Materials Science
Direct observation of anisotropic exciton dispersion in the 2D semiconductor CrSBr
Yiwen Song, Peiyi He, Weizhe Zhang et al. (+7 more)
We report momentum-resolved measurements of
exciton dispersion in multilayer CrSBr using defocus-engineered electron energy-loss spectroscopy, supported by first-principles calculations. A pronounced in-plane anisotropy is observed, with the
exciton exhibiting a linear dispersion along $\Gamma$Y within $\lvert \boldsymbol{q} \rvert$ < 0.007 Å$^{-1}$, while remaining nearly dispersionless along $\Gamma$X. The slope reaches 7.02 eV Å, among the largest reported in low-dimensional systems. The calculations reproduce the experimentally observed linear dispersion, confirming its intrinsic origin. We attribute the anisotropic dispersion to the long-range electron–hole exchange interaction, enhanced by strong out-of-plane confinement and governed by the directional selection rules of the transition dipole moment. Comparative measurements across the
magnetic phase transition from the paramagnetic to the A-type
antiferromagnetic state show that the dispersion remains essentially unchanged, indicating negligible coupling between
exciton propagation and
magnetic order. These results establish CrSBr as a model system for investigating anisotropic
exciton dynamics in low-
symmetry layered
semiconductors.
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All authors Yiwen Song, Peiyi He, Weizhe Zhang, Wenyuan Ouyang, Wenjing Liu, Jinlong Du, Zuxin Chen, Jiuyu Sun, Peng Gao, Yu Ye
Quantum Physics
High-rate continuous-variable quantum key distribution coexisting with Tb/s coherent classical transmission in hollow-core fiber
Xitao Ji, Siyu Chen, Peng Li et al. (+7 more)
Quantum key distribution (QKD) can provide secret keys with security rooted in
quantum mechanics, but operation alongside high-capacity classical traffic remains limited by the excess-noise budget of weak
quantum states in conventional solid-core fiber. Here, we combine ultralow-loss anti-resonant hollow-core fiber with residual-carrier-assisted discrete-modulation continuous-variable QKD (DM-CV-QKD) to address both propagation-induced coexistence noise and low-SNR phase recovery. Over a 24.3-km hollow-core link with 3.3-dB end-to-end loss, a dual-polarization 15-Gbaud DM-CV-QKD channel achieves an average asymptotic secret-key rate (SKR) of 153.22 Mb/s and a finite-size SKR of 149.99 Mb/s, while 39 coherent wavelength-division-multiplexed channels deliver an aggregate data rate of 7.6 Tb/s and a net data rate of 7.2 Tb/s. The system can even sustain a positive SKR under a high classical launch power of up to 15 dBm, without an optical bandpass filter (BPF). Finite-size analysis against collective attacks further yields a projected positive secret-key rate at a 100-km-equivalent condition. These results show that an anti-resonant hollow-core fiber, combined with carrier-assisted phase recovery, can greatly extend the operating regime of shared-fiber
quantum-secured coherent links, pointing to a promising approach for integrating high-rate CV-QKD with high-capacity optical networks.
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All authors Xitao Ji, Siyu Chen, Peng Li, Mingming Zhang, Yilun Chen, Jun Gao, Rui Lin, Bacco Davide, Siqi Yan, Ming Tang
Superconductivity
Imaging and characterization of spontaneous vortices in a proximity-induced superconductor
Iku Nakaaki, Kotaro Taki, Mio Nomura et al. (+11 more)
Observation of spontaneous
symmetry breaking is crucial for understanding continuous second-order phase transitions from disordered to ordered states, which often leads to the formation of topological defects. In
superconductors, such topological defects manifest as quantized
vortices. However, the formation and observation of spontaneous
vortices in a uniform
superconductor are challenging because extremely rapid cooling (>108 K/s) is generally required for that purpose. Here we conducted scanning superconducting
quantum interference device microscope (SSM) measurements on an MgB2-based proximity-induced
superconductor, an intrinsically inhomogeneous system. In this system, individual superconducting domains will reach internal
equilibrium independently during cooling and choose their own phase before the global phase coherence is established via the long-range proximity coupling. The SSM measurements demonstrate that
vortices are nucleated spontaneously even at a relatively slow cooling rate (~0.2 K/s). We also find that the
vortices with different polarities, sizes, and shapes appear stochastically under near-zero-field conditions. The geometry of the spontaneous
vortices is more extended than that of the field-induced Abrikosov
vortices.
Magnetic field profile analysis based on the London model elucidates that penetration depths of the extended
vortices are anomalously large, exceeding several micrometers. This unusual morphology of the spontaneous
vortices most likely imprints the information that is frozen at the moment of
vortex formation. Our findings not only provide insights into the local phase differences present in the early stage of the phase transition in this proximity-induced superconducting system, but they also shed insights into the structure, formation, and stabilization of topological defects in highly disordered and inhomogeneous superconducting systems.
