Astrophysics of Galaxies
A Partial Lyman Limit Absorber in the Halo of a Galaxy Pair: A Possible Signature of Gas Inflow
Sumukha R. Bharadwaj, Anand Narayanan, Sowgat Muzahid et al. (+2 more)
We present an analysis of a partial Lyman limit system at z = 0.87641 detected in the HST/COS spectrum of the background
quasar LBQS 0107-0235. The absorber exhibits a simple kinematic structure, with the metal-lines and the H I Lyman-series absorption well described by a single component. Photoionization modeling yields a gas
metallicity of one-tenth
solar and a hydrogen number density of n_H \approx 8.5 \times 10^{-4} cm^{-3} (log_{10}(n_H/cm^{-3}) \approx -3.1). At the absorber
redshift, the VLT/MUSE data show two
galaxies (G1 and G2) at normalized impact parameters of \rho/R_{vir} \approx 0.9 and velocity separations of |\Delta v| = 18 and 99 km s^{-1}, respectively, from the absorber. Both
galaxies have rotating disks with
stellar masses of M_* \approx 6 \times 10^9 and \approx 2.2 \times 10^{10} M_{\odot}. Their 100-Myr-averaged
star formation rates are \approx 2.5 and \approx 2.2 M_{\odot} yr^{-1}, though their instantaneous rates place G2 on the
star-forming main sequence and G1 above it, which is actively
star-forming at this
redshift. The absorber is positioned very close to the projected major axis of both
galaxies. The absorber's orientation, kinematics, and sub-
solar metallicity (log_{10}(Z/Z_{\odot}) = -1.05) are consistent with the absorption tracing a sub-
solar metallicity inflowing stream, though a
galaxy-
galaxy interaction origin cannot be excluded. We discuss these scenarios in the context of cosmological simulations of cold-mode
accretion and CGM gas flows around
galaxies with
halos of mass M_h \lesssim 10^{12} M_{\odot}.
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All authors Sumukha R. Bharadwaj, Anand Narayanan, Sowgat Muzahid, Jane C. Charlton, Sebastiano Cantalupo
Mesoscale and Nanoscale Physics
Noisy Braiding of Majorana Modes: A Comparison of Nanowire Trijunction and Quantum-Dot-Assisted Architectures
Dibyajyoti Sahu and Suhas Gangadharaiah
Majorana zero modes have emerged as one of the most promising platforms for topological
quantum computation, since their non-Abelian braiding statistics allow
quantum information to be encoded nonlocally and manipulated through braiding operations that are, in principle, protected against local perturbations. In practice, however, a braid is only as robust as its physical implementation: finite-time operation, residual couplings, and environmental noise can all convert local excitations into logical errors during the exchange process. Here, we address this question through a microscopic comparison of two representative braiding architectures, a nanowire trijunction and a
quantum-dot-assisted setup, simulating the full time-dependent Bogoliubov–de Gennes dynamics under both noiseless and noisy conditions. We show that the dot-assisted architecture consistently achieves a lower error over a shorter timescale than the trijunction, owing to its more localized exchange mechanism. This advantage persists in the presence of noise, and a spatially resolved analysis further reveals that, in the dot-assisted geometry, fast noise localized on the dot produces a smaller error than equivalent noise on the wires, whereas slow, quasi-static noise on the dot becomes the dominant limitation. Taken together, these findings link the different error contributions directly to device geometry, pointing to concrete design principles for noise-resilient Majorana-based
quantum gates.
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Strongly Correlated Electrons
Geometrical approach and topological electron density in the $p_x + ip_y$ superconductor
Karyn Le Hur, Kabir Narayanan and Óscar Mañas Chambert
We present an analysis on the geometrical and physical nature of the $p_x + ip_y$
superconductor on the square
lattice, with an emphasis on the topological phase transition at half-filling. We develop a local topological marker from specific Dirac points within the Brillouin zone, which is introduced via the addition of two one-dimensional (1D) $\mathbb{Z}$ $(\mathbb{Z}_2$) invariants defined on the Bloch sphere. We relate this topological marker to the electron spectral function integrated on frequency through the local momentum-resolved electron density, which may be measured via Angle Resolved Photoemission Spectroscopy (ARPES), and show that it remains well-protected including temperature effects. Integrating on a small area around a specific point in momentum space associated to the measure uncertainty, this also reveals the Van Hove logarithmic profile of the density of states in the derivative of the local marker while preserving the topological information. Topological transitions correspond to a protected semi-metal. We analyse the real space representation of this topological marker from correlation functions. We present physical responses such as the topological superfluid density.
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Statistical Mechanics
Ensemble-level loopy message passing with generalized-edge closure for percolation
L.-H. Wang and Y.-M. Du
Predicting the percolation threshold of highly clustered networks from local statistics remains difficult, because short loops break the independence assumption underlying tree-like message passing. Existing remedies address loopy connectivity either through prescribed local motifs in random-graph ensembles or through a single network's realized
topology, leaving an ensemble-level treatment of arbitrary connectivity patterns absent. Here, we develop a loopy message-passing framework for random clustered graph ensembles based on generalized-edge statistics, which characterize overlap patterns among the neighborhoods of different nodes. This yields a progressively refined approximation scheme based on neighborhoods of increasing size around each node. The low-order approximations recover previous equations for random network ensembles, and the new result that yields refined threshold prediction is developed by the second-order approximation. We show that the effectiveness of this framework depends not only on short-cycle density but also on the internal consistency of generalized edges. To diagnose this effectiveness, we introduce the generalized-edge closure coefficient (GECC) to quantify this consistency. Because GECC is computed entirely from local statistics and does not rely on any percolation calculation, it serves as an a priori diagnostic for the reliability of the approximation. Using synthetic and real networks, the threshold is evaluated via the second-order and lower-order approximations. Comparisons with Monte Carlo simulations show that GECC captures key structural features that strongly affect the percolation threshold. These results establish ensemble-based loopy message passing as an efficient route for predicting the percolation threshold in large clustered networks.
