Showing 1–50 of 104 results for author: Murakami, K

Non-Abelian $A_4$ vortices in $SO(3)$ gauge theory and non-invertible symmetries

Authors: Yoshihiko Abe, Tetsutaro Higaki, Kazuya Murakami, Muneto Nitta, Ryo Yokokura

Abstract: We construct finite-tension non-Abelian vortex solutions in a renormalizable $(3+1)$-dimensional $SO(3)$ gauge theory Higgsed to the tetrahedral group $A_4$ by a Higgs field in the spin-3 representation. Since the vacuum manifold is $SO(3)/A_4$, the vortices are characterized by the non-Abelian fundamental group $π_1(SO(3)/A_4)\simeq \widetilde{A}_4$, the binary tetrahedral group. We obtain explic… ▽ More We construct finite-tension non-Abelian vortex solutions in a renormalizable $(3+1)$-dimensional $SO(3)$ gauge theory Higgsed to the tetrahedral group $A_4$ by a Higgs field in the spin-3 representation. Since the vacuum manifold is $SO(3)/A_4$, the vortices are characterized by the non-Abelian fundamental group $π_1(SO(3)/A_4)\simeq \widetilde{A}_4$, the binary tetrahedral group. We obtain explicit axisymmetric vortex solutions carrying holonomies corresponding to the order-two and order-three conjugacy classes of $A_4$, determine their tensions numerically, and show that they exhibit type-I, type-II, and Bogomol'nyi--Prasad--Sommerfield-like behavior depending on the Higgs and gauge boson mass ratios. The vortices are classified by conjugacy classes of $\widetilde{A}_4$, while their infrared descriptions are labeled by conjugacy classes of $A_4$. We further demonstrate that the smooth finite-tension vortices reduce in the infrared to Gukov--Witten surface operators of the $A_4$ discrete gauge theory, thereby establishing a finite-energy ultraviolet completion of non-invertible defects in a renormalizable gauge-Higgs theory. △ Less

Submitted 14 July, 2026; originally announced July 2026.

Comments: 14 pages, 4 figures, 2 tables

Low-Noise SiPM Light Readout and ASIC-Based Charge Readout of a Liquid Argon Time Projection Chamber for MeV Gamma-Ray Measurements

Authors: Satoshi Takashima, Hirokazu Odaka, Shota Arai, Kentaro Shirahama, Ryutaro Tatsumi, Hodaka Kawamura, Masashi Tanaka, Shintaro Arai, Tsuguo Aramaki, Aya Bamba, Lorenzo Fabris, Georgia Karagiorgi, Haruki Kuramoto, Jonathan LeyVa, John W. Mitchell, Aiko Miyamoto, Reshmi Mukherjee, Kaito Murakami, Azuki Nagao, Arathi Suraj, Sayana Takatsuka, Chihiro Watanabe, Shin Watanabe, Yutaro Yano, Kazushi Yawata , et al. (3 additional authors not shown)

Abstract: We have developed a compact liquid argon time projection chamber (LArTPC), NanoGRAMS, as a technology demonstrator for the Gamma-Ray and AntiMatter Survey (GRAMS). LArTPCs have the potential to enable Compton cameras with unprecedented effective area in the MeV gamma-ray band. NanoGRAMS has an active volume of $5.12 \times 5.12 \times 10~\mathrm{cm^3}$ and is equipped with a low-noise scintillatio… ▽ More We have developed a compact liquid argon time projection chamber (LArTPC), NanoGRAMS, as a technology demonstrator for the Gamma-Ray and AntiMatter Survey (GRAMS). LArTPCs have the potential to enable Compton cameras with unprecedented effective area in the MeV gamma-ray band. NanoGRAMS has an active volume of $5.12 \times 5.12 \times 10~\mathrm{cm^3}$ and is equipped with a low-noise scintillation and charge readout system. The scintillation light is detected by an array of 16 SiPMs ($6 \times 6~\mathrm{mm^2}$ each), whose signals are summed and amplified by a low-noise transimpedance amplifier operable at liquid argon temperature. Ionization electrons are read out with $3.2\,\mathrm{mm}$-pitch pixels and processed by VATA-SGD ASICs, with synchronization provided by an FPGA-based data acquisition system. We irradiated the detector with a $^{60}\mathrm{Co}$ source (1173 and $1332\,\mathrm{keV}$) and successfully detected both 1-hit and 2-hit events. The collected charge was converted to deposited energy using a phenomenological recombination model, and the detector response was evaluated with a Geant4-based Monte Carlo simulation. The reconstructed energy spectrum shows Compton edges at 963 and $1118\,keV$, consistent with the expected values. For 2-hit events, the sequence of interactions was identified, and the reconstructed back-projection image agrees with the source position. These results demonstrate the feasibility of NanoGRAMS as a Compton camera for MeV gamma-ray imaging spectroscopy. △ Less

Submitted 13 July, 2026; originally announced July 2026.

Comments: 8 pages, 7 figures, accepted for publication in NIM-A

Hadron spectra of finite-density QC$_2$D

Authors: Kei Iida, Etsuko Itou, Kotaro Murakami, Daiki Suenaga

Abstract: We investigate the chemical-potential dependence of hadron spectra in two-color QCD using first-principles lattice simulations. We compute two-point correlation functions for all allowed hadronic operators by newly including the contributions from disconnected diagrams, and extract the corresponding effective masses. In the meson sector, the mass hierarchy in the hadronic phase (normal vacuum) is… ▽ More We investigate the chemical-potential dependence of hadron spectra in two-color QCD using first-principles lattice simulations. We compute two-point correlation functions for all allowed hadronic operators by newly including the contributions from disconnected diagrams, and extract the corresponding effective masses. In the meson sector, the mass hierarchy in the hadronic phase (normal vacuum) is found to be $m_π\lesssim m_η < m_σ\mathrm{(noisy)} < m_ρ\sim m_ω\ll m_{a_1}$, which is similar to that in three-color QCD. In the superfluid phase, this hierarchy is modified, and with increasing density it changes to $m_σ\mathrm{(noisy)} < m_{a_1} < m_ρ< m_π\sim m_η \mathrm{(noisy)} \ll m_ω \mathrm{(noisy)}$. In the diquark sector, the ordering remains as $m_{NG} \lesssim m_{I=0, S} < m_{I=1, AV} < m_{I=0, PS} \lesssim m_{I=0, V}$ in both phases, and the Nambu--Goldstone mode associated with spontaneous breaking of $U(1)_B$ is confirmed to be nearly massless. Furthermore, by comparing correlators for chiral partners, we find indications of chiral symmetry restoration at high density. △ Less

Submitted 11 August, 2026; v1 submitted 11 June, 2026; originally announced June 2026.

Comments: 42pages, 30figures; (ver2) Minor improvements; correlation-function data made publicly available on Zenodo (Ref.[66])

Report number: YITP-26-46, RIKEN-iTHEMS-Report-26

Estimation of potential radius based on momentum distribution of a constituent particle

Authors: Eisuke Kawamura, Kotaro Murakami, Daisuke Jido

Abstract: We propose using the potential radius as a probe of the structure of hadrons, particularly to classify exotic hadrons as hadronic or quark composite states.In this study, we focus on the radius of the effective potential felt by each constituent particle. Using a simple model with a square-well potential, we demonstrate that the potential radius can be estimated from the momentum distribution of a… ▽ More We propose using the potential radius as a probe of the structure of hadrons, particularly to classify exotic hadrons as hadronic or quark composite states.In this study, we focus on the radius of the effective potential felt by each constituent particle. Using a simple model with a square-well potential, we demonstrate that the potential radius can be estimated from the momentum distribution of a constituent particle not only for deeply bound states but also for shallowly bound states.We find that the momentum-based quantity provides a more robust estimate of the potential radius in the shallow-binding regime.This is because the momentum-based length scale decreases to zero as the potential radius vanishes, whereas the RMS radius approaches a finite value set by the binding energy.As a result, the momentum distribution avoids the finite-intercept problem that can make the inverse estimate of the potential radius ill-defined.With future experimental data on the momentum distribution of the constituent nucleon in $\overline{K}NNN$ production at J-PARC, the potential radius may be determined within the present framework. △ Less

Submitted 27 May, 2026; originally announced May 2026.

Comments: 5 pages, 1 figure, proceedings contribution

Report number: RIKEN-iTHEMS-Report-26

A XRISM Study of Highly Ionized Iron Emission Lines from the Low-Eddington-ratio AGN in NGC 7213

Authors: Kaito Murakami, Taiki Kawamuro, Ryota Tomaru, Hirokazu Odaka, Elias Kammoun, Shoji Ogawa, Stefano Bianchi, Hirofumi Noda, Claudio Ricci, Yuichi Terashima, Yoshihiro Ueda, Satoshi Yamada, Hironori Matsumoto

Abstract: We present an analysis of XRISM and NuSTAR data obtained for the nearby low-Eddington active galactic nucleus NGC 7213. Our goal is to examine whether its He-like and H-like iron emission lines can be reproduced by photoionization or collisional ionization processes. Using the broad-band energy coverage of our data (2-60 keV), we first constrained the continuum shape. Then, we focused on the iron-… ▽ More We present an analysis of XRISM and NuSTAR data obtained for the nearby low-Eddington active galactic nucleus NGC 7213. Our goal is to examine whether its He-like and H-like iron emission lines can be reproduced by photoionization or collisional ionization processes. Using the broad-band energy coverage of our data (2-60 keV), we first constrained the continuum shape. Then, we focused on the iron-K band in the Resolve spectrum. Gaussian fits to Fe XXV He$α$ and Fe XXVI Ly$α$ lines suggest that they may have different velocity widths: $v_σ=790^{+370}_{-240}$ km s$^{-1}$ for Fe XXV and $v_σ=2610^{+1700}_{-1580}$ km s$^{-1}$ for Fe XXVI. In this case, the He$α$ resonance line (w) and forbidden line (z) have similar intensities of $\approx0.5$-$0.6\times10^{-5}$ ph s$^{-1}$ cm$^{-2}$, while the intercombination lines (x+y) are not significantly detected with upper limits of $\lesssim 0.2\times10^{-5}$ ph s$^{-1}$ cm$^{-2}$. Motivated by the possible difference in the line widths, we tested one- and two-zone photoionized and collisionally ionized models. Our results show that the additional ionized component is not significantly required, and the current data cannot uniquely determine whether photoionization or collisional ionization dominates. Moreover, if the Fe XXV He$α$ complex implies that the weak x+y lines are suppressed relative to the w and z lines, such a structure is difficult to reproduce with either ionization model adopted. Finally, by comparing NGC 7213 with M 81$^\ast$, accreting at a much lower Eddington ratio of $λ_{\rm Edd}\sim 10^{-5}$, we found a decrease in the density of the gas responsible for highly ionized iron emission, which may imply that the density decreases with decreasing $λ_{\rm Edd}$. △ Less

Submitted 17 April, 2026; originally announced April 2026.

