume of $V = 48^3 \times 96$ and coupling $β= 5.65$ ($a = 0.068(3) \, {\rm fm}$). We directly compute the physical Compton amplitude using the Feynman-Hellmann approach and extract moments of th… ▽ More We calculate the lowest even isovector moment of the $F_2$ structure function in $2+1$-flavour lattice QCD with varying quark masses corresponding to $m_π\approx [410, 360, 300] \; {\rm MeV}$, at a fixed volume of $V = 48^3 \times 96$ and coupling $β= 5.65$ ($a = 0.068(3) \, {\rm fm}$). We directly compute the physical Compton amplitude using the Feynman-Hellmann approach and extract moments of the physical structure function. We report on the quark-mass dependence of the lowest isovector moment and estimate its value at the physical quark-mass point with $\sim 10\%$ uncertainty at fixed $Q^2$. By analysing the $Q^2$ dependence of the moments at the $SU(3)$ symmetric point ($m_π\approx 410 \; {\rm MeV}$), we separate the leading- and higher-twist contributions and estimate the parton momentum fraction, $\langle x \rangle_{u-d}$, which agrees with existing results. △ Less

Submitted 6 May, 2025; originally announced May 2025.

Comments: 14 pages, 4 figues. Contribution to the the XVIth Quark Confinement and the Hadron Spectrum Conference (QCHSC24) 19-24 August, 2024 Cairns Convention Centre, Cairns, Queensland, Australia

Report number: ADP-25-18/T1280, DESY-25-069, LTH 1400, PoS(QCHSC24)085

Multi-nucleon matrix elements on the lattice with the Feynman-Hellmann theorem

Authors: N. Humphrey, K. U. Can, R. Horsley, P. E. L. Rakow, G. Schierholz, H. Stüben, R. D. Young, J. M. Zanotti

Abstract: This work presents the first calculation of the lowest moment of the forward Compton structure function $\mathcal{F}_2$ for a multi-nucleon deuteron-like state using Feynman-Hellmann lattice QCD techniques. Using this result as a prototypical example, we chart a course for the systematic study of multi-nucleon structure by building on techniques developed to optimise the computation of the factori… ▽ More This work presents the first calculation of the lowest moment of the forward Compton structure function $\mathcal{F}_2$ for a multi-nucleon deuteron-like state using Feynman-Hellmann lattice QCD techniques. Using this result as a prototypical example, we chart a course for the systematic study of multi-nucleon structure by building on techniques developed to optimise the computation of the factorially increasing number of Wick contraction terms required to calculate multi-nucleon matrix elements via lattice QCD. △ Less

Submitted 6 May, 2025; originally announced May 2025.

Comments: The XVIth Quark Confinement and the Hadron Spectrum Conference (QCHSC24)

Report number: ADP-25-17/T1279, DESY-25-070, LTH 1401

The case of AT2022wtn: a Tidal Disruption Event in an interacting galaxy

Authors: F. Onori, M. Nicholl, P. Ramsden, S. McGee, R. Roy, W. Li, I. Arcavi, J. P. Anderson, E. Brocato, M. Bronikowski, S. B. Cenko, K. Chambers, T. W. Chen, P. Clark, E. Concepcion, J. Farah, D. Flammini, S. González-Gaitán, M. Gromadzki, C. P. Gutiérrez, E. Hammerstein, K. R. Hinds, C. Inserra, E. Kankare, A. Kumar , et al. (13 additional authors not shown)