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High Energy Astrophysical Phenomena
Hyperaccreting Magnetised Neutron Stars inside Rotating Massive Envelopes: Low-Power Jets and Precursor Flares
Patrick Chi-Kit Cheong, Christopher L. Fryer and David Radice
The engulfment of a
neutron star (NS) by a massive companion initiates a highly dynamic common-envelope (CE)
evolution phase. As the NS spirals into the dense
stellar core, it is subjected to hypercritical
accretion rates that threaten to rapidly collapse the NS into a black hole (BH). However, if the infalling envelope possesses sufficient angular momentum and
magnetic fields, the NS might survive longer and launch feedback-driving jets. To investigate this, we perform fully coupled, axisymmetric General Relativistic Magnetohydrodynamic (GRMHD) simulations of hyperaccreting NSs, featuring energy-integrated two-moment
neutrino transport and a 13-isotope
nuclear reaction network. We systematically vary the envelope rotation profile and the
magnetic field strength of the NS surface ($B_{\rm surf} \sim 5 \times 10^{10} - 5 \times 10^{13}$~G). In non-magnetised models, we find that envelope rotation naturally forms a centrifugal barrier and a geometrically thick
accretion disk, which suppresses the mass
accretion rate and lowers the
neutrino luminosity; conversely, the intrinsic
spin of the NS has a negligible global impact. In magnetised models, the differential rotation of the
accretion flow vigorously amplifies the toroidal
magnetic field via the $\Omega$-effect, driving the expansion of
magnetic towers. Crucially, for strong initial surface
magnetic fields ($B_{\rm surf} \gtrsim 2.3 \times 10^{13}$~G), the intense
magnetic pressure could completely halt the
accretion flow at the NS surface and evacuates a low-density polar funnel. We conclude that while this highly magnetised NS engine successfully delays
prompt BH formation and may launch low-power precursor jets (with powers up to ${\sim} 10^{46}~{\rm erg/s}$) capable of generating observable X-ray
flares, it lacks the energy budget to unbind the massive envelope, potentially setting the stage for a subsequent BH-driven explosion.
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Cosmology and Nongalactic Astrophysics
Big-Bang Nucleosynthesis and WIMP Dark Matter Freeze-Out as Probes of Yukawa Cosmology
Ava Shahbazi Sooraki and Ahmad Sheykhi
We investigate Big-Bang Nucleosynthesis (BBN) in the context of Yukawa cosmology. We first derive the modified Friedmann equations by starting from the first law of thermodynamics on the apparent horizon. Using observational data on \(^4\mathrm{He}\), deuterium, and \(^7\mathrm{Li}\) abundances, we place stringent bounds on the Yukawa coupling \(\alpha\). The \(^4\mathrm{He}\) and deuterium constraints are mutually consistent (\(-0.24 \lesssim \alpha \lesssim 0.12\)), while \(^7\mathrm{Li}\) requires $\alpha \in [-0.76,\,-0.72]$. This indicate that Yukawa cosmology cannot resolve the Lithium Problem. We then extend our analysis to WIMP freeze-out, and show that the modified Hubble parameter alters the relic abundance, yielding an independent constraint \(-0.017 \lesssim \alpha \lesssim 0.018\) from \(\Omega_{\mathrm{CDM}}h^2 = 0.120 \pm 0.001\). We also derive the modified time-temperature relation, and show that the positive \(\alpha\) raises the early Universe temperature. Our analysis demonstrates that BBN and dark matter relic abundance serve as complementary probes of modified
gravity. Our studies confirm that Yukawa cosmology is a testable framework for early-Universe physics.
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Nuclear Theory
Long-lived opposite-parity states and the onset of octupole collectivity in atomic nuclei
Bui Minh Loc, Hoang Thai An, Nguyen Le Anh et al. (+2 more)
Octupole deformation in atomic
nuclei is of interest for both
nuclear structure and precision tests of fundamental
symmetries, but identifying regions of octupole collectivity remains challenging. We analyze low-energy spectra of odd-mass
nuclei and uncover a previously unrecognized empirical regularity that serves as a signature of octupole collectivity in neighboring even-even systems. The observed patterns, which can be understood within a core-coupling picture, are consistent with previous theoretical studies and lead to predictions for
neutron-rich and
proton-deficient
nuclei. These findings provide a simple empirical guide for identifying promising candidates for future experiments and microscopic calculations.
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All authors Bui Minh Loc, Hoang Thai An, Nguyen Le Anh, Panagiota Papakonstantinou, Naftali Auerbach
Optics
Impact of Terminal Noise on Polarization Rotation Vector for Sensing Applications
Mohammad M. Hosseini, Miquel Masanas, Giuseppe Paris et al. (+4 more)
State-of-Polarization sensing with coherent transponders enables wide-area geophysical monitoring over existing submarine cables, but its performance is limited by polarization noise from both the fiber and terminal hardware. This work investigates how terminal noise affects polarization rotation estimates derived from receiver equalizer coefficients and how it can obscure
stochastic polarization drift used for sensing. We analyze Jones-
matrix time series from two deployed receivers in the Sparkle Mediterranean link MedNautilus (approximately 2000 km and 450 km) and compare them with a laboratory back-to-back reference. Power Spectral Density (PSD) analysis reveals a low-frequency random-walk regime and a high-frequency white-noise floor, separated by a link-dependent corner frequency. The rotation innovation variance increases with link length, while the longest field link also shows elevated white noise consistent with accumulated amplifier and terminal contributions. Additionally, harmonic spectral components are observed, indicating a transponder-related artifact that should be considered in practical sensing applications.
