Showing 1–50 of 480 results for author: Carvalho, M

Search for the lepton-flavor-violating decay $ τ^{\pm} \to μ^{\pm} γ$ at Belle II

Authors: Belle II Collaboration, M. Abumusabh, I. Adachi, A. Aggarwal, H. Ahmed, Y. Ahn, H. Aihara, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, A. Aloisio, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, D. M. Asner, H. Atmacan, T. Aushev, V. Aushev, R. Ayad, V. Babu, H. Bae , et al. (445 additional authors not shown)

Abstract: We present a search for the lepton-flavor-violating decay $τ^{\pm}\toμ^{\pm}γ$ using a data sample that corresponds to an integrated luminosity of 428 fb$^{-1}$ recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e^{+}e^{-}$ collider. We employ a multivariate classifier to suppress the backgrounds from the Standard Model processes, and the signal extraction is performed using a… ▽ More We present a search for the lepton-flavor-violating decay $τ^{\pm}\toμ^{\pm}γ$ using a data sample that corresponds to an integrated luminosity of 428 fb$^{-1}$ recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e^{+}e^{-}$ collider. We employ a multivariate classifier to suppress the backgrounds from the Standard Model processes, and the signal extraction is performed using an extended maximum-likelihood fit. Since no significant excess over the expected background is observed, we set an upper limit on the branching fraction $\mathcal{B}(τ^{\pm}\toμ^{\pm}γ) < 9.5$ $ (12.2)\times10^{-8}$ at the 90\% (95\%) confidence level, using the CL${_s}$ technique. △ Less

Submitted 24 August, 2026; originally announced August 2026.

Report number: KEK preprint: 2026-8, Belle II preprint:2026-012

Hepatitis C Virus Genotyping with a Transformer Neural Network

Authors: Ariella Aro, Taimá Furuyama, Marcelo R. S. Briones, Luis Mário R. Janini, Isabel M. V. Guedes de Carvalho, Fernando Antoneli

Abstract: This study aims to explore the applicability of Transformer-based models for genetic sequence classification by evaluating their performance in predicting hepatitis C virus (HCV) genotypes and subtypes after fine-tuning. A total of 2,881 HCV whole-genome sequences obtained from the Los Alamos HCV Sequence Database were used, including genotypes 1 to 6 and all confirmed subtypes. Genotypes 7 and 8… ▽ More This study aims to explore the applicability of Transformer-based models for genetic sequence classification by evaluating their performance in predicting hepatitis C virus (HCV) genotypes and subtypes after fine-tuning. A total of 2,881 HCV whole-genome sequences obtained from the Los Alamos HCV Sequence Database were used, including genotypes 1 to 6 and all confirmed subtypes. Genotypes 7 and 8 were excluded due to an insufficient number of samples. The fine-tuning process was based on several datasets that differed in fragmentation method, data volume per file, and labeling. In genotype classification, fine-tuning strategies employing homogeneous fragmentation and balanced sample distribution resulted in higher performance, with precision ranging from 98.48% to 100%. In contrast, fine-tuning conducted using a fragmentation strategy that caused data imbalance, along with an arbitrary distribution of samples across training files, achieved a precision of 48.12%, which is considered low compared with other models. This configuration, which was also manually evaluated, resulted in a high error rate in genotype 5 prediction due to its low frequency in the datasets used. In subtype classification, the best-performing fine-tuning approach achieved 99.89% accuracy and 99.87% precision. Models that included additional genotypes showed a slight decrease in performance due to the increased complexity of the task. This study demonstrates that, when fine-tuning datasets contain properly fragmented, distributed, and labeled genetic sequences, Transformer-based neural networks can achieve high performance and are a promising approach for HCV genotype and subtype classification. △ Less

Submitted 19 August, 2026; originally announced August 2026.

Comments: 13 pages, 2 figures, 5 tables

MSC Class: 92B20 (Primary) 92-80; 62M45 (Secondary)

CoRCi: Cross-Reconstruction of Coherent Interests Modeling in Cross-Domain Sequential Recommendation

Authors: Qingtian Bian, Tieying Li, Marcus de Carvalho, Jiaxing Xu, Hui Fang, Yiping Ke

Abstract: Cross-Domain Sequential Recommendation (CDSR) aims to alleviate data sparsity by transferring dynamic user interests across related domains. A key challenge lies in effectively bridging these domains. In single-domain modeling, models cannot distinguish between domain-specific and domain-invariant interests. Recent methods merge domain-specific sequences chronologically into a mixed-domain sequenc… ▽ More Cross-Domain Sequential Recommendation (CDSR) aims to alleviate data sparsity by transferring dynamic user interests across related domains. A key challenge lies in effectively bridging these domains. In single-domain modeling, models cannot distinguish between domain-specific and domain-invariant interests. Recent methods merge domain-specific sequences chronologically into a mixed-domain sequence to capture domain-invariant knowledge. However, they typically deploy separate encoders for the mixed-domain sequence and train them with per-domain loss aggregation. This workflow magnifies inter-domain discrepancies and disrupts domain-invariant interest coherence, especially when query target pairs in Seq2Seq originate from different domains. In this paper, we present CoRCi (Cross-Reconstruction for Coherent Interest), a dual-target CDSR framework that tackles these drawbacks. Specifically, CoRCi proposes a Cross-Reconstruction approach that generates mixed-domain representations directly from pre-encoded specific-domain representations via cross-attention. The generated representations are then trained using a single, sequence-level, domain-agnostic loss to preserve the coherence of domain-invariant interests. To further suppress domain discrepancies in mixed-domain modeling, CoRCi introduces FocalNCE, which embeds Focal Loss into the preceding mixed-domain InfoNCE objective. The new loss assigns higher penalties to negatives drawn from the same domain as the query, thereby strengthening domain-invariant alignment. Extensive experiments on four real-world datasets demonstrate that CoRCi consistently outperforms state-of-the-art CDSR counterparts, achieving statistically significant gains across all metrics. △ Less

Submitted 10 August, 2026; originally announced August 2026.

Distributed Team Orchestration via Supervisor Networks: Convergence, Optimality, and Resilience

Authors: Juntian Zhu, Guanpu Chen, Tongtian Zhu, Miguel de Carvalho, Zhouwang Yang, Fengxiang He

Abstract: In this paper, we study zero-sum potential team games with a supervisor network, where agents rely on supervisor-provided belief information rather than accurate common beliefs. The main challenge is that such belief information can be inaccurate because of supervisors' belief-estimation errors and the misreporting of joint actions by Byzantine teams. We propose the distributed team-orchestrating… ▽ More In this paper, we study zero-sum potential team games with a supervisor network, where agents rely on supervisor-provided belief information rather than accurate common beliefs. The main challenge is that such belief information can be inaccurate because of supervisors' belief-estimation errors and the misreporting of joint actions by Byzantine teams. We propose the distributed team-orchestrating algorithm (DTOA), which combines team fictitious play with supervisor-based distributed belief learning. We prove the convergence of supervisors' belief estimates and establish that the induced learning dynamics converge to a near team-Nash equilibrium (TNE) in terms of the team-Nash gap (TNG). In the Byzantine setting, we consider a misreporting attack model and develop a Byzantine-resilient DTOA. We further provide probabilistic guarantees for Byzantine-team identification and establish an asymptotic bound on the honest TNG. Numerical experiments illustrate the theoretical findings, compare DTOA with baseline learning methods, and evaluate its performance in a Markov decision process setting. △ Less

Submitted 10 August, 2026; originally announced August 2026.

Multi-Agent Reinforcement Learning for Online Traffic Scheduling in Time-Sensitive Application

Authors: Marcos Carvalho, Fatih Temiz, Shavbo Salehi, Melike Erol-Kantarci, Daniel F. Macedo

Abstract: Time-sensitive networking (TSN) is increasingly integrated into mobile edge computing (MEC) to support applications with stringent latency requirements, such as extended reality (XR). However, existing TSN scheduling solutions predominantly rely on static optimization techniques or centralized learning models that are based on fixed traffic patterns, limiting their effectiveness in dynamic environ… ▽ More Time-sensitive networking (TSN) is increasingly integrated into mobile edge computing (MEC) to support applications with stringent latency requirements, such as extended reality (XR). However, existing TSN scheduling solutions predominantly rely on static optimization techniques or centralized learning models that are based on fixed traffic patterns, limiting their effectiveness in dynamic environments. In practice, MEC environments often host multiple co-located XR traffic flows whose characteristics evolve over time, creating complex inter-queue dependencies that current schedulers fail to capture. Addressing these challenges requires adaptive, decentralized scheduling mechanisms capable of coordinating multiple TSN queues under varying traffic conditions. To this end, this paper proposes a multi-agent reinforcement learning (MARL) framework for TSN scheduling, where each TSN queue is modeled as an autonomous agent. The Heterogeneous-Agent Proximal Policy Optimization (HAPPO) algorithm is employed to explicitly model inter-agent dependencies and jointly optimize service delivery across queues. The simulation results demonstrate that the proposed approach reduces average frame waiting times by up to 26.8% and worst-case delays by approximately 16.8%, highlighting its effectiveness in dynamic XR-driven MEC scenarios. △ Less

Submitted 5 August, 2026; originally announced August 2026.

Multi-Agent Transformer for Queue-Level XR Traffic Scheduling in TSN Networks

Authors: Marcos Carvalho, Fatih Temiz, Shavbo Salehi, Melike Erol-Kantarci, Daniel F. Macedo

Abstract: Time-Sensitive Networking (TSN) and Mobile Edge Computing (MEC) hold strong potential for enabling ultra-reliable low-latency communication for time-sensitive applications, such as eXtended Reality (XR). However, the widespread adoption of XR introduces significant challenges due to co-located services in MEC environments, leading to contention for shared network resources. Moreover, XR traffic ty… ▽ More Time-Sensitive Networking (TSN) and Mobile Edge Computing (MEC) hold strong potential for enabling ultra-reliable low-latency communication for time-sensitive applications, such as eXtended Reality (XR). However, the widespread adoption of XR introduces significant challenges due to co-located services in MEC environments, leading to contention for shared network resources. Moreover, XR traffic types have distinct characteristics and criticality in terms of timing requirements, further increasing the complexity and dynamics of such environments. Although reinforcement learning has shown promise for TSN scheduling optimization in dynamic network scenarios, existing approaches rely on centralized or high-level multi-agent designs and are typically tailored to periodic and predictable industrial traffic, limiting their applicability to XR workloads. As a result, these approaches suffer from (i) limited ability to capture inter-queue dependencies due to coarse-grained control, and (ii) poor adaptability to highly dynamic and heterogeneous XR traffic. To address these gaps, we propose a multi-agent reinforcement learning approach for queue-level XR traffic scheduling. We adopt the multi-agent transformer (MAT) to model inter-queue dependencies via attention over agents' observations and actions, enabling implicit coordination across heterogeneous co-located XR applications. Our simulation results show that the proposed method outperforms baselines, achieving up to 71.42% latency reduction and up to 83.2% reduction in failure rate, while consistently achieving high reliability across all queues. △ Less

Submitted 5 August, 2026; originally announced August 2026.

BRHC: Backend-driven Reactive Hypermedia Controls with a Statically Typed Kotlin DSL

Authors: Fernando Miguel Carvalho, Paulo Carvalho, Leonel Correia, Ricardo Gomes, Juho Vepsäläinen

Abstract: AI-assisted coding tools (e.g., Copilot, Cursor, Claude) are increasingly ubiquitous and enable rapid generation of web applications. However, this raises concerns regarding complexity, longevity and the long-term maintainability of generated systems. A key source of complexity is the heterogeneity between backend and frontend programming models, where multiple languages and paradigms are combined… ▽ More AI-assisted coding tools (e.g., Copilot, Cursor, Claude) are increasingly ubiquitous and enable rapid generation of web applications. However, this raises concerns regarding complexity, longevity and the long-term maintainability of generated systems. A key source of complexity is the heterogeneity between backend and frontend programming models, where multiple languages and paradigms are combined within a single application, often leading to duplicated logic and fragmented state management. To address this issue, recent approaches (e.g., HTMX, Turbo Hotwire, Datastar, etc.) follow the Hypermedia-Driven Application (HDA) model, positioning HTML as the primary communication medium between client and server. Unlike SPA-centric architectures, HDA systems shift the application state and interaction logic to the server, where backend-driven reactive signals synchronize with the client user interface. However, these approaches still introduce complexity through custom attributes and do not fully eliminate JavaScript, particularly in computed expressions. In this work, we propose a statically typed approach using a Kotlin-based HTML DSL (Domain-Specific Language) for backend-driven reactive web applications. We extend the HtmlFlow Kotlin DSL with typed custom HTML attributes (i.e., Datastar data-* attributes) and signal-based bindings using statically typed builders. We demonstrate the approach through a catalog of reactive interaction patterns and a Petclinic Spring MVC case study. The results indicate that the proposed approach can nearly eliminate the need for JavaScript while improving type safety and preserving a homogeneous programming model across frontend and backend, bridged through a backend-driven reactive, signal-centric architecture. △ Less

Submitted 31 July, 2026; originally announced July 2026.