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All authors Iku Nakaaki, Kotaro Taki, Mio Nomura, Haruna Ishimaru, Minagi Yono, Jun Chen, Hiroyo Segawa, Akiko Nakamura, Taku Moronaga, Minoru Tachiki, Shuuichi Ooi, Shunichi Arisawa, Tsutomu Nojima, Takashi Uchino
High Energy Astrophysical Phenomena
Early Near-Infrared Excess and Rapid Disk-Corona Evolution in the Tidal Disruption Event 2024aepd
Yongxin Wu, Yanan Wang, Thomas M. Reynolds et al. (+38 more)
We present multi-wavelength observations of the
tidal disruption event (TDE) 2024aepd, spanning primarily the first $\sim$300 days after discovery. A prominent near-infrared (NIR) excess is detected as early as $\sim$40 days. Its nearly flat power-law spectrum strongly deviates from the Rayleigh-Jeans tail of the UV-optical blackbody. Although a conventional
dust-echo origin cannot be completely ruled out, free-free emission from a reprocessing photospheric envelope provides a more plausible explanation. The spectral break between the UV-optical and NIR components shifts to higher frequencies, while the inferred density-profile index remains nearly constant, suggesting evolving reprocessing conditions within a broadly unchanged density structure. In addition, the X-ray spectrum is initially dominated by a thermal disk component accompanied by a hard excess. From $\sim$178 days onward, the spectrum becomes power-law dominated and subsequently hardens, indicating the rapid emergence and strengthening of a hot corona. These results provide evidence for frequency-dependent reprocessing at early times and for the rapid development of a disk-corona system, placing new constraints on the structure and
evolution of the reprocessing layer around supermassive black holes.
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All authors Yongxin Wu, Yanan Wang, Thomas M. Reynolds, Shuyuan Wei, Shiyan Zhong, Zikun Lin, Megan Newsome, Sebastian Gomez, Iair Arcavi, Panos Charalampopoulos, Chun Chen, Rongfeng Shen, Ning-Chen Sun, David Aguado, Ismael Pérez-Fournon, Frédérick Poidevin, Zhongnan Dong, Niu Li, Weijian Guo, Hu Zou, Jingbo Sun, Nieves Castro-Rodríguez, Antonio Cabrera-Lavers, Ning Jiang, Hengxiao Guo, J. P. Anderson, Tomás E. Müller-Bravo, Seppo Mattila, Claudia P. Gutiérrez, Amit Kumar, G. Pignata, Xiangkun Liu, R. Dastidar, Brajesh Kumar, Xiaowei Liu, Bin Ma, M. Dennefeld, Francesca Onori, Lydia Makrygianni, Mariusz Gromadzki, Xuan Fang
Mathematical Physics · Cross-listed from math.QA
Twisted Yangians of split types BI, CI, DI and Drinfeld type current relations
Vidas Regelskis
We study twisted Yangians associated with the split symmetric pairs of types BI, CI and DI. We introduce a new presentation of these
algebras, which we call the transposed presentation, governed by a twisted reflection equation that interacts naturally with the Gaussian decomposition of the generating
matrix. Working entirely within the $R$-
matrix presentation, we derive Drinfeld-type current presentations of the special twisted Yangian $SY^{\mathrm{tw}}(\mathfrak{g}_N)$ and of the extended twisted Yangian $X^{\mathrm{tw}}(\mathfrak{g}_N)$, in which the Serre relations are stated in a closed current form. Extracting coefficients recovers the Drinfeld presentation of Lu, Wang and Zhang, in the normalisation of Lu. As a consequence, we establish an explicit isomorphism between the $R$-
matrix and Drinfeld presentations conjectured by Lu, Wang and Zhang. As a byproduct, we obtain a tensor product decomposition of $X^{\mathrm{tw}}(\mathfrak{g}_N)$ into the twisted Yangian in the Drinfeld presentation and a
polynomial ring in countably many central variables. We also obtain Poincaré-Birkhoff-Witt bases in the Drinfeld generators and the coideal coproduct on the low Drinfeld modes at all but the last node.
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Instrumentation and Detectors
Summary of quality control (QC) of ATLAS18 production ITk strip sensors
P. Federičováa, A. Affolder, K. Affolder et al. (+38 more)
To address the demanding operational requirements of the High-Luminosity upgrade of the Large
Hadron Collider (HL-LHC), the ATLAS experiment is replacing its current Inner Detector with a new all-silicon Inner Tracker (ITk). The ITk will feature an active area of 165 m2, with its outer tracking layers populated by approximately 18,000 ATLAS18 n+-in-p silicon strip sensors. The silicon sensors, available in eight geometries tailored to two barrel and six endcap types, respectively, are designed to tolerate fluences of up to 1.6 x 10^15 neq/cm2 and ionizing doses of 66 Mrad. A comprehensive, multi-year Quality Control (QC) program is underway across multiple international institutes to evaluate these ITk strip sensors for mechanical and electrical conformity. The QC process includes IV/CV characterization, full strip tests, long-term current stability monitoring, visual inspection, and metrology tests. To manage the high throughput of about 500 sensors per month, the collaboration has implemented standardized test procedures, software packages for data monitoring and integrity checks, unified data formats, and automated analysis tools. The standardization ensures consistent pass/fail evaluation and centralized data handling that enables effective identification of trends and anomalies at all sites during the production. This contribution presents an overview of the ITk strip sensor production and QC framework, along with key findings throughout the whole production, such as charge-up of sensors, stability of the leakage currents, nonrecoverable IV breakdown, and low inter-strip isolation within wafers. It provides insights into sensor yield, quality trends, and reviews specific case studies, such as p-stop doping non-uniformity. Over 91% of the production, totaling over 590 batches, were tested and accepted. Six batches were rejected. These account for 2.8% of the total tested sensors.