Abstract: We present the results from our multi-wavelength monitoring campaign of the transient AT2022wtn, discovered by the Zwicky Transient Facility in the nucleus of SDSSJ232323.79+104107.7, the less massive galaxy in an active merging pair with a mass ratio of ~10:1. AT2022wtn shows spectroscopic and photometric properties consistent with a X-ray faint N-strong TDE-H+He with a number of peculiarities. S… ▽ More We present the results from our multi-wavelength monitoring campaign of the transient AT2022wtn, discovered by the Zwicky Transient Facility in the nucleus of SDSSJ232323.79+104107.7, the less massive galaxy in an active merging pair with a mass ratio of ~10:1. AT2022wtn shows spectroscopic and photometric properties consistent with a X-ray faint N-strong TDE-H+He with a number of peculiarities. Specifically, a 30-days long plateau at maximum luminosity, a corresponding dip in temperature and the development of a double-horned N III+ He II line profile. Strong and time-evolving velocity offsets in the TDE broad emission lines and the detection of a transient radio emission, indicate the presence of outflows. Overall, the observed properties are consistent with the full disruption of a low-mass star by a ~10$^{6}$ M$_{\odot}$ SMBH followed by an efficient disk formation and the launch of a quasi-spherical reprocessing envelope of fast expanding outflowing material. The observed differences between the He II and the Hydrogen and N III lines can be explained either with a spatial separation of the lines emitting region or with a late-time reveal of shocks from the returning debris streams, as the photosphere recedes. Finally, we present an extensive analysis of the hosting environment and discuss the implications for the discovery of two TDEs in interacting galaxy pairs, finding indication for an over-representation of TDEs in these systems. The AT2022wtn host galaxy properties suggest that it is in the early stages of the merger, therefore we may be witnessing the initial enhanced rate of TDEs in interacting galaxies before the post-starburst phase. △ Less

Submitted 30 April, 2025; originally announced April 2025.

Comments: 23 pages, 16 Figures, accepted for publication in MNRAS

Atmospheric C/O Ratios of Sub-Neptunes with Magma Oceans: Homemade rather than Inherited

Authors: Aaron Werlen, Caroline Dorn, Hilke E. Schlichting, Simon L. Grimm, Edward D. Young

Abstract: Recently, the James Webb Space Telescope has enabled detailed spectroscopic characterization of sub-Neptune atmospheres. With detections of carbon- and oxygen-bearing species such as CO, CO$_2$, CH$_4$, and H$_2$O, a central question is whether the atmospheric C/O ratio, commonly used to trace formation location in giant planets, can serve a similar diagnostic role for sub-Neptunes. We use the glo… ▽ More Recently, the James Webb Space Telescope has enabled detailed spectroscopic characterization of sub-Neptune atmospheres. With detections of carbon- and oxygen-bearing species such as CO, CO$_2$, CH$_4$, and H$_2$O, a central question is whether the atmospheric C/O ratio, commonly used to trace formation location in giant planets, can serve a similar diagnostic role for sub-Neptunes. We use the global chemical equilibrium framework of Schlichting & Young (2022) to quantify how magma ocean-atmosphere interactions affect the atmospheric C/O ratio. We find that the resulting C/O ratios range from several orders of magnitude below solar to a few times solar. The atmospheric C/O ratio in sub-Neptunes is therefore not inherited from the protoplanetary disk, but instead emerges from chemical equilibrium between the atmosphere and the underlying magma ocean. Planetary mass, atmospheric mass fraction, and thermal state all strongly influence the atmospheric C/O ratio. In addition, carbon partitioning into the metal phase typically reduces the atmospheric C/O ratio substantially, particularly for atmospheric mass fractions less than a few percent. Finally, we couple the deep equilibrium compositions to 1D atmospheric models that self-consistently solve for the pressure-temperature structure and chemical composition, including photochemistry. We find that the C/O ratio varies with altitude under low vertical mixing conditions (K$_\text{zz}=10^4$ cm$^2$s$^{-1}$), but remains constant under strong mixing (K$_\text{zz}=10^7$ cm$^2$s$^{-1}$). Our results imply that observed C/O ratios of sub-Neptunes can be used to probe their interiors. Specifically, C/O ratios much lower than host star values would imply an underlying magma ocean with iron metal having sequestered significant amounts of carbon. △ Less

Submitted 17 July, 2025; v1 submitted 29 April, 2025; originally announced April 2025.