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All authors Mohammad M. Hosseini, Miquel Masanas, Giuseppe Paris, Antonio Mecozzi, Alberto Marullo, Danilo Decaroli, Antonio Napoli
Computational Physics
Coordinate-Residual Physics-Driven Neural Network for Inverse Scattering Imaging
Yutong Du, Zicheng Liu, Bo Qi et al. (+2 more)
Electromagnetic inverse scattering is a nonlinear and ill-posed computational imaging problem, where accurate reconstruction is challenging due to measurement limitations, noise, and high computational costs, especially for 3-D imaging. Although physics-driven neural networks (PDNNs) reduce the dependence on labeled training data, existing accelerated PDNN frameworks often rely on preliminary reconstruction-based region selection, which may introduce instability when the selected region is inaccurate. In this paper, a coordinate-residual physics-driven neural network (CRPDNN) is proposed for 3-D electromagnetic inverse scattering. CRPDNN represents the unknown complex contrast distribution using normalized spatial coordinates and a residual convolutional network, whose parameters are optimized by enforcing consistency between the measured and model-predicted scattered fields. Unlike existing subregion-accelerated PDNN approaches, CRPDNN does not require a preliminary reconstruction, thereby avoiding dependence on its accuracy. For the reported noise-free 3-D synthetic cases, CRPDNN achieves an average relative error of 2.10%, compared with 7.97% for CSI and 3.99% for $L_{2/3}$-FBE-WCIE, while providing approximately 5.5- and 12.1-fold speedups over the two baselines, respectively. Additional 2-D comparisons further demonstrate its stability and computational efficiency relative to existing PDNN frameworks. CRPDNN also maintains reliable reconstruction performance under noisy measurements, and the 3-D Fresnel experiments further indicate its potential for practical imaging applications.
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All authors Yutong Du, Zicheng Liu, Bo Qi, Yali Zong, Peixian Han
General Relativity and Quantum Cosmology
Observational constraints on fractional holographic dark energy in the light of DESI DR2
Qihong Huang, Yuchen Zhang, Bing Xu et al. (+1 more)
Based on the fractional
entropy from fractional
quantum mechanics, fractional
holographic dark energy (FHDE) has been proposed with the Hubble horizon as the IR cutoff (FHDEH). We extend this framework by adopting the future event horizon and the particle horizon as the IR cutoff, proposing the FHDEF and FHDEP models. Using the SN+OHD+DESI DR2
dataset to constrain these models, we find that all three models provide a marginally lower $\chi^{2}_{min}$ compared to $\Lambda$CDM but without significant preference according to AIC and BIC. When CMB distance priors are included, the FHDEH and FHDEP models are strongly ruled out. We further analyze the cosmological
evolution for these models, and find that only the FHDEF model predicts nearly identical evolutions of $\Omega_{m}$ and $\Omega_{de}$ to those of the $\Lambda$CDM model across
cosmic history, but its deceleration parameter $q$ deviate from the $\Lambda$CDM model in the future, indicating richer late time dynamics beyond the standard $\Lambda$CDM cosmology.
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All authors Qihong Huang, Yuchen Zhang, Bing Xu, Kaituo Zhang
Soft Condensed Matter
Effective one-body interactions due to the presence of a liquid-vapor interface
Melih Gül and Roland Roth
In this study we investigate the behavior of additive binary square-well mixtures within the framework of classical density functional theory. By leveraging on the geometrical structure of the square-well interaction, we propose a novel form of the perturbation theory contribution to the density functional in terms of weighted densities, inspired by fundamental measure theory. We apply this functional in order to study the effective one-body interaction due to the
liquid-vapor interface of the solvent acting on a dilute component of dissolved nano particles. The effective one-body interaction attracts the nano particles strongly to the interface. We show that this effective interaction potential can be calculated either from the density profiles of the full mixture, at low but non-vanishing concentrations of the nano particles, or by employing the Widom insertion
theorem in the dilute limit of vanishing density of nano particles. Both routes display excellent agreement.
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Materials Science
Magnetotransport evolution and nonlinear Hall effect in altermagnetic MnTe
Wei Zhou, Zhifeng Xue, Yunxing Li et al. (+6 more)
Hexagonal MnTe is a prototypical semiconducting altermagnet whose properties are heavily influenced by intrinsic disorder, yet how the resulting diverse transport regimes shape its magnetotransport behavior remains to be clarified alongside the role of relativistic
spin-orbit coupling (SOC). Here, we present a systematic study of the anisotropic magnetoresistance (AMR), planar
Hall effect (PHE), and nonlinear transport in MnTe bulk single
crystals. Below the Néel temperature (TN ~ 304 K), the emergence of high-order harmonics in AMR and PHE within the high-temperature metallic regime reveals the interplay of
magnetic order, crystalline
symmetry, and SOC. At relatively lower temperatures, the disappearance of higher-order
symmetries coincides with a transport crossover into the hopping conduction regime, suggesting that carrier localization diminishes the transport sensitivity to the
Fermi-surface
topology. In addition, we detect distinct second-order nonlinear
Hall signals, providing evidence for a macroscopic inversion-asymmetric response in altermagnetic MnTe. Extending the investigations into the localized regime provides key insights into the subtle role of disorder and SOC in macroscopic charge transport. Our work thus underscores the necessity of exploring magnetotransport across diverse conducting regimes to comprehensively understand altermagnetic properties.