Comments: Submitted to Software: Practice and Experience (Wiley)

Even More Deception: Objective Misalignment in Mixed-Motive LLM Multi-Agent Systems

Authors: Marylou Fauchard, Florian Carichon, Margarida Carvalho, Golnoosh Farnadi

Abstract: Large Language Models (LLMs)-powered multi-agent systems are increasingly deployed in mixed-motive environments, where agents operate under asymmetric information and strategic deception due to conflicting or hidden objectives. In these settings, misalignment with collective goals becomes a central concern. We propose a novel framework for evaluating objective misalignment using the social deducti… ▽ More Large Language Models (LLMs)-powered multi-agent systems are increasingly deployed in mixed-motive environments, where agents operate under asymmetric information and strategic deception due to conflicting or hidden objectives. In these settings, misalignment with collective goals becomes a central concern. We propose a novel framework for evaluating objective misalignment using the social deduction game Werewolf, modifying the objective of a single agent while preserving its assigned role. Across LLMs from four different model families and sizes, four player roles, and three objective formulations, we introduce a dual analysis of the agents' internal reasoning and their public cheap-talk behavior (i.e costless, non-binding communication that does not directly affect the agents' utilities), complemented by an analysis of game outcomes. Our results show that objective misalignment undermines outcomes in inherently adversarial environments, an effect exacerbated by asymmetric information and specialized roles. While compromised agents consistently develop distinct objective-dependent reasoning strategies, these adaptations remain largely invisible in their public behavior. More broadly, our findings suggest that even subtle objective misalignment can profoundly affect collective decision-making, highlighting the need for effective mitigation strategies for LLM-based multi-agent systems. △ Less

Submitted 28 July, 2026; originally announced July 2026.

Comments: Accepted at AIWILD@ICLR 2026

Search for the $\boldsymbol{B^0 \to K^0_{\rm S} τ^+ τ^-}$ decay

Authors: Belle, Belle II Collaborations, :, M. Abumusabh, I. Adachi, A. Aggarwal, Y. Ahn, H. Aihara, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, A. Aloisio, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, D. M. Asner, H. Atmacan, T. Aushev, V. Aushev, R. Ayad, V. Babu, H. Bae , et al. (410 additional authors not shown)

Abstract: We present the first search for $B^0 \to K^0_{\rm S} τ^+τ^-$ decays. We look for signal decays in $B^0\bar B^0$ events produced in asymmetric-energy electron-positron collisions. This work uses samples from the Belle and Belle~II detectors, comprising 1.16 billion $Υ(4S)$ events. In $Υ(4S)\to B^0\bar{B}^0$ decays, the non-signal $\bar{B}^0$ meson is fully reconstructed in a hadronic channel. For t… ▽ More We present the first search for $B^0 \to K^0_{\rm S} τ^+τ^-$ decays. We look for signal decays in $B^0\bar B^0$ events produced in asymmetric-energy electron-positron collisions. This work uses samples from the Belle and Belle~II detectors, comprising 1.16 billion $Υ(4S)$ events. In $Υ(4S)\to B^0\bar{B}^0$ decays, the non-signal $\bar{B}^0$ meson is fully reconstructed in a hadronic channel. For the signal $B^0$ meson, $τ$-lepton decays into final states with a single charged particle are selected. A multivariate classifier is used to combine several discriminating inputs into a single fit observable. We observe no evidence for the signal and set an upper limit on the branching fraction $\mathcal{B}(B^0\to K^0_{\rm S} τ^+τ^-) < 8.3 \times 10^{-4}$ at the 90\% confidence level. Combining this with the recent measurement of the isospin-partner decay $B^+\to K^+τ^+τ^-$, we determine an upper limit $\mathcal{B}(B\to Kτ^+τ^-) < 5.4\times10^{-4}$ at the 90\% confidence level. △ Less

Submitted 28 July, 2026; originally announced July 2026.

Report number: Belle II preprint 2026-008, KEK preprint 2026-4

Dark Matter Sensitivity of the CYGNO Detector with HFO-1234ze Enhanced Gas Mixtures

Authors: F. D. Amaro, R. Antonietti, E. Baracchini, L. Benussi, F. M. Brunbauer, C. Capoccia, M. Caponero, L. G. M. de Carvalho, G. Cavoto, I. A. Costa, A. Croce, M. D'Astolfo, G. D'Imperio, E. Dane', G. Dho, E. Di Marco, J. M. F. dos Santos, D. Fiorina, F. Iacoangeli, Z. Islam, E. Kemp, H. P. Lima Jr, G. Maccarrone, R. D. P. Mano, D. J. G. Marques , et al. (20 additional authors not shown)

Abstract: The CYGNO collaboration introduces an innovative approach to direct dark matter detection, proposing a high-resolution optical Time Projection Chamber. It operates at atmospheric pressure with a He:CF$_{4}$ (60:40) gas mixture and uses a triple Gas Electron Multiplier stage for signal amplification. A key feature is its optical readout system, which captures the scintillation light produced during… ▽ More The CYGNO collaboration introduces an innovative approach to direct dark matter detection, proposing a high-resolution optical Time Projection Chamber. It operates at atmospheric pressure with a He:CF$_{4}$ (60:40) gas mixture and uses a triple Gas Electron Multiplier stage for signal amplification. A key feature is its optical readout system, which captures the scintillation light produced during the electron avalanche. This setup allows 3D event reconstruction by combining the time profile of the light detected by photomultiplier tubes with high-granularity, pixelated X-Y tracking recorded by a scientific camera. The CYGNO experiment's projected sensitivity to both spin-independent and spin-dependent interactions is competitive in the framework of directional dark matter detectors. However, incorporating a hydrogen-based gas would introduce an even lighter target, further improving the detection potential at low dark matter masses. In this work, we present the performance characterization of one of the CYGNO experiment prototypes, MANGO, operated with the standard gas mixture enriched with varying concentrations of HFO-1234ze, a gas with a promising low global warming potential. The study includes measurements of the detector charge gain and scintillation yield for each configuration. In addition, to evaluate the impact of HFO-1234ze on scintillation light quenching, the secondary scintillation spectrum was collected for each gas mixture tested. △ Less

Submitted 23 July, 2026; v1 submitted 22 July, 2026; originally announced July 2026.

Comments: Corrected abstract metadata

Distributed Topological Charge and Spinorial Holonomy in Yukawa-Regularized Graphene Disclinations

Authors: A. M. de M. Carvalho, G. Q. Garcia, E. Brito, C. Furtado

Abstract: Conical geometries provide the standard description of disclinations, but they concentrate the curvature at a singular apex. We introduce a Yukawa-type regularization that replaces this singularity by a smooth curvature distribution while preserving the asymptotic topology of the defect. Exact expressions are obtained for the conformal factor, curvature, and enclosed topological charge. The result… ▽ More Conical geometries provide the standard description of disclinations, but they concentrate the curvature at a singular apex. We introduce a Yukawa-type regularization that replaces this singularity by a smooth curvature distribution while preserving the asymptotic topology of the defect. Exact expressions are obtained for the conformal factor, curvature, and enclosed topological charge. The resulting geometry exhibits a scale-dependent topological charge and a corresponding radius-dependent holonomy, establishing a direct connection between distributed curvature and geometric phases. We further investigate the dynamics of massless Dirac quasiparticles in this background and show that the regularized core modifies the spin connection while preserving the asymptotic topological signature of the defect. These results provide a finite-core extension of the conventional conical description and offer a natural framework for studying geometric and topological effects in graphene-like systems. △ Less

Submitted 18 July, 2026; originally announced July 2026.

The S-PLUS Fifth Data-Release: Over 4500 square degrees of the Southern Sky and a multicolor view of the Hydra and Antlia galaxy clusters

Authors: Erik Vinicius Rodrigues de Lima, Gustavo Bernhard Oliveira Schwarz, Fábio Rafael Herpich, Felipe Almeida-Fernandes, Lilianne Nakazono, Eduardo Alberto Duarte Lacerda, André Santos, André Luiz Figueiredo, Luis Angel Gutiérrez-Soto, Marília Jobim Sartori, Marcos Antonio Fonseca-Faria, Maiara Sampaio Carvalho, Bárbara Cubillos Palma, Elismar Lösch, Gissel Pardo Montaguth, José Yuri Santos Silva, Liana Li, Marina Izabela, Natanael Magalhães Cardoso, Thais Santos-Silva, Paulo Afrânio Augusto Lopes, Pedro K. Humire, Roberta Vassallo Bordoni, Amanda Reis Lopes, Analía Viviana Smith Castelli , et al. (33 additional authors not shown)

Abstract: We present the 5th data release (DR5) of the Southern Photometric Local Universe Survey (S-PLUS), covering 4592 square degrees across 2491 fields. Observations were conducted with the T80-South, a Brazilian robotic telescope equipped with the Javalambre 12-filter system, containing five broad- and seven narrowband filters. Data products feature FITS images and extensive catalogs containing fluxes,… ▽ More We present the 5th data release (DR5) of the Southern Photometric Local Universe Survey (S-PLUS), covering 4592 square degrees across 2491 fields. Observations were conducted with the T80-South, a Brazilian robotic telescope equipped with the Javalambre 12-filter system, containing five broad- and seven narrowband filters. Data products feature FITS images and extensive catalogs containing fluxes, magnitudes, and shape parameters for over 113 million detections. In addition, several value-added catalogs are provided, offering photometric redshifts (photo-zs), object classifications, masks, and extinction coefficients. For the first time, this release includes coverage of 110 square degrees along the Galactic disk, facilitating new research into Galactic structure and stellar populations. The release also provides full coverage of the Hydra Supercluster and numerous other nearby clusters with improved data reduction and calibration, enhancing photo-z accuracy, which is vital for large-scale structure studies. A preliminary analysis of the Hydra and Antlia galaxy clusters up to $5 \times R_{200}$ yields an updated catalog of 1706 cluster members based on both spectroscopic and high-quality photo-zs. Our photometric data shows that both clusters have a similar proportion of galaxies with an H$α$ excess relative to their clustercentric distance, though Hydra has a higher fraction near its center. Additionally, the spatial distribution of all objects in our sample highlights a bridge connecting both clusters. We verify that S-PLUS DR5 provides a solid foundation for future scientific investigations, ranging from Solar System studies to Cosmology. △ Less

Submitted 17 July, 2026; originally announced July 2026.

Comments: 18 pages, 10 figures, 2 tables. Submitted to ApJ and revised

On the Computational Complexity of Bilevel Integer Linear Programming

Authors: Nagisa Sugishita, Margarida Carvalho

Abstract: We investigate the computational complexity of bilevel integer linear programming. While Jeroslow~(1985) established that the decision version of this problem is $Σ^p_2$-complete when restricted to binary variables, we prove that this $Σ^p_2$-completeness persists even for general integer variables, settling a question that remained open for over 40 years. Furthermore, we analyze the impact of var… ▽ More We investigate the computational complexity of bilevel integer linear programming. While Jeroslow~(1985) established that the decision version of this problem is $Σ^p_2$-complete when restricted to binary variables, we prove that this $Σ^p_2$-completeness persists even for general integer variables, settling a question that remained open for over 40 years. Furthermore, we analyze the impact of various structural assumptions on computational complexity. Notably, we strengthen the result of Köppe et al.~(2010) by proving polynomial-time solvability whenever the total number of upper- and lower-level variables is fixed, without any additional assumptions. △ Less

Submitted 16 July, 2026; originally announced July 2026.