Comments: Accepted for publication in PASJ (11 pages, 7 figures)

Refined Constraints on the Hard X-ray Polarization of the Crab Pulsar and Nebula Derived from an Extended XL-Calibur Dataset

Authors: Matthew G. Baring, Jacob Casey, Sohee Chun, Ephraim Gau, Tomohiro Hakamata, Kun Hu, Daiki Ishi, Fabian Kislat, Mózsi Kiss, Merlin Kole, Henric Krawczynski, Haruki Kuramoto, Lindsey Lisalda, Bingkun Liu, Yoshitomo Maeda, Hironori Matsumoto, Shravan Vengalil Menon, Takuya Miyazawa, Kaito Murakami, Takashi Okajima, Mark Pearce, Brian Rauch, Kentaro Shirahama, Sean Spooner, Hiromitsu Takahashi , et al. (4 additional authors not shown)

Abstract: We present updated hard X-ray polarization measurements of the Crab pulsar and nebula obtained with the balloon-borne polarimeter XL-Calibur in the ~19-64 keV energy range. During the flight, intermittent GPS-failure resulted in poorly constrained timing for ~38% of the Crab dataset. By implementing a new phase-recovery method that reconstructs timing during extended GPS-off intervals, phase tag d… ▽ More We present updated hard X-ray polarization measurements of the Crab pulsar and nebula obtained with the balloon-borne polarimeter XL-Calibur in the ~19-64 keV energy range. During the flight, intermittent GPS-failure resulted in poorly constrained timing for ~38% of the Crab dataset. By implementing a new phase-recovery method that reconstructs timing during extended GPS-off intervals, phase tag data is recovered for ~95% of the GPS-off dataset, increasing the precision of the phase-resolved analysis. Phase-information for the data is recovered by using the Crab pulsar, with its 33 ms period, as an external timing source. Using a Markov-Chain Monte-Carlo framework to jointly fit phase offsets and frequency derivatives, sufficient phase accuracy is achieved, across multiple periods without GPS for a phase-resolved analysis. This enables inclusion of nearly the full dataset in the polarization study. The polarization degree of the nebular emission is found to be (27.7${\pm}$4.9)% at a polarization angle of 127.2°${\pm}$5.1° confirming previous XL-Calibur results and remaining aligned with the Crab's spin axis, consistent with synchrotron emission from the inner nebula. Phase-resolved measurements show that the off-pulse and bridge intervals exhibit a strong polarization, while the pulsar peaks, although weakly constrained, remain in agreement with the softer-energy trends of IXPE. These findings reinforce a scenario in which hard X-ray emission arises primarily in the nebular torus and wind regions. The successful recovery of precise phase tagging from GPS-off data demonstrates the capacity to use the pulsar as an external clock even in the case of sparsely populated data. △ Less

Submitted 16 April, 2026; originally announced April 2026.

Journal ref: The Astrophysical Journal, Volume 1002 (2026), Number 2

Sensitivity Improvement by Sample Vibration Excitation in Resistivity Measurement for Non-Magnetic Material Using MFM

Authors: Kazuma Okamoto, Takumi Imura, Naruto Nakamura, Satoshi Abo, Katsuhisa Murakami, Masayoshi Nagao, Fujio Wakaya

Abstract: A novel approach for measuring the electrical resistivity of non-magnetic materials using magnetic force microscopy (MFM) is discussed. In this method, MFM detects magnetic fields generated by eddy currents induced by the oscillation of a magnetized probe tip. To enhance measurement sensitivity, it is essential to increase the magnitude of these eddy currents. It is discussed that introducing cont… ▽ More A novel approach for measuring the electrical resistivity of non-magnetic materials using magnetic force microscopy (MFM) is discussed. In this method, MFM detects magnetic fields generated by eddy currents induced by the oscillation of a magnetized probe tip. To enhance measurement sensitivity, it is essential to increase the magnitude of these eddy currents. It is discussed that introducing controlled sample vibration amplifies eddy current generation by increasing the relative velocity between the probe tip and the sample surface. Theoretical analysis predicts increase of the phase shift by sample vibration, and experimental validation using a modified MFM system confirms the improvement in sensitivity. The calculated and experimental results exhibit relatively good agreement, establishing that sample vibration excitation is an effective strategy for high-sensitivity resistivity measurements. △ Less

Submitted 16 April, 2026; originally announced April 2026.

Comments: 7 pages, 8 figures

$\bar{D}$-meson Nucleon Scattering from Lattice QCD at the Physical Point

Authors: Wren Yamada, Yan Lyu, Kotaro Murakami, Takumi Doi

Abstract: We report the first lattice QCD study of the $s$-wave scattering of the $\bar{D}$-meson and the nucleon at the physical point, utilizing (2+1)-flavor configurations generated by the HAL QCD collaboration with a pion mass of $m_π\simeq 137$ MeV and a lattice spacing of $a\simeq0.084$ fm. By applying the HAL QCD method to the four-point correlation function of the $\bar{D}N$ system, we obtain a lead… ▽ More We report the first lattice QCD study of the $s$-wave scattering of the $\bar{D}$-meson and the nucleon at the physical point, utilizing (2+1)-flavor configurations generated by the HAL QCD collaboration with a pion mass of $m_π\simeq 137$ MeV and a lattice spacing of $a\simeq0.084$ fm. By applying the HAL QCD method to the four-point correlation function of the $\bar{D}N$ system, we obtain a leading-order potential of the derivative expansion of the interaction kernel, which is then used to extract the $s$-wave phase shifts of low-energy $\bar{D}N$ scattering. Both the isospin $I=0$ and $I=1$ channels have a short-range repulsive core and a shallow attractive pocket in the intermediate to long-range region, though the $I=0$ channel is more attractive than the $I=1$ channel. We also observe that the $\bar{D}N$ potential exhibits more attraction than the $KN$ potential, which is its analog in the strange sector. In terms of the $s$-wave phase shifts, the $I=0$ channel shows a weak attractive behavior in the low-energy region with a positive scattering length of $0.246 \pm 0.105 (_{-0.051}^{+0.084})$ fm, whereas the $I=1$ channel shows repulsion with a negative scattering length of $-0.086 \pm 0.050 (_{-0.001}^{+0.037})$ fm. No bound states are found in both isospin channels, indicating the absence of a pentaquark state in the $s$-wave $\bar{D}N$ system. △ Less

Submitted 12 March, 2026; originally announced March 2026.

Comments: 26 pages, 11 figures, 5 tables

Report number: RIKEN-iTHEMS-Report-26

Instant and Reversible Adhesive-free Bonding Between Silicones and Glossy Papers for Soft Robotics

Authors: Takumi Shibuya, Kazuya Murakami, Akitsu Shigetou, Jun Shintake

Abstract: Integrating silicone with non-extensible materials is a common strategy used in the fabrication of fluidically-driven soft actuators, yet conventional approaches often rely on irreversible adhesives or embedding processes that are labor-intensive and difficult to modify. This work presents silicone-glossy paper bonding (SGB), a rapid, adhesive-free, and solvent-reversible bonding approach that for… ▽ More Integrating silicone with non-extensible materials is a common strategy used in the fabrication of fluidically-driven soft actuators, yet conventional approaches often rely on irreversible adhesives or embedding processes that are labor-intensive and difficult to modify. This work presents silicone-glossy paper bonding (SGB), a rapid, adhesive-free, and solvent-reversible bonding approach that forms robust silicone-paper interfaces simply through contact. The SGB interface withstands high mechanical loads (shear strength > 61 kPa) and can be fully detached and reassembled via ethanol immersion without loss of performance, enabling component reuse and rapid redesign. Characterization studies indicate that surface functional groups primarily govern adhesion on the glossy paper and the modulus of the silicone, while durability and environmental response clarify the conditions for reversible debonding. The results further suggest a synergistic interaction of hydrogen bonding and oligomer diffusion, yielding strong yet reconfigurable adhesion. Soft actuators fabricated using SGB design exhibit equal or greater performance compared to conventional embedded-layer design and enable programmable actuation modes, including contraction, bending, and twisting. By simplifying fabrication while supporting reuse and rapid iteration, SGB offers a scalable and sustainable platform for rapid prototyping in soft robotics. △ Less

Submitted 2 March, 2026; originally announced March 2026.

Deconstructing Taste: Toward a Human-Centered AI Framework for Modeling Consumer Aesthetic Perceptions

Authors: Matthew K. Hong, Joey Li, Alexandre Filipowicz, Monica Van, Kalani Murakami, Yan-Ying Chen, Shiwali Mohan, Shabnam Hakimi, Matthew Klenk

Abstract: Understanding and modeling consumers' stylistic taste such as "sporty" is crucial for creating designs that truly connect with target audiences. However, capturing taste during the design process remains challenging because taste is abstract and subjective, and preference data alone provides limited guidance for concrete design decisions. This paper proposes an integrated human-centered computatio… ▽ More Understanding and modeling consumers' stylistic taste such as "sporty" is crucial for creating designs that truly connect with target audiences. However, capturing taste during the design process remains challenging because taste is abstract and subjective, and preference data alone provides limited guidance for concrete design decisions. This paper proposes an integrated human-centered computational framework that links subjective evaluations (e.g., perceived luxury of car wheels) with domain-specific features (e.g., spoke configuration) and computer vision-based measures (e.g., texture). By jointly modeling human-derived (consumer and designer) and machine-extracted features, our framework advances aesthetic assessment by explicitly linking model outcomes to interpretable design features. In particular, it demonstrates how perceptual features, domain-specific design patterns, and consumers' own interpretations of style contribute to aesthetic evaluations. This framework will enable product teams to better understand, communicate, and critique aesthetic decisions, supporting improved anticipation of consumer taste and more informed exploration of design alternatives at design time. △ Less

Submitted 23 January, 2026; originally announced January 2026.

Speed of sound exceeding the conformal bound in dense QCD-like theories

Authors: Etsuko Itou, Kei Iida, Kotaro Murakami, Daiki Suenaga

Abstract: We investigated the phase structure and the equation of state (EoS) for dense two-color QCD at low temperatures using the lattice Monte Carlo simulations. A rich phase structure below the pseudo-critical temperature $T_c$ as a function of quark chemical potential has been revealed. In a high-density regime, we can see a superfluid phase, where the diquark condensate takes a non-zero expectation va… ▽ More We investigated the phase structure and the equation of state (EoS) for dense two-color QCD at low temperatures using the lattice Monte Carlo simulations. A rich phase structure below the pseudo-critical temperature $T_c$ as a function of quark chemical potential has been revealed. In a high-density regime, we can see a superfluid phase, where the diquark condensate takes a non-zero expectation value. We have newly found that the speed of sound exceeds the conformal bound, which is the value of the relativistic free theory. This talk is based on Refs.~\cite{Iida:2022hyy, Iida:2024irv, Itou:2025vcy}. △ Less

Submitted 27 November, 2025; originally announced November 2025.

Comments: 5pages, Proceedings of the 29th International Nuclear Physics Conference (INPC2025), Deajon, Korea, May 25-30, 2025

Report number: YITP-25-182, RIKEN-iTHEMS-Report-25

Monochromatic Electron Emission from Graphene-Insulator-Semiconductor-Structured Electron Source Utilizing Interference Efficets

Authors: Takao Koichi, Shogo Kawashima, Hiroshi Miyake, Satoshi Abo, Fujio Wakaya, Masayoshi Nagao, Katsuhisa Murakami

Abstract: The graphene-insulator-semiconductor-structured electron source has garnered significant attention due to its high electron emission efficiency and highly monochromatic electron emission. Graphene, with its c-axis orientation and well-defined interlayer spacing, exhibits electron interference effects that can influence the properties of emitted electrons. In this work, motion of an electron wave p… ▽ More The graphene-insulator-semiconductor-structured electron source has garnered significant attention due to its high electron emission efficiency and highly monochromatic electron emission. Graphene, with its c-axis orientation and well-defined interlayer spacing, exhibits electron interference effects that can influence the properties of emitted electrons. In this work, motion of an electron wave packet is numerically calculated to discuss the energy spread of the zero-order and first-order diffracted electron waves by mono- and multilayer graphene. It is found that the effects of multiple reflections of electron between the layers broaden the energy spread especially for the incident energy of 13.4 eV, and that highly monochromatic electron emission can be achieved by using diffracted electron wave with a small aperture. △ Less

Submitted 4 November, 2025; originally announced November 2025.

