arXivDaily arXiv每日学术速递 周一至周五更新
全部学科分类 1220
2602.16817 2026-02-20 quant-ph cond-mat.quant-gas cond-mat.stat-mech nlin.CD

Dissipation as a Resource: Synchronization, Coherence Recovery, and Chaos Control

Debabrata Mondal, Lea F. Santos, S. Sinha

详情
英文摘要

Dissipation is commonly regarded as an obstacle to quantum control, as it induces decoherence and irreversibility. Here we demonstrate that dissipation can instead be exploited as a resource to reshape the dynamics of interacting quantum systems. Using an experimentally realizable Bose-Josephson junction containing two bosonic species, we demonstrate that dissipation enables distinct dynamical behaviors: synchronized phase-locked oscillations, transient chaos with long-time coherence recovery, and steady-state chaos. The emergence of each behavior is determined by experimentally tunable parameters. At weak interactions, the two components synchronize despite dissipation, exhibiting long-lived coherent oscillations reminiscent of a boundary time crystal. Stronger interactions induce a dissipative phase transition into a self-trapped regime accompanied by chaotic dynamics. Remarkably, dissipation regulates the lifetime of chaos and enables the recovery of coherence at long times. By introducing a controlled tilt between the wells, transient chaos can be converted into persistent steady-state chaos. We further show that standard spectral diagnostics fail to distinguish between the two chaotic regimes, revealing that spectral statistics primarily reflect short-time instability. These results establish dissipation as a powerful tool for engineering dynamical phases, restoring quantum coherence, and controlling the duration of chaotic behavior and information scrambling.

2602.16816 2026-02-20 astro-ph.EP

Observational Signatures of Circumstellar Gas Tori Formed by Planetary Mass-Loss from Close-In Exoplanets

Ethan Schreyer, Ruth Murray-Clay

Comments Accepted for publication in MNRAS

详情
英文摘要

Close-in exoplanets with H/He atmospheres often undergo hydrodynamic escape. In extreme cases, it is hypothesized that the mass loss can be high enough for the escaping planetary material to wrap around the star, forming a long-lasting circumstellar torus. In this work, we develop a physical model of such circumstellar tori and use a ray tracing scheme to calculate the attenuation of stellar light passing through them. We show that the presence of a circumstellar torus significantly increases the equivalent width of the observed stellar He I 10830~Å~line. When combined with observations of the star's Ca II H & K lines, these systems can typically be distinguished from field stars. Based on these results, we propose a survey of stars hosting close-in planets, combining observations of the He I 10830~Å~and Ca II H & K lines to search for circumstellar tori generated from planetary mass-loss in these systems.

2602.16815 2026-02-20 math.AG math.AC math.NT

Classifying binary quadratic forms using Clifford invariants

Soham Mondal, T. E. Venkata Balaji

Comments 43 pages, Accepted in Proceedings of the Indian Academy of Sciences: Mathematical Sciences

详情
英文摘要

We functorially identify similarity classes of line-bundle-valued quadratic forms on rank two vector bundles with isomorphism classes of pairs consisting of the degree zero and the degree one parts of the associated generalized Clifford algebras. As applications, we generalize the Gauss Composition and explore connections with Picard groups of quadratic algebras.

2602.16809 2026-02-20 cs.PL

Haskell meets Evariste

Paulo R. Pereira, Jose N. Oliveira

详情
英文摘要

Since its birth as a new scientific body of knowledge in the late 1950s, computer programming has become a fundamental skill needed in many other disciplines. However, programming is not easy, it is prone to errors and code re-use is key for productivity. This calls for high-quality documentation in software libraries, which is quite often not the case. Taking a few Haskell functions available from the Hackage repository as case-studies, and comparing their descriptions with similar functions in other languages, this paper shows how clarity and good conceptual design can be achieved by following a so-called easy-hard-split formal strategy that is quite general and productive, even if used informally. This strategy is easy to use in functional programming and can be applied to both program analysis and synthesis.