Comments: 12 pages

Search for axion-like particles decaying to two photons at Belle II

Authors: Belle II Collaboration, M. Abumusabh, I. Adachi, A. Aggarwal, H. Ahmed, Y. Ahn, H. Aihara, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, A. Aloisio, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, D. M. Asner, H. Atmacan, T. Aushev, V. Aushev, R. Ayad, V. Babu, H. Bae , et al. (428 additional authors not shown)

Abstract: Axion-like particles (ALPs) are predicted in many extensions of the Standard Model and provide a well-motivated portal between visible and hidden sectors through their coupling to photons. We search for ALPs produced in the process $e^{+}e^{-}\toγa$, $a\toγγ$, using a data sample corresponding to an integrated luminosity of $408~\mathrm{fb}^{-1}$ recorded by the Belle~II detector at the SuperKEKB… ▽ More Axion-like particles (ALPs) are predicted in many extensions of the Standard Model and provide a well-motivated portal between visible and hidden sectors through their coupling to photons. We search for ALPs produced in the process $e^{+}e^{-}\toγa$, $a\toγγ$, using a data sample corresponding to an integrated luminosity of $408~\mathrm{fb}^{-1}$ recorded by the Belle~II detector at the SuperKEKB $e^{+}e^{-}$ collider. Events containing three photons are used to reconstruct the ALP as a narrow peak in the di-photon invariant mass spectrum over the range $0.17 < m_{a} < 9.80~\mathrm{GeV}/c^{2}$. No significant excess above background is observed. We set 95\% confidence level upper limits on the production cross section and on the ALP-photon coupling $g_{aγγ}$, reaching sensitivities at the level of $10^{-4}~\mathrm{GeV}^{-1}$. The limits are the most restrictive to date over nearly the entire mass range $0.17 < m_{a} < 5.00~\mathrm{GeV}/c^{2}$, and improve upon previous results by up to a factor 9. △ Less

Submitted 8 July, 2026; originally announced July 2026.

Comments: 9 pages, 4 figures, Submitted for publication to Physical Review Letters

Report number: Belle II Preprint 2026-015, KEK Preprint 2026-11

First measurement of the masses of the $Υ_1(1D)$ and $Υ_3(1D)$ states and the energy dependence of the cross sections for $e^+e^-\toΥ_J(1D)η$ and $e^+e^-\toΥ_J(1D)π^+π^-$

Authors: Belle, Belle II Collaborations, :, M. Abumusabh, I. Adachi, K. Adamczyk, A. Aggarwal, H. Ahmed, Y. Ahn, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, H. Atmacan, T. Aushev, V. Aushev, R. Ayad, V. Babu, H. Bae , et al. (376 additional authors not shown)

Abstract: We study the processes $e^+e^-\toΥ_J(1D)η$ and $e^+e^-\toΥ_J(1D)π^+π^-$ at center-of-mass energies $\sqrt{s}$=(10.73 -- 11.02) GeV using a $142.5\,\mathrm{fb}^{-1}$ data sample, including 122~fb$^{-1}$ near the $Υ$(10860) peak ($\sqrt{s}$ = 10.866 GeV), collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. From the peak sample, the products of Born cross section times… ▽ More We study the processes $e^+e^-\toΥ_J(1D)η$ and $e^+e^-\toΥ_J(1D)π^+π^-$ at center-of-mass energies $\sqrt{s}$=(10.73 -- 11.02) GeV using a $142.5\,\mathrm{fb}^{-1}$ data sample, including 122~fb$^{-1}$ near the $Υ$(10860) peak ($\sqrt{s}$ = 10.866 GeV), collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. From the peak sample, the products of Born cross section times branching fraction are obtained for $σ_{\rm Born}(e^+e^-\toΥ_J(1D)η)$ or $σ_{\rm Born}(e^+e^-\toΥ_J(1D)π^+π^-)$ and ${\cal B}(Υ_J(1D)\toχ_{b1}γ)$ or ${\cal B}(Υ_J(1D)\toχ_{b2}γ)$ for each $Υ_J(1D)$ state. The corresponding branching fractions for $Υ(10860)$ decays are also obtained. The significances of the $Υ_1(1D)$, $Υ_2(1D)$, and $Υ_3(1D)$ signals are 4.8$σ$, ${>}10σ$, and 3.0$σ$, respectively, including systematic uncertainties. The mass for $Υ_2(1D)$ is measured to be $(10167.0\pm 1.0\pm 0.2)$ MeV/$c^2$, where the first and second uncertainties are statistical and systematic. The mass splittings $Δm_{12}=m(Υ_2(1D))-m(Υ_1(1D))$ and $Δm_{23}=m(Υ_3(1D))-m(Υ_2(1D))$ are $(11.8\pm1.5\pm0.4)$ MeV/$c^2$ and $(7.6\pm2.4\pm0.6)$ MeV/$c^2$, respectively.~We determine the energy dependence of the cross sections for $e^+e^-\toΥ_J(1D)η$ and $e^+e^-\toΥ_J(1D)π^+π^-$ for the $Υ_1(1D)$, $Υ_2(1D)$, and $Υ_3(1D)$ states, combined. △ Less

Submitted 5 July, 2026; originally announced July 2026.

Comments: 12 pages, 7 figures

Report number: Belle II Preprint 2026-014; KEK Preprint 2026-10

S-PLUS Clusters And Large-scale Environments (SCALE): I. A catalog of known clusters and groups in DR5 and a pilot study of Abell 4038

Authors: C. Mendes de Oliveira, N. M. Cardoso, P. A. A. Lopes, A. L. B. Ribeiro, D. E. Olave-Rojas, A. Krabbe, L. Sodré Jr., R. Demarco, A. V. Smith Castelli, R. Cid Fernandes, F. R. Herpich, S. Torres-Flores, E. R. Carrasco, E. V. R. Lima, G. Oliveira Schwarz, A. P. Costa, L. Doubrawa, G. P. Montaguth, C. Lima-Dias, E. S. Cypriano, M. S. Carvalho, C. Lobo, M. Fonseca-Faria, L. Nakazono, A. R. Lopes , et al. (4 additional authors not shown)

Abstract: Within the framework of the Southern Photometric Local Universe Survey (S-PLUS), we introduce ${\bf S}$-PLUS ${\bf C}$lusters ${\bf A}$nd ${\bf L}$arge-scale ${\bf E}$nvironments (SCALE), a project dedicated to the study of galaxy clusters, groups, and their environments using 12-band photometry of S-PLUS combined with spectroscopic and photometric data from the literature. In this first paper, we… ▽ More Within the framework of the Southern Photometric Local Universe Survey (S-PLUS), we introduce ${\bf S}$-PLUS ${\bf C}$lusters ${\bf A}$nd ${\bf L}$arge-scale ${\bf E}$nvironments (SCALE), a project dedicated to the study of galaxy clusters, groups, and their environments using 12-band photometry of S-PLUS combined with spectroscopic and photometric data from the literature. In this first paper, we present a catalog of 83 previously known systems in the redshift range $0.008 \leq z_{\rm spec} \leq 0.1$, for which we derive $R_{200}$, $M_{200}$, and velocity dispersions. Spectroscopic members are selected and matched with S-PLUS photometric redshifts (photo-$z$s). We find very good agreement between literature spectroscopic redshifts (spec-$z$s) and S-PLUS photometric redshifts (photo-$z$s), demonstrating the potential of the latter for cluster and group membership determination. As a proof of concept, we obtain photometric memberships for Abell 4038 using the Reliable Photometric Membership technique. A two- and three-dimensional analysis of the region within $10 h^{-1}$ Mpc ($10\times R_{200}$) from the center of Abell 4038 reveals about a dozen substructures including two additional clusters within $1.3\times R_{200}$ (Abell 4038B and Abell 4049). A color-luminosity segregation analysis shows that more luminous (less luminous) galaxies are redder (bluer), as expected. Low-concentration galaxies ($C \leq 2.5$) exhibit a weaker color-luminosity dependence, compared to higher-concentration ones, indicating mass-dependent evolutionary pathways that challenge a simple morphology-color dichotomy, with low-luminosity galaxies presenting bluer colors largely independent of concentration. The SCALE catalog provides a valuable basis for future studies of large-scale structures and their connection to galaxy evolution. △ Less

Submitted 2 July, 2026; originally announced July 2026.

Comments: Paper I of the SCALE project. 23 pages, 7figures. Accepted for publication in ApJ on 01/07/2026

From streaks to synergies: A multi-scale analysis of performance and scoring in the NBA

Authors: Malvina Bozhidarova, Yanpei Cai, Ricardo M. S. Carvalho, Daniele Cirulli, Quentin Dehaene, Martin Diaz, Alexandra Krasnokutskaya, Bernardo Pereira, Onkar Sadekar, Federico Battiston

Abstract: Modern play-by-play data make it possible to test long-standing intuitions about basketball with the same statistical rigour now routinely applied to other professional sports. Using play-by-play data from 7,054 regular-season and 504 playoff NBA games spanning the 2020-2025 seasons, we provide quantitative insights into scoring patterns and the performance of individual players and teams through… ▽ More Modern play-by-play data make it possible to test long-standing intuitions about basketball with the same statistical rigour now routinely applied to other professional sports. Using play-by-play data from 7,054 regular-season and 504 playoff NBA games spanning the 2020-2025 seasons, we provide quantitative insights into scoring patterns and the performance of individual players and teams through methods from statistics, network science, and complexity science. Our findings offer an evidence-based perspective on in-season and in-game performance that can inform coaching strategies, player evaluation, and tactical decision-making. △ Less

Submitted 26 June, 2026; originally announced June 2026.

Comments: Prepared at the Complexity72h workshop London, June 2026

Charged-lepton identification at Belle~II

Authors: Belle II Collaboration, M. Abumusabh, I. Adachi, A. Aggarwal, H. Ahmed, Y. Ahn, H. Aihara, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, H. Atmacan, V. Aushev, R. Ayad, V. Babu, H. Bae, N. K. Baghel, P. Bambade, Sw. Banerjee , et al. (387 additional authors not shown)

Abstract: Effective particle identification capabilities are a strategic priority for the physics program of the Belle~II experiment. We describe the algorithms used at Belle~II for identifying electrons and muons and separating them from charged hadrons. We present the performance obtained by the experiment during Run 1, which consists of 428 fb$^{-1}$ of data collected at the energy-asymmetric $e^+e^-$ co… ▽ More Effective particle identification capabilities are a strategic priority for the physics program of the Belle~II experiment. We describe the algorithms used at Belle~II for identifying electrons and muons and separating them from charged hadrons. We present the performance obtained by the experiment during Run 1, which consists of 428 fb$^{-1}$ of data collected at the energy-asymmetric $e^+e^-$ collider SuperKEKB between 2019 and 2022 at center-of-mass energies near the mass of the $Υ(4S)$. △ Less

Submitted 24 June, 2026; originally announced June 2026.