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All authors P. Federičováa, A. Affolder, K. Affolder, A. Awais, G.A. Beck, A. J. Bevan, Z. Chen, J. Dandoy, I. Dawson, V. Fadeyev, J. Fernandez-Tejero, E. C. Hill, S. Hirose, L. Hommels, T. Ivison, C. Jessiman, K. Kariyapperuma, S. Katznelson, J. Keller, C. T. Klein, T. Koffas, I. Kopsalis, J. Kozáková, J. Kroll, M. Kůtová, J. Kvasnička, K. Maeyama, R.R. Marcelo Gregorio, F. Martinez-Mckinney, M. Mikeštíková, P. S. Miyagawa, L. Morelos-Zaragoza, K. Nakamura, Q. Paddock, K. Sato, E. Staats, P. Tůma, M. Ullan, Y. Unno, Y. Zhao, S. C. Zenz
Quantum Physics
Electrons Hopping across a Molecular Network: Spectra and Symmetries
Ludwig Schulz, Max Best and Carsten Henkel
We investigate interacting spinless electrons on finite molecular ring networks described by a tight-binding Hubbard
Hamiltonian. The interplay between
lattice geometry, Coulomb interactions and discrete
symmetries is analysed for rings with $L=3,4,5,6$ nodes, filled with one, two or three electrons. Special
attention is devoted to the role of the network
symmetries in determining the structure of the many-body spectrum and the Mulliken classification of the eigenstates. Using group-theoretical methods, we examine the
evolution of the spectra in the presence of an external
magnetic flux. The Zeeman effect lifts degeneracies and results in combination with the Coulomb interaction to avoided crossings in
symmetry sectors. We identify a qualitatively distinction between systems with an even and odd number of particles. At half-filling, particle-hole
symmetry (duality) protects selected
symmetry sectors against Zeeman splitting.
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Optics
Vortex-Beam Transient Absorption Microspectroscopy Resolves Ultrafast Free-Exciton and Polaron Diffusion in 2D Perovskites
Ju-Young Kim, Anirban Mondal, Gi Rim Han et al. (+4 more)
Two-dimensional (2D) Ruddlesden Popper perovskites are promising optoelectronic materials with strongly confined excitonic properties; however, probing their ultrafast carrier transport dynamics, particularly the initial nonequilibrium
diffusion regime, remains challenging because conventional transient absorption microscopy requires complex spatial imaging and lacks sufficient temporal sensitivity to resolve early time
diffusion dynamics. Here, we demonstrate a
vortex beam based transient absorption microspectroscopy platform (VTAM) enabling imaging free measurement of carrier transport by encoding spatial
diffusion information into the mode dependent pump probe signal. By employing
vortex probes with different topological charges, VTAM provides mode selective spatial sensitivity to excitonic dynamics with subpicosecond temporal resolution. Using VTAM, we resolved rapid free
exciton (FE)
diffusion followed by relaxation toward a slower steady state transport regime. A theoretically derived time dependent
diffusion model separated transient and steady state transport contributions, yielding a transient
diffusion enhancement (68.84 cm2 per s) and a steady state
diffusion coefficient (1.85 cm2 per s), thus providing an initial
diffusion coefficient (70.69 cm2 per s), and a cooling time of 0.35 ps. Measurements at the
exciton-polaron (EP) resonance revealed strongly suppressed
diffusion with nearly time independent signal ratios, indicating
lattice-coupled EP transport. These parameters were extracted without spatial scanning or image reconstruction, establishing V-TAM as a powerful imaging free platform for investigating carrier transport in perovskites and other
semiconductor systems.
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All authors Ju-Young Kim, Anirban Mondal, Gi Rim Han, Kwang Jin Lee, Jong Min Lim, Myeongsam Jen, Minhaeng Cho
Superconductivity
Spin-fluctuation-mediated unconventional $d_{xy}$-wave superconductivity in ThFeAsN from first-principles
Guang-Yu Guo, Jau-Wen Liu and Mitsuaki Kawamura
Superconducting (SC) pairing mechanism, origin of high $T_c$ and
symmetry of SC order parameter in Fe-based
superconductors are among the important unsolved problems in condensed matter and materials physics. We study the SC properties of ThFeAsN, a Fe-based high $T_c$
superconductor, by ab initio superconducting density functional theory calculations with electron-
phonon coupling, screened static and dynamic electron-electron Coulomb repulsion and
spin fluctuation (SF) mediated pair-interaction fully taken into account. Our calculations reveal that ThFeAsN is a SF-mediated multiband
superconductor with the calculated $T_c$ of 22.4 K and the $d_{xy}$-wave SC order parameter with different signs on different
Fermi surface sheets, in consistent with experiments. We also present distinct SC properties such as quasiparticle density of states and ultrasonic attenuation coefficient which can be immediately verified by experiments.
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High Energy Astrophysical Phenomena
Cosmogenic photon fluxes at ultra-high energies
Marcus Niechciol, Chiara Jane Papior and Markus Risse
During their propagation, ultra-high energy
cosmic rays produce cosmogenic
photons. The expected flux level of these
photons may vary by orders of magnitude depending on parameters such as the spectrum and composition of
cosmic rays at injection or the source distance. We investigate the
photon yields for various assumptions on injection parameters. The
photon yield is largest for
proton-emitting sources at about 15 Mpc distance for cosmogenic
photons above $10^{18}$ eV. While the
photon yield from
protons always exceeds the one from heavier
nuclei of the same total energy, the differences are reduced for larger source distances. Then, we quantify the cosmogenic
photon fluxes for different source scenarios. We regard mixed-composition scenarios that were found to provide a reasonable description of the data from the Pierre Auger Observatory. In addition,
benchmark scenarios leading to comparably high (“maximum”) or low (“minimum”)
photon fluxes are determined assuming pure
proton or pure iron primaries. For the mixed-composition scenarios that do not contain initial
protons, the predicted cosmogenic
photon fluxes are below present experimental limits by more than 1.5 orders of magnitude. In case of a substantial fraction of
protons at the highest energies, the related
photon flux might be in reach. Certain parameter combinations of pure
proton scenarios are constrained already by present
photon limits.