Comments: 9 pages, 10 figures

XRISM/Resolve reveals the complex iron structure of NGC 7213: Evidence for radial stratification between inner disk and broad-line region

Authors: E. Kammoun, T. Kawamuro, K. Murakami, S. Bianchi, F. Nicastro, A. Luminari, E. Aydi, M. Eracleous, O. K. Adegoke, E. Bertola, P. G. Boorman, V. Braito, G. Bruni, A. Comastri, P. Condò, M. Dadina, T. Enoto, J. A. García, V. E. Gianolli, F. A. Harrison, G. Lanzuisi, M. Laurenti, A. Marinucci, G. Mastroserio, H. Matsumoto , et al. (27 additional authors not shown)

Abstract: We present the first high-resolution X-ray spectrum of NGC 7213 obtained with XRISM/Resolve, supported by simultaneous XMM-Newton, NuSTAR, and SOAR optical data. The XRISM spectrum resolves the neutral Fe\,K$α$ into two components: a narrow core ($\rm FWHM = 650_{-220}^{+240}\,\rm km\,s^{-1}$) consistent with emission at the dust sublimation radius, and a broader, asymmetric line best described by… ▽ More We present the first high-resolution X-ray spectrum of NGC 7213 obtained with XRISM/Resolve, supported by simultaneous XMM-Newton, NuSTAR, and SOAR optical data. The XRISM spectrum resolves the neutral Fe\,K$α$ into two components: a narrow core ($\rm FWHM = 650_{-220}^{+240}\,\rm km\,s^{-1}$) consistent with emission at the dust sublimation radius, and a broader, asymmetric line best described by disk-like emission from $\sim 100\,\rm R_{g}$. This disk component mirrors the profile of the double-peaked H$α$ line observed in the optical. In addition, we detect broadened Fe XXV and Fe XXVI emission lines whose inferred locations bridge the gap between the inner disk and the optical broad-line region. The weak narrow Fe K$α$ equivalent width ($\rm EW = 32 \pm 6\,eV$) and absence of a Compton hump imply a low-covering-fraction, Compton-thin torus. Together, these results reveal a radially stratified structure in NGC 7213, spanning nearly four orders of magnitude in radius, and place the source in an intermediate accretion state ($\rm λ_{Edd} = 0.001-0.01$) where the inner disk and BLR remain, while the torus shows signs of dissipation. △ Less

Submitted 28 October, 2025; originally announced October 2025.

Comments: Accepted for publication in ApJL

$S$-wave kaon-nucleon interactions from lattice QCD at the physical point

Authors: Kotaro Murakami, Sinya Aoki, Takumi Doi, Yan Lyu, Wren Yamada

Abstract: We investigate S-wave kaon-nucleon ($KN$) interactions with strangeness $S=+1$ in lattice QCD using the time-dependent HAL QCD method. Employing the $(2+1)$-flavor gauge configuration with $m_π\approx 137~\textrm{MeV}$ and $m_{K}\approx 502~\textrm{MeV}$, we calculate the $KN$ potentials at the leading order in the derivative expansion. The potentials in both isospin channels ($I=1$ and $I=0$) exh… ▽ More We investigate S-wave kaon-nucleon ($KN$) interactions with strangeness $S=+1$ in lattice QCD using the time-dependent HAL QCD method. Employing the $(2+1)$-flavor gauge configuration with $m_π\approx 137~\textrm{MeV}$ and $m_{K}\approx 502~\textrm{MeV}$, we calculate the $KN$ potentials at the leading order in the derivative expansion. The potentials in both isospin channels ($I=1$ and $I=0$) exhibit repulsion at short distances, while only the $I=0$ potential has a small attractive pocket at intermediate distances. From these potentials, we compute the phase shifts as well as the low-energy scattering parameters. The obtained phase shifts show no signals corresponding to resonances or bound states in both isospin channels, suggesting the absence of the $Θ^{+}(1540)$ pentaquark in the S-wave $KN$ systems. The results for $I=0$ suggest that the scattering amplitudes in this channel are dominated by P-wave components rather than S-wave. △ Less

Submitted 31 July, 2026; v1 submitted 31 August, 2025; originally announced September 2025.

Comments: 34 pages, 20 figures, 4 tables. v3: This version contains an erratum followed by the original manuscript, which is identical to arXiv:2509.00838v2. A numerical error in the KN four-point correlation functions was corrected, and the results affected by this error were updated accordingly. The erratum presents the corrected results and discusses how the conclusions are affected

Report number: RIKEN-iTHEMS-Report-25, FQSP-2025-4, YITP-25-133

XL-Calibur Polarimetry of Cyg X-1 Further Constrains the Origin of its Hard-state X-ray Emission

Authors: Hisamitsu Awaki, Matthew G. Baring, Richard Bose, Jacob Casey, Sohee Chun, Adrika Dasgupta, Pavel Galchenko, Ephraim Gau, Kazuho Goya, Tomohiro Hakamata, Takayuki Hayashi, Scott Heatwole, Kun Hu, Daiki Ishi, Manabu Ishida, Fabian Kislat, Mózsi Kiss, Kassi Klepper, Henric Krawczynski, Haruki Kuramoto, Lindsey Lisalda, Yoshitomo Maeda, Hironori Matsumoto, Shravan Vengalil Menon, Aiko Miyamoto , et al. (14 additional authors not shown)

Abstract: The balloon-borne hard X-ray polarimetry mission XL-Calibur observed the Black Hole X-ray Binary (BHXRB) Cygnus X-1 (Cyg X-1) during its nearly six-day Long Duration Balloon (LDB) flight from Sweden to Canada in July 2024. The XL-Calibur observations allowed us to derive the most precise constraints to date of the Polarization Degree (PD) and Polarization Angle (PA) of the hard X-ray emission from… ▽ More The balloon-borne hard X-ray polarimetry mission XL-Calibur observed the Black Hole X-ray Binary (BHXRB) Cygnus X-1 (Cyg X-1) during its nearly six-day Long Duration Balloon (LDB) flight from Sweden to Canada in July 2024. The XL-Calibur observations allowed us to derive the most precise constraints to date of the Polarization Degree (PD) and Polarization Angle (PA) of the hard X-ray emission from a BHXRB. XL-Calibur observed Cyg X-1 in the hard state and measured a $\sim$19-64 keV PD of ($5.0^{+2.7}_{-3.0}$)% at a PA of $-28^{\circ}\pm 17^{\circ}$, with an 8.7% chance probability of detecting larger PDs than the one observed, given an unpolarized signal. The XL-Calibur results are thus comparable to the 2-8 keV PD and PA found by IXPE, with a similar agreement between the hard X-ray PA and the radio jet direction. We also discuss the implications of our polarization measurements in the context of models describing the origin of the broadband X-ray and $γ$-ray emission, to which XL-Calibur provides independent constraints on any proposed emission modeling. △ Less

Submitted 30 July, 2025; originally announced July 2025.

Comments: 11 pages, 9 figures, 1 table

Sparse identification of nonlinear dynamics with library optimization mechanism: Recursive long-term prediction perspective

Authors: Ansei Yonezawa, Heisei Yonezawa, Shuichi Yahagi, Itsuro Kajiwara, Shinya Kijimoto, Hikaru Taniuchi, Kentaro Murakami

Abstract: The sparse identification of nonlinear dynamics (SINDy) approach can discover the governing equations of dynamical systems based on measurement data, where the dynamical model is identified as the sparse linear combination of the given basis functions. A major challenge in SINDy is the design of a library, which is a set of candidate basis functions, as the appropriate library is not trivial for m… ▽ More The sparse identification of nonlinear dynamics (SINDy) approach can discover the governing equations of dynamical systems based on measurement data, where the dynamical model is identified as the sparse linear combination of the given basis functions. A major challenge in SINDy is the design of a library, which is a set of candidate basis functions, as the appropriate library is not trivial for many dynamical systems. To overcome this difficulty, this study proposes SINDy with library optimization mechanism (SINDy-LOM), which is a combination of the sparse regression technique and the novel learning strategy of the library. In the proposed approach, the basis functions are parametrized. The SINDy-LOM approach involves a two-layer optimization architecture: the inner-layer, in which the data-driven model is extracted as the sparse linear combination of the candidate basis functions, and the outer-layer, in which the basis functions are optimized from the viewpoint of the recursive long-term (RLT) prediction accuracy; thus, the library design is reformulated as the optimization of the parametrized basis functions. The dynamical model obtained by SINDy-LOM has good interpretability and usability, as this approach yields a parsimonious closed-form model. The library optimization mechanism significantly reduces user burden. The RLT perspective improves the reliability of the resulting model compared with the traditional SINDy approach that can only ensure the one-step-ahead prediction accuracy. The effectiveness of the proposed approach is verified through numerical experiments. △ Less

Submitted 2 February, 2026; v1 submitted 24 July, 2025; originally announced July 2025.

Comments: Published in IEEE Transactions on Cybernetics (https://ieeexplore.ieee.org/document/11365958)

Wavefunction-based operator optimization for two-hadron systems in lattice QCD

Authors: Yan Lyu, Sinya Aoki, Takumi Doi, Tetsuo Hatsuda, Kotaro Murakami, Takuya Sugiura

Abstract: A systematic way to constructing optimized interpolating operators for two-hadron systems is developed by incorporating inter-hadron spatial wavefunctions. The wavefunctions can be obtained from an iterative process with an appropriate initial guess. To implement these operators, a novel quark smearing technique utilizing $Z_3$ noise vectors is proposed, which allows for effectively incorporating… ▽ More A systematic way to constructing optimized interpolating operators for two-hadron systems is developed by incorporating inter-hadron spatial wavefunctions. The wavefunctions can be obtained from an iterative process with an appropriate initial guess. To implement these operators, a novel quark smearing technique utilizing $Z_3$ noise vectors is proposed, which allows for effectively incorporating inter-hadron spatial wavefunctions at the source without using all-to-all quark propagators. Proof-of-principle application to the $Ω_{ccc}Ω_{ccc}$ system using physical-point lattice configurations with a large size $La\simeq8.1$~fm demonstrates that optimized operators outperform combinations of limited plane-wave operators in the variational analysis, enabling clear identification of states around $2m_{Ω_{ccc}}\simeq 9700$ MeV with the energy gap as narrow as $\sim 5$ MeV. A comparison on correlation functions, effective energies, and HAL QCD potentials between unoptimized operators and optimized operators is given, with a special emphasis on the effects from nearby elastic scattering states. Potential applicability of the optimized operator to various two-hadron systems and its relation to the variational method are also discussed. △ Less

Submitted 3 August, 2026; v1 submitted 14 July, 2025; originally announced July 2025.