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All authors Wei Zhou, Zhifeng Xue, Yunxing Li, Nannan Tang, Ye Tao, Dingyong Zhong, Jiawei Luo, Donghui Guo, Huichao Wang
Atmospheric and Oceanic Physics
Identifying the large-scale synoptic drivers contributing to the Kerala floods using multivariate feature-based analysis
Marion P. Mittermaier
Parts of Kerala were hit by devastating floods three years in a row. This sequence was historically without precedent. This paper uses a multivariate object-based approach to examine the global forecasts of the Met Office Unified Model for the 2018, 2019 and 2020 monsoon seasons to identify and understand the large-scale synoptic drivers that led to the floods. Identifying similarities between synoptic drivers behind these flooding events was a key objective, as was understanding whether one could enhance predictability by using a multivariate approach for post-processing forecast output, using variables other than just precipitation, which is often inherently less predictable on its own. To this end event identification focused on the analyses first, and then on a day 5 forecast. The study found that the multivariate version of the Method for Object-based Diagnostic Evaluation (MvMODE) was able to successfully identify sequences of days in all three seasons corresponding to the event dates, which in combination, had flood-producing potential. This was achieved in both the analyses and in the 5-day forecasts, proving that a) the events share common synoptic drivers and b) there is inherent predictability which can be tapped into. The 5-day forecasts matched the analysed objects on each occasion, proving that the underlying large-scale drivers may be predictable into the medium-range. Based on the results, the paper proposes a conceptual synoptic pattern
evolution which can help identify such events in future. The synoptic pattern has some similarities to atmospheric rivers in the mid-latitudes.
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Earth and Planetary Astrophysics
A Machine Learning Based Search for Lunar Anomalies
Cameron Kelahan, Daniel Angerhausen, Adam Lesnikowski et al. (+1 more)
The Lunar Reconnaissance Orbiter (LRO) has been collecting high-resolution images (at around 0.5-2 meters per pixel linearly with its Narrow Angle Camera) of the Moon since 2009, amassing a large
dataset of images and offering researchers the opportunity to study the surface of the Moon at unprecedented scale. Here, we aim to test the abilities of the Beta-Variational Autoencoder (VAE) created by Lesnikowski et al. (2024), an unsupervised learning model which identifies anomalous features across the Moon's surface, locating not only scientifically useful geologic formations such as rockfall deposits, fresh impact craters, irregular mare patches, or volcanic pits/collapsed lava tubes, but also artificial objects such as landed spacecraft. This investigation further gauged the model's ability to locate anomalous surface features, successfully recovering two places of interest (Plaskett Crater and Paracelsus C Crater) and numerous landed technological assets at a statistically significant rate.
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All authors Cameron Kelahan, Daniel Angerhausen, Adam Lesnikowski, Valentin T. Bickel
Quantum Physics · Cross-listed from cs.IT
Binary code rate bounds via classical–quantum channels
Omar Alrabiah and Venkatesan Guruswami
We derive the four principal asymptotic rate-distance tradeoffs for binary codes—Plotkin, Elias–Bassalygo, and the two McEliece–Rodemich–Rumsey–Welch (MRRW) bounds—from one
theorem, the “pretty good criterion.” If the bit error rate under the pretty good measurement (PGM)—the
quantum analog of posterior sampling—of a binary-input output-symmetric classical–
quantum (cq) channel lies below $\delta$, then every length-$n$ binary code, linear or nonlinear, of relative distance $\delta$ has rate at most the channel's capacity, up to an $O(n^{-1/2})$ correction. Rate–distance bounds thereby reduce to a channel design problem, wherein the task is to minimize channel capacity subject to the posterior bit error rate constraint. Via the pretty good criterion, the binary erasure channel (BEC) yields Plotkin, the binary symmetric channel (BSC) yields Elias–Bassalygo, the pure-state channel (PSC) yields the first MRRW bound, and a masked PSC yields the second MRRW bound exactly. This framework is then instantiated with new channels to improve upon the MRRW bounds. Specifically, the mixed-
qubit channel (MQC), a mixed-state version of PSC, strictly improves the first MRRW bound at every $0 < \delta < \frac{1}{2}$, while the masked mixed-
qubit channel (2MQC) strictly improves the second MRRW bound throughout the same interval.
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Quantum Physics
A high-performance quantum pulse gate in thin-film lithium niobate
Silia Babel, Alejandra Alarcón, Laura Serino et al. (+10 more)
In this work, we demonstrate a
quantum pulse gate (QPG) in thin-film lithium niobate. QPGs enable the selective manipulation and detection of temporal modes of
quantum light and form the basis of numerous applications in photonic
quantum technologies. To date, their widespread adaption is held back by two main limitations: restricted wavelength and polarization combinations of the involved fields and low normalized conversion efficiencies. We overcome these limitations through developing a QPG in thin-film lithium niobate. We design a waveguide geometry that provides the required dispersion properties for a highly efficient type-0 sum-frequency generation.We verify our design through mapping of the phase matching intensity, and demonstrate high-quality QPG operation by measuring a temporal-mode selectivity of (96.8$\pm$1.7)% on par with existing QPGs. Thanks to the strong confinement in thin-film lithium niobate, we succeed in demonstrating an internal conversion efficiency of (89.6$\pm$0.1)% for a pump power of only 20mW in front of our sample. This yields a lower-bound estimate for the normalized conversion efficiency of (1810$\pm$10)$\mathrm{W}^{-1}\mathrm{cm}^{-2}$, three orders of magnitude higher than in previous QPGs. Our results establish thin-film lithium niobate as ideal platform for high-performance QPGs and are a major step towards practical QPGs for photonic
quantum technologies.