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Instrumentation and Methods for Astrophysics
Optical design of a direct fibre-fed MO-IFS for the NLOT
Nitish Singh, S. Sriram, Totan Chand et al. (+3 more)
The initial optical design and performance analysis of a dual-channel fibre-fed Multi-Object Integral Field spectrograph (Mo-IFS) being designed for a future National Large Optical/Infrared
Telescope (NLOT) in India. The front end will be a moveable lenslet+fiber based integral field unit. The spectrograph is designed to directly accept an f/4 beam from the approximately 200 optical fibers, each with a 100 um core diameter without additional fore-optics. The instrument consists of two optimized spectral channels covering wavelength ranges of 0.32-0.62 um (blue channel) and 0.60-1.00 um (red channel). The optical design aims to achieve moderate spectral resolutions of approximately R ~ 2700 in the blue channel and R ~ 2500 in the red channel while maintaining high throughput over a broad spectral range. The spectrograph architecture includes a fiber-fed entrance slit, collimator optics, dichroic beam splitting system, dispersive elements, and dedicated camera optics for each channel. Zemax simulations were carried out to evaluate image quality, spot size distribution, spectral resolution, and detector sampling across the full wavelength range. The current work presents the initial optical configuration, design methodology, and expected performance of the instrument.
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All authors Nitish Singh, S. Sriram, Totan Chand, Jurgen Schmoll, Bharat Kumar Yerra, Savitha M S
Biological Physics
Rate-Independent Epigenetics: a thermodynamically consistent framework for modelling epigenetic response
Jacobo Ayensa-Jiménez and Ignacio ROmero
Epigenetic changes – heritable, long-lived, yet actively reversible modifications of the chromatin state – display
memory, threshold activation and hysteresis, features that are the hallmark of rate-independent dissipative
evolution. We propose a mathematical framework, Rate-Independent Epigenetics, that models epigenetic change within the theory of rate-independent systems and is consistent with two fundamental principles identified with the laws of thermodynamics. In this framework, a model is specified by a state space of epigenetic configurations, a stored-energy functional depending on the state and on an external loading, and a 1-homogeneous dissipation potential encoding the resistance of the epigenetic machinery to change. Assuming an energetic
evolution principle, the governing equations follow, with no further modelling hypotheses. The energy balance is exact energy conservation, and the 1-homogeneity of the dissipation potential forces a non-negative, minimal (economical) dissipation. Under natural coercivity and continuity assumptions we establish existence of energetic solutions and, via vanishing viscosity, of balanced-viscosity solutions that resolve the ambiguity of the energetic formulation at epigenetic switches; uniqueness holds under convexity and, in the scalar case, under a mild finite-multiplicity condition. We then build a variational time integrator, prove its convergence to energetic solutions and a global energy-consistency estimate. The framework is illustrated on the scalar linear play operator, on an example with a double-well energetic potential, showing the ability of the framework to study multi-stability scenarios and catastrophic switches and on a nonlinear problem, proving that the theoretical results hold. The presented framework can be seen as a skeleton for a richer thermodynamically-consistent theory incorporating viscous dissipation features.
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Quantum Physics
Tuning the universality class of a quantum process by Trotterization
Robin Prampain dit Boulan, Jerom Jebai and Hendrik Weimer
We numerically analyze a discretized version of the
quantum contact process, a non-
equilibrium model having a competition between a coherent infection process and a dissipative recovery process. Previously, the continuous-time version has been discussed to have a phase transition in a novel
quantum universality class, while experimental investigations of a related process have pointed towards the transition being in the classical directed percolation class. We demonstrate that these differences stem from details of the discretization of the process and construct a systematic way to continuously interpolate between these results. Finally, we provide evidence that the modification of the universality class is due to destructive interference effects, showing a clear
quantum-mechanical origin.
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High Energy Physics (Theory)
Bosonic SPT and invertible phases and its relation to Steenrod's problem
Shota Saito, Yuji Tachikawa and Yi Zhang
Bosonic invertible and
symmetry-protected topological (SPT) phases are well-known to be described by ordinary
cohomology groups in low dimensions, but `beyond-
cohomology' phases appear in higher dimensions. We make a systematic study of them, and find that the first major non-triviality is a mod-3 phenomenon, and not a mod-2 phenomenon as in the case of fermionic phases. We also point out that this is a dual manifestation of the classic question of Steenrod, namely the issue of the existence of homology cycles without
manifold representatives. Thom developed the theory of cobordisms to answer this question, and we explain how the same analysis leads to Dijkgraaf-Witten phases which are nontrivial on general simplicial complexes but become trivial on
manifolds.