2602.16808 2026-02-20 astro-ph.CO astro-ph.GA astro-ph.HE gr-qc

Analytical Estimates of Gravitational Wave Background Anisotropies from Shot Noise and Large-Scale Structure in Pulsar Timing Arrays

Meng-Xiang Lin, Adam Lidz, Chung-Pei Ma

Comments 13 pages, 6 figures

详情
英文摘要

An important next step for pulsar timing arrays (PTAs) is to measure anisotropies in the gravitational wave background (GWB) at $\sim$ nano-Hz frequencies. We calculate the expected GWB anisotropies using empirically calibrated models for the merger rates of supermassive black hole binaries (SMBHBs). The anisotropies reflect both shot-noise in the discrete SMBHB populations while also tracing, in part, the large-scale structure (LSS) of the universe. The shot-noise term is sensitive to the high-mass end of the merging SMBH mass function, depends somewhat on the low-redshift tail of the merger distribution, and is a strong function of observing frequency. The precise frequency dependence provides a test of SMBHB residence times. In our models, the mean shot-noise anisotropy typically lies close to or above the broad frequency-band NANOGrav upper limits. Consequently, near-future PTA data, and potentially re-analyses of existing measurements using frequency-dependent shot-noise anisotropy templates, should be capable of detecting this signal or placing meaningful constraints on SMBHB merger models. A full interpretation, however, will require modeling the probability distribution of shot-noise amplitudes rather than relying solely on ensemble-averaged predictions. The LSS-induced anisotropies are at least two to three orders of magnitude smaller. Although the LSS contribution contains valuable information regarding the redshift distribution and clustering bias of the merging SMBHBs, detecting this component will be challenging.

2602.16806 2026-02-20 cs.HC

Exploring the Design and Impact of Interactive Worked Examples for Learners with Varying Prior Knowledge

Sutapa Dey Tithi, Xiaoyi Tian, Ally Limke, Min Chi, Tiffany Barnes

详情
英文摘要

Tutoring systems improve learning through tailored interventions, such as worked examples, but often suffer from the aptitude-treatment interaction effect where low prior knowledge learners benefit more. We applied the ICAP learning theory to design two new types of worked examples, Buggy (students fix bugs), and Guided (students complete missing rules), requiring varying levels of cognitive engagement, and investigated their impact on learning in a controlled experiment with 155 undergraduate students in a logic problem solving tutor. Students in the Buggy and Guided examples groups performed significantly better on the posttest than those receiving passive worked examples. Buggy problems helped high prior knowledge learners whereas Guided problems helped low prior knowledge learners. Behavior analysis showed that Buggy produced more exploration-revision cycles, while Guided led to more help-seeking and fewer errors. This research contributes to the design of interventions in logic problem solving for varied levels of learner knowledge and a novel application of behavior analysis to compare learner interactions with the tutor.

2602.16804 2026-02-20 hep-ph nucl-ex physics.atom-ph

Probing Ultralight Dark Matter at the Mega-Planck Scale with the Thorium Nuclear Clock

Jason Arakawa, Jack F. Doyle, Elina Fuchs, Jacob S. Higgins, Fiona Kirk, Kai Li, Tian Ooi, Gilad Perez, Wolfram Ratzinger, Marianna S. Safronova, Thorsten Schumm, Jun Ye, Chuankun Zhang

Comments 14 pages, 9 figures

详情
英文摘要

Ultralight dark matter is expected to induce oscillations of nuclear parameters. These oscillations are characterized by extremely weak couplings or high suppression scales, with the Planck scale - the characteristic scale of quantum gravity - serving as a natural benchmark. Probing this phenomenon requires systems with exceptional sensitivity to shifts in nuclear energies. The uniquely low-energy nuclear isomeric transition in ${}^{229}$Th provides such sensitivity: it directly probes the nuclear interaction and, owing to a near cancellation between electromagnetic and nuclear contributions, its response to changes in nuclear structure is greatly amplified. We devise and perform a new type of ultrasensitive search for dark matter which uses the precision nuclear spectroscopy at JILA to set the strongest bounds in the mass range $10^{-21}\,{\rm eV} \lesssim m_{\rm DM} \lesssim 10^{-19}\,{\rm eV}$. Our results probe effective interaction scales exceeding $10^6$ times the Planck scale (the Mega-Planck scale) and establish the ${}^{229}$Th system as the leading probe of dark matter couplings to the nuclear sector.