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All authors Silia Babel, Alejandra Alarcón, Laura Serino, Christian Golla, Laura Bollmers, Sebastian Lengeling, Jiayu Yang, Bernhard Reineke, Christof Eigner, Benjamin Brecht, Marko Lončar, Laura Padberg, Christine Silberhorn
High Energy Astrophysical Phenomena
Rapid Orbital Decay in the Ultracompact Double-degenerate Binary eRASSU J060839.5$-$704014
Rahul Sharma, Chandreyee Maitra, Frank Haberl et al. (+9 more)
We present timing and spectral analysis of the recently identified ultracompact double-degenerate (DD) white
dwarf binary eRASSU J060839.5$-$704014 using observations from NICER and Einstein Probe (EP), together with archival XMM-Newton data. By phase-connecting the long-term XMM-Newton, NICER, and EP observations, we obtain a coherent quadratic timing solution, yielding an orbital period of 374.15013 (2) s and an orbital decay rate of $\dot{P}= -4.7\,(1) \times 10^{-11} \mathrm{~s~s^{-1}}$. This orbital decay exceeds that measured in the prototypical DD binaries HM Cnc and V407 Vul. Assuming that the observed orbital
evolution is primarily driven by gravitational-wave (GW) angular momentum loss, the inferred chirp mass is $\sim0.43\, M_{\odot}$, placing the source among the most massive known systems of this class. The phase-averaged spectra of NICER and EP-Follow-up X-ray
Telescope (FXT) are described by a soft thermal component with temperatures of ~126 and ~144 eV, respectively, confirming the supersoft nature of the source. Phase-resolved spectroscopy reveals a clear decrease in temperature across the bright phase in both instruments, indicating a structured emission region with significant temperature gradients. These results establish eRASSU J060839.5$-$704014 as one of the most rapidly evolving ultracompact DD binaries presently known, belonging to the rare class of direct-impact ultracompact binaries, and a promising verification source for future low-frequency GW studies.
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All authors Rahul Sharma, Chandreyee Maitra, Frank Haberl, Joheen Chakraborty, Susanne Friedrich, Yong-Feng Huang, Chichuan Jin, Zhaosheng Li, Georgios Vasilopoulos, Yanjun Xu, Haonan Yang, Weimin Yuan
Instrumentation and Methods for Astrophysics
Kratos-linerad: GPU-accelerated Monte Carlo radiative transfer of lines with efficient imaging
Lile Wang
Spectral lines encode the velocity, the temperature, and the chemical structure of astrophysical gas; interpreting them requires radiative transfer that is accurate at high optical depth, consistent with the local excitation, and efficient enough to synthesize velocity-resolved images. We present Kratos-linerad, a GPU-accelerated Monte Carlo radiative transfer code for spectral lines. The level populations can be iterated to statistical
equilibrium together with the escaping
photon distribution, treating angle-dependent partial frequency redistribution through constant-
memory sampling tables. The code adopts the two-step imaging scheme to line transfer, in which a Monte Carlo pass samples a velocity-resolved scattering emissivity, and a deterministic ray-tracing pass synthesizes channel maps decoupled from the scattering geometry. Validation reproduces the analytic scaling of escaped spectra and the imaging double-peak profiles. GPU parallelism enables both stages sufficiently fast for routine application to astrophysically realistic models.
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High Energy Physics (Experiment)
Amplitude analysis for charmed meson decays at BESIII
Han Zhang, Zhenxuan Li, Chunyi Guan et al. (+9 more)
Amplitude analysis bridges the gap between experimental measurements of multibody charmed-
meson decays and theoretical predictions of intermediate two-body processes. This work presents a comprehensive overview of the amplitude-analysis methodology employed by the BESIII Collaboration, emphasizing practical implementation. We detail the construction of the probability density function and likelihood function for unbinned maximum-likelihood fits. This encompasses Monte Carlo integration techniques for normalization, the incorporation of detection efficiency and resolution effects, and multidimensional background modeling utilizing XGBoost classifiers. Furthermore, we describe the amplitude formalism for both hadronic and semileptonic decays, incorporating standard resonance-propagator parametrizations. Key analytical aspects, including the evaluation of fit fractions, the generation of kinematic projections, and the estimation of statistical uncertainties, are also discussed.
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All authors Han Zhang, Zhenxuan Li, Chunyi Guan, Zehui Lu, Hui Li, Liping Yang, Yechun Yu, Nan Zhang, Minggang Zhao, Yu Lu, Bai-Cian Ke, Liaoyuan Dong
High Energy Astrophysical Phenomena
Astrophysical origins of TeV features in the cosmic-ray lepton spectrum
Zhen Xie and Ruizhi Yang
Precise measurements of high-energy
cosmic-ray electrons and positrons have revealed spectral structures that are difficult to capture with a single smooth power-law background. The rising positron fraction measured by PAMELA and AMS-02, together with the all-electron excess reported by ATIC and the high-precision all-electron spectrum measured by DAMPE, has motivated interpretations ranging from nearby astrophysical accelerators to dark-matter annihilation or decay. In this work we revisit the conventional diffuse electron background and the possible contribution from nearby
pulsars in a common propagation framework. The diffuse component is modeled with GALPROP configurations calibrated by
cosmic-ray
nuclei and diffuse gamma-ray observations. We then use the Green-function solution for nearby discrete sources with radiative losses to study
pulsar contributions with both burst-like and continuous injection histories, including the effect of
stochastic inverse-Compton cooling on the propagated spectra. We also use the highest-energy DAMPE data points as an illustrative case to compare possible local-source contributions from
pulsars and
supernova-remnant-like burst sources. The spectral shape of such features provides a useful diagnostic for distinguishing physically plausible nearby-source features from more exotic interpretations.