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Quantum Physics
Worst-Case Quantum Algorithm for Optimal Polynomial Intersection Beyond Decoded Quantum Interferometry
Shuji Horinaga and Takashi Yamakawa
The Optimal
Polynomial Intersection (OPI) problem asks us to find a low-degree
polynomial over a finite field whose values lie in prescribed subsets on as many given inputs as possible. Decoded
quantum interferometry (DQI) gives a
quantum algorithm for OPI in parameter regimes beyond those achieved by the best known classical heuristics. Follow-up works improve the parameter regimes, but their analyses are limited to average-case settings. Recently, Sun and Wootters showed that, even in the worst case, OPI has a solution in a larger parameter regime than the one covered by DQI. However, they left open whether one can design a
quantum algorithm that solves OPI in the worst-case beyond the DQI regime. We give such a
quantum algorithm. As a byproduct, we also improve the existential bound of Sun and Wootters in certain parameter regimes. In particular, when each subset contains roughly half of the field elements, our
algorithm finds a solution with satisfaction rate $s=1$ whenever the rate satisfies $R>0.75$. This matches the previous average-case bound, whereas DQI cannot achieve $s=1$ unless $R=1$. Our existential bound guarantees the existence of a solution when $R> 0.7158$, improving over the previous threshold $R>0.7495$. More generally, our existential results extend to the Max-LINSAT problem with respect to arbitrary maximum distance separable (MDS) codes. The corresponding algorithmic results apply only to MDS codes whose dual admits an efficient list decoder. Our results are obtained through a novel application of a Brascamp–Lieb-type inequality in the MDS setting, which may have further applications.
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High Energy Physics (Theory) · Cross-listed from math.NT
Multiple Clausen values and deformed Apéry-like series
Zhi-Wei Sun and Yajun Zhou
With generalized central binomial coefficients $ \binom{2x}{x}:=\frac{\Gamma(2x+1)}{[\Gamma(x+1)]^2}$ defined through Euler's gamma function, we represent deformed Apéry-like series \[ \mathscr A_{s,n}:=\sum_{k=1}^\infty\left.\!\frac{\partial^n}{\partial x^n}\frac{1}{x^s\binom{2x}{x}}\right|_{x=k} \] by multiple Clausen values (MCVs), which belong to a special class of cyclotomic multiple
zeta values (CMZVs) at level $3$. For example, exploiting provable algebraic relations among MCVs, we show that \[\mathscr A_{1,5}=-\frac{9[495L(\chi_{-3},6)-30\pi^{2}L(\chi_{-3},4)-2\pi^{4}L(\chi_{-3},2)]}{4}\]and\[\mathscr A_{4,4}=\frac{352\zeta_{5,3}}{15}+\frac{752537\pi^{8}}{10206000},\]where $ L(\chi_{-3},s):=\sum_{n=0}^\infty\left[(3n+1)^{-s}-(3n+2)^{-s}\right]$ and $\zeta_{5,3}:=\sum_{m>n>0}m^{-5}n^{-3}$.
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Solar and Stellar Astrophysics
Efficiency of Tidal Dissipation in Convective Flow Under Rapid Tidal Forcing
Hongzhe Zhou and Dong Lai
For close binaries and
star-
planet systems,
tidal interactions mediate the energy transfer between the orbital motion and the internal flows of the bodies involved, thus playing a central role in their
evolution. For
equilibrium tides, the associated energy transfer is commonly modeled through an effective viscosity acting on the
tidal flow. However, the scaling of viscous dissipation efficiency with
tidal frequency $\omega_\text{T}$ remains debated, particularly when $\omega_\text{T}$ greatly exceeds the convective eddy turnover frequency $\omega_\text{c}$. Previous numerical studies have addressed this issue by subjecting a turbulent convective flow to an oscillating background shear mimicking
equilibrium tides. In this work, we adopt a novel three-layered convective box – designed to represent a
stellar convection zone sandwiched between two stable layers – driven by an external periodic forcing. We quantify
tidal dissipation efficiency by the forcing power on the flow in steady state. Our results yield a shallower scaling of
tidal power per unit mass with $\omega_\text{T}$ than reported in earlier shear-flow simulations. This scaling is consistent with the prediction by \cite{Terquem2021}, suggesting that the effective turbulent viscosity depends only weakly on $\omega_\text{T}$, although our simulations are restricted to $\omega_\text{T}\lesssim 10\omega_\text{c}$. Moreover, we find no evidence of inverse energy transfer (or “negative viscosity”), a phenomenon observed in some prior shear-flow simulations. We further investigate the influence of rotation within the same local framework. Slow rotation ($\Omega\lesssim \omega_\text{T}$) tends to enhance the
tidal power, whereas fast rotation ($\Omega\gtrsim\omega_\text{T}$) significantly suppresses it. We discuss the limitations of our approach and the broader implications of our findings.
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Solar and Stellar Astrophysics
The coronal mass ejection productivity of solar active region 13664/8
Lijuan Liu, Yuming Wang, Quanhao Zhang et al. (+2 more)
In May 2024, NOAA active region (AR) complex 13664/8 was one of the most productive regions of the current
solar cycle, producing 12 X-class
flares and over 20 coronal mass ejections (CMEs) and triggering the strongest geomagnetic storm since 2003. We investigate why this AR complex was so CME-productive. Using primarily SDO/AIA and SDO/HMI observations, we analyzed its photospheric
magnetic evolution, eruption sources, eruption waiting times, and
magnetic parameters in comparison with five other ARs. The region initially contained only AR 13664 and exhibited limited
flare activity until AR 13668 emerged on May 4, after which clustered major
flares and CMEs occurred. Rapid, complex flux emergence substantially increased the region's area,
magnetic flux, complexity, and nonpotentiality. The increased complexity was manifested by at least 12 emerging bipoles and six collisional polarity inversion lines (cPILs) formed between nonconjugated polarities, all showing sustained collision and shearing and serving as eruption sources. Decay index distributions show systematically lower critical heights (<45 Mm) above CME source regions. The CME waiting time distribution exhibits two peaks, suggesting that multiple cPILs enhanced CME productivity by increasing both recurrent CMEs from the same source and disturbance-triggered CMEs from nearby sources. These results indicate that, in addition to sufficient nonpotentiality and rapid background-field decay, high
magnetic complexity accompanied by dynamical collisional shearing at multiple cPILs was crucial for the extreme CME productivity of AR 13664/8.