Comments: 27 pages; Published version, more detailed results are added including comparisons with plane-wave operators, and sink-operator dependence of potentials

Report number: RIKEN-iTHEMS-Report-25, FQSP-25-3, YITP-25-110

Journal ref: Physical Review D 114, 014506 (2026)

Decoding Two-Particle States in QCD with Spatial Wavefunctions

Authors: Yan Lyu, Sinya Aoki, Takumi Doi, Tetsuo Hatsuda, Kotaro Murakami, Takuya Sugiura

Abstract: A systematic framework for constructing optimized interpolating operators strongly coupled to QCD two-particle states is developed, which is achieved by incorporating inter-hadron spatial wavefunctions. To efficiently implement these operators in lattice QCD, a novel quark smearing technique utilizing noise vectors is proposed. Applied to the $Ω_{ccc}Ω_{ccc}$ system, these optimized operators prov… ▽ More A systematic framework for constructing optimized interpolating operators strongly coupled to QCD two-particle states is developed, which is achieved by incorporating inter-hadron spatial wavefunctions. To efficiently implement these operators in lattice QCD, a novel quark smearing technique utilizing noise vectors is proposed. Applied to the $Ω_{ccc}Ω_{ccc}$ system, these optimized operators prove superior to combinations of limited plane-wave operators, enabling the resolution of distinct eigenstates separated by only $\sim 5$ MeV near the threshold $2m_{Ω_{ccc}} \simeq 9700$ MeV. This exceptional resolving power opens new possibilities for studies of a wide range of hadronic systems in QCD. △ Less

Submitted 3 August, 2026; v1 submitted 14 July, 2025; originally announced July 2025.

Comments: 6 pages; Including comparisons with plane-wave operators to match with the published version

Report number: RIKEN-iTHEMS-Report-25, FQSP-25-2, YITP-25-109

Journal ref: Physical Review D 114, L011503 (2026)

Optimal SVI-Weighted PSPS Decisions with Decision-Dependent Outage Uncertainty

Authors: Ryan Greenough, Kohei Murakami, Jan Kleissl, Adil Khurram

Abstract: Public Safety Power Shutoffs (PSPS) are a pre-emptive strategy to mitigate the wildfires caused by power system malfunction. System operators implement PSPS to balance wildfire mitigation efforts through de-energization of transmission lines against the risk of widespread blackouts modeled with load shedding. Existing approaches do not incorporate decision-dependent wildfire-driven failure proba… ▽ More Public Safety Power Shutoffs (PSPS) are a pre-emptive strategy to mitigate the wildfires caused by power system malfunction. System operators implement PSPS to balance wildfire mitigation efforts through de-energization of transmission lines against the risk of widespread blackouts modeled with load shedding. Existing approaches do not incorporate decision-dependent wildfire-driven failure probabilities, as modeling outage scenario probabilities requires incorporating high-order polynomial terms in the objective. This paper uses distribution shaping to develop an efficient MILP problem representation of the distributionally robust PSPS problem. Building upon the author's prior work, the wildfire risk of operating a transmission line is a function of the probability of a wildfire-driven outage and its subsequent expected impact in acres burned. A day-ahead unit commitment and line de-energization PSPS framework is used to assess the trade-off between total cost and wildfire risk at different levels of distributional robustness, parameterized by a level of distributional dissimilarity $κ$. We perform simulations on the IEEE RTS 24-bus test system. △ Less

Submitted 15 April, 2025; originally announced April 2025.

Comments: 10 pages, 7 figures, and 3 tables

Resistivity measurement for non-magnetic materials using high-order resonance mode of mfm-cantilever oscillation

Authors: Kazuma Okamoto, Takumi Imura, Satoshi Abo, Fujio Wakaya, Katsuhisa Murakami, Masayoshi Nagao

Abstract: A method to measure the electrical resistivity of materials using magnetic-force microscopy (MFM) is discussed, where MFM detects the magnetic field caused by the tip-oscillation-induced eddy current. To achieve high sensitivity, a high cantilever oscillation frequency is preferable, because it induces large eddy currents in the material. Higher-order resonance modes of the cantilever oscillation… ▽ More A method to measure the electrical resistivity of materials using magnetic-force microscopy (MFM) is discussed, where MFM detects the magnetic field caused by the tip-oscillation-induced eddy current. To achieve high sensitivity, a high cantilever oscillation frequency is preferable, because it induces large eddy currents in the material. Higher-order resonance modes of the cantilever oscillation leads to higher frequency. To discuss such high-order-mode oscillation, a differential equation governing MFM cantilever oscillation in the high-order resonance mode is formulated, and an analytical solution of the phase difference is obtained. The result shows that the phase difference decreases at higher modes, because the effective spring constant increases faster than the force from the eddy current. △ Less

Submitted 8 April, 2025; originally announced April 2025.

Comments: 12 pages, 6 figures, 2024MNC, published in JJAP

Journal ref: Japanese Journal of Applied Physics 64, 04SP24 (2025)

XL-Calibur measurements of polarised hard X-ray emission from the Crab

Authors: Hisamitsu Awaki, Matthew G. Baring, Richard Bose, Dana Braun, Jacob Casey, Sohee Chun, Pavel Galchenko, Ephraim Gau, Kazuho Goya, Tomohiro Hakamata, Takayuki Hayashi, Scott Heatwole, Kun Hu, Ryo Imazawa, Daiki Ishi, Manabu Ishida, Fabian Kislat, Mózsi Kiss, Kassi Klepper, Henric Krawczynski, Haruki Kuramoto, R. James Lanzi, Lindsey Lisalda, Yoshitomo Maeda, Filip af Malmborg , et al. (24 additional authors not shown)

Abstract: We report measurements of the linear polarisation degree (PD) and angle (PA) for hard X-ray emission from the Crab pulsar and wind nebula. Measurements were made with the XL-Calibur ($\sim$15-80 keV) balloon-borne Compton-scattering polarimeter in July 2024. The polarisation parameters are determined using a Bayesian analysis of Stokes parameters obtained from X-ray scattering angles. Well-constra… ▽ More We report measurements of the linear polarisation degree (PD) and angle (PA) for hard X-ray emission from the Crab pulsar and wind nebula. Measurements were made with the XL-Calibur ($\sim$15-80 keV) balloon-borne Compton-scattering polarimeter in July 2024. The polarisation parameters are determined using a Bayesian analysis of Stokes parameters obtained from X-ray scattering angles. Well-constrained ($\sim$8.5$σ$) results are obtained for the polarisation of the $\sim$19-64 keV signal integrated over all pulsar phases: PD=(25.1$\pm$2.9)% and PA=(129.8$\pm$3.2)$^\circ$. In the off-pulse (nebula-dominated) phase range, the PD is constrained at $\sim$4.5$σ$ and is compatible with the phase-integrated result. The PA of the nebular hard X-ray emission aligns with that measured by IXPE in the 2-8 keV band for the toroidal inner region of the pulsar wind nebula, where the hard X-rays predominantly originate. For the main pulsar peak, PD=(32.8$^{+18.2}_{-28.5}$)% and PA=(156.0 $\pm$ 21.7)$^\circ$, while for the second peak (inter-pulse), PD=(0.0$^{+33.6}_{-0.0}$)% and PA=(154.5 $\pm$ 34.5)$^\circ$. A low level of polarisation in the pulsar peaks likely does not favour emission originating from the inner regions of the pulsar magnetosphere. Discriminating between Crab pulsar emission models will require deeper observations, e.g. with a satellite-borne hard X-ray polarimeter. △ Less

Submitted 18 August, 2025; v1 submitted 18 March, 2025; originally announced March 2025.

Comments: 8 pages, 4 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society; Stokes _uncertainties_ in Table 2 updated

Journal ref: Monthly Notices of the Royal Astronomical Society 540 (2025) L34-L40

ConjointNet: Enhancing Conjoint Analysis for Preference Prediction with Representation Learning

Authors: Yanxia Zhang, Francine Chen, Shabnam Hakimi, Totte Harinen, Alex Filipowicz, Yan-Ying Chen, Rumen Iliev, Nikos Arechiga, Kalani Murakami, Kent Lyons, Charlene Wu, Matt Klenk

Abstract: Understanding consumer preferences is essential to product design and predicting market response to these new products. Choice-based conjoint analysis is widely used to model user preferences using their choices in surveys. However, traditional conjoint estimation techniques assume simple linear models. This assumption may lead to limited predictability and inaccurate estimation of product attribu… ▽ More Understanding consumer preferences is essential to product design and predicting market response to these new products. Choice-based conjoint analysis is widely used to model user preferences using their choices in surveys. However, traditional conjoint estimation techniques assume simple linear models. This assumption may lead to limited predictability and inaccurate estimation of product attribute contributions, especially on data that has underlying non-linear relationships. In this work, we employ representation learning to efficiently alleviate this issue. We propose ConjointNet, which is composed of two novel neural architectures, to predict user preferences. We demonstrate that the proposed ConjointNet models outperform traditional conjoint estimate techniques on two preference datasets by over 5%, and offer insights into non-linear feature interactions. △ Less

Submitted 12 March, 2025; originally announced March 2025.

$Λ$(1405) in the flavor SU(3) limit using a separable potential in the HAL QCD method

Authors: Kotaro Murakami, Sinya Aoki

Abstract: Using the HAL QCD method, we investigate S-wave meson-baryon interactions in singlet and two octet channels in the flavor SU(3) limit, where the chiral unitary model predicts that a combination of bound-state poles in these channels corresponds to $Λ(1405)$. To avoid the singular behavior of the leading-order potentials of these channels in the derivative expansion, we instead employ a separable p… ▽ More Using the HAL QCD method, we investigate S-wave meson-baryon interactions in singlet and two octet channels in the flavor SU(3) limit, where the chiral unitary model predicts that a combination of bound-state poles in these channels corresponds to $Λ(1405)$. To avoid the singular behavior of the leading-order potentials of these channels in the derivative expansion, we instead employ a separable potential in the time-dependent HAL QCD method. To calculate all-to-all propagators in the three-point correlation functions including $Λ$-baryon source operators with zero momentum, we employ the conventional stochastic estimation combined with the covariant approximation averaging. Separable potentials both in the singlet and octet channels show attraction without singular behavior. Our results of the corresponding phase shifts indicate that the attractive interaction in the singlet channel is stronger than that in the octet. Binding energies are consistent with the estimates from the two-point correlation function within one (two) sigma for the singlet (octet) channel, and this ordering of binding energies is consistent with the mass hierarchy suggested by the chiral unitary model. △ Less

Submitted 29 January, 2025; originally announced January 2025.

Comments: 10 pages, 2 figures, Proceedings of the 41st International Symposium on Lattice Field Theory (LATTICE2024), 28 July - 3 August 2024, Liverpool, UK

Report number: RIKEN-iTHEMS-Report-25, YITP-25-11

Grassmann Tensor Renormalization Group for two-flavor massive Schwinger model with a theta term

Authors: Hayato Kanno, Shinichiro Akiyama, Kotaro Murakami, Shinji Takeda

Abstract: We investigate the $N_f=2$ Schwinger model with the massive staggered fermions in the presence of a $2π$ periodic $θ$ term, using the Grassmann tensor renormalization group. Thanks to the Grassmann tensor network formulation, there is no difficulty in dealing with the massive staggered fermions. We study the $θ$ dependence of the free energy in the thermodynamic limit. Our calculation provides con… ▽ More We investigate the $N_f=2$ Schwinger model with the massive staggered fermions in the presence of a $2π$ periodic $θ$ term, using the Grassmann tensor renormalization group. Thanks to the Grassmann tensor network formulation, there is no difficulty in dealing with the massive staggered fermions. We study the $θ$ dependence of the free energy in the thermodynamic limit. Our calculation provides consistent results with the analytical solution in the large mass limit. The results also suggest that the $N_f=2$ Schwinger model on a lattice has a different phase structure from that described by the continuum theory. △ Less

Submitted 23 January, 2025; originally announced January 2025.