2602.16803 2026-02-20 cond-mat.mtrl-sci

A Kinetic Phase-Field Model of Diffusion Bonding: A Nonlocal Approach to Interface Coalescence

Maryam Khodadad, Noel Walkington, Suresh Kalyanam, Matteo Pozzi, Kaushik Dayal

Comments To appear in Journal of Applied Mechanics

详情
英文摘要

Conventional phase-field models often drive solid-solid interfaces to coalesce when in close proximity. This feature limits their use for processes like diffusion bonding, where the interfaces might need to remain distinct under certain thermodynamic conditions. We develop a kinetic phase-field model to address this problem, using an evolution equation based on a geometric conservation law for interfaces, rather than the gradient descent evolution that is typical in phase-field modeling. This formulation enables us to specify complex kinetic laws, and we use this to incorporate a physically-motivated geometric criterion to control interface merging. This criterion, based on nonlocal higher-derivative curvature invariants of the phase field, can be temperature-dependent, allows for a range of behaviors from complete coalescence to the preservation of distinct boundaries. Simulations show controlled bonding kinetics, demonstrating capabilities that are not available with existing methods for modeling interfaces that must remain distinct under given thermodynamic conditions.

2602.16801 2026-02-20 astro-ph.EP

Using EUV driven external photoevaporation to test viscous evolution of protoplanetary discs

Giulia Ballabio, James E. Owen

Comments 13 pages, 10 figures

详情
英文摘要

Protoplanetary discs are thought to evolve either through angular momentum transport driven by viscous processes or through angular momentum removal induced by magnetohydrodynamic (MHD) winds. One proposed method to distinguish between these two evolutionary pathways is by comparing mass accretion rates and disc sizes, but observational constraints complicate this distinction. In this study, we investigate how extreme ultraviolet (EUV) external photoevaporation affects the evolution of protoplanetary discs, particularly in environments such as the Orion Nebula Cluster. Using a combination of analytical derivations and 1D numerical simulations, we explore the impact of externally induced mass-loss on disc structure and accretion dynamics. We demonstrate that, in the viscous scenario, there exists a clear, near one-to-one correlation between the mass-loss rate due to external photoevaporative outflows and the mass accretion rate onto the central star. In contrast, MHD wind-driven discs do not exhibit such trend, leading to a distinct evolutionary path. External photoevaporative mass-loss rates and mass accretion rates can both be accurately measured for a population of discs, without a strong model dependence. Thus, our findings provide a robust observational test to distinguish between viscous and MHD wind-driven disc evolution, offering a new approach to constraining angular momentum transport mechanisms in protoplanetary discs. Applying this diagnostic observationally requires joint measurements of $\dot{M}_{\rm acc}$ and $\dot{M}_{\rm pe}$ for the same objects, which are currently scarce in bright HII regions due to contamination and sensitivity limitations.

2602.16799 2026-02-20 hep-ex

Measurement of the Muon Flux at the Sanford Underground Research Facility with the LUX-ZEPLIN Dark Matter Detector