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All authors Lijuan Liu, Yuming Wang, Quanhao Zhang, Jingnan Guo, Yutian Chi
Solar and Stellar Astrophysics
Runaway OB stars within 1 kpc of the Sun
Juan Martinez Garcia, Nicholas Wright and Alexis Quintana
Runaway
stars are high-velocity
stars ejected from their birth environments that can provide insights into the kinematic history of the
stellar cluster they were ejected from. We derived runaway
star probabilities for 40 O-type
stars and $24,487$ B-type
stars taken from a recently published volume-complete sample of OB
stars within 1 kpc of the Sun. We fit a
Galactic rotation model to the observed proper motions of these
stars and identify runaway
stars using both a fixed 2D peculiar velocity threshold of $23\,km\,s^{-1}$ and by comparing individual peculiar velocities to the dispersion of the whole sample. We find runaway fractions of $17.5^{+0.1}_{-2.5}\%$ for O-type
stars and $6.9\pm0.1\%$ for B-type
stars; both using the fixed velocity threshold method. These values are consistent with previous studies, but with differences that are largely attributable to the underlying samples of OB
stars used in various studies to identify runaway
stars and to variations in the methods used to select them.
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Physics and Society
Criticality and reduced dynamical resilience in PM2.5 pollution systems
Yuan Chen, Yongwen Zhang, Xu Li et al. (+5 more)
Concentration-based metrics underpin air-quality assessment, while dynamical persistence and recovery describe how rapidly high-PM2.5 episodes dissipate and how strongly they retain
memory. Here we introduce a finite-
memory multiplicative reversion (FMMR) process that links the lognormal concentration backbone of PM2.5 variability with event recurrence, temporal
memory, variance amplification and local dynamical resilience. Across station observations and reanalysis data, elevated PM2.5 regimes show a coherent set of critical signatures: stronger
memory, rising autocorrelation, broader upper tails, amplified variance, reduced resilience and more clustered exceedance events. Together, these co-occurring signals reveal dynamical criticality in PM2.5 pollution systems, with critical slowing down expressed as a loss of restoring capacity under high-pollution conditions. A gridded comparison across populated and emission-influenced regions further shows that areas with similar PM2.5 burden can differ in recovery capacity, while eastern China has shifted toward higher resilience during recent air-quality improvements and India and West Africa occupy lower-resilience states. By identifying where pollution burden and recovery capacity diverge, these findings establish dynamical persistence and resilience as complementary dimensions of PM2.5 risk and provide a quantitative basis for resilience-oriented air-quality assessment.
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All authors Yuan Chen, Yongwen Zhang, Xu Li, Dean Chen, Jingfang Fan, Yosef Ashkenazy, Deliang Chen, Shlomo Havlin
Quantum Physics
Emergence and Recovery of (logical) Kochen-Specker Contextuality via Hamilton Extension
Jayashree Karmakar, Biswadeep Chatterjee, Rafiuddin Gazi et al. (+5 more)
Logical Kochen-Specker (KS) contextuality is widely regarded as an intrinsic property of specially constructed measurement configurations. We show instead that it can emerge from KS-colorable vector sets through a constructive procedure we call the Hamilton extension. Defined for four-dimensional vector sets, the Hamilton extension associates each real vector with a measurement context while inducing additional measurement contexts among Hamilton-extended children of distinct parent vectors. These emergent contexts fundamentally alter the compatibility structure, transforming KS-colorable configurations into KS-uncolorable ones and recovering logical contextuality lost under apex-vertex augmentation. We establish a sharp and optimal threshold – the Hamilton extension of every five-vector parent set remains KS-colorable, whereas suitably chosen six-vector parent sets already generate logical KS contradictions. Thus, six vectors constitute the smallest parent set capable of generating KS contradiction through this mechanism. Our results reveal a new structural route to contextuality, provide a systematic framework for constructing compact KS sets, and have implications for contextuality-based
quantum information protocols and graph-theoretic approaches to nonclassicality.