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Mesoscale and Nanoscale Physics
Parity-Resolved Quantum Capacitance and Quantum Inductance in Topological, Trivial, and Normal Nanowire Interferometers
Viktoriia Pinchenkova, Valerii K. Kozin, Maximilian Hünenberger et al. (+2 more)
Quantum-capacitance measurements convert the
curvature of a
quantum-dot energy in a flux-threaded nanowire loop into fast parity-sensitive signals and, therefore, have become a promising readout tool for Majorana devices. However, Majorana-like
quantum-capacitance responses can also arise from topologically trivial Andreev bound states, making capacitance alone insufficient to identify a topological phase. To analyze this problem, we consider a
quantum dot coupled to both ends of four nanowire realizations: a topological nanowire hosting Majorana bound states, non-topological superconducting nanowires hosting one or two Andreev bound states, and a fully normal nanowire. Motivated by proposals to use
quantum inductance as an additional phase-sensitive probe, we compute both the parity-resolved
quantum capacitance $C_\mathrm{Q}$ and inverse
quantum inductance $L_\mathrm{Q}^{-1}$ as functions of the
magnetic flux by exact diagonalization. We show that signatures associated with zero-energy Majorana bound states, such as $h/e$ periodicity and an $h/(2e)$ flux shift between even and odd parity sectors in $C_\mathrm{Q}$ and $L_\mathrm{Q}^{-1}$, are not sufficient indicators of topological superconductivity. In certain realistic parameter regimes, similar Majorana-like behavior can arise from a trivial Andreev bound state and even from a purely normal nanowire. By contrast, two nearly zero-energy Andreev bound states can generate a pronounced $h/(2 e)$-periodic component associated with charge-$2e$ transfer, providing a clear non-Majorana signature. A low-energy projection shows that the Majorana, single-Andreev-state, and normal cases can be mapped onto the same minimal low-energy model explaining their similar flux-dependent responses despite their different physical origins.
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All authors Viktoriia Pinchenkova, Valerii K. Kozin, Maximilian Hünenberger, Daniel Loss, Jelena Klinovaja
Instrumentation and Methods for Astrophysics · Cross-listed from math.NA
High-order fully discrete multi-entropy-stable and bound-preserving schemes for relativistic Euler equations
Linfeng Xu and Kailiang Wu
A discrete
entropy inequality is the principal nonlinear stability estimate available for systems of conservation laws, and evaluating it presupposes a physically admissible state. So far, however, the two have been secured separately.
Entropy-stable schemes are almost always semi-discrete, are built around one selected
entropy pair, and take for granted the positivity of density and pressure that makes the
entropy well defined in the first place, whereas bound-preserving limiters keep the solution admissible but deliver no
entropy estimate. For the special relativistic Euler equations, the two cannot be separated at all, since the conservative-to-primitive map is implicit, and an inadmissible state therefore has no
entropy to correct. Here we construct high-order discontinuous Galerkin and finite volume schemes that, to our knowledge, for the first time, are
entropy stable in the fully discrete sense for an arbitrary prescribed finite family of convex
entropy pairs, a property we call multi-
entropy stability, and are provably admissible wherever an
entropy is evaluated. All of this is achieved by a single cellwise projection, and neither conservation nor the design order is lost. The construction rests on relativistic causality, which bounds every characteristic speed by the speed of light. Consequently, the numerical viscosity can be fixed once for all states and all equations of state, and one two-point building block then serves the whole
entropy family. Since only the convexity of the admissible set and this speed bound are used, the same route remains open for related systems. Finally, in computations with four equations of state, the schemes retain high-order accuracy close to
vacuum, produce no inadmissible state in strong shocks, near-
vacuum shock–
vortex interaction or jets with Lorentz factor above $70$, and confirm the monotone decay of every enforced discrete
entropy.
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General Relativity and Quantum Cosmology
Geodesic structure, eikonal quasinormal modes and thermodynamic properties of a Schwarzschild-de Sitter-like black hole with global monopole in Bumblebee gravity
Irengbam Roshila Devi, Yenshembam Priyobarta Singh, Dhruba Jyoti Gogoi et al. (+1 more)
We investigate the geodesic dynamics, eikonal quasinormal modes (QNMs), and extended phase space thermodynamics of a Schwarzschild-de Sitter-like black hole coupled with a global monopole in Bumblebee
gravity. Our analysis reveals that spontaneous Lorentz
symmetry breaking and topological defects modify the effective radial dynamics, leading to lower effective potential barriers and a reduced magnitude of the effective force. For null geodesics, higher monopole parameters expand the
photon sphere and critical impact parameter, implying an enlarged black hole shadow, while mitigating dynamical instability. For massive particles, the stable circular orbit window narrows significantly as the Outermost Stable Circular Orbit (OSCO) shrinks, alongside a marked enhancement in perihelion precession. In addition, we examine the correspondence between the eikonal QNMs and the properties of null geodesics. The excellent agreement between the eikonal approximation and the WKB method for scalar and electromagnetic perturbations supports the validity of the correspondence for the spacetime under consideration. In the extended thermodynamic phase space, we evaluate the black hole as a
holographic heat engine. We demonstrate that classical efficiency is mathematically blind to Lorentz violation; however, introducing a
quantum-corrected modified
entropy tightly couples the macroscopic work output to the
symmetry-breaking framework. Ultimately, the necessity to respect the Carnot bound imposes a strict macroscopic constraint on the Lorentz-violating parameter, safeguarding the Second Law of Thermodynamics.