Report number: Belle II Preprint 2026-009, KEK Preprint 2026-5

First evidence of $X(3872)\toπ^0χ_{c0}(1P)$ and search for $X(3915)\toπ^0χ_{c1}(1P)$

Authors: Belle, Belle II Collaborations, :, M. Abumusabh, I. Adachi, A. Aggarwal, H. Ahmed, Y. Ahn, H. Aihara, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, H. Atmacan, T. Aushev, V. Aushev, R. Ayad, V. Babu, H. Bae , et al. (390 additional authors not shown)

Abstract: We search for the pionic transitions $X(3872)\toπ^0χ_{cJ}(1P)$ $(J = 0,~1,~2)$ and $X(3915)\toπ^0χ_{c1}$ in $B^+\to π^0χ_{cJ}K^+$ decays using the Belle and Belle~II data samples collected at the $Υ(4S)$ resonance, corresponding to integrated luminosities of $711~\mathrm{fb}^{-1}$ and $492~\mathrm{fb}^{-1}$, respectively. We report the first evidence for the decay $X(3872)\toπ^0χ_{c0}$ with a sign… ▽ More We search for the pionic transitions $X(3872)\toπ^0χ_{cJ}(1P)$ $(J = 0,~1,~2)$ and $X(3915)\toπ^0χ_{c1}$ in $B^+\to π^0χ_{cJ}K^+$ decays using the Belle and Belle~II data samples collected at the $Υ(4S)$ resonance, corresponding to integrated luminosities of $711~\mathrm{fb}^{-1}$ and $492~\mathrm{fb}^{-1}$, respectively. We report the first evidence for the decay $X(3872)\toπ^0χ_{c0}$ with a significance of $3.4σ$, including systematic uncertainties. We measure the product of branching fractions ${\cal B}(B^+\to X(3872)K^+)\times{\cal B}(X(3872)\toπ^0χ_{c0})=(20.0\pm6.8\pm2.3)\times10^{-6}$ and the branching fraction ratio ${\cal B}(X(3872)\toπ^0χ_{c0})/{\cal B}(X(3872)\toπ^+π^-J/ψ)=2.3\pm0.8\pm0.4$, where the first and second uncertainties are statistical and systematic, respectively. The upper limits at 90\% credibility on the products of branching fractions for the $π^0χ_{c1}$ and $π^0χ_{c2}$ modes are $7.5\times10^{-6}$ and $15.3\times10^{-6}$, respectively. The corresponding upper limits on the branching fraction ratios relative to the $π^+π^-J/ψ$ decay are $0.9$ and $1.8$. The measured branching fractions for $X(3872)\toπ^0χ_{cJ}$ are consistent with several theoretical predictions based on the hadronic molecular interpretation of the $X(3872)$. No significant signal is seen for the $X(3915)\toπ^0χ_{c1}$ decay, and we set the 90\% credibility upper limit of ${\cal B}(B^+\to X(3915)K^+)\times{\cal B}(X(3915)\toπ^0χ_{c1})<6.6\times10^{-6}$, while the decays for $J=0$ and 2 are forbidden by parity conservation. △ Less

Submitted 23 June, 2026; originally announced June 2026.

Comments: 9 pages, 2 figures

Report number: Belle Preprint:2026-6, KEK Preprint: 2026-2

Measurement of mixing-induced CP violation in the decay $B^0 \to π^0 π^0$

Authors: Belle II Collaboration, M. Abumusabh, I. Adachi, K. Adamczyk, A. Aggarwal, Y. Ahn, H. Aihara, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, H. Atmacan, T. Aushev, V. Aushev, R. Ayad, V. Babu, H. Bae, N. K. Baghel, S. Bahinipati , et al. (415 additional authors not shown)

Abstract: Measurements of charge-parity (CP) violation in quark transitions provide stringent tests of the current theory and sensitive probes of particles or interactions beyond it. We report the first measurement of mixing-induced CP violation in $B^0\toπ^0π^0$ decays. The measurement uses 190 million $Υ(4S)\to B^{0}\overline{B}{}^0$ events collected with the Belle II experiment at the SuperKEKB asymmetri… ▽ More Measurements of charge-parity (CP) violation in quark transitions provide stringent tests of the current theory and sensitive probes of particles or interactions beyond it. We report the first measurement of mixing-induced CP violation in $B^0\toπ^0π^0$ decays. The measurement uses 190 million $Υ(4S)\to B^{0}\overline{B}{}^0$ events collected with the Belle II experiment at the SuperKEKB asymmetric-energy electron-positron collider. A new approach that exploits the quantum entanglement of the $B^{0}\overline{B}{}^0$ pair enables a decay-time-dependent analysis without reconstructing the $B^0 \to π^0π^0$ decay position. We measure the mixing-induced CP-violating coefficient to be $S_{π^{0}π^{0}} = 0.61^{+0.75}_{-0.79}\,(\mathrm{stat}) \pm 0.11\,(\mathrm{syst})$, attaining a precision that would require a data set twenty times as large with a conventional analysis. We also measure the direct CP-violating coefficient to be $C_{π^{0}π^{0}} = 0.05 \pm 0.28\,(\mathrm{stat}) \pm 0.07\,(\mathrm{syst})$. These results substantially improve the constraints from $B \to ππ$ decays on the CP-violating phase $φ_2$ of the quark-mixing matrix using far less data than had previously been assumed necessary. △ Less

Submitted 18 June, 2026; originally announced June 2026.

Comments: 20 pages, 11 figues, 2 tables

Report number: Belle II Preprint 2026-013, KEK Preprint 2026-9

Intermediate Bilevel Optimization: Modeling Endogenous Follower Tie-Breaking Behavior

Authors: Maria Bazotte, Margarida Carvalho, Thibaut Vidal

Abstract: In bilevel optimization, optimistic and pessimistic follower behaviors are the most commonly used forms to define how the follower ties-breaks among multiple optimal solutions. In this work, we go beyond these extreme tie-breaking behaviors and investigate the intermediate bilevel optimization program (I-BO), where the follower's selected optimal response is a decision-dependent random event, with… ▽ More In bilevel optimization, optimistic and pessimistic follower behaviors are the most commonly used forms to define how the follower ties-breaks among multiple optimal solutions. In this work, we go beyond these extreme tie-breaking behaviors and investigate the intermediate bilevel optimization program (I-BO), where the follower's selected optimal response is a decision-dependent random event, with a probability measure influenced by the leader's decision. We formally introduce a class of such endogenous measures, including the special case of strong-weak decision-dependent I-BO. We reformulate the I-BO as a Transformed I-BO (T-I-BO) with exogenous uncertainty by defining inverse and Markov-chain transformations, which represent the follower's response as a function of the leader's decision and exogenous randomness. We handle the T-I-BO's uncertainty via sample-average approximation (SAA), and we propose tailored approaches for its SAA program according to the chosen transformation. Computationally, our methods solve reasonable-sized instances efficiently and outperform the deterministic equivalent when available. Furthermore, experiments stress the critical need to accurately model follower tie-breaking behavior, particularly depending on its alignment with the leader's objective, as misspecification leads to suboptimal leader decisions. △ Less

Submitted 16 June, 2026; originally announced June 2026.

Observation of the decays $B^{+} \to Σ_{c}(2455)^{++} \barΞ_{c}^{\prime-}$ and $B^{0} \to Σ_{c}(2455)^{0} \barΞ_{c}^{\prime0}$

Authors: Belle, Belle II Collaborations, :, M. Abumusabh, A. Aggarwal, H. Ahmed, J. K. Ahn, Y. Ahn, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, H. Atmacan, V. Aushev, R. Ayad, V. Babu, H. Bae, N. K. Baghel, S. Bahinipati , et al. (381 additional authors not shown)

Abstract: We report the first observation of the decays $B^{+} \to Σ_{c}(2455)^{++} \barΞ_{c}^{\prime-}$ and $B^{0} \to Σ_{c}(2455)^{0} \barΞ_{c}^{\prime0}$, with significances of $6.4\,σ$ and $5.3\, σ$, respectively, including systematic uncertainties. This analysis is based on data samples containing $771.6 \times 10^{6}$ $Υ(4S)$ decays collected with the Belle detector at the KEKB collider and… ▽ More We report the first observation of the decays $B^{+} \to Σ_{c}(2455)^{++} \barΞ_{c}^{\prime-}$ and $B^{0} \to Σ_{c}(2455)^{0} \barΞ_{c}^{\prime0}$, with significances of $6.4\,σ$ and $5.3\, σ$, respectively, including systematic uncertainties. This analysis is based on data samples containing $771.6 \times 10^{6}$ $Υ(4S)$ decays collected with the Belle detector at the KEKB collider and $520.6 \times 10^{6}$ $Υ(4S)$ decays collected with the Belle~II detector at the SuperKEKB collider. The branching fractions are measured to be $\mathcal{B}(B^+ \to Σ_c(2455)^{++} \barΞ_c^{\prime -}) = (1.68 \pm 0.31 \pm 0.12^{+1.49}_{-0.54}) \times 10^{-3}$ and $\mathcal{B}(B^0 \to Σ_c(2455)^{0} \barΞ_c^{\prime 0}) = (1.28 \pm 0.32 \pm 0.10^{+0.30}_{-0.21}) \times 10^{-3}$, where the first and second uncertainties are statistical and systematic, respectively, and the third arises from the uncertainties in the absolute branching fractions of $\barΞ_{c}^{-}$ and $\barΞ_{c}^{0}$ decays. This result represents the first observation of $B$-meson decays into a pair of charmed baryon-antibaryon states belonging to the same $SU(3)$ flavor sextet. △ Less

Submitted 11 June, 2026; originally announced June 2026.

Report number: Belle II Preprint 2026-011; KEK Preprint 2026-7

DAL-PCQA: Enabling Distortion-Level and Language-Driven Reasoning for Point Cloud Quality Assessment

Authors: Swarna Chakraborty, Gabriel De Castro Araújo, Syeda Tasmi Faria, Marcelo M. Carvalho, Mylene C. Q. Farias

Abstract: Point Cloud Quality Assessment (PCQA) methods typically predict scalar Mean Opinion Scores (MOS), which quantify overall perceptual degradation but do not reveal its causes. In contrast, human observers naturally reason in terms of specific distortions such as blur, color shifts, point density changes, missing regions, and geometric deformations. To close this gap, we introduce DAL-PCQA, a distort… ▽ More Point Cloud Quality Assessment (PCQA) methods typically predict scalar Mean Opinion Scores (MOS), which quantify overall perceptual degradation but do not reveal its causes. In contrast, human observers naturally reason in terms of specific distortions such as blur, color shifts, point density changes, missing regions, and geometric deformations. To close this gap, we introduce DAL-PCQA, a distortion-aware, language-annotated dataset for PCQA. DAL-PCQA augments benchmark point clouds with multi-level distortion severity labels, discrete quality categories, and structured natural language descriptions aligned with human perception. We define a point-cloud-specific distortion taxonomy that covers both photometric and geometric artifacts. Statistical analysis reveals characteristic degradation patterns across distortion types and quality levels. To assess the utility of these annotations, we compare zero-shot and fine-tuned multimodal models for generating perceptual quality descriptions. Experiments show that distortion-aware supervision substantially improves lexical and semantic alignment with ground-truth descriptions. By enabling interpretable, distortion-level reasoning, DAL-PCQA facilitates language-driven, explainable point cloud quality assessment. The dataset is publicly available at https://github.com/swarna96/DAL-PCQA. △ Less

Submitted 5 June, 2026; originally announced June 2026.

Comments: Accepted at Qomex 2026

Measurement of time-dependent $CP$ violation parameters in $B^{0} \to K_{S}^{0} π^{0} γ$ decays at Belle and Belle II

Authors: Belle, Belle II Collaborations, :, M. Abumusabh, I. Adachi, A. Aggarwal, Y. Ahn, H. Aihara, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, H. Atmacan, V. Aushev, R. Ayad, V. Babu, H. Bae, N. K. Baghel, S. Bahinipati , et al. (394 additional authors not shown)

Abstract: We perform a measurement of time-dependent $CP$ violation parameters in $B^{0} \to K_{S}^{0} π^{0} γ$ decays using a dataset of approximately $772 \times 10^6$ and $521 \times 10^6$ $Υ(4S)$ decays collected by the Belle and Belle II experiments, respectively. The measured parameters for the combined dataset in the $K^{*0}(892)$ dominated region (… ▽ More We perform a measurement of time-dependent $CP$ violation parameters in $B^{0} \to K_{S}^{0} π^{0} γ$ decays using a dataset of approximately $772 \times 10^6$ and $521 \times 10^6$ $Υ(4S)$ decays collected by the Belle and Belle II experiments, respectively. The measured parameters for the combined dataset in the $K^{*0}(892)$ dominated region ($M_{K_{S}^{0} π^{0}} \in [0.8,1.0] \mathrm{GeV}/c^2$) are $S = 0.09 \pm 0.16 \pm 0.02$ and $C = -0.09 \pm 0.08 \pm 0.04$. For the non-$K^{*0}(892)$ region ($M_{K_{S}^{0} π^{0}} \in [1.0,1.8] \mathrm{GeV}/c^2$), the corresponding values are $S = -0.32 \pm 0.33 \pm 0.09$ and $C = -0.07 \pm 0.17 \pm 0.08$. The first quoted uncertainties are statistical, while the second ones are systematic. These results are consistent with Standard Model predictions and more precise than previous measurements. △ Less

Submitted 3 June, 2026; originally announced June 2026.