Comments: 9 pages, 4 figures, Contribution to The 41st International Symposium on Lattice Field Theory (LATTICE2024), 28 July - 3 August 2024, Liverpool, UK

Report number: UTHEP-798, UTCCS-P-162, RIKEN-iTHEMS-Report-25

Phase and equation of state of finite density QC$_2$D at lower temperature

Authors: Etsuko Itou, Kei Iida, Kotaro Murakami, Daiki Suenaga

Abstract: We investigate the phase structure and the equation of state (EoS) for dense two-color QCD at low temperatures, $T = 40$ MeV ($32^4$ lattice) and $T = 80$ MeV ($16^4$ lattice). A rich phase structure below the pseudo-critical temperature $T_c$ as a function of quark chemical potential $μ$ has been revealed. By performing $T = 40$ MeV simulations, essentially similar results to the previous ones at… ▽ More We investigate the phase structure and the equation of state (EoS) for dense two-color QCD at low temperatures, $T = 40$ MeV ($32^4$ lattice) and $T = 80$ MeV ($16^4$ lattice). A rich phase structure below the pseudo-critical temperature $T_c$ as a function of quark chemical potential $μ$ has been revealed. By performing $T = 40$ MeV simulations, essentially similar results to the previous ones at $T = 80$ MeV are obtained, but several finer understandings are achieved. Breaking of the conformal bound is also confirmed thanks to smaller statistical errors. This talk is mainly based on Refs.~\cite{Iida:2022hyy, Iida:2024irv}. It also includes related studies and subsequent developments that were not mentioned in the original papers. △ Less

Submitted 25 December, 2024; originally announced December 2024.

Comments: 1+7+3pages; The 41st International Symposium on Lattice Field Theory (LATTICE2024), 28 July - 3 August 2024, Liverpool, UK

Report number: YITP-24-179, RIKEN-iTHEMS-Report-24

Grassmann tensor renormalization group for the massive Schwinger model with a $θ$ term using staggered fermions

Authors: Hayato Kanno, Shinichiro Akiyama, Kotaro Murakami, Shinji Takeda

Abstract: We use the Grassmann tensor renormalization group method to investigate the $N_f=2$ Schwinger model with the staggered fermions in the presence of a $2π$ periodic $θ$ term in a broad range of mass. The method allows us to deal with the massive staggered fermions straightforwardly and to study the $θ$ dependence of the free energy and topological charge in the thermodynamic limit. Our calculation p… ▽ More We use the Grassmann tensor renormalization group method to investigate the $N_f=2$ Schwinger model with the staggered fermions in the presence of a $2π$ periodic $θ$ term in a broad range of mass. The method allows us to deal with the massive staggered fermions straightforwardly and to study the $θ$ dependence of the free energy and topological charge in the thermodynamic limit. Our calculation provides consistent results with not only the analytical solution in the large mass limit but also the previous Monte Carlo studies in the small mass regime. Our numerical results also suggest that the $N_f=2$ Schwinger model on a lattice has a different phase structure, than the model in the continuum limit. △ Less

Submitted 11 November, 2025; v1 submitted 12 December, 2024; originally announced December 2024.

Comments: 37 pages, 11 figures

Report number: UTCCS-P-156, KANAZAWA 24-07, RIKEN-iTHEMS-Report-24

Wildfire Risk Metric Impact on Public Safety Power Shut-off Cost Savings

Authors: Ryan Greenough, Kohei Murakami, Jan Kleissl, Adil Khurram

Abstract: Public Safety Power Shutoffs (PSPS) are a proactive strategy to mitigate fire hazards from power system infrastructure failures. System operators employ PSPS to deactivate portions of the electric grid with heightened wildfire risks to prevent wildfire ignition and redispatch generators to minimize load shedding. A measure of vegetation flammability, called the Wildland Fire Potential Index (WFPI)… ▽ More Public Safety Power Shutoffs (PSPS) are a proactive strategy to mitigate fire hazards from power system infrastructure failures. System operators employ PSPS to deactivate portions of the electric grid with heightened wildfire risks to prevent wildfire ignition and redispatch generators to minimize load shedding. A measure of vegetation flammability, called the Wildland Fire Potential Index (WFPI), has been widely used to evaluate the risk of nearby wildfires to power system operation. However, the WFPI does not correlate as strongly to historically observed wildfire ignition probabilities (OWIP) as WFPI-based the Large Fire Probability (WLFP).Prior work chose not to incorporate wildfire-driven failure probabilities, such as the WLFP, because constraints with Bernoulli random variables to represent wildfire ignitions could require non-linear or non-convex constraints. This paper uses a deterministic equivalent of an otherwise complicating line de-energization constraint by quantifying the wildfire risk of operating transmission line as a sum of each energized line's wildfire ignition log probability (log(WIP)) rather than as a sum of each energized line's WFPI. A day-ahead unit commitment and line de-energization PSPS framework is used to assess the cost differences driven by the choice between the WFPI and WLFP risk metrics. Training the optimization on scenarios developed by mapping WLFP to log(WIP) rather than mapping the WFPI to log(WIP) leads to reductions in the total real-time costs. For the IEEE RTS 24-bus test system, mapping transmission line WLFP values to log(WIP) resulted in a 14.8 % (on average) decrease in expected real-time costs. △ Less

Submitted 16 November, 2024; originally announced November 2024.

Comments: 10 pages, 9 figures, 2 tables

Mini-Proceedings of the "Fourth International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility (HEF-ex 2024)"

Authors: P. Achenbach, K. Aoki, S. Aoki, C. Curceanu, S. Diehl, T. Doi, M. Endo, M. Fujita, T. Fukuda, H. Garcia-Tecocoatzi, L. S. Geng, T. Gunji, C. Hanhart, M. Harada, T. Harada, S. Hayakawa, B. R. He, E. Hiyama, R. Honda, Y. Ichikawa, M. Isaka, D. Jido, A. Jinno, K. Kamada, Y. Kamiya , et al. (36 additional authors not shown)

Abstract: The mini proceedings of the "Fourth International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility (HEF-ex 2024) [https://kds.kek.jp/event/46965]" held at J-PARC, February 19-21, 2024, are presented. The workshop was devoted to discussing the physics case that connects both the present and the future Hadron Experimental Facility at J-PARC, covering a wide range of topi… ▽ More The mini proceedings of the "Fourth International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility (HEF-ex 2024) [https://kds.kek.jp/event/46965]" held at J-PARC, February 19-21, 2024, are presented. The workshop was devoted to discussing the physics case that connects both the present and the future Hadron Experimental Facility at J-PARC, covering a wide range of topics in flavor, hadron, and nuclear physics related to both experimental and theoretical activities being conducted at the facility. △ Less

Submitted 31 August, 2024; originally announced September 2024.

Plant Robots: Harnessing Growth Actuation of Plants for Locomotion and Object Manipulation

Authors: Kazuya Murakami, Misao Sato, Momoki Kubota, Jun Shintake

Abstract: Plants display physical displacements during their growth due to photosynthesis, which converts light into chemical energy. This can be interpreted as plants acting as actuators with a built-in power source. This paper presents a method to create plant robots that move and perform tasks by harnessing the actuation output of plants: displacement and force generated from the growing process. As the… ▽ More Plants display physical displacements during their growth due to photosynthesis, which converts light into chemical energy. This can be interpreted as plants acting as actuators with a built-in power source. This paper presents a method to create plant robots that move and perform tasks by harnessing the actuation output of plants: displacement and force generated from the growing process. As the target plant, radish sprouts are employed, and their displacement and force are characterized, followed by the calculation of power and energy densities. Based on the characterization, two different plant robots are designed and fabricated: a rotational robot and a gripper. The former demonstrates ground locomotion, achieving a travel distance of 14.6 mm with an average speed of 0.8 mm/h. The latter demonstrates the picking and placing of an object with a 0.1-g mass by the light-controlled open-close motion of plant fingers. A good agreement between the experimental and model values is observed in the specific data of the mobile robot, suggesting that obtaining the actuation characteristics of plants can enable the design and prediction of behavior in plant robots. These results pave the way for the realization of novel types of environmentally friendly and sustainable robots. △ Less

Submitted 25 September, 2024; v1 submitted 23 July, 2024; originally announced July 2024.

Comments: 16 pages, 4 figures

Journal ref: Advanced Science, 2024

Scale setting and hadronic properties in light quark sector with $(2+1)$-flavor Wilson fermions at the physical point

Authors: Tatsumi Aoyama, Takahiro M. Doi, Takumi Doi, Etsuko Itou, Yan Lyu, Kotaro Murakami, Takuya Sugiura

Abstract: We report scale setting and hadronic properties for our new lattice QCD gauge configuration set (HAL-conf-2023). We employ $(2+1)$-flavor nonperturbatively improved Wilson fermions with stout smearing and the Iwasaki gauge action on a $96^4$ lattice, and generate configurations of 8,000 trajectories at the physical point. We show the basic properties of the configurations such as the plaquette val… ▽ More We report scale setting and hadronic properties for our new lattice QCD gauge configuration set (HAL-conf-2023). We employ $(2+1)$-flavor nonperturbatively improved Wilson fermions with stout smearing and the Iwasaki gauge action on a $96^4$ lattice, and generate configurations of 8,000 trajectories at the physical point. We show the basic properties of the configurations such as the plaquette value, topological charge distribution and their auto-correlation times. The scale setting is performed by detailed analyses of the $Ω$ baryon mass. We calculate the physical results of quark masses, decay constants of pseudoscalar mesons and single hadron spectra in light quark sector. The masses of the stable hadrons are found to agree with the experimental values within a sub-percent level. △ Less

Submitted 10 November, 2024; v1 submitted 24 June, 2024; originally announced June 2024.

Comments: 32 pages and 18 figures; v2: reference(s) added; v3: accepted for publication in Phys. Rev. D; v4: typo(s) corrected, published version

Report number: RIKEN-iTHEMS-Report-24, YITP-24-73

Journal ref: Phys. Rev. D 110, 094502 (2024)

Predicting drug-gene relations via analogy tasks with word embeddings

Authors: Hiroaki Yamagiwa, Ryoma Hashimoto, Kiwamu Arakane, Ken Murakami, Shou Soeda, Momose Oyama, Yihua Zhu, Mariko Okada, Hidetoshi Shimodaira

Abstract: Natural language processing (NLP) is utilized in a wide range of fields, where words in text are typically transformed into feature vectors called embeddings. BioConceptVec is a specific example of embeddings tailored for biology, trained on approximately 30 million PubMed abstracts using models such as skip-gram. Generally, word embeddings are known to solve analogy tasks through simple vector ar… ▽ More Natural language processing (NLP) is utilized in a wide range of fields, where words in text are typically transformed into feature vectors called embeddings. BioConceptVec is a specific example of embeddings tailored for biology, trained on approximately 30 million PubMed abstracts using models such as skip-gram. Generally, word embeddings are known to solve analogy tasks through simple vector arithmetic. For example, subtracting the vector for man from that of king and then adding the vector for woman yields a point that lies closer to queen in the embedding space. In this study, we demonstrate that BioConceptVec embeddings, along with our own embeddings trained on PubMed abstracts, contain information about drug-gene relations and can predict target genes from a given drug through analogy computations. We also show that categorizing drugs and genes using biological pathways improves performance. Furthermore, we illustrate that vectors derived from known relations in the past can predict unknown future relations in datasets divided by year. Despite the simplicity of implementing analogy tasks as vector additions, our approach demonstrated performance comparable to that of large language models such as GPT-4 in predicting drug-gene relations. △ Less

Submitted 27 May, 2025; v1 submitted 3 June, 2024; originally announced June 2024.