Comments: Accepted for publication in The Astrophysical Journal Letters

Journal ref: ApJL 988 L55 (2025)

Relationships between minimum rank problem parameters for cobipartite graphs

Authors: Louis Deaett, Derek Young

Abstract: For a simple graph, the minimum rank problem is to determine the smallest rank among the symmetric matrices whose off-diagonal nonzero entries occur in positions corresponding to the edges of the graph. Bounds on this minimum rank (and on an equivalent value, the maximum nullity) are given by various graph parameters, most notably the zero forcing number and its variants. For a matrix, replacing e… ▽ More For a simple graph, the minimum rank problem is to determine the smallest rank among the symmetric matrices whose off-diagonal nonzero entries occur in positions corresponding to the edges of the graph. Bounds on this minimum rank (and on an equivalent value, the maximum nullity) are given by various graph parameters, most notably the zero forcing number and its variants. For a matrix, replacing each nonzero entry with the symbol \(\ast\) gives its zero-nonzero pattern. The associated minimum rank problem is to determine, given only this pattern, the smallest possible rank of the matrix. The most fundamental lower bound on this minimum rank is the triangle number of the pattern. A cobipartite graph is the complement of a bipartite graph; its vertices can be partitioned into two cliques. Such a graph corresponds to a zero-nonzero pattern in a natural way. Over an infinite field, the minimum rank of the graph and that of the pattern obey a simple relationship. We show that this same relationship is followed by the zero forcing number of the graph and the triangle number of the pattern. This has implications for the relationship between the two minimum rank problems. We also explore how, for cobipartite graphs, variants of the zero forcing number and other parameters important to the minimum rank problem are related, as well as how, for graphs in general, these parameters can be interpreted in terms of the zero-nonzero patterns of the symmetric matrices associated with the graph. △ Less

Submitted 31 October, 2025; v1 submitted 3 April, 2025; originally announced April 2025.

MSC Class: 05C50 (Primary); 15B35 (Secondary)

Observational diversity of bright long-lived Type II supernovae

Authors: T. Nagao, T. M. Reynolds, H. Kuncarayakti, R. Cartier, S. Mattila, K. Maeda, J. Sollerman, P. J. Pessi, J. P. Anderson, C. Inserra, T. -W. Chen, L. Ferrari, M. Fraser, D. R. Young, M. Gromadzki, C. P. Gutiérrez, G. Pignata, T. E. Muller-Bravo, F. Ragosta, A. Reguitti, S. Moran, M. González-Bañuelos, M. Kopsacheili, T. Petrushevska

Abstract: In various types of supernovae (SNe), strong interaction between the SN ejecta and circumstellar material (CSM) has been reported. This raises questions on their progenitors and mass-loss processes shortly before the explosion. Recently, the bright long-lived Type~II SN 2021irp was proposed to be a standard Type II SN interacting with disk-like CSM. The observational properties suggest that the pr… ▽ More In various types of supernovae (SNe), strong interaction between the SN ejecta and circumstellar material (CSM) has been reported. This raises questions on their progenitors and mass-loss processes shortly before the explosion. Recently, the bright long-lived Type~II SN 2021irp was proposed to be a standard Type II SN interacting with disk-like CSM. The observational properties suggest that the progenitor was a massive star in a binary system and underwent a mass-ejection process due to the binary interaction just before the explosion. Here, we study the diversity of the observational properties of bright long-lived Type II (21irp-like) SNe. We analyse the diversity of their CSM properties, in order to understand their progenitors and mass-loss mechanisms and their relations with the other types of interacting SNe. We performed photometry, spectroscopy, and/or polarimetry for four 21irp-like SNe. Based on these observations as well as published data of SN~2021irp itself and well-observed bright and long-lived type II SNe including SNe~2010jl, 2015da and 2017hcc, we discuss their CSM characteristics. This sample of SNe shows luminous and long-lived photometric evolution, with some variations in the photometric evolution (from $\sim-17$ to $\sim-20$ absolute mag in the $r$/$o$ band even at $\sim 200$ days after the explosion). They show photospheric spectra characterized mainly by Balmer lines for several hundreds of days, with some variations in the shapes of the lines. They show high polarization with slight variations in the polarization degrees with rapid declines with time (from $\sim3-6$ \% before the peak to $\sim1$ \% at $\sim200$ days after the peak). The observational properties are consistent with the disk-CSM-interaction scenario, i.e., typical Type~II SNe interacting with disk-like CSM. △ Less

Submitted 2 April, 2025; originally announced April 2025.