Report number: Belle II preprint: 2026-010, KEK preprint: 2026-06

He-CF4-CH4 ternary mixtures as target gas for the CYGNO directional dark matter experiment

Authors: F. D. Amaro, R. Antonietti, E. Baracchini, L. Benussi, C. Capoccia, M. Caponero, L. G. M de Carvalho, G. Cavoto, I. A. Costa, A. Croce, M. D'Astolfo, G. D'Imperio, G. Dho, E. Di Marco, J. M. F. dos Santos, D. Fiorina, F. Iacoangeli, Z. Islam, H. P. Lima Jr, G. Maccarrone, R. D. P. Mano, D. J. G. Marques, L. G. M. de Carvalho, G. Mazzitelli, P. Meloni , et al. (19 additional authors not shown)

Abstract: The CYGNO collaboration is advancing a high-resolution optical Time Projection Chamber (TPC) for directional dark matter searches and solar neutrino spectroscopy at LNGS. The detector uses a He-40%CF4 gas mixture at atmospheric pressure and a triple-GEM cascade for ionization signal amplification. Scintillation light from GEM electron avalanches is read out using sCMOS cameras, enabling high sensi… ▽ More The CYGNO collaboration is advancing a high-resolution optical Time Projection Chamber (TPC) for directional dark matter searches and solar neutrino spectroscopy at LNGS. The detector uses a He-40%CF4 gas mixture at atmospheric pressure and a triple-GEM cascade for ionization signal amplification. Scintillation light from GEM electron avalanches is read out using sCMOS cameras, enabling high sensitivity to interactions in the few keV range, alongside precise ionization event tracking and particle identification. This study investigates the effects of adding 3-10% methane to the He-40%CF4 mixture. Methane improves the electrical stability of the TPC, allowing for higher GEM voltages before discharge onset, which compensates for its scintillation quenching and leads to enhanced overall scintillation yield. Compared to prior studies performed with isobutane, methane demonstrates a lower quenching effect on visible and UV photons while maintaining good energy resolution. Importantly, the inclusion of methane lowers the dark matter detection threshold by providing a lighter target and extending track lengths of light nuclear recoils, thus enhancing directional discrimination. These results establish methane as a promising additive for optimizing CYGNO's performance in detecting low-mass dark matter candidates. △ Less

Submitted 31 May, 2026; originally announced June 2026.

Price of Coupling in Multilevel Linear Programming

Authors: Nagisa Sugishita, Margarida Carvalho

Abstract: Multilevel programming is the standard framework for modeling hierarchical decision-making. In this paper, we characterize the computational complexity of deciding the existence of feasible and optimal solutions, as well as computing the optimal objective value in multilevel linear programming (LP). Our analysis considers various combinations of modeling assumptions, including the presence or abse… ▽ More Multilevel programming is the standard framework for modeling hierarchical decision-making. In this paper, we characterize the computational complexity of deciding the existence of feasible and optimal solutions, as well as computing the optimal objective value in multilevel linear programming (LP). Our analysis considers various combinations of modeling assumptions, including the presence or absence of linking (coupling) constraints and whether all variables are bounded. In particular, we show the feasibility problem of $k$-level LP is $Σ^{p}_{k-1}$-complete for $k \ge 2$. Without linking constraints and unbounded variables, it is polynomial-time solvable for $k \le 4$ but becomes $Σ^{p}_{k-1}$-complete for $k \ge 5$, indicating a sharp jump in computational complexity assuming the polynomial hierarchy does not collapse. Combined with other results, one major implication is that no polynomial-time Turing machine can transform a bilevel LP instance with linking constraints into one without linking constraints while preserving feasibility unless P $=$ NP. In contrast, such machines exist for all $k \ge 5$. We observe similar phenomena with the decision of the existence of an optimal solution. In the bilevel case, feasibility and boundedness fully characterize the existence of an optimal solution, implying that the problem is DP-complete. However, these conditions are insufficient for $k \ge 3$ and the problem for $k \ge 3$ is $Δ^{p}_k$-complete. Similar to the feasibility problem, the problem becomes polynomially solvable for $k=2,3$ without linking constraints and unbounded variables. However, the problem is $Δ^{p}_k$-complete for $k \ge 4$, even with these simplifying assumptions. The computation of the optimal objective value is F$Δ^{p}_k$-complete for any $k \ge 2$, even without linking constraints and unbounded variables. △ Less

Submitted 24 May, 2026; originally announced May 2026.

Comments: 25 pages

Assessing socio-economic climate impacts from text data

Authors: Mariana Madruga de Brito, Brielen Madureira, Taís Maria Nunes Carvalho, Damien Delforge, Aglaé Jézéquel, Murathan Kurfalı, Ni Li, Gabriele Messori, Joakim Nivre, Barbara Pernici, Niko Speybroeck, Stefano Terzi, Wim Thiery, Bram Valkenborg, Jingxian Wang, Shorouq Zahra, Jakob Zscheischler, Jan Sodoge

Abstract: Recent advances in natural language processing (NLP) and large language models (LLMs) have enabled the systematic use of large-scale textual data from news, social media, and reports to create datasets with socio-economic impacts of climate hazards such as floods, droughts, storms, and multi-hazard events. As the field of text-as-data for impact assessment expands, so does its methodological compl… ▽ More Recent advances in natural language processing (NLP) and large language models (LLMs) have enabled the systematic use of large-scale textual data from news, social media, and reports to create datasets with socio-economic impacts of climate hazards such as floods, droughts, storms, and multi-hazard events. As the field of text-as-data for impact assessment expands, so does its methodological complexity. Yet research remains fragmented, with no clear guidelines for defining what constitutes an impact, handling temporal and spatial biases, and selecting appropriate modeling and post-processing strategies. This lack of coherence limits transparency and comparability across studies. Here, we address this gap by synthesising common practices, describing key challenges specific to the use of text-as-data methods for analyzing socio-economic impact data, and proposing recommendations to address them. By providing guidance on best practices, we aim to support the construction of robust text-derived socio-economic impact datasets that can more accurately inform disaster risk management and attribution studies. △ Less

Submitted 20 May, 2026; originally announced May 2026.

Comments: Work in progress

The Impact of Process Competition on Energy Consumption: Analysis and Modeling

Authors: Eduardo Gomes Campos, Rafaela Sousa de Alencar Lacerda, Adnei Willian Donatti, Joberto S. B. Martins, Charles C. Miers, Tereza C. M. B. Carvalho

Abstract: With the development of distributed systems, the need to manage the sharing of machines among multiple simultaneous users arises. In the cloud computing context, the instantiation of virtual machines and containers by different users utilizing the same infrastructure leads to a dispute for physical computational resources. In this regard, this paper analyses a process's energy consumption as a fun… ▽ More With the development of distributed systems, the need to manage the sharing of machines among multiple simultaneous users arises. In the cloud computing context, the instantiation of virtual machines and containers by different users utilizing the same infrastructure leads to a dispute for physical computational resources. In this regard, this paper analyses a process's energy consumption as a function of the competition for computational resources it encounters. Investigating this behavior is fundamental for many applications, such as pricing in cloud computing services, and for task scheduling and load balancing, while increasing energy efficiency. To determine this behavior, experiments were conducted and resulted in a dependency on the number of processor cores of the physical machine hosting the process. As the number of cores increases, the process's energy consumption as a function of the competition it faces transitions from linear to a root function. △ Less

Submitted 14 February, 2026; originally announced May 2026.

Comments: 11 pages, 17 figuras, ADVANCE: International Workshop on ADVANCEs in ICT Infrastructures and Services, March 25--28, 2026, Florianópolis, Brazil

BCS-BEC crossover in trapped one-dimensional Fermi-Hubbard chains: entanglement and correlation signatures from DMRG and effective-pairing theory

Authors: G. Diniz, I. M. Carvalho, M. Sanino, F. Iemini, V. V. França

Abstract: Confined ultracold atoms in optical lattices provide a versatile platform for simulating lattice models of strongly correlated quantum systems, where pairing phenomena and superfluid phases can be explored under controlled conditions. While the crossover between the Bardeen-Cooper-Schrieffer (BCS) phase and the Bose-Einstein condensation (BEC) is well understood in homogeneous systems, spatial con… ▽ More Confined ultracold atoms in optical lattices provide a versatile platform for simulating lattice models of strongly correlated quantum systems, where pairing phenomena and superfluid phases can be explored under controlled conditions. While the crossover between the Bardeen-Cooper-Schrieffer (BCS) phase and the Bose-Einstein condensation (BEC) is well understood in homogeneous systems, spatial confinement breaks translational symmetry and reshapes correlation patterns, making the BCS-BEC identification in trapped geometries challenging and allowing unconventional phases to emerge with no direct analog in homogeneous systems. Here we present a characterization of the BCS-BEC crossover in harmonically confined one-dimensional Fermi-Hubbard chains. Our analysis combines Density Matrix Renormalization Group (DMRG) simulations and entanglement-based diagnostics with effective models describing the formation of tightly bound fermion pairs. This combined approach enables a detailed understanding of how the interplay between interactions and confinement reshapes the crossover, leading to insulating regions coexisting with persistent superfluid correlations. Within this framework, we further introduce conditioned correlation functions whose power-law decay allows a clear distinction between BCS-like and BEC-like regimes. The consistency between the effective descriptions and the numerical DMRG results yields a unified picture of the crossover in harmonically confined geometries. △ Less

Submitted 11 May, 2026; originally announced May 2026.

A Multi-Interface Firmware Acquisition and Validation Methodology for Low-Cost Consumer Drones: A Case Study on Three Holy Stone Platforms

Authors: Sandesh More, Sneha Sudhakaran, Marco Carvalho

Abstract: Consumer unmanned aerial vehicles (UAVs) have evolved into capable computing platforms, yet their embedded firmware remains largely inaccessible to the security community. Entry-level models, in particular those marketed to first-time and younger operators, commonly ship with limited protection mechanisms and no public documentation of their software internals. This paper presents a systematic stu… ▽ More Consumer unmanned aerial vehicles (UAVs) have evolved into capable computing platforms, yet their embedded firmware remains largely inaccessible to the security community. Entry-level models, in particular those marketed to first-time and younger operators, commonly ship with limited protection mechanisms and no public documentation of their software internals. This paper presents a systematic study of firmware extraction and validation applied to three Holy Stone consumer drone models: the HS175D, HS720, and HS360S. Rather than pursuing reverse-engineering outcomes, the work focuses on obtaining reliable, ground-truth firmware images across heterogeneous hardware designs using only commercially available, low-cost tooling. Four acquisition methods are evaluated SPI flash in-circuit reading, SWD/JTAG debug-port access, UART boot-message capture, and a clip-based contact approach that avoids chip desoldering and each is assessed for success rate, image completeness, and operational practicality. Post-acquisition quality is evaluated through sliding-window Shannon entropy profiling and structural-signature analysis using binwalk, together forming a three-tier validation framework that distinguishes validated images from those that appear successful at the tool level but contain no meaningful firmware content. Static analysis via the EMBA framework confirms that validated images contain identifiable OS components, aging library stacks with known CVE exposure, and no binary-hardening mechanisms. The resulting corpus and methodology provide a reproducible baseline for firmware rehosting, vulnerability analysis, secure-boot assessment, and embedded-systems education within the consumer UAV domain. Index Terms: consumer UAV, drone firmware, embedded systems security, entropy analysis, firmware extraction, IoT security, SPI flash, SWD/JTAG, UART. △ Less

Submitted 11 May, 2026; originally announced May 2026.