Journal ref: Sci Rep 15, 17240 (2025)

Lattice study on finite density QC$_2$D towards zero temperature

Authors: Kei Iida, Etsuko Itou, Kotaro Murakami, Daiki Suenaga

Abstract: We investigate the phase structure and the equation of state (EoS) for dense two-color QCD (QC$_2$D) at low temperature ($T = 40$ MeV, $32^4$ lattice) for the purpose of extending our previous works~\cite{Iida:2019rah, Iida:2022hyy} at $T=80$ MeV ($16^4$ lattice). Indeed, a rich phase structure below the pseudo-critical temperature $T_c$ as a function of quark chemical potential $μ$ has been revea… ▽ More We investigate the phase structure and the equation of state (EoS) for dense two-color QCD (QC$_2$D) at low temperature ($T = 40$ MeV, $32^4$ lattice) for the purpose of extending our previous works~\cite{Iida:2019rah, Iida:2022hyy} at $T=80$ MeV ($16^4$ lattice). Indeed, a rich phase structure below the pseudo-critical temperature $T_c$ as a function of quark chemical potential $μ$ has been revealed, but finite volume effects in a high-density regime sometimes cause a wrong understanding. Therefore, it is important to investigate the temperature dependence down to zero temperature with large-volume simulations. By performing $32^4$ simulations, we obtain essentially similar results to the previous ones, but we are now allowed to get a fine understanding of the phase structure via the temperature dependence. Most importantly, we find that the hadronic-matter phase, which is composed of thermally excited hadrons, shrinks with decreasing temperature and that the diquark condensate scales as $\langle qq \rangle \propto μ^2$ in the BCS phase, a property missing at $T=80$ MeV. From careful analyses, furthermore, we confirm a tentative conclusion that the topological susceptibility is independent of $μ$. We also show the temperature dependence of the pressure, internal energy, and sound velocity as a function of $μ$. The pressure increases around the hadronic-superfluid phase transition more rapidly at the lower temperature, while the temperature dependence of the sound velocity is invisible. Breaking of the conformal bound is also confirmed thanks to the smaller statistical error. △ Less

Submitted 24 July, 2024; v1 submitted 30 May, 2024; originally announced May 2024.

Comments: 29 pages, 11 figures, (v2) minor update, a reference added

Report number: YITP-24-68, RIKEN-iTHEMS-Report-24

RakutenAI-7B: Extending Large Language Models for Japanese

Authors: Rakuten Group, Aaron Levine, Connie Huang, Chenguang Wang, Eduardo Batista, Ewa Szymanska, Hongyi Ding, Hou Wei Chou, Jean-François Pessiot, Johanes Effendi, Justin Chiu, Kai Torben Ohlhus, Karan Chopra, Keiji Shinzato, Koji Murakami, Lee Xiong, Lei Chen, Maki Kubota, Maksim Tkachenko, Miroku Lee, Naoki Takahashi, Prathyusha Jwalapuram, Ryutaro Tatsushima, Saurabh Jain, Sunil Kumar Yadav , et al. (5 additional authors not shown)

Abstract: We introduce RakutenAI-7B, a suite of Japanese-oriented large language models that achieve the best performance on the Japanese LM Harness benchmarks among the open 7B models. Along with the foundation model, we release instruction- and chat-tuned models, RakutenAI-7B-instruct and RakutenAI-7B-chat respectively, under the Apache 2.0 license. We introduce RakutenAI-7B, a suite of Japanese-oriented large language models that achieve the best performance on the Japanese LM Harness benchmarks among the open 7B models. Along with the foundation model, we release instruction- and chat-tuned models, RakutenAI-7B-instruct and RakutenAI-7B-chat respectively, under the Apache 2.0 license. △ Less

Submitted 21 March, 2024; originally announced March 2024.

Wildfire Resilient Unit Commitment under Uncertain Demand

Authors: Ryan Greenough, Kohei Murakami, Michael Davidson, Jan Kleissl, Adil Khurram

Abstract: Public safety power shutoffs (PSPS) are a common pre-emptive measure to reduce wildfire risk due to power system equipment. System operators use PSPS to de-energize electric grid elements that are either prone to failure or located in regions at a high risk of experiencing a wildfire. Successful power system operation during PSPS involves coordination across different time scales. Adjustments to g… ▽ More Public safety power shutoffs (PSPS) are a common pre-emptive measure to reduce wildfire risk due to power system equipment. System operators use PSPS to de-energize electric grid elements that are either prone to failure or located in regions at a high risk of experiencing a wildfire. Successful power system operation during PSPS involves coordination across different time scales. Adjustments to generator commitments and transmission line de-energizations occur at day-ahead intervals while adjustments to load servicing occur at hourly intervals. Generator commitments and operational decisions have to be made under uncertainty in electric grid demand and wildfire potential forecasts. This paper presents deterministic and two-stage mean-CVaR stochastic frameworks to show how the likelihood of large wildfires near transmission lines affects generator commitment and transmission line de-energization strategies. The optimal costs of commitment, operation, and lost load on the IEEE 14-bus test system are compared to the costs generated from prior optimal power shut-off (OPS) formulations. The proposed mean-CVaR stochastic program generates less total expected costs evaluated with respect to higher demand scenarios than costs generated by risk-neutral and deterministic methods. △ Less

Submitted 14 March, 2024; originally announced March 2024.

Comments: 10 pages, 7 figures, 5 tables

Differentiating Warm Dark Matter Models through 21cm Line Intensity Mapping: A Convolutional Neural Network Approach

Authors: Koya Murakami, Kenji Kadota, Atsushi J. Nishizawa, Kentaro Nagamine, Ikkoh Shimizu

Abstract: We apply the convolutional neural networks (CNNs) to the mock 21cm maps from the post-reionization epoch to show that the $Λ$ cold dark matter and warm dark matter (WDM) model can be distinguished for WDM particle masses $m_{FD}<3$\,keV, under the assumption of thermal production of WDM following the Fermi-Dirac (FD) distribution. We demonstrate that the CNN is a potent tool in distinguishing the… ▽ More We apply the convolutional neural networks (CNNs) to the mock 21cm maps from the post-reionization epoch to show that the $Λ$ cold dark matter and warm dark matter (WDM) model can be distinguished for WDM particle masses $m_{FD}<3$\,keV, under the assumption of thermal production of WDM following the Fermi-Dirac (FD) distribution. We demonstrate that the CNN is a potent tool in distinguishing the dark matter masses, highlighting its sensitivity to the subtle differences in the 21cm maps produced by varying dark matter masses. Furthermore, we extend our analysis to encompass different WDM production mechanisms, recognizing that the dark matter production mechanism in the early Universe is among the sources of the most significant uncertainty for the dark matter model building. In this work, given the mass of the dark matter, we discuss the feasibility of discriminating four different WDM models: Fermi-Dirac (FD) distribution model, neutrino minimal Standard Model ($ν$MSM), Dodelson-Widrow (DW), and Shi-Fuller (SF) model. For instance, when the WDM mass is 2\,keV, we show that one can differentiate between CDM, FD, $ν$MSM, and DW models while discerning between the DW and SF models turns out to be challenging. Our results reinforce the viability of the CNN as a robust analysis for 21cm maps and shed light on its potential to unravel the features associated with different dark matter production mechanisms. △ Less

Submitted 20 July, 2024; v1 submitted 10 March, 2024; originally announced March 2024.

Comments: 16 pages, 13 figures, published in PRD

Mass spectrum of spin-one hadrons in dense two-color QCD: Novel predictions by extended linear sigma model

Authors: Daiki Suenaga, Kotaro Murakami, Etsuko Itou, Kei Iida

Abstract: We construct an extended version of the linear sigma model in such a way as to describe spin-$1$ hadrons as well as spin-$0$ hadrons in two-color QCD (QC$_2$D) by respecting the Pauli-Gürsey $SU(4)$ symmetry. Within a mean-field approximation, we therefrom examine a mass spectrum of the spin-$1$ hadrons at finite quark chemical potential ($μ_q$) and zero temperature. Not only mean fields of scalar… ▽ More We construct an extended version of the linear sigma model in such a way as to describe spin-$1$ hadrons as well as spin-$0$ hadrons in two-color QCD (QC$_2$D) by respecting the Pauli-Gürsey $SU(4)$ symmetry. Within a mean-field approximation, we therefrom examine a mass spectrum of the spin-$1$ hadrons at finite quark chemical potential ($μ_q$) and zero temperature. Not only mean fields of scalar mesons and scalar-diquark baryons but also of vector mesons and vector-diquark baryons are incorporated. As a result, we find that, unless all of those four types of mean fields are taken into account, neither lattice result for the critical $μ_q$ that corresponds to the onset of baryon superfluidity nor for $μ_q$ dependence of the pion mass can be reproduced. We also find that a slight suppression of the $ρ$ meson mass in the superfluid phase, which was suggested by the lattice simulation, is reproduced by subtle mixing effects between spin-$0$ and spin-$1$ hadrons. Moreover, we demonstrate the emergence of an axialvector condensed phase and possibly of a vector condensed phase by identifying the values of $μ_q$ at which the corresponding hadron masses vanish. The possible presence of iso-triplet $1^-$ diquarks that may be denoted by a tensor-type quark bilinear field is also discussed. △ Less

Submitted 28 December, 2023; originally announced December 2023.

Comments: 24 pages, 11 figures

Report number: YITP-23-172, RIKEN-iTHEMS-Report-23

Study on Lambda(1405) in the flavor SU(3) limit in the HAL QCD method

Authors: Kotaro Murakami, Sinya Aoki

Abstract: We study interactions between the S-wave octet pseudo-scalar (PS) meson and octet baryon in the flavor SU(3) limit using the HAL QCD method at the PS meson mass $m_M\approx 670~\textrm{MeV}$. We focus on the singlet and two octet channels, where the poles corresponding to $Λ(1405)$ have been predicted in the chiral unitary model. For calculations with $Λ$-baryon source operators with zero momentum… ▽ More We study interactions between the S-wave octet pseudo-scalar (PS) meson and octet baryon in the flavor SU(3) limit using the HAL QCD method at the PS meson mass $m_M\approx 670~\textrm{MeV}$. We focus on the singlet and two octet channels, where the poles corresponding to $Λ(1405)$ have been predicted in the chiral unitary model. For calculations with $Λ$-baryon source operators with zero momentum, we employ the conventional stochastic calculation combined with the covariant-approximation averaging to calculate the all-to-all propagators. Due to a zero of the R-correlator (a kind of wave function), the leading order (LO) potential obtained by the single channel analysis has a singular point in all channels, which makes it difficult to obtain reliable binding energies. To overcome this problem, we take a linear combination of two octet R-correlators with a relative weight such that it does not cross zero, as two octet channels are suggested to couple to the same low-energy states with different weights. The potential calculated from such the linear combination shows strong attraction without singularities, though its shape depends on the relative weight. Our estimation for the binding energy in the octet channel is $E^{8_{s(a)}}_{\textrm{bind}}=163(7)(^{+16} _{-64})~\textrm{MeV}$, which is consistent with 156(8) MeV estimated from the two-point correlation function within errors. △ Less

Submitted 29 November, 2023; originally announced November 2023.