D. S. Akerib, A. K. Al Musalhi, F. Alder, B. J. Almquist, C. S. Amarasinghe, A. Ames, T. J. Anderson, N. Angelides, H. M. Araújo, J. E. Armstrong, M. Arthurs, A. Baker, S. Balashov, J. Bang, J. W. Bargemann, E. E. Barillier, K. Beattie, A. Bhatti, T. P. Biesiadzinski, H. J. Birch, E. Bishop, G. M. Blockinger, C. A. J. Brew, P. Brás, S. Burdin, M. C. Carmona-Benitez, M. Carter, A. Chawla, H. Chen, Y. T. Chin, N. I. Chott, S. Contreras, M. V. Converse, R. Coronel, A. Cottle, G. Cox, D. Curran, C. E. Dahl, I. Darlington, S. Dave, A. David, J. Delgaudio, S. Dey, L. de Viveiros, L. Di Felice, C. Ding, J. E. Y. Dobson, E. Druszkiewicz, S. Dubey, C. L. Dunbar, S. R. Eriksen, N. M. Fearon, N. Fieldhouse, S. Fiorucci, H. Flaecher, E. D. Fraser, T. M. A. Fruth, P. W. Gaemers, R. J. Gaitskell, A. Geffre, J. Genovesi, C. Ghag, J. Ghamsari, A. Ghosh, R. Gibbons, S. Gokhale, J. Green, M. G. D. van der Grinten, J. J. Haiston, C. R. Hall, T. Hall, R. H. Hampp, S. J. Haselschwardt, M. A. Hernandez, S. A. Hertel, G. J. Homenides, M. Horn, D. Q. Huang, D. Hunt, R. S. James, E. Jacquet, K. Jenkins, A. C. Kaboth, A. C. Kamaha, M. K. Kannichankandy, D. Khaitan, A. Khazov, J. Kim, Y. D. Kim, D. Kodroff, E. V. Korolkova, H. Kraus, S. Kravitz, L. Kreczko, V. A. Kudryavtsev, C. Lawes, D. S. Leonard, K. T. Lesko, C. Levy, J. Lin, A. Lindote, W. H. Lippincott, J. Long, M. I. Lopes, W. Lorenzon, C. Lu, S. Luitz, V. Mahajan, P. A. Majewski, A. Manalaysay, R. L. Mannino, R. J. Matheson, C. Maupin, M. E. McCarthy, D. N. McKinsey, J. McLaughlin, J. B. Mclaughlin, R. McMonigle, B. Mitra, E. Mizrachi, M. E. Monzani, K. Morå, E. Morrison, B. J. Mount, M. Murdy, A. St. J. Murphy, H. N. Nelson, F. Neves, A. Nguyen, C. L. O'Brien, F. H. O'Shea, I. Olcina, K. C. Oliver-Mallory, J. Orpwood, K. Y. Oyulmaz, K. J. Palladino, N. J. Pannifer, N. Parveen, S. J. Patton, B. Penning, G. Pereira, E. Perry, T. Pershing, A. Piepke, S. S. Poudel, Y. Qie, J. Reichenbacher, C. A. Rhyne, G. R. C. Rischbieter, E. Ritchey, H. S. Riyat, R. Rosero, N. J. Rowe, T. Rushton, D. Rynders, S. Saltão, D. Santone, I. Sargeant, A. B. M. R. Sazzad, R. W. Schnee, G. Sehr, B. Shafer, S. Shaw, W. Sherman, K. Shi, T. Shutt, C. Silva, G. Sinev, J. Siniscalco, A. M. Slivar, R. Smith, V. N. Solovov, P. Sorensen, J. Soria, T. Stenhouse, T. J. Sumner, A. Swain, M. Szydagis, D. R. Tiedt, M. Timalsina, D. R. Tovey, J. Tranter, M. Trask, K. Trengove, M. Tripathi, A. Usón, A. C. Vaitkus, O. Valentino, V. Velan, A. Wang, J. J. Wang, Y. Wang, L. Weeldreyer, T. J. Whitis, K. Wild, M. Williams, J. Winnicki, L. Wolf, F. L. H. Wolfs, S. Woodford, D. Woodward, C. J. Wright, Q. Xia, J. Xu, Y. Xu, M. Yeh, D. Yeum, J. Young, W. Zha, H. Zhang, T. Zhang, Y. Zhou