Comments: 13 pages, 3 figures, 7 tables, 36 references. Preprint of a manuscript being prepared for submission to the journal Internet of Things (Elsevier)

On singular problems in nonreflexive fractional Orlicz-Sobolev spaces

Authors: Marcos L. M. Carvalho, Luana C. M. Lima, Carlos A. P. Santos, Maxwell L. Silva

Abstract: In this work, we deal with existence and uniqueness of positive solution $u_s$ for the singular quasilinear problem $(-Δ_Φ)^su=u^{-γ}$ in the nonreflexive fractional Orlicz-Sobolev $ W^{s}_0L^Φ(Ω)$ for $0<s<1$. Furthermore, we show that $u_s$ converges in $L^Φ(Ω)$ to the unique positive solution $u\in W^{1}_0L^Φ(Ω)$ of the problem $-Δ_Ψu=u^{-γ}$ as $s \uparrow 1$, where $Ψ$ is an appropriate $N$-f… ▽ More In this work, we deal with existence and uniqueness of positive solution $u_s$ for the singular quasilinear problem $(-Δ_Φ)^su=u^{-γ}$ in the nonreflexive fractional Orlicz-Sobolev $ W^{s}_0L^Φ(Ω)$ for $0<s<1$. Furthermore, we show that $u_s$ converges in $L^Φ(Ω)$ to the unique positive solution $u\in W^{1}_0L^Φ(Ω)$ of the problem $-Δ_Ψu=u^{-γ}$ as $s \uparrow 1$, where $Ψ$ is an appropriate $N$-function equivalent to the $N$-function $Φ$. The main difficulties to obtain existence of weak solutions for both singular quasilinear problems are that their associate energy functionals may not be well-defined on their whole natural workspaces due to the lack of the reflexivity and the presence of the singular term. To overcome these difficulties, we will use the minimization method and present a new approach to building appropriate test functions to prove that the problems have positive minimizers that we showed to be weak solutions of them, respectively. △ Less

Submitted 12 May, 2026; v1 submitted 9 May, 2026; originally announced May 2026.

Comments: 23 pages

The Wristband Gaussian Loss: Deterministic, Composable Latents via a Sphere-Interval Decomposition

Authors: Mikhail Parakhin, André M. Carvalho, Patrick Haluptzok

Abstract: We present the Wristband Gaussian Loss, a deterministic batch loss for Gaussianizing point embeddings without sampling, KL terms, or iterative transport. Each $x \in \mathbb{R}^d$ is mapped to a direction $u = x/\|x\|$ and a CDF-transformed radius $t = F_{χ^2_d}(\|x\|^2)$ on the wristband $S^{d-1} \times [0,1]$. We prove (and machine-verify in Lean~4) that for $d \ge 2$ the pushforward wristband m… ▽ More We present the Wristband Gaussian Loss, a deterministic batch loss for Gaussianizing point embeddings without sampling, KL terms, or iterative transport. Each $x \in \mathbb{R}^d$ is mapped to a direction $u = x/\|x\|$ and a CDF-transformed radius $t = F_{χ^2_d}(\|x\|^2)$ on the wristband $S^{d-1} \times [0,1]$. We prove (and machine-verify in Lean~4) that for $d \ge 2$ the pushforward wristband map equals $σ_{d-1} \otimes \mathrm{Unif}[0,1]$ iff the source is $\mathcal{N}(0, I_d)$, and that the Neumann-reflected wristband repulsion energy is uniquely minimized at the uniform target. We compute this reflected-kernel objective in two ways: a nearest three-image pairwise truncation at $O(N^2 d)$, and a spectral Neumann path joining angular and radial Mercer modes (spherical-harmonic and cosine) at $O(N d K)$, with empirically matched gradients. A 1D Wasserstein radial term and a moment penalty serve as finite-sample accelerators with the same optimum, and Monte-Carlo null calibration turns the components into a single standardized statistic. We evaluate direct point-cloud Gaussianization with a calibrated barycentric $W_2$ score: a deterministic Gaussian reference batch is built by recursive Hungarian averaging, with each method reported as a $z$-score against same-size Gaussian batches. On the axis-uniform X benchmark, Wristband is competitive in 2D and gives the best 10D score. On a harder radial--angular-copula impostor whose Gaussian radial and angular marginals are correct but dependent, Wristband gives the best 10D and 128D scores. Coupled with learnable-key Euclidean attention and exact invertible flows, the resulting Deterministic Gaussian Autoencoder delivers a Gaussian-latent interface for counterfactual sampling with independent factors and a context/residual construction for dependent factors. △ Less

Submitted 9 May, 2026; originally announced May 2026.

Comments: preprint

Welcome to the Statverse: A Metaverse for Data Science

Authors: Ronny Vallejos, Miguel de Carvalho, Roberto Cruz, Nicolás Iribarra, José Allende, Edmundo Casas, Francisco Marshall, Sebastián Suárez, Leopoldo Cárdenas, Ozan Evkaya

Abstract: This paper introduces the Statverse, a Metaverse framework designed to revolutionize statistical education in the digital age. Our key goal is to report our progress and encourage others to integrate similar strategies into their programs. The proposed framework seamlessly integrates the physical and digital realms to provide an immersive environment for the nuanced representation of complex stati… ▽ More This paper introduces the Statverse, a Metaverse framework designed to revolutionize statistical education in the digital age. Our key goal is to report our progress and encourage others to integrate similar strategies into their programs. The proposed framework seamlessly integrates the physical and digital realms to provide an immersive environment for the nuanced representation of complex statistical concepts. Finally, we discuss the potential impact of Statverse on advancing Statistical Education, offering a transformative approach to teaching and learning in the digital age. Statverse is the outcome of an academic partnership between Universidad Técnica Federico Santa María (UTFSM) and the University of Edinburgh (UoE). △ Less

Submitted 6 May, 2026; originally announced May 2026.

Comments: 11 pages, 5 figures

Decision Problems in Multilevel Linear Programming

Authors: Nagisa Sugishita, Margarida Carvalho

Abstract: We study the computational complexity of decision problems in $k$-level linear programming (LP). Seminal work by Jeroslow establishes that determining whether the optimal objective value of a $k$-level LP is at least as good as a given threshold is $Σ^{\mathrm{p}}_{k-1}$-hard. In this paper, we demonstrate the matching upper bound and thereby prove that this problem is $Σ^{\mathrm{p}}_{k-1}$-compl… ▽ More We study the computational complexity of decision problems in $k$-level linear programming (LP). Seminal work by Jeroslow establishes that determining whether the optimal objective value of a $k$-level LP is at least as good as a given threshold is $Σ^{\mathrm{p}}_{k-1}$-hard. In this paper, we demonstrate the matching upper bound and thereby prove that this problem is $Σ^{\mathrm{p}}_{k-1}$-complete. To this end, we show that the feasible region of a $k$-level LP can be expressed as a union of sets defined by weak and strict linear inequalities. Moreover, we show that the decision of the unboundedness is $Σ^{\mathrm{p}}_{k-1}$-complete. Finally, we discuss the extension of our results to the mixed-binary cases. In short, this work closes lasting open questions in multilevel programming. △ Less

Submitted 6 May, 2026; originally announced May 2026.

Comments: 18 pages

Evaluating Temporal and Structural Anomaly Detection Paradigms for DDoS Traffic

Authors: Yasmin Souza Lima, Rodrigo Moreira, Larissa F. Rodrigues Moreira, Tereza Cristina M. de B. Carvalho, Flávio de Oliveira Silva

Abstract: Unsupervised anomaly detection is widely used to detect Distributed Denial-of-Service (DDoS) attacks in cloud-native 5G networks, yet most studies assume a fixed traffic representation, either temporal or structural, without validating which feature space best matches the data. We propose a lightweight decision framework that prioritizes temporal or structural features before training, using two d… ▽ More Unsupervised anomaly detection is widely used to detect Distributed Denial-of-Service (DDoS) attacks in cloud-native 5G networks, yet most studies assume a fixed traffic representation, either temporal or structural, without validating which feature space best matches the data. We propose a lightweight decision framework that prioritizes temporal or structural features before training, using two diagnostics: lag-1 autocorrelation of an aggregated flow signal and PCA cumulative explained variance. When the probes are inconclusive, the framework reserves a hybrid option as a future fallback rather than an empirically validated branch. Experiments on two statistically distinct datasets with Isolation Forest, One-Class SVM, and KMeans show that structural features consistently match or outperform temporal ones, with the performance gap widening as temporal dependence weakens. △ Less

Submitted 17 April, 2026; originally announced April 2026.

Comments: Paper accepted for publication at Experimental Research Workshop on the Future Internet (2026) in conjunction with Brazilian Symposium on Computer Networks and Distributed Systems (2026)

Software Vulnerability Detection Using a Lightweight Graph Neural Network

Authors: Miles Farmer, Ekincan Ufuktepe, Anne Watson, Hialo Muniz Carvalho, Vadim Okun, Zineb Maasaoui, Kannappan Palaniappan

Abstract: Large Language Models (LLMs) have emerged as a popular choice in vulnerability detection studies given their foundational capabilities, open source availability, and variety of models, but have limited scalability due to extensive compute requirements. Using the natural graph relational structure of code, we show that our proposed graph neural network (GNN) based deep learning model VulGNN for vul… ▽ More Large Language Models (LLMs) have emerged as a popular choice in vulnerability detection studies given their foundational capabilities, open source availability, and variety of models, but have limited scalability due to extensive compute requirements. Using the natural graph relational structure of code, we show that our proposed graph neural network (GNN) based deep learning model VulGNN for vulnerability detection can achieve performance almost on par with LLMs, but is 100 times smaller in size and fast to retrain and customize. We describe the VulGNN architecture, ablation studies on components, learning rates, and generalizability to different code datasets. As a lightweight model for vulnerability analysis, VulGNN is efficient and deployable at the edge as part of real-world software development pipelines. △ Less

Submitted 30 March, 2026; originally announced March 2026.

Comments: 12 pages, 3 figures, preprint of journal submission

Dynamical metric order

Authors: Maria Carvalho, Fagner B. Rodrigues

Abstract: We introduce the notion of dynamical metric order of a continuous map on a compact metric space, study its basic properties, and compute it for several classes of maps. This concept which is a counterpart of the metric mean dimension with the role of the box-counting dimension being played by the metric order. It is devised for maps acting on spaces with infinite box-counting dimension but finite… ▽ More We introduce the notion of dynamical metric order of a continuous map on a compact metric space, study its basic properties, and compute it for several classes of maps. This concept which is a counterpart of the metric mean dimension with the role of the box-counting dimension being played by the metric order. It is devised for maps acting on spaces with infinite box-counting dimension but finite metric order. For example, it brings forward new information about full shifts whose alphabets have infinite box-counting dimension; and provides a sharper estimate of complexity for the induced map determined by a continuous transformation on a compact metric space, whose upper metric mean dimension is known to admit only two values (zero or infinity). We also show that it satisfies a variational principle where maximization is taken over the space of invariant probability measures and whose equilibrium states always exist. △ Less

Submitted 10 April, 2026; v1 submitted 30 March, 2026; originally announced March 2026.

MSC Class: 28D20; 37A05; 37C45; 37B40; 37D35

Search for the decay $B^+ \rightarrow K^+τ^+τ^-$ using data from the Belle and Belle II experiments

Authors: Belle, Belle II Collaborations, :, M. Abumusabh, I. Adachi, K. Adamczyk, A. Aggarwal, L. Aggarwal, H. Ahmed, Y. Ahn, H. Aihara, N. Akopov, S. Alghamdi, M. Alhakami, A. Aloisio, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, D. M. Asner, H. Atmacan, T. Aushev, R. Ayad, V. Babu , et al. (414 additional authors not shown)

Abstract: We report a search for the rare decay $B^{+} \rightarrow K^{+} τ^{+} τ^{-}$ using $1.2 \times 10^9$ $Υ(4S)$ mesons produced near threshold in electron-positron collisions and collected by the Belle and Belle~II experiments. We fully reconstruct the hadronic decay of one $B$ meson produced in the $Υ(4S)\rightarrow B^{+} B^{-}$ decay, and search for $B^{\pm}\rightarrow K^{\pm} τ^{+}τ^{-}$ candidates… ▽ More We report a search for the rare decay $B^{+} \rightarrow K^{+} τ^{+} τ^{-}$ using $1.2 \times 10^9$ $Υ(4S)$ mesons produced near threshold in electron-positron collisions and collected by the Belle and Belle~II experiments. We fully reconstruct the hadronic decay of one $B$ meson produced in the $Υ(4S)\rightarrow B^{+} B^{-}$ decay, and search for $B^{\pm}\rightarrow K^{\pm} τ^{+}τ^{-}$ candidates among the remaining collision products, reconstructing a charged kaon and leptonic decays of the $τ$ leptons. We optimize the selection for best sensitivity and look for an excess over background at low values of the residual energy detected in the calorimeter after full event reconstruction. We observe no significant excess and set the limit $\mathcal{B}(B^{+}\rightarrow K^{+}τ^{+}τ^{-})< 0.56\times 10^{-3}$ at the 90% confidence level, improving on the only previous result by a factor of four. △ Less

Submitted 25 March, 2026; originally announced March 2026.