Comments: 7 pages, 2 figures, 2 tables, Proceedings of the 40th International Symposium on Lattice Field Theory (Lattice 2023) at Fermilab, Batavia, Illinois, USA, from July 31 to August 4, 2023

Report number: YITP-23-153, RIKEN-iTHEMS-Report-23

Chemical potential (in)dependence of hadron scatterings in the hadronic phase of QCD-like theories and its applications

Authors: Kotaro Murakami, Etsuko Itou, Kei Iida

Abstract: We formulate a method for calculating the hadron-hadron scattering amplitudes at nonzero chemical potential ($μ$) in the hadronic phase at zero temperature, where the baryon number symmetry remains to be violated. Although it is widely believed that the physical quantities do not change even if we turn on a small $μ$ at zero temperature, the shape of correlation functions for a single hadron depen… ▽ More We formulate a method for calculating the hadron-hadron scattering amplitudes at nonzero chemical potential ($μ$) in the hadronic phase at zero temperature, where the baryon number symmetry remains to be violated. Although it is widely believed that the physical quantities do not change even if we turn on a small $μ$ at zero temperature, the shape of correlation functions for a single hadron depends on $μ$. Then, the dispersion relation of the single hadron is modified to $E({\bf p},μ) = \sqrt{{\bf p}^2+m^2}-μn_{O}$. Here, $m$ and $n_O$ denote the hadron mass at $μ=0$ and the quantum number, respectively. From this relation, it is possible that the effective mass of the hadron depends on $μ$. We extend the HAL QCD method at $μ=0$ to the case of $μ\ne 0$, which allows us to extract the scattering phase shifts via the interaction potential. We have found that the interaction potential can depend on $μ$ only through the effective mass while the scattering phase shifts, obtained by solving the Schrödinger equation with the interaction potential, are independent of $μ$. We also numerically analyze the S-wave scatterings of two pions with isospin $I=2$ and two scalar diquarks within the framework of QC$_{2}$D at nonzero quark chemical potential. While the lattice is not exactly set to zero temperature, the $μ$-independence can be observed. Furthermore, we improve the results for the S-wave scatterings of two hadrons obtained above by taking the $μ$-independence for granted. Thanks to the asymmetric property of the correlation functions for diquarks at $μ\neq0$, we can access a long-$τ$ regime and can reduce the systematic error coming from inelastic contributions. △ Less

Submitted 31 January, 2024; v1 submitted 15 September, 2023; originally announced September 2023.

Comments: 33 pages, 13 figures, (ver2) minor improvements

Report number: YITP-23-112, RIKEN-iTHEMS-Report-23

Non-Linearity-Free prediction of the growth-rate $fσ_8$ using Convolutional Neural Networks

Authors: Koya Murakami, Indira Ocampo, Savvas Nesseris, Atsushi J. Nishizawa, Sachiko Kuroyanagi

Abstract: The growth-rate $fσ_8(z)$ of the large-scale structure of the Universe is an important dynamic probe of gravity that can be used to test for deviations from General Relativity. However, for galaxy surveys to extract this key quantity from cosmological observations, two important assumptions have to be made: i) a fiducial cosmological model, typically taken to be the cosmological constant and cold… ▽ More The growth-rate $fσ_8(z)$ of the large-scale structure of the Universe is an important dynamic probe of gravity that can be used to test for deviations from General Relativity. However, for galaxy surveys to extract this key quantity from cosmological observations, two important assumptions have to be made: i) a fiducial cosmological model, typically taken to be the cosmological constant and cold dark matter ($Λ$CDM) model and ii) the modeling of the observed power spectrum, especially at non-linear scales, which is particularly dangerous as most models used in the literature are phenomenological at best. In this work, we propose a novel approach involving convolutional neural networks (CNNs), trained on the Quijote N-body simulations, to predict $fσ_8(z)$ directly and without assuming a model for the non-linear part of the power spectrum, thus avoiding the second of the assumptions above. This could serve as an initial step towards the future development of a method for parameter inference in Stage IV surveys. We find that the predictions for the value of $fσ_8$ from the CNN are in excellent agreement with the fiducial values since they outperform a maximum likelihood analysis and the CNN trained on the power spectrum. Therefore, we find that the CNN reconstructions provide a viable alternative to avoid the theoretical modeling of the non-linearities at small scales when extracting the growth rate. △ Less

Submitted 20 July, 2024; v1 submitted 22 May, 2023; originally announced May 2023.

Comments: 15 pages, 5 figures, 5 tables

Report number: IFT-UAM/CSIC-23-57

Impact of astrophysical effects on the dark matter mass constraint with 21cm intensity mapping

Authors: Koya Murakami, Atsushi J. Nishizawa, Kentaro Nagamine, Ikko Shimizu

Abstract: We present an innovative approach to constraining the non-cold dark matter model using a convolutional neural network (CNN). We perform a suite of hydrodynamic simulations with varying dark matter particle masses and generate mock 21cm radio intensity maps to trace the dark matter distribution. Our proposed method complements the traditional power spectrum analysis. We compare our CNN classificati… ▽ More We present an innovative approach to constraining the non-cold dark matter model using a convolutional neural network (CNN). We perform a suite of hydrodynamic simulations with varying dark matter particle masses and generate mock 21cm radio intensity maps to trace the dark matter distribution. Our proposed method complements the traditional power spectrum analysis. We compare our CNN classification results with those from the power spectrum of the differential brightness temperature map of 21cm radiation, and find that the CNN outperforms the latter. Moreover, we investigate the impact of baryonic physics on the dark matter model constraint, including star formation, self-shielding of HI gas, and UV background model. We find that these effects may introduce some contamination in the dark matter constraint, but they are insignificant when compared to the realistic system noise of the SKA instruments. △ Less

Submitted 21 April, 2024; v1 submitted 2 May, 2023; originally announced May 2023.

Comments: 16 pages, 15 figures

Deformed Cartan matrices and generalized preprojective algebras II: General type

Authors: Ryo Fujita, Kota Murakami

Abstract: We propose a definition of deformed symmetrizable generalized Cartan matrices with several deformation parameters, which admit a categorical interpretation by graded modules over the generalized preprojective algebras in the sense of Geiß-Leclerc-Schröer. Using the categorical interpretation, we deduce a combinatorial formula for the inverses of our deformed Cartan matrices in terms of braid group… ▽ More We propose a definition of deformed symmetrizable generalized Cartan matrices with several deformation parameters, which admit a categorical interpretation by graded modules over the generalized preprojective algebras in the sense of Geiß-Leclerc-Schröer. Using the categorical interpretation, we deduce a combinatorial formula for the inverses of our deformed Cartan matrices in terms of braid group actions. Under a certain condition, which is satisfied in all the symmetric cases or in all the finite and affine cases, our definition coincides with that of the mass-deformed Cartan matrices introduced by Kimura-Pestun in their study of quiver $\mathcal{W}$-algebras. △ Less

Submitted 4 February, 2024; v1 submitted 28 February, 2023; originally announced February 2023.

Comments: 27 pages, v2: final version, minor corrections

MSC Class: 16G20; 17B37; 16W50; 17B67; 81R50

Journal ref: Math. Z. 305, 63 (2023)

Measurement of hadron masses in 2-color finite density QCD

Authors: Kotaro Murakami, Daiki Suenaga, Kei Iida, Etsuko Itou

Abstract: We investigate hadron spectra in 2-color QCD using lattice simulation with $N_{f}=2$ at low temperature and finite density in which there appears not only the hadronic phase but also the superfluid phase. We first calculate the pion and rho meson spectrum, which is well-known from previous works. The spectral ordering of these mesons flips around the quark chemical potential $μ=m^{0}_π/2$ (… ▽ More We investigate hadron spectra in 2-color QCD using lattice simulation with $N_{f}=2$ at low temperature and finite density in which there appears not only the hadronic phase but also the superfluid phase. We first calculate the pion and rho meson spectrum, which is well-known from previous works. The spectral ordering of these mesons flips around the quark chemical potential $μ=m^{0}_π/2$ ($m^{0}_π$: the pion mass at $μ=0$), where the phase transition between the hadronic and superfluid phases occurs. For $μ\gtrsim m^{0}_π/2$, the effective mass for the pion linearly increases while the one for the rho meson monotonically decreases. Furthermore, we measure hadron spectra with the isospin $I=0$ and the angular momentum $J^{P}=0^{\pm}$. The effective masses for the meson, diquark, and antidiquark with the same quantum number become degenerate just below $μ= m^{0}_π/2$, and the three hadrons have the same mass in the superfluid phase. It suggests that mixing occurs between spectra associating with mesons and baryons due to the $U(1)_{B}$ symmetry breaking. This phenomenon can be explained in the linear sigma model with the approximate $SU(4)$ Pauli-Gursey symmetry. △ Less

Submitted 24 November, 2022; originally announced November 2022.

Comments: 9 pages, 5 figures, Proceedings of the 39th International Symposium on Lattice Field Theory, 8th-13th August 2022, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany

Report number: YITP-22-146, RIKEN-iTHEMS-Report-22

Probing the hadron mass spectrum in dense two-color QCD with the linear sigma model

Authors: Daiki Suenaga, Kotaro Murakami, Etsuko Itou, Kei Iida

Abstract: We investigate modifications of hadron masses at finite quark chemical potential in two-flavor and two-color QCD, of which the data are available from lattice simulations, within a linear sigma model based on approximate Pauli-Gursey $SU(4)$ symmetry. The model describes not only ground-state scalar diquarks and pseudo-scalar mesons but also the excited pseudo-scalar diquarks and scalar mesons; ea… ▽ More We investigate modifications of hadron masses at finite quark chemical potential in two-flavor and two-color QCD, of which the data are available from lattice simulations, within a linear sigma model based on approximate Pauli-Gursey $SU(4)$ symmetry. The model describes not only ground-state scalar diquarks and pseudo-scalar mesons but also the excited pseudo-scalar diquarks and scalar mesons; each ground-state diquark (meson) has the corresponding excited diquark (hadron) with opposite parity as a chiral partner. Effects of chiral symmetry breaking and diquark condensates are incorporated by a mean-field treatment. We show that various mixings among the hadrons, which are triggered by the breakdown of baryon number conservation in the superfluid phase, lead to a rich hadron mass spectrum. We discuss the influence of $U(1)_A$ anomaly on the density dependence of the mass spectrum and also manifestations of the chiral partner structures as density increases in the superfluid phase. The predicted hadron masses are expected to provide future lattice simulations with useful information on such symmetry properties in dense two-color QCD. △ Less

Submitted 3 March, 2023; v1 submitted 3 November, 2022; originally announced November 2022.