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All authors Jayashree Karmakar, Biswadeep Chatterjee, Rafiuddin Gazi, Anushko Chattopadhyay, Ananya Chakraborty, Snehasish Roy Chowdhury, Amit Mukherjee, Manik Banik
Astrophysics of Galaxies
Relativistic Tidal Transitions of Saturated Kerr Boson Clouds
Yi-kun Li and Lang Cui
Rotating black holes can bind ultralight
bosons in macroscopic clouds whose level structure is swept by the
tidal field of a binary companion. Existing estimates of the resulting resonant transitions have largely used hydrogenic wave functions, even where the cloud grows most efficiently and the Kerr geometry appreciably deforms its quasibound states. I compute
tidal transition
matrix elements on the numerically determined saturation branches of the $|211\rangle$, $|322\rangle$, and $|433\rangle$ clouds. The calculation combines Kerr quasibound modes, their relativistic bilinear normalization, and an adiabatic uadrupolar perturbation of the Kerr metric. Across five $\Delta m=-2$ channels, the relativistic
matrix element differs from its hydrogenic value by as much as $21.67\%$. Corrections above $10\%$ persist when $99\%$ of the cloud lies within $7\%$ of the orbital separation. A component-resolved comparison attributes $78.7-82.5\%$ of the logarithmic change to the radial mode profile and $13.3-16.2\%$ to the bilinear normalization; the relativistic
tidal geometry supplies a smaller additional correction. Exact Newtonian multipoles and an independent complex-contour construction confirm the quadrupole
matrix elements. For resonances with intermediate Landau–Zener adiabaticity, the corrected
matrix elements change the predicted cloud depletion by up to $13.7\%$. Relativistic cloud structure is therefore quantitatively important for binary histories that cross saturated-cloud resonances.
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General Relativity and Quantum Cosmology
Random walks around black holes and low-frequency X-ray variability
Arthur G. Suvorov
The
stochastic dynamics of a grain embedded within a turbulent fluid subject to strong gravitational fields can be formulated as a random walk on a Riemannian
manifold. Such
curvature-weighted walks provide a framework to model the intrinsic variability of
accretion onto compact objects. By solving the relevant Fokker-Planck equation on a black hole background, we find the counterintuitive result that the escape probability of a grain is actually higher compared to flat space. This is a consequence of the stretching of radial
cells near the event horizon: there is a greater spatial volume for the particle to wander through before being captured. By simulating a large number of grain trajectories, initially distributed on concentric shells with a density profile set by the thin-disc structure equations, we also study particle fluxes through the horizon. Shallower spectral indices emerge at low frequencies relative to flat space, primarily due to time dilation, and steeper ones at high frequencies. We find that Schwarzschild-weighted spectra broadly match observations of low-frequency X-ray variability from systems like Cygnus X-1 in their hard state, suggesting that
geometric drifts may be important in describing
stochastic accretion processes.
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Earth and Planetary Astrophysics
Observational planning for the 2026 August 5 Falcon 9 Upper Stage lunar impact
Benjamin Fernando, Jennifer Heldmann, Bill Grey et al. (+20 more)
On 2026 August 5, at approximately 06:35 UT, a spent Falcon 9 upper stage will impact the lunar surface near Einstein Crater. This event will occur on sunlit terrain near the eastern limb as seen from Earth. The impact flash and resultant ejecta plume from this event are potentially observable from ground- and space-based observational facilities. This event provides an opportunity to attempt the recording of an artificial impact in real-time; although many of the properties of the event (such as visual magnitude) are imprecisely predicted at present. Moreover, this event provides an opportunity to test a pipeline for localising impacts on the lunar surface for future seismic experiments, investigating the
dust and plume dynamics from impact events on the Moon, and considering hazards from artificial space debris impacts. Both professional and amateur astronomers are encouraged to attempt observations of this event.
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All authors Benjamin Fernando, Jennifer Heldmann, Bill Grey, John Ortiz, Bryan Euser, Darryl Z. Seligman, Eunhyeuk Kim, Anthony Colaprete, Elisa Maria Alessi, Detlef Koschny, Anthony Cook, Joel Green, Patrick King, Stacy Teng, Dawn Graninger, Arnold Goldberg, William Cooke, Mike F. Skrutskie, Kevin Schlaufman, Nicholas Schmerr, Carly M. Donahue, Carl A. Schmidt, Nancy J. Chanover
General Relativity and Quantum Cosmology
Scalarization of Charged Black Hole in Gauss-Bonnet Extended Starobinsky-Maxwell Gravity
Rui-Xi Zhu and Hai-Shan Liu
We re-examine spontaneous scalarization of black holes within Starobinsky
gravity supplemented by the Gauss-Bonnet invariant. A novel feature is uncovered: scalarized solutions split into two smooth branches that connect at a common minimal horizon radius, a multi-branch structure previously unreported for static, spherically symmetric scalarization. Extending the theory with a Maxwell field, we find that this multi-branch structure persists, while a new additional disconnected branch emerges within certain parameter ranges. We thoroughly analyse the transition from a single smooth branch to two disconnected branches. Lastly, we verify, employing the standard Maxwell thermodynamic relations, that all charged hairy solutions obey the first law exactly.
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Instrumentation and Detectors
Machine Learning for Complex Instrument Design and Optimization
Barry C. Barish, Jonathan W. Richardson, Evangelos E. Papalexakis et al. (+1 more)
In modern experimental physics, particle accelerators and gravitational-wave observatories enable a wide-range of research at the frontiers of science. These instruments are highly complex consisting of many interacting systems which can face significant operational challenges. Apart from the experiment's main data product, a lot of data about the experimental apparatus and its environment is recorded. Machine learning techniques can analyze this big data at scale and find useful insights into operational faults potentially improving the instrument's performance and achieving the design goals. Speaking of design, machine learning can also accelerate/augment the expensive physics simulations used during the design phase of such large-scale instruments.