Report number: Belle II preprint 2026-003, KEK preprint 2025-43

Journal ref: Phys. Rev. Lett. 137, 051805 (2026)

The CYGNO experiment: a gaseous TPC with optical readout for rare events searches

Authors: F. D. Amaro, R. Antonietti, E. Baracchini, L. Benussi, C. Capoccia, M. Caponero, L. G. M de Carvalho, G. Cavoto, I. A. Costa, A. Croce, M. D'Astolfo, G. D'Imperio, G. Dho, E. Di Marco, J. M. F. dos Santos, D. Fiorina, F. Iacoangeli, Z. Islam, H. P. Lima Jr, G. Maccarrone, R. D. P. Mano, D. J. G. Marques, G. Mazzitelli, P. Meloni, A. Messina , et al. (17 additional authors not shown)

Abstract: The CYGNO collaboration is developing a novel strategy for directional Dark Matter searches based on a gaseous Time Projection Chamber (TPC). The detector is optimized for the exploration of light (0.5-50 GeV) WIMPs-like particles and employs a He/CF4 gas mixture at atmospheric pressure, sensitive to both spin-dependent and spin-independent interactions. A key feature of the project is its optical… ▽ More The CYGNO collaboration is developing a novel strategy for directional Dark Matter searches based on a gaseous Time Projection Chamber (TPC). The detector is optimized for the exploration of light (0.5-50 GeV) WIMPs-like particles and employs a He/CF4 gas mixture at atmospheric pressure, sensitive to both spin-dependent and spin-independent interactions. A key feature of the project is its optical readout, which relies on photon detection rather than charge collection. In CYGNO detectors, electrons released by ionizing tracks drift toward an amplification stage of three Gas Electron Multipliers (GEMs). The electron avalanches generate scintillation light that is captured by scientific CMOS (sCMOS) cameras for high-resolution two-dimensional imaging and by Photomultiplier Tubes (PMTs) that provide a precise time profile along the drift direction. This allows a 3D event reconstruction, detailed energy deposition mapping, and effective topology and head-to-tail discrimination. Building on the achievements of the 50 L prototype (LIME), which successfully operated underground at LNGS, the next step is the deployment of a 0.4 m3 demonstrator, CYGNO-04, to be completed in 2026. The demonstrator will validate scalability and confirm the advantages of the proposed technique. Recent results from LIME highlight strong progress in 3D tracking and particle identification. The current status of CYGNO-04 and its role in advancing the program will be presented as well. △ Less

Submitted 23 March, 2026; originally announced March 2026.

On quantization and the classical variational principle for the metric mean dimension

Authors: Maria Carvalho, Gustavo Pessil

Abstract: This paper investigates the relationship between quantization of measures and metric mean dimension of topological dynamical systems. We introduce the concept of mean quantization dimension for invariant probability measures and establish a classical variational principle: the metric mean dimension of a dynamical system is equal to the maximum mean quantization dimension among all invariant measur… ▽ More This paper investigates the relationship between quantization of measures and metric mean dimension of topological dynamical systems. We introduce the concept of mean quantization dimension for invariant probability measures and establish a classical variational principle: the metric mean dimension of a dynamical system is equal to the maximum mean quantization dimension among all invariant measures. This approach effectively characterizes the complexity of systems with infinite entropy by identifying a measure that captures information across all scales; and yields a fundamental property that allows for the exchange of limits and suprema in the Lindenstrauss-Tsukamoto variational principles, a feat that most known entropy-like maps fail to achieve due to convexity. Nevertheless, we show that the Katok and Shapira entropies do satisfy this property and, therefore, a classical variational principle for the metric mean dimension, for which maximizing measures always exist. △ Less

Submitted 20 May, 2026; v1 submitted 17 March, 2026; originally announced March 2026.

Upgrade of the Trigger and Data Acquisition System for Continuous Imaging and Multi-Camera Operation in CYGNO

Authors: F. D. Amaro, R. Antonietti, E. Baracchini, L. Benussi, C. Capoccia, M. Caponero, L. G. M. de Carvalho, G. Cavoto, I. A. Costa, A. Croce, M. D'Astolfo, G. D'Imperio, G. Dho, E. Di Marco, J. M. F. dos Santos, D. Fiorina, F. Iacoangeli, Z. Islam, E. Kemp, H. P. Lima Jr, G. Maccarrone, R. D. P. Mano, D. J. G. Marques, G. Mazzitelli, P. Meloni , et al. (19 additional authors not shown)

Abstract: The CYGNO experiment employs an optical readout to image particle interactions in a gaseous Time Projection Chamber (TPC), combining cameras and photomultiplier tubes (PMTs) to achieve high spatial resolution and timing information. This approach enables detailed track reconstruction but poses significant challenges for data acquisition, particularly in view of the next experimental phase, CYGNO-0… ▽ More The CYGNO experiment employs an optical readout to image particle interactions in a gaseous Time Projection Chamber (TPC), combining cameras and photomultiplier tubes (PMTs) to achieve high spatial resolution and timing information. This approach enables detailed track reconstruction but poses significant challenges for data acquisition, particularly in view of the next experimental phase, CYGNO-04, which will operate multiple cameras simultaneously. In this paper, we present an upgrade of the CYGNO Trigger and Data Acquisition (T-DAQ) system, developed starting from the LIME configuration and validated on the MANGO prototype. The upgrade introduces a continuous imaging acquisition mode, substantially reducing the camera dead time, together with an extended trigger time-tagging scheme that provides a robust global time reference for PMT signals. A synchronous multi-camera DAQ architecture is also implemented and tested, enabling coordinated operation of multiple optical sensors without a master camera. The performance of the upgraded system is validated through dedicated tests, demonstrating stable continuous acquisition, reliable time-tagging, and consistent synchronization across multiple cameras. These results establish a solid and scalable foundation for the CYGNO-04 DAQ and represent a key step toward efficient data acquisition in future large-scale optical TPC detectors. △ Less

Submitted 30 April, 2026; v1 submitted 16 March, 2026; originally announced March 2026.

Journal ref: JINST 21 (2026) T04004

Searches for charged-lepton-flavor violation in $χ_{bJ}(1P)$ decays

Authors: Belle, Belle II Collaborations, :, M. Abumusabh, I. Adachi, A. Aggarwal, L. Aggarwal, H. Ahmed, Y. Ahn, H. Aihara, N. Akopov, S. Alghamdi, M. Alhakami, A. Aloisio, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, D. M. Asner, H. Atmacan, T. Aushev, R. Ayad, V. Babu, H. Bae , et al. (394 additional authors not shown)

Abstract: We report the first searches for charged-lepton-flavor violation in decays of $χ_{bJ}(1P)$ ($J=0, 1,$ and $2$) to a pair of charged leptons using 158 million $Υ(2S)$ decays collected with the Belle detector in $e^+e^-$ collisions at the KEKB collider. No significant signal is observed, and we set upper limits on the branching fractions for $χ_{bJ}(1P)$ decays to $e^\pmμ^\mp$ at the level of… ▽ More We report the first searches for charged-lepton-flavor violation in decays of $χ_{bJ}(1P)$ ($J=0, 1,$ and $2$) to a pair of charged leptons using 158 million $Υ(2S)$ decays collected with the Belle detector in $e^+e^-$ collisions at the KEKB collider. No significant signal is observed, and we set upper limits on the branching fractions for $χ_{bJ}(1P)$ decays to $e^\pmμ^\mp$ at the level of $10^{-6}$ and to $e^\pmτ^\mp$ or $μ^\pmτ^\mp$ at the level of $10^{-5}$. Limits on $χ_{b0}(1P)$ decays are translated into bounds on the corresponding Wilson coefficients of scalar operators that mediate charged-lepton-flavor violation. △ Less

Submitted 7 July, 2026; v1 submitted 11 March, 2026; originally announced March 2026.

Comments: 5 pages, 4 figures, HQL 2025, QWG 2025

Report number: Belle~II Preprint 2026-005, KEK Preprint 2026-1

Journal ref: Phys. Rev. Lett. 137, 071803 (2026)

First Optical Observation of Negative Ion Drift at Surface Pressure

Authors: F. D. Amaro, R. Antonietti, E. Baracchini, L. Benussi, C. Capoccia, M. Caponero, L. G. M. de Carvalho, G. Cavoto, I. A. Costa, A. Croce, M. D'Astolfo, G. D'Imperio, G. Dho, F. Di Giambattista, E. Di Marco, J. M. F. dos Santos, D. Fiorina, F. Iacoangeli, Z. Islam, H. P. Lima Jr., G. Maccarrone, R. D. P. Mano, D. J. G. Marques, G. Mazzitelli, P. Meloni , et al. (19 additional authors not shown)

Abstract: We report the first observation of Negative Ion Drift (NID) at surface pressure of $900 \pm 7$ mbar at Laboratori Nazionali del Gran Sasso in a He:CF$_4$:SF$_6$ mixture using an optically read out Time Projection Chamber (TPC) within the CYGNO/INITIUM project. We present the first PMT waveform analysis in the NID regime, interpreting the temporal light pattern through a model that combines track g… ▽ More We report the first observation of Negative Ion Drift (NID) at surface pressure of $900 \pm 7$ mbar at Laboratori Nazionali del Gran Sasso in a He:CF$_4$:SF$_6$ mixture using an optically read out Time Projection Chamber (TPC) within the CYGNO/INITIUM project. We present the first PMT waveform analysis in the NID regime, interpreting the temporal light pattern through a model that combines track geometry and charge transport. The inferred drift velocities correspond to mobilities of O(cm$^2$ V$^{-1}$ s$^{-1}$), consistent with negative ion transport. The observed linear scaling of the time extension mean with drift distance reveals the presence of a faster minority charge carrier population in addition to the dominant SF$_6^-$ species, drifting at a $\sim$25\% higher velocity under external inputs. These results demonstrate multi-species negative ion drift operation at surface pressure in a He:CF$_4$:SF$_6$ mixture and open a concrete path toward large scale, low diffusion optical TPCs for rare event searches. △ Less

Submitted 6 March, 2026; originally announced March 2026.

Comments: 6 pages, 3 figures + Supplemental Material (9 pages, 3 figures). Submitted to Physical Review Letters

Caught in the web: galaxy mergers along cosmic filaments

Authors: Carolina Dulcien, Yara L. Jaffe, Jacob P. Crossett, Raul Baier-Soto, Hugo Mendez-Hernandez, Christopher P. Haines, Guillermo Cabrera-Vives, Patricio Olivares, P. Vasquez-Bustos, Maria Argudo-Fernandez, Javiera Vivanco, Lawrence Bilton, Clecio R. Bom, Giuseppe D'Ago, Alexis Finoguenov, Ulrike Kuchner, Ciria Lima-Dias, Paola Merluzzi, Antonela Monachesi, Diego Pallero, Nicolas Tejos, Gabriel S. M. Teixeira, Cristobal Sifon, Maiara S. Carvalho, Ricardo Demarco , et al. (9 additional authors not shown)

Abstract: Galaxy clusters grow through the accretion of galaxies from groups, filaments, and other clusters. During this process, galaxies may undergo pre-processing in lower-density environments, where galaxy-galaxy mergers and other interactions can significantly alter their properties prior to cluster infall. We investigate the role of galaxy mergers in the pre-processing of galaxies prior to cluster inf… ▽ More Galaxy clusters grow through the accretion of galaxies from groups, filaments, and other clusters. During this process, galaxies may undergo pre-processing in lower-density environments, where galaxy-galaxy mergers and other interactions can significantly alter their properties prior to cluster infall. We investigate the role of galaxy mergers in the pre-processing of galaxies prior to cluster infall by studying the spatial distribution of mergers across the cosmic web. We use a sample of 43,922 galaxies targeted by the 4MOST CHANCES survey in and around 33 low-redshift clusters (z < 0.07). Using Zoobot, a deep-learning framework trained on Galaxy Zoo data, we identify 698 galaxy mergers. We measure their distances to cosmic web filaments and compare them with those of non-merging galaxies. We find that galaxy mergers are significantly closer to filaments than the non-merging galaxy population, with this trend being strongest beyond the cluster virial radius. This suggests that filaments provide conditions conducive to mergers, possibly moderating relative velocities and enhancing gas availability. Our findings support a scenario in which filaments play a key role in transforming galaxies through pre-processing by promoting mergers before they enter cluster cores where star formation quenches. △ Less

Submitted 6 March, 2026; originally announced March 2026.