Comments: 19 pages, 13 figures, submitted to A&A

Journal ref: A&A 699, A283 (2025)

The Type I Superluminous Supernova Catalogue II: Spectroscopic Evolution in the Photospheric Phase, Velocity Measurements, and Constraints on Diversity

Authors: Aysha Aamer, Matt Nicholl, Sebastian Gomez, Edo Berger, Peter Blanchard, Joseph P. Anderson, Charlotte Angus, Amar Aryan, Chris Ashall, Ting-Wan Chen, Georgios Dimitriadis, Lluis Galbany, Anamaria Gkini, Mariusz Gromadzki, Claudia P. Gutierrez, Daichi Hiramatsu, Griffin Hosseinzadeh, Cosimo Inserra, Amit Kumar, Hanindyo Kuncarayakti, Giorgos Leloudas, Paolo Mazzali, Kyle Medler, Tomás E. Müller-Bravo, Mauricio Ramirez , et al. (7 additional authors not shown)

Abstract: Hydrogen-poor superluminous supernovae (SLSNe) are among the most energetic explosions in the universe, reaching luminosities up to 100 times greater than those of normal supernovae. Detailed spectral analysis hold the potential to reveal their progenitors and underlying energy sources. This paper presents the largest compilation of SLSN photospheric spectra to date, encompassing data from ePESSTO… ▽ More Hydrogen-poor superluminous supernovae (SLSNe) are among the most energetic explosions in the universe, reaching luminosities up to 100 times greater than those of normal supernovae. Detailed spectral analysis hold the potential to reveal their progenitors and underlying energy sources. This paper presents the largest compilation of SLSN photospheric spectra to date, encompassing data from ePESSTO+, the FLEET search and all published spectra up to December 2022. The dataset includes a total of 974 spectra of 234 SLSNe. By constructing average phase binned spectra, we find SLSNe initially exhibit high temperatures (10000 to 11000 K), with blue continua and weak lines. A rapid transformation follows, as temperatures drop to 5000 to 6000 K by 40 days post peak, leading to stronger P-Cygni features. These averages also suggest a fraction of SLSNe may contain some He at explosion. Variance within the dataset is slightly reduced when defining the phase of spectra relative to explosion, rather than peak, and normalising to the population's median e-folding time. Principal Component Analysis (PCA) supports this, requiring fewer components to explain the same level of variation when binning data by scaled days from explosion, suggesting a more homogeneous grouping. Using PCA and K-Means clustering, we identify outlying objects with unusual spectroscopic evolution and evidence for energy input from interaction, but find not support for groupings of two or more statistically significant subpopulations. We find Fe II λ5169 lines velocities closely track the radius implied from blackbody fits, indicating formation near the photosphere. We also confirm a correlation between velocity and velocity gradient, which can be explained if all SLSNe are in homologous expansion but with different scale velocities. This behaviour aligns with expectations for an internal powering mechanism. △ Less

Submitted 1 April, 2025; v1 submitted 27 March, 2025; originally announced March 2025.

Comments: Updated author metadata

Journal ref: Mon Not R Astron Soc (2025) 2674-2706

Terrier: A Deep Learning Repeat Classifier

Authors: Robert Turnbull, Neil D. Young, Edoardo Tescari, Lee F. Skerratt, Tiffany A. Kosch