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All authors Barry C. Barish, Jonathan W. Richardson, Evangelos E. Papalexakis, Rutuja Gurav
Soft Condensed Matter
Numerical and experimental framework for bending elasticity of highly flexible slender structures
Shunsuke Nomura, Satsuki Shibuya, Isamu Hashiguchi et al. (+2 more)
Slender structures are highly flexible, spanning several orders of magnitude in length scale. Their deformation depends on the slenderness of their cross sections, highlighting that the elasticity and geometry of structures are intrinsically coupled. The deformation of the cross-section becomes significant, particularly when tubes and pipes are subjected to bending, known as the Brazier instability. Although the bending performance of slender structures is quantified experimentally using a canonical three-point bending test, their numerical counterparts remain under-explored because complex contact mechanics must be implemented in simulations. In this study, we develop a computational framework to simulate experimental three-point bending tests using a hybrid material point method (hybrid-MPM) approach, which integrates Lagrangian finite element and Eulerian finite difference frameworks. We adapt our framework to elastic tubes and tape springs as canonical examples that exhibit characteristic bending deformation in which the cross-sectional and lengthwise bending are coupled. The predictions of numerical simulations are validated against desktop experiments and classical theory. The excellent agreement between the simulation and the experiments implies that the hybrid-MPM framework provides a robust computational framework for predicting the large deformation of structures involving complex contact, such as soft
robots and deployable structures.
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All authors Shunsuke Nomura, Satsuki Shibuya, Isamu Hashiguchi, Ryuichi Tarumi, Tomohiko G. Sano
Quantum Physics
Adaptive Entanglement Management in Quantum Multi-Core Architectures
Rajeswari Suance P S, Anubhab Dutta, Ruchika Gupta et al. (+1 more)
Scalable
quantum computing architectures increasingly rely on multi-core designs, where
qubits are distributed across multiple processing cores interconnected through a
quantum Network-on-Chip (NoC). In such systems, inter-core communication is typically realized through
entanglement-assisted
quantum teleportation, making efficient
entanglement generation critical for performance. In this paper, we perform a comparative study of three
entanglement management paradigms for multi-core
quantum processors: reactive on-demand generation (ODG), proactive continuous pre-generation (CGP), and an adaptive continuous pre-generation approach (ACGP). While ODG generates
entanglement only when required, CGP reduces average teleportation latency by pre-generating EPR pairs in the background. To improve upon this, we propose ACGP which dynamically adjusts
entanglement generation probabilities based on observed inter-core communication patterns. We evaluate these approaches using an extended SeQUeNCe simulator on mesh-based multi-core architectures on real
benchmark circuits. Results show that ACGP significantly reduces average teleportation latency compared to ODG and CGP. Although pre-generation introduces fidelity degradation due to storage time,
entanglement purification effectively restores fidelity with minimal impact on latency. These results demonstrate that adaptive
entanglement managements can substantially improve communication efficiency in scalable
quantum multi-core systems.
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All authors Rajeswari Suance P S, Anubhab Dutta, Ruchika Gupta, John Jose
Materials Science
Second-Order Optical Nonlinearity of AlScN Films Grown By Molecular Beam Epitaxy
Joongwon Lee, Thai-Son Nguyen, Len van Deurzen et al. (+8 more)
Alloys of AlN have rapidly emerged as a material platform for nonlinear optics. In this paper, we measure the second-order optical nonlinearity of AlScN films grown directly on nitrided c-plane sapphire by molecular beam epitaxy. This direct growth approach, which bypasses a thick AlN buffer layer, allows us to isolate the true nonlinear response of the AlScN film. Our results show a large enhancement of d31, but a suppression of d33 in AlScN films compared to AlN. We observe that d31 can be as high as 4.92 pm/V , which is 60 times larger than that of AlN. The development of AlScN-based photonic devices can enable energy-efficient nonlinear optical operations that can be epitaxially integrated with electronic and photonic devices based on Si, GaN and AlN.
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All authors Joongwon Lee, Thai-Son Nguyen, Len van Deurzen, Debaditya Bhattacharya, Chandrashekhar Savant, Siddhartha Ghosh, Patrick Shea, Carl Bernard, Huili Grace Xing, Debdeep Jena, Farhan Rana
Astrophysics of Galaxies
A Catalog of Compact High-Velocity Clouds from the FAST All-Sky HI Survey (FASHI) DR2
Jin-Long Xu, Chuan-Peng Zhang, Xiao-Lan Liu et al. (+3 more)
High-velocity clouds (HVCs) – especially compact HVCs (CHVCs) – are thought to serve as gaseous tracers of dark-matter-dominated subhalos, providing a crucial empirical link between the predicted dark matter substructure and observed satellite
galaxies. In this paper, we present a new catalog of 192 CHVCs identified from the FAST All-Sky HI Survey (FASHI) Data Release 2 (DR2). Among these, 108 are ultra-compact HVCs (UCHVCs), the majority of which are new discoveries. We find that 185 of the 192 CHVCs are spatially and kinematically concentrated around the Andromeda
galaxy (M31), with a median LSR velocity of -296.1 km/s, suggesting physical association with M31. Adopting an M31 distance of 0.8 Mpc, we derive HI masses in the range 1.9*10^{5} to 4.0*10^{6} Msun and dynamical masses from 1.0*10^{7} to 6.3*10^{8} Msun. Approximately half of the CHVCs follow the baryonic Tully–Fisher relation. No optical counterparts are detected in Pan-STARRS1 imaging down to a limiting magnitude of m_g = 22.8. We conclude that these CHVCs likely represent a population of gas-rich, starless minihalos and provide an excellent sample for the search for dark
galaxies.
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All authors Jin-Long Xu, Chuan-Peng Zhang, Xiao-Lan Liu, Nai-Ping Yu, Mei Ai, Ming Zhu