Journal ref: A&A 708, L5 (2026)

AstroInspect: a web-based system to organize, assess, and visually inspect astronomical objects

Authors: Natanael M. Cardoso, Claudia Mendes de Oliveira, Angela C. Krabbe, Analia V. Smith Castelli, Gustavo B. Oliveira Schwarz, Lilianne Nakazono, Ricardo Demarco, Maiara S. Carvalho, William Schoenell, Tiago Ribeiro, Antonio Kanaan, Antonio M. Saraiva

Abstract: The rapid growth of imaging and spectroscopic surveys has intensified the need for efficient tools that support visual inspection, a practice that remains essential for tasks such as classification, catalog refinement, and validation of automated methods. Existing solutions, however, often require the use of multiple platforms and complex workflows to integrate heterogeneous data. To address this… ▽ More The rapid growth of imaging and spectroscopic surveys has intensified the need for efficient tools that support visual inspection, a practice that remains essential for tasks such as classification, catalog refinement, and validation of automated methods. Existing solutions, however, often require the use of multiple platforms and complex workflows to integrate heterogeneous data. To address this challenge, we present the first release of the AstroInspect (https://astroinspect.github.io), a web-based system which ensures seamless access to several astronomical resources. The system provides an intuitive graphical user interface (GUI) through which users can upload catalogs of objects defined by celestial coordinates. AstroInspect automatically enriches these catalogs with complementary information, including imaging, spectroscopic, and photometric data retrieved in real time from surveys such as the Sloan Digital Sky Survey (SDSS), the Legacy Surveys (LS), and the Southern Photometric Local Universe Survey (S-PLUS). As an example of its scientific utility, we used AstroInspect to identify H$α$ emission-line galaxies within a 7 deg radius in the direction of the Hydra I cluster (also known as Abell 1060) by visual inspection. Using a candidate set of 981 galaxies selected from S-PLUS photometric data, we produced a catalog of 80 galaxies with confirmed H$α$ emission. These results highlight the potential of AstroInspect to support efficient visual inspection workflows. △ Less

Submitted 4 March, 2026; originally announced March 2026.

Comments: 20 pages, 7 figures, 1 table, accepted in AJ

Spatial Confounding: A review of concepts, challenges, and current approaches

Authors: Isaque Vieira Machado Pim, Luiz Max Fagundes de Carvalho, Marcos Oliveira Prates

Abstract: Spatial confounding is a persistent challenge in spatial statistics, influencing the validity of statistical inference in models that analyze spatially-structured data. The concept has been interpreted in various ways but is broadly defined as bias in estimates arising from unmeasured spatial variation. In this paper we review definitions, classical spatial models, and recent methodological advanc… ▽ More Spatial confounding is a persistent challenge in spatial statistics, influencing the validity of statistical inference in models that analyze spatially-structured data. The concept has been interpreted in various ways but is broadly defined as bias in estimates arising from unmeasured spatial variation. In this paper we review definitions, classical spatial models, and recent methodological advances, including approaches from spatial statistics and causal inference. We provide an unified view of the many available approaches for areal as well as geostatistical data and discuss their relative merits both theoretically and empirically with a head-to-head comparison on real datasets. Finally, we leverage the results of the empirical comparisons to discuss directions for future research. △ Less

Submitted 19 February, 2026; originally announced February 2026.

Comments: 34 pages, 4 figures

Stackelberg Dynamic Location Planning under Cumulative Demand

Authors: Warley Almeida Silva, Margarida Carvalho, Sanjay Dominik Jena

Abstract: Dynamic facility location problems predominantly suppose a monopoly over the service or product provided. Nonetheless, this premise can be a severe oversimplification in the presence of market competitors, as customers may prefer facilities installed by one of them. The monopolistic assumption can particularly worsen planning performance when demand depends on prior location decisions of the marke… ▽ More Dynamic facility location problems predominantly suppose a monopoly over the service or product provided. Nonetheless, this premise can be a severe oversimplification in the presence of market competitors, as customers may prefer facilities installed by one of them. The monopolistic assumption can particularly worsen planning performance when demand depends on prior location decisions of the market participants, namely, when unmet demand from one period carries over to the next. Such a demand behaviour creates an intrinsic relationship between customer demand and location decisions of all market participants, and requires the decision-maker to anticipate the competitor's response. This work studies a novel competitive facility location problem that combines cumulative demand and market competition to devise high-quality solutions. We propose bilevel mixed-integer programming formulations for two variants of our problem, prove that the optimistic variant is $Σ^{p}_{2}$-hard, and develop branch-and-cut algorithms with tightened value-function cuts that significantly outperform general-purpose bilevel solvers. Our results quantify the severe cost of planning under a monopolistic assumption (profit drops by half on average) and the gains from cooperation over competition (6% more joint profit), while drawing managerial guidelines on how instance attributes and duopolistic modelling choices shape robust location schedules. △ Less

Submitted 19 February, 2026; originally announced February 2026.

Comments: 48 pages, 17 figures

S-PLUS: Beyond Spectroscopy IV. Stellar Parameters and Elemental-abundance Ratios for Six Million Stars from DR4 and First Results for the Magellanic Clouds

Authors: Yang Huang, Timothy C. Beers, Kai Xiao, C. Mendes de Oliveira, Felipe Almeida-Fernandes, G. B. Oliveira Schwarz, Young Sun Lee, Jihye Hong, Huiling Chen, Huawei Zhang, Guilherme Limberg, Maiara S. Carvalho, P. K. Humire, André Luiz Figueiredo, Bruno Dias, Alvaro Alvarez-Candal, Marcos Fonseca-Faria, A. Kanaan, T. Ribeiro, W. Schoenell, Silvia Rossi

Abstract: We combine narrow/medium-band filter photometry from the Southern Photometric Local Universe Survey (S-PLUS) DR4 with ultra broad-band filter photometry from Gaia EDR3 to derive fundamental stellar parameters ($T_{\rm eff}$, $\log g$, [Fe/H], ages) and elemental-abundance ratios ([C/Fe] and [$α$/Fe]) for 5.4 million stars in the Galaxy (4.9 million dwarfs and 0.5 million giants), as well as for ov… ▽ More We combine narrow/medium-band filter photometry from the Southern Photometric Local Universe Survey (S-PLUS) DR4 with ultra broad-band filter photometry from Gaia EDR3 to derive fundamental stellar parameters ($T_{\rm eff}$, $\log g$, [Fe/H], ages) and elemental-abundance ratios ([C/Fe] and [$α$/Fe]) for 5.4 million stars in the Galaxy (4.9 million dwarfs and 0.5 million giants), as well as for over 0.7 million red giant stars in the Large and Small Magellanic Clouds (LMC and SMC). The precisions of the abundance estimates range from 0.05-0.10 dex for metallicity in the relatively metal-rich range ([Fe/H] $> -1.0$) to 0.10-0.30 dex in the metal-poor regime ([Fe/H] $<-1.0$), 0.10-0.20\,dex for [C/Fe], and 0.05 dex for [$α$/Fe]. The stellar parameters for LMC and SMC member stars are somewhat less precise than those from the S-PLUS main survey, primarily because of the effect of high reddening. The use of both metallicity- and carbon-sensitive filters provides unbiased measurements of both [Fe/H] and [C/Fe], of particular importance for very low-metallicity ([Fe/H] $< -2.0$) stars, where carbon enhancement can lead to systematically high estimates of [Fe/H] when only a single metallicity-sensitive filter is employed. Furthermore, multiple narrow-band filters enable metallicity estimates down to [Fe/H] $\sim -4.0$ with an accuracy of around 0.3 dex, exceeding the precision typically achieved by low/medium-resolution spectroscopy. This extensive photometric dataset, combined with the other three datasets in this series, will serve as a valuable legacy resource for Milky Way and Magellanic Clouds studies. △ Less

Submitted 15 February, 2026; originally announced February 2026.

Comments: 19 pages, 15 figures, 2 tables. Accepted for publication in ApJ

Elastic field causing noncommutativity

Authors: A. L. Silva Netto, A. M. de M. Carvalho, G. Q. Garcia, C. Furtado

Abstract: We study how a uniform torsion background, modeling a continuous density of screw dislocations and induces effective spatial noncommutativity and reshapes the energy spectrum of a free quantum particle. Within the geometric theory of defects, the metric yields a first-order (magnetic-like) coupling in the transverse dynamics, equivalent to an effective magnetic field $B_{eff}$ proportional to… ▽ More We study how a uniform torsion background, modeling a continuous density of screw dislocations and induces effective spatial noncommutativity and reshapes the energy spectrum of a free quantum particle. Within the geometric theory of defects, the metric yields a first-order (magnetic-like) coupling in the transverse dynamics, equivalent to an effective magnetic field $B_{eff}$ proportional to $p_z Omega$, where $Omega$ encodes the torsion strength. In the strong-coupling (Landau) regime, the planar coordinates obey [x,y] != 0 and the spectrum organizes into Landau-like levels with a slight electric-field-driven tilt and a uniform shift. Thus, increasing $Omega$ drives the system continuously toward the familiar Landau problem in flat space, with torsion setting the noncommutativity scale and controlling the approach to the Landau limit. △ Less

Submitted 9 February, 2026; originally announced February 2026.

Comments: 5 pages

Electroactive morphing effects on the aerodynamic performance through wobulation around an A320 wing with vibrating trailing edge at high Reynolds number

Authors: C. Rouaix, C. Jiménez-Navarro, M. Carvalho, C. Raibaudo, J. Abou-Khalil, A. Marouf, Y. Hoarau, G. Harran, J. C. R. Hunt, H. Hangan, J. F. Rouchon, M. Braza

Abstract: This study aims to investigate the effects of electroactive morphing on a 70cm chord A320 wing by means of near trailing edge slight deformation and vibration. Wing morphing is performed by Macro Fiber Composites (MFC) mini-piezoelectric actuators distributed along the span of the ''Reduced Scale'' (RS) A320 prototype of the H2020 No 723402 European research project SMS, ''Smart Morphing and Sensi… ▽ More This study aims to investigate the effects of electroactive morphing on a 70cm chord A320 wing by means of near trailing edge slight deformation and vibration. Wing morphing is performed by Macro Fiber Composites (MFC) mini-piezoelectric actuators distributed along the span of the ''Reduced Scale'' (RS) A320 prototype of the H2020 No 723402 European research project SMS, ''Smart Morphing and Sensing for aeronautical configurations'', (https://cordis.europa.eu/project/id/723402 and www.smartwing.org/SMS/EU). The configuration studied corresponds to a low-subsonic regime (Mach number 0.063) with a 10 degree incidence and a Reynolds number of 1 Million. The numerical simulations are carried out with the Navier-Stokes Multi-Block (NSMB) solver, which takes into account the deformation of the rear part of the wing implemented experimentally with the piezoelectric actuators. A detailed physical analysis of the morphing effects on the wake dynamics and on the aerodynamic performance is conducted with a constant amplitude of 0.7cm over a wide range of actuation frequencies [10-600]Hz. Optimal vibration ranges of [180-192]Hz and [205-215]Hz were found to respectively provide a 1% drag reduction and a 2% lift-to-drag ratio increase compared to the non-morphing (static) configuration. The natural frequencies associated with the shear layer Kelvin-Helmholtz (KH) vortices and the Von-Karman (VK) vortex shedding were found to play a central role in the modification of the wake dynamics by morphing as well as in the increase of the aerodynamic performance. Actuating at (or close to) the upper shear layer (USL) natural frequency (~185Hz) provides an order of 1% drag reduction and 1% lift-to-drag ratio increase, while actuating at (or close to) the lower shear layer (LSL) natural frequency (~208Hz) provides an order of 8% lift increase and 2% lift-to-drag increase. Furthermore, the linear variation of the actuation frequency over time, called wobulation, was shown to have significant effects. This approach demonstrated, through an appropriate mapping, the ability to quickly and efficiently detect optimal constant actuation frequency ranges providing aerodynamic performance increase and simultaneously reducing the amplitude of the main instability modes. △ Less

Submitted 30 January, 2026; originally announced January 2026.

Journal ref: Journal of Fluids and Structures, 2023, 123, pp.104016