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All authors Irengbam Roshila Devi, Yenshembam Priyobarta Singh, Dhruba Jyoti Gogoi, Telem Ibungochouba Singh
Instrumentation and Detectors
Openable Force-Balanced Halbach Magnets: From Fibonacci Sphere Simulations to Icosahedral Realizations
Ingo Rehberg, Helmut Soltner and Peter Blümler
A long-standing goal in magnet design is to completely surround a volume of highly homogeneous
magnetic field with permanent magnets while maintaining practical access to that volume. In this work, we present a theoretical and experimental investigation of mechanically accessible spherical magnets in Halbach configuration that can be opened with minimal or vanishing force. Focusing on dipolar Halbach spheres composed of discrete
magnetic subunits, we derive conditions for force-free opening along specific cutting planes. These conditions define a continuous set of geometries for which tensile
magnetic forces cancel, leaving only shear components, enabling mechanically effortless opening. The theoretical predictions are validated experimentally using icosahedral approximations of the Halbach sphere, for which both opening forces and
magnetic field properties are measured. The results demonstrate that excellent field homogeneity can be preserved while reducing opening forces by orders of magnitude. Although discussed in detail for the dipolar case, the theoretical framework is general and applicable to higher-order multipole Halbach systems. Finally, the concepts are extended to spherocylindrical Halbach configurations, highlighting their potential for large-volume, highly homogeneous, and mechanically accessible permanent-magnet systems for
magnetic resonance
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Astrophysics of Galaxies
Active galactic nucleus activity in nearby disk galaxies: The roles of bar strength and spiral arm morphology
Zh. R. Martirosyan, A. A. Hakobyan, V. Adibekyan et al. (+3 more)
(abridged) We investigate the dependence of AGN activity on bar strength and spiral arm morphology in nearby spiral
galaxies, with a particular emphasis on disentangling their individual and joint effects while controlling for
galaxy stellar mass and color. We constructed a sample of 843 morphologically undisturbed Sa-Sd
galaxies from the MaNGA survey in the
redshift range $0.026 \leq z \leq 0.1$. Bar strengths,
stellar masses, colors, and AGN classes were adopted from the literature, while spiral arm classes (ACs), i.e., flocculent (FL), multi-armed (MA), and grand design (GD) systems, were visually determined for the entire sample using optical imaging together with bulge-disk decomposition residual maps. The AGN fraction increases systematically with bar strength, from $0.10^{+0.02}_{-0.02}$ in unbarred
galaxies to $0.34^{+0.03}_{-0.03}$ in strongly barred systems. After controlling for
stellar mass and color, a statistically significant enhancement remains detectable primarily at intermediate
stellar masses ($10.5 \lesssim \log(M_\star/M_\odot) \lesssim 11.0$), whereas no significant dependence is found at higher masses. In contrast, spiral arm morphology alone does not show a robust independent connection with AGN activity once
stellar mass and color are controlled, although a weak enhancement is present in intermediate-mass GD and MA systems. When bar strength and spiral AC are considered jointly, the highest AGN fraction is observed in strongly barred GD$+$MA
galaxies $(0.39^{+0.04}_{-0.04})$, while the lowest AGN fractions are found in unbarred FL systems $(0.09^{+0.03}_{-0.02})$. Our results suggest that
stellar mass and color drive the primary trend in AGN activity in nearby disk
galaxies, while
stellar bars and spiral arms act as secondary structural drivers.
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All authors Zh. R. Martirosyan, A. A. Hakobyan, V. Adibekyan, L. V. Barkhudaryan, M. H. Gevorgyan, A. G. Karapetyan
General Relativity and Quantum Cosmology
Massive neutral Dirac quasibound states in a Newman-Janis-generated rotating charged Kalb-Ramond black-hole geometry
Sardor Murodov, Olimjon Kholturayev, Bahodir Ahmedov et al. (+3 more)
We study quasibound states of a massive neutral Dirac field in the Newman-Janis-generated rotating charged geometry used in Lorentz-violating Kalb-Ramond (KR)
gravity. Rather than assuming that the Kerr separation survives the deformation, we first recast the metric in four-dimensional off-shell Carter form. The corresponding principal closed conformal Killing-Yano tensor then provides the hidden
symmetry needed to separate the torsion-free, minimally coupled Dirac equation. We derive the horizon and large-radius boundary conditions, including the non-Minkowskian asymptotic normalization, and determine the complex spectrum from coupled angular and
matrix radial continued fractions. The code reproduces the Kerr spectrum and is checked by truncation studies and independent two-sided radial integrations. In scans at fixed metric parameters, increasing the KR parameter moves most real frequencies toward the mass threshold and reduces most decay rates. These trends are not invariant, however, because the same variation changes both the asymptotic potential scale and the distance from extremality. A scan in which these two quantities are held fixed changes the absolute ground-state trend but preserves a reversal in the real-frequency ordering of the maximal-$m$, $j=3/2$, $\ell=1$ pair. The location of the crossing shifts with the normalization convention. Thus the level reordering is more robust than the individual monotonic trends in binding energy or lifetime within this background family.