Abstract: Repetitive DNA sequences underpin genome architecture and evolutionary processes, yet they remain challenging to classify accurately. Terrier is a deep learning model designed to overcome these challenges by classifying repetitive DNA sequences using a publicly available, curated repeat sequence library trained under the RepeatMasker schema. Poor representation of taxa within repeat databases ofte… ▽ More Repetitive DNA sequences underpin genome architecture and evolutionary processes, yet they remain challenging to classify accurately. Terrier is a deep learning model designed to overcome these challenges by classifying repetitive DNA sequences using a publicly available, curated repeat sequence library trained under the RepeatMasker schema. Poor representation of taxa within repeat databases often limits the classification accuracy and reproducibility of current repeat annotation methods, limiting our understanding of repeat evolution and function. Terrier overcomes these challenges by leveraging deep learning for improved accuracy. Trained on Repbase, which includes over 100,000 repeat families -- four times more than Dfam -- Terrier maps 97.1% of Repbase sequences to RepeatMasker categories, offering the most comprehensive classification system available. When benchmarked against DeepTE, TERL, and TEclass2 in model organisms (rice, fruit flies, humans, and mice), Terrier achieved superior accuracy while classifying a broader range of sequences. Further validation in non-model amphibian, flatworm and Northern krill genomes highlights its effectiveness in improving classification in non-model species, facilitating research on repeat-driven evolution, genomic instability, and phenotypic variation. △ Less

Submitted 8 July, 2025; v1 submitted 12 March, 2025; originally announced March 2025.

Comments: 14 pages, 9 figures

ACM Class: I.2

SN 2024abfo: a partially stripped SN II from a yellow supergiant

Authors: A. Reguitti, A. Pastorello, S. J. Smartt, G. Valerin, G. Pignata, S. Campana, T. -W. Chen, A. Sankar. K., S. Moran, P. A. Mazzali, J. Duarte, I. Salmaso, J. P. Anderson, C. Ashall, S. Benetti, M. Gromadzki, C. P. Gutierrez, C. Humina, C. Inserra, E. Kankare, T. Kravtsov, T. E. Muller-Bravo, P. J. Pessi, J. Sollerman, D. R. Young , et al. (13 additional authors not shown)

Abstract: We present photometric and spectroscopic data of the type IIb supernova (SN) 2024abfo in NGC 1493 (at 11 Mpc). The ATLAS survey discovered the object just a few hours after the explosion, and observed a fast rise on the first day. Signs of the sharp shock break-out peak and the subsequent cooling phase are observed in the ultraviolet and the bluest optical bands in the first couple of days, while… ▽ More We present photometric and spectroscopic data of the type IIb supernova (SN) 2024abfo in NGC 1493 (at 11 Mpc). The ATLAS survey discovered the object just a few hours after the explosion, and observed a fast rise on the first day. Signs of the sharp shock break-out peak and the subsequent cooling phase are observed in the ultraviolet and the bluest optical bands in the first couple of days, while no peak is visible in the reddest filters. Subsequently, in analogy with normal SNe IIb, the light curve of SN 2024abfo rises again in all bands to the broad peak, with the maximum light reached around one month after the explosion. Its absolute magnitude at peak is $M_r=-16.5\pm0.1$ mag, making it a faint SN IIb. The early spectra are dominated by Balmer lines with broad P-Cygni profiles indicating ejecta velocity of 22,500 km/s. One month after the explosion, the spectra display a transition towards being He-dominated, though the H lines do not completely disappear, supporting the classification of SN 2024abfo as a relatively H-rich SN IIb. We identify the progenitor of SN 2024abfo in archival images of the Hubble Space Telescope, the Dark Energy Survey, and the XMM-Newton space telescope, in multiple optical filters. From its spectral energy distribution, the progenitor is consistent with being a yellow supergiant, having an initial mass of 15 $M_{\odot}$. This detection supports an emerging trend of SN IIb progenitors being more luminous and hotter than SN II ones, and being primaries of massive binaries. Within the SN IIb class, fainter events such as SN 2024abfo tend to have cooler and more expanded progenitors than luminous SNe IIb. △ Less

Submitted 25 April, 2025; v1 submitted 5 March, 2025; originally announced March 2025.