Comments: 16 pages, 6 figures

Report number: RIKEN-iTHEMS-Report-22, YITP-22-127

Journal ref: Phys.Rev.D 107, 054001 (2023)

Lattice QCD studies on decuplet baryons as meson-baryon bound states in the HAL QCD method

Authors: Kotaro Murakami, Yutaro Akahoshi, Sinya Aoki, Takumi Doi, Kenji Sasaki

Abstract: We study decuplet baryons from meson-baryon interactions in lattice QCD, in particular, $Δ$ and $Ω$ baryons from P-wave $I=3/2$ $Nπ$ and $I=0$ $Ξ\bar{K}$ interactions, respectively. Interaction potentials are calculated in the HAL QCD method using 3-quark-type source operators at $m_π \approx 410~\textrm{MeV}$ and $m_{K} \approx 635~\textrm{MeV}$, where $Δ$ as well as $Ω$ baryons are stable. We us… ▽ More We study decuplet baryons from meson-baryon interactions in lattice QCD, in particular, $Δ$ and $Ω$ baryons from P-wave $I=3/2$ $Nπ$ and $I=0$ $Ξ\bar{K}$ interactions, respectively. Interaction potentials are calculated in the HAL QCD method using 3-quark-type source operators at $m_π \approx 410~\textrm{MeV}$ and $m_{K} \approx 635~\textrm{MeV}$, where $Δ$ as well as $Ω$ baryons are stable. We use the conventional stochastic estimate of all-to-all propagators combined with the all-mode averaging to reduce statistical fluctuations. We have found that the $Ξ\bar K$ system has a weaker attraction than the $Nπ$ system while the binding energy from the threshold is larger for $Ω$ than $Δ$. This suggests that an inequality $m_{N}+m_π-m_Δ<m_Ξ+m_{\bar K}-m_Ω$ comes mainly from a smaller spatial size of a $Ξ\bar K$ bound state due to a larger reduced mass, rather than its interaction. Root-mean-square distances of bound states in both systems are small, indicating that $Δ$ and $Ω$ are tightly bound states and thus can be regarded qualitatively as composite states of 3 quarks. Results of binding energies agree with those obtained from temporal 2-point functions within large systematic errors, which arise dominantly from the lattice artifact at short distances. △ Less

Submitted 27 April, 2023; v1 submitted 11 October, 2022; originally announced October 2022.

Comments: 28 pages, 14 figures, 4 tables

Report number: YITP-22-113, RIKEN-iTHEMS-Report-22

AutoQC: Automated Synthesis of Quantum Circuits Using Neural Network

Authors: Kentaro Murakami, Jianjun Zhao

Abstract: While the ability to build quantum computers is improving dramatically, developing quantum algorithms is limited and relies on human insight and ingenuity. Although a number of quantum programming languages have been developed, it is challenging for software developers who are not familiar with quantum computing to learn and use these languages. It is, therefore, necessary to develop tools to supp… ▽ More While the ability to build quantum computers is improving dramatically, developing quantum algorithms is limited and relies on human insight and ingenuity. Although a number of quantum programming languages have been developed, it is challenging for software developers who are not familiar with quantum computing to learn and use these languages. It is, therefore, necessary to develop tools to support developing new quantum algorithms and programs automatically. This paper proposes AutoQC, an approach to automatically synthesizing quantum circuits using the neural network from input and output pairs. We consider a quantum circuit a sequence of quantum gates and synthesize a quantum circuit probabilistically by prioritizing with a neural network at each step. The experimental results highlight the ability of AutoQC to synthesize some essential quantum circuits at a lower cost. △ Less

Submitted 6 October, 2022; originally announced October 2022.

Comments: 9 pages, 15 figures

Finite element method modeling of expansion of irradiated rocks: focusing on the minerals

Authors: Y. Oida, S. Sakuragi, T. Igari, Y. Nakajima, E. Ro, F. Shimizu, M. Futami, Y. Hakozaki, T. Ohkubo, H. Ishikawa, S. Takada, S. Sawada, K. Murakami, K. Suzuki, I. Maruyama

Abstract: Finite element method (FEM) modeling of the volumetric expansion phenomenon associated with the accumulation of irradiation was performed on rocks in a concrete for nuclear power plant. The FEM mesh of sandstone, tuff, and granite was created based on microscopic images, and the volumetric expansion due to irradiation was calculated. The saturated value of the volume expansion due to irradiation a… ▽ More Finite element method (FEM) modeling of the volumetric expansion phenomenon associated with the accumulation of irradiation was performed on rocks in a concrete for nuclear power plant. The FEM mesh of sandstone, tuff, and granite was created based on microscopic images, and the volumetric expansion due to irradiation was calculated. The saturated value of the volume expansion due to irradiation accumulation was calculated, and it was shown that the saturated value of the volume expansion was well explained by the experimental value. In addition, the FEM analysis indicates that irradiation-induced degradation of rock propagates through a localized concentration of stress followed by fracture with cracks spreading throughout the rock. △ Less

Submitted 6 June, 2022; originally announced June 2022.

Comments: 5 pages, 4 figures

Understanding and Shifting Preferences for Battery Electric Vehicles

Authors: Nikos Arechiga, Francine Chen, Rumen Iliev, Emily Sumner, Scott Carter, Alex Filipowicz, Nayeli Bravo, Monica Van, Kate Glazko, Kalani Murakami, Laurent Denoue, Candice Hogan, Katharine Sieck, Charlene Wu, Kent Lyons

Abstract: Identifying personalized interventions for an individual is an important task. Recent work has shown that interventions that do not consider the demographic background of individual consumers can, in fact, produce the reverse effect, strengthening opposition to electric vehicles. In this work, we focus on methods for personalizing interventions based on an individual's demographics to shift the pr… ▽ More Identifying personalized interventions for an individual is an important task. Recent work has shown that interventions that do not consider the demographic background of individual consumers can, in fact, produce the reverse effect, strengthening opposition to electric vehicles. In this work, we focus on methods for personalizing interventions based on an individual's demographics to shift the preferences of consumers to be more positive towards Battery Electric Vehicles (BEVs). One of the constraints in building models to suggest interventions for shifting preferences is that each intervention can influence the effectiveness of later interventions. This, in turn, requires many subjects to evaluate effectiveness of each possible intervention. To address this, we propose to identify personalized factors influencing BEV adoption, such as barriers and motivators. We present a method for predicting these factors and show that the performance is better than always predicting the most frequent factors. We then present a Reinforcement Learning (RL) model that learns the most effective interventions, and compare the number of subjects required for each approach. △ Less

Submitted 8 February, 2022; originally announced February 2022.

Comments: 5 pages, 5 figures

Application of Particle Swarm Optimization method to On-going Monitoring for estimating vehicle-bridge interaction system

Authors: Kyosuke Yamamoto, Kakeru Murakami, Ryota Shin, Yukihiko Okada

Abstract: This study proposes a method for estimating the mechanical parameters of vehicles and bridges and the road unevenness, using only vehicle vibration and position data. In the proposed method, vehicle input and bridge vibration are estimated using randomly assumed vehicle and bridge parameters. Then, the road profiles at the front and rear wheels can be determined from the vehicle input and bridge v… ▽ More This study proposes a method for estimating the mechanical parameters of vehicles and bridges and the road unevenness, using only vehicle vibration and position data. In the proposed method, vehicle input and bridge vibration are estimated using randomly assumed vehicle and bridge parameters. Then, the road profiles at the front and rear wheels can be determined from the vehicle input and bridge vibration. The difference between the two road profiles is used as the objective function because they are expected to coincide when synchronized. Using the particle swarm optimization (PSO) method, the vehicle and bridge parameters and the road unevenness can be estimated by updating the parameters to minimize the objective function. Numerical experiments also verify the applicability of this method. In the numerical experiments, it is confirmed that the proposed method can estimate the vehicle weight with reasonable accuracy, but the accuracy of other parameters is not sufficient. It is necessary to improve the accuracy of the proposed method in the future. △ Less

Submitted 20 January, 2022; originally announced January 2022.

Comments: 31 pages, 22 figures, 6 tables, submited to Journal of Mechanical Systems and Signal Processing

Investigations of decuplet baryons from meson-baryon interactions in the HAL QCD method

Authors: Kotaro Murakami, Yutaro Akahoshi, Sinya Aoki, Kenji Sasaki

Abstract: We study decuplet baryons from meson-baryon interactions, in particular, $Δ$ and $Ω$ baryons from P-wave $I=3/2$ $Nπ$ and $I=0$ $Ξ\bar{K}$ interactions, respectively. The interaction potentials are calculated in the HAL QCD method using 3-quark-type source operators at $m_π \approx 410~\textrm{MeV}$. We use the conventional stochastic estimation of all-to-all propagators combined with the all-mode… ▽ More We study decuplet baryons from meson-baryon interactions, in particular, $Δ$ and $Ω$ baryons from P-wave $I=3/2$ $Nπ$ and $I=0$ $Ξ\bar{K}$ interactions, respectively. The interaction potentials are calculated in the HAL QCD method using 3-quark-type source operators at $m_π \approx 410~\textrm{MeV}$. We use the conventional stochastic estimation of all-to-all propagators combined with the all-mode averaging to reduce statistical fluctuations. We have found that two potentials have quite similar behaviors, suggesting that a mass difference between $Δ$ and $Ω$ comes mainly from a difference of kinematical structure between $Nπ$ and $Ξ\bar K$, rather than their interactions. The scattering phase shifts calculated from the potentials indicate that $Δ$ and $Ω$ baryons exist as bound states in this lattice setup, whose binding energies are consistent with those obtained from 2-point functions. △ Less

Submitted 30 November, 2021; originally announced November 2021.

Comments: 9 pages, 3 figures, 1 table, talk presented at The 38th International Symposium on Lattice Field Theory, LATTICE2021, 26th-30th July 2021, Zoom/Gather@Massachusetts Institute of Technology

Report number: YITP-21-145, RIKEN-QHP-509

Deformed Cartan matrices and generalized preprojective algebras I: Finite type

Authors: Ryo Fujita, Kota Murakami

Abstract: We give an interpretation of the $(q,t)$-deformed Cartan matrices of finite type and their inverses in terms of bigraded modules over the generalized preprojective algebras of Langlands dual type in the sense of Geiß-Leclerc-Schröer [Invent. math. 209 (2017)]. As an application, we compute the first extension groups between the generic kernels introduced by Hernandez-Leclerc [J. Eur. Math. Soc. 18… ▽ More We give an interpretation of the $(q,t)$-deformed Cartan matrices of finite type and their inverses in terms of bigraded modules over the generalized preprojective algebras of Langlands dual type in the sense of Geiß-Leclerc-Schröer [Invent. math. 209 (2017)]. As an application, we compute the first extension groups between the generic kernels introduced by Hernandez-Leclerc [J. Eur. Math. Soc. 18 (2016)], and propose a conjecture that their dimensions coincide with the pole orders of the normalized $R$-matrices between the corresponding Kirillov-Reshetikhin modules. △ Less

Submitted 22 February, 2022; v1 submitted 16 September, 2021; originally announced September 2021.

Comments: 41 pages, v3: changed the title, minor corrections and added explanations, updated references

MSC Class: 16G20; 17B37; 16W50; 17B67; 81R50