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All authors Sardor Murodov, Olimjon Kholturayev, Bahodir Ahmedov, Bekzod Rahmatov, Islom Egamberdiev, Bobomurat Ahmedov
Chaotic Dynamics
Dynamics and non-integrability of the Swinging Atwood Machine with a massive string: chaos, periodic orbits and resonance structures
Wojciech Szumiński and Jakub Bembenek
Building upon our previous studies on nonlinear variable-length pendulum systems, we investigate the Swinging Atwood Machine with a massive string. In contrast to the classical model, string inertia introduces a configuration-dependent moment of inertia, leading to a modified
Hamiltonian structure and substantially richer dynamics. To uncover the global organization of the phase space, we combine Poincaré sections, bifurcation diagrams, and Lyapunov exponent maps with our recently developed numerical framework ,,Lyapunov Refined Maps". This approach provides a unified visualization of periodic, quasi-periodic, chaotic, and terminating motions, revealing intricate resonance networks and high-order periodic structures. We investigate the influence of the string mass, system parameters, and energy by constructing Lyapunov maps in parameter and initial-condition spaces and on fixed-energy surfaces. Liouville integrability is studied within the Morales-Ramis theory. By analyzing the normal variational equations along explicit non-stationary radial solutions and applying the Kovacic
algorithm, we prove that the differential Galois group is generically SL(2,C), providing a rigorous obstruction to meromorphic Liouville integrability for every nonzero string mass. Thus, the exceptional integrable case of the classical Swinging Atwood Machine is destroyed by the inclusion of string inertia.
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Mesoscale and Nanoscale Physics
Magnetically induced Circular Photogalvanic Effect in Symmetric Two-dimensional Materials
Peng Liu, Fanhao Jia, Ruixue Li et al. (+3 more)
Photocurrents that depend on the helicity of the incident light can be generated in both bulk and low-dimensional materials lacking inversion
symmetry, known as the circular photogalvanic effect (CPGE). We propose that by employing a
magnetic effect, the limitation on the inversion
symmetry broken materials can be overcome, such that helicity-dependent photocurrent can be generated in a symmetric material, i.e., a magneto-circular photogalvanic effect (MCPGE). As a proof of principle, we elucidate the mechanism of such an MCPGE through an effective
Hamiltonian of a monolayer SbH on a
magnetic substrate with an adjustable magnetization. Moreover, the associated response in optical absorption is analyzed, both single-particle and excitonic, through a Bethe-Salpeter equation to describe the Coulomb interaction in
excitons. Our result broadens the mechanism of CPGE and opens new opportunities for optoelectronic devices.
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All authors Peng Liu, Fanhao Jia, Ruixue Li, Yuan Li, Igor Zutic, Gaofeng Xu
High Energy Physics (Theory)
Xin-Xiang Ju, Ya-Wen Sun, Yang Zhao et al. (+1 more)
We study how multipartite
entanglement is dynamically reorganized during
holographic thermalization following a global quench in AdS$_3$/CFT$_2$. We first use the $n$-partite information $(-1)^n I_n$ to probe collective multipartite
entanglement in
holographic configurations where the full $n$-region
entanglement wedge is connected while all fewer-party ones are disconnected, thereby excluding fewer-party contributions. The spatial range of multipartite
entanglement first expands and then contracts as the system approaches its late-time locally thermal state.
Entanglement involving different numbers of parties develops on comparable early-time scales, while the
entanglement that involves more parties relaxes more slowly, revealing a transient propagation from shorter to longer spatial distances. We further compute the Markov gap and the genuine tripartite multi-
entropy as complementary probes of tripartite
entanglement. The Markov gap can remain enhanced after local thermalization, whereas the genuine tripartite multi-
entropy undergoes a nonmonotonic
evolution and returns to its
vacuum value for the adjacent tripartition considered in this work. These results show that a global quench redistributes the
entanglement across spatial scales and reorganizes its multipartite structure.
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All authors Xin-Xiang Ju, Ya-Wen Sun, Yang Zhao, Hao-Ran Zhou
Quantum Physics
High-fidelity controlled-phase gates for distinguishable quantum walkers via extended interactions
Gaia Forghieri and Matteo G. A. Paris
We investigate the implementation of controlled-phase (CP) gates with
quantum walks in a dual-rail encoding through the use of interacting particles. While previous proposals have focused on indistinguishable particles (
bosons or
fermions) to achieve
unitary fidelity for plane-wave scattering, practical implementations require finite-size wavepackets and routing through single-particle gates, both factors that introduce unavoidable fidelity losses. We show that extending the interaction range beyond on-site or first-neighbor terms provides sufficient control over the scattering potential to engineer CP gates with distinguishable particles that match the ideal bosonic/fermionic performance. For finite Gaussian wavepackets, we derive analytical approximations for the gate fidelity in terms of the transmission coefficient's magnitude and phase derivatives. We find that while distinguishable-particle scattering alone exhibits slightly lower fidelity than the indistinguishable case, the overall architecture that we propose avoids the additional single-particle gates required for routing indistinguishable particles. The roundabout gates needed for the latter indeed introduce fidelity losses approximately one order of magnitude larger than the interaction-induced losses, making the distinguishable-particle approach competitive for practical implementations. Our results establish multi-neighbor interactions as a tool for
quantum information processing with continuous-time
quantum walks and provide quantitative guidelines for optimizing gate fidelities in finite-size systems.
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