Comments: 9 pages, 9 figures, 4 tables, accepted for publication on A&A

Journal ref: A&A 698, A129 (2025)

Gross-Llewellyn Smith sum rule from lattice QCD

Authors: K. Utku Can, Joshua A. Crawford, Roger Horsley, Paul E. L. Rakow, Thomas G. Schar, Gerrit Schierholz, Hinnerk Stüben, Ross D. Young, James M. Zanotti

Abstract: We compute the Gross-Llewellyn Smith sum rule, i.e. the lowest odd moment of the parity-violating structure function, $F_3$, of the nucleon from a lattice QCD calculation of the Compton amplitude. Our calculations are performed on $48^3 \times 96$ lattices at the $SU(3)$ symmetric point for two lattice spacings. We extract the moments for several values of the current momenta in the range… ▽ More We compute the Gross-Llewellyn Smith sum rule, i.e. the lowest odd moment of the parity-violating structure function, $F_3$, of the nucleon from a lattice QCD calculation of the Compton amplitude. Our calculations are performed on $48^3 \times 96$ lattices at the $SU(3)$ symmetric point for two lattice spacings. We extract the moments for several values of the current momenta in the range $0.5 \lesssim Q^2 \lesssim 10 \; {\rm GeV}^2$, covering both the nonperturbative and perturbative regimes. We compare our moments to the Gross-Llewellyn Smith sum rule and discuss the implications for higher-twist effects, a determination of $α_s(Q^2)$ from a hadronic quantity complementing the phenomenological and other lattice approaches, and electroweak box contributions crucial for Cabibbo-Kobayashi-Maskawa matrix unitarity studies. △ Less

Submitted 11 June, 2025; v1 submitted 26 February, 2025; originally announced February 2025.

Comments: 16 pages, 12 figures

Report number: ADP-25-6/T1268, DESY-25-019, LTH 1394

Journal ref: Phys.Rev.D 111 (2025) 11, 114505

Defects in the $β$-Ga$_2$O$_3$($\bar201$)/HfO$_2$ MOS system and the effect of thermal treatments

Authors: Khushabu. S. Agrawal, Paolo LaTorraca, Jonas Valentijn, Roberta Hawkins, Adam A. Gruszecki, Joy Roy, Vasily Lebedev, Lewys Jones, Robert M. Wallace, Chadwin D. Young, Paul K. Hurley, Karim Cherkaoui

Abstract: We have investigated the properties of the $β$-Ga$_2$O$_3$($\bar201$)/HfO$_2$/Cr/Au MOS (metal-oxide-semiconductor) system after annealing (450$^\circ$C) in different ambient conditions (forming gas, N$_2$ and O$_2$). Defect properties have been analyzed using an approach combining experimental impedance measurements with physics-based simulations of the capacitance-voltage (C-V) and conductance-v… ▽ More We have investigated the properties of the $β$-Ga$_2$O$_3$($\bar201$)/HfO$_2$/Cr/Au MOS (metal-oxide-semiconductor) system after annealing (450$^\circ$C) in different ambient conditions (forming gas, N$_2$ and O$_2$). Defect properties have been analyzed using an approach combining experimental impedance measurements with physics-based simulations of the capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics of $β$-Ga$_2$O$_3$/HfO$_2$ MOS capacitors. This approach enabled us to detect two defect bands in HfO$_2$ characterized by thermal ionization energies of ~1.1eV (acceptor-like) and ~2eV (donor-like) attributed to a polaronic self-trapping state and an oxygen vacancy in HfO$_2$, respectively. This study demonstrates how thermal treatments affect the energy distributions and densities of the observed defects. The adopted methodology also enabled the extraction of the spatial distribution of defects across the HfO$_2$ thickness and Cr/HfO$_2$ interface. The high concentration of oxygen vacancies close to the Cr/HfO$_2$ interface extracted from experimental and simulated electrical data is confirmed by in-situ XPS analysis which shows how Cr is scavenging oxygen from the HfO$_2$ and creating the donor band confined near the Cr/HfO$_2$ interface. This donor band density is observed to be reduced after annealing as per simulation and unchanged for different annealing conditions. We speculate this may be due to the formation of dense films and polyforms of HfO$_2$ under different ambient as revealed by high-resolution TEM images. △ Less

Submitted 24 February, 2025; originally announced February 2025.

Comments: Main article: 23 pages, 6 figures, Supporting information:7 pages, 5 Figures

Journal ref: APL Materials 2025

Transverse force distributions in the proton from lattice QCD

Authors: K. U. Can, J. A. Crawford, R. Horsley, P. E. L. Rakow, G. Schierholz, H. Stüben, R. D. Young, J. M. Zanotti

Abstract: Single-spin asymmetries observed in polarised deep-inelastic scattering are important probes of hadron structure. The Sivers asymmetry provides information about the transverse momentum of the struck quark and can be related to final-state interactions. Understanding these asymmetries at the quark level has been the subject of much interest in QCD phenomenology. In this contribution, we present a… ▽ More Single-spin asymmetries observed in polarised deep-inelastic scattering are important probes of hadron structure. The Sivers asymmetry provides information about the transverse momentum of the struck quark and can be related to final-state interactions. Understanding these asymmetries at the quark level has been the subject of much interest in QCD phenomenology. In this contribution, we present a lattice QCD calculation of the transverse spatial distribution of a colour-Lorentz force acting on the struck quark in a proton. Our lattice calculations employ $N_f = 2 + 1$ flavours of dynamical fermions at the SU(3) symmetric point across three lattice spacings. We determine a central, spin-independent confining force, as well as spin-dependent force distributions with local forces larger than the QCD string tension. These distributions offer a new, complimentary picture that underlies the Sivers asymmetry in transversely polarised deep-inelastic scattering. △ Less

Submitted 1 February, 2025; originally announced February 2025.

Comments: 11 pages, 4 figures, talk presented at the 41st International Symposium on Lattice Field Theory (Lattice2024), July 28th - August 3rd, 2024, Liverpool, UK

Report number: ADP-25-3/T1265, DESY-25-020, Liverpool LTH 1395

Renormalisation Group Equations for 2+1 clover fermions

Authors: K. U. Can, R. Horsley, P. E. L. Rakow, G. Schierholz, H. Stüben, R. D. Young, J. M. Zanotti

Abstract: Many lattice QCD simulations now have many lattice spacings available, and it is of interest to investigate how they scale. In this talk we first derive renormalisation group equations appropriate for 2+1 clover fermions. This is then used together with pion mass and gradient flow results at five lattice spacings to study scaling. Many lattice QCD simulations now have many lattice spacings available, and it is of interest to investigate how they scale. In this talk we first derive renormalisation group equations appropriate for 2+1 clover fermions. This is then used together with pion mass and gradient flow results at five lattice spacings to study scaling. △ Less

Submitted 28 January, 2025; originally announced January 2025.

Comments: Contribution to the Proceedings of the 41st International Symposium on Lattice Field Theory, 28 July - 3 August 2024, University of Liverpool, UK

Lattice QCD calculation of the Compton amplitude subtraction function

Authors: K. U. Can, A. Hannaford-Gunn, R. Horsley, P. E. L. Rakow, T. Schar, G. Schierholz, H. Stüben, R. D. Young, J. M. Zanotti

Abstract: The Compton amplitude subtraction function is an essential component in work concerning both the proton radius puzzle and the proton-neutron mass difference. However, owing to the difficulty in determining the subtraction function, it remains a key source of uncertainty in these two contexts. Here, we use the Feynman-Hellmann method to determine this subtraction function directly from lattice QCD.… ▽ More The Compton amplitude subtraction function is an essential component in work concerning both the proton radius puzzle and the proton-neutron mass difference. However, owing to the difficulty in determining the subtraction function, it remains a key source of uncertainty in these two contexts. Here, we use the Feynman-Hellmann method to determine this subtraction function directly from lattice QCD. Furthermore, we demonstrate how to control dominant discretisation artefacts for this calculation, eliminating a major source of systematic error. This calculation is performed for a range of hard momentum scales, and three different sets of gauge configurations for pion masses about 400 MeV. Our results show good agreement with continuum OPE expectations. As such, this work paves the way for model-independent and precise determinations of the subtraction function over a wide range of kinematics. △ Less

Submitted 21 May, 2025; v1 submitted 15 January, 2025; originally announced January 2025.

Comments: 15 pages, 8 figures. Version accepted for publication in Phys. Rev. D

Report number: ADP-24-23/T1262, DESY-24-221, Liverpool LTH 1390

Journal ref: Phys. Rev. D. 111, 094513 (2025)