Comments 17 pages, 6 figures, and 2 tables

详情
英文摘要

High-energy cosmic-ray muons reaching deep underground laboratories can cause events in detectors that mimic signals expected from dark matter particles, neutrinos, or rare decays. Knowledge of the muon flux and energy spectrum is important for evaluating the background rate caused by muons and their secondaries. In this paper, we report the measurement of the cosmic-ray muon flux in the Davis Campus of the Sanford Underground Research Facility with the LUX-ZEPLIN detector. Using 366.4~days of exposure, the muon rate through the detector was measured as $10.94\pm0.17_\textrm{stat.}~\textrm{day}^{-1}$ with energy thresholds of 20~MeV in the inner xenon detector and 8 MeV in the outer liquid scintillator detector. This rate corresponds to a muon flux of $(5.09\pm0.08_\textrm{stat.}\pm0.10_\textrm{sys.})\times10^{-9}~\textrm{cm}^{-2}\textrm{s}^{-1}$ in the Davis Cavern.

2602.16797 2026-02-20 math.NA cs.NA

Fast, High-Accuracy, Randomized Nullspace Computations for Tall Matrices

Ethan N. Epperly, Taejun Park, Yuji Nakatsukasa

Comments 20 pages, 5 figures

详情
英文摘要

In this paper, we develop RLOBPCG, an efficient method for computing a small number of singular triplets corresponding to the smallest singular values of large, tall matrices. The algorithm combines randomized preconditioner from the sketch-and-precondition techniques with the LOBPCG eigensolver: a small sketch is used to construct a high-quality preconditioner, and LOBPCG is run on the Gram matrix to refine the singular vector. Under the standard subspace embedding assumption and a modest singular value gap between the two smallest singular values, we prove that RLOBPCG converges geometrically to the minimum singular vector. In numerical experiments, RLOBPCG achieves near-optimal accuracy on matrices with up to $10^6$ rows, outperforming classical LOBPCG and Lanczos methods by a speedup of up to $12\times$ and maintaining robustness when other iterative methods fail to converge.

2602.16795 2026-02-20 astro-ph.CO

The Sign-Switching of the Cosmological Constant

Mariam Bouhmadi-López, Beñat Ibarra-Uriondo

Comments 21 pages, 5 figures. Contribution to the proceedings of the Corfu Summer Institute 2025 "School and Workshops on Elementary Particle Physics and Gravity" (CORFU2025) 2 - 8 September, 2025 Corfu, Greece

详情
英文摘要

We propose and investigate a class of dynamical dark energy models in which the cosmological constant evolves from negative values in the early Universe to a positive value at low redshifts. This framework includes a generalised ladder-step evolution, as well as smooth-transition scenarios, providing a unified description of sign-changing cosmological constants. We analyse the theoretical construction and background dynamics of these models using cosmographic diagnostics. Extending this study to the linear perturbation regime, we solve the perturbation equations from the radiation-dominated era with adiabatic initial conditions. We examine the evolution of the matter density contrast, gravitational potential, and the $fσ_8$ observable. Our results are compared against the standard $Λ$CDM model and confronted with current observational data, illustrating the phenomenological viability of sign-changing dark energy models and revealing distinctive imprints on cosmic structure formation arising from the transition of the cosmological constant.

2602.16792 2026-02-20 astro-ph.IM astro-ph.HE gr-qc

Fast pre-merger detection of massive black-hole binaries in LISA based on time-frequency excess power

Francesco Nobili, Malvina Bellotti, Riccardo Buscicchio, Massimo Dotti, Alessandro Lupi

详情
英文摘要

The Laser Interferometer Space Antenna is expected to observe gravitational waves from massive black hole binaries across cosmic time. Many are anticipated to be detectable hours to weeks before coalescence. We present a fast algorithm for the pre-merger detection and preliminary characterization of such binaries. The method performs a search for excess power with a chirping time-frequency morphology in short-time Fourier transform spectrograms. By tiling the time-frequency plane with slices defined by the quadrupole frequency evolution, we define a signal significance relative to a fitted background distribution of instrumental noise and Galactic foreground. Individual search triggers are followed by a coherence tracker, which groups over time triggers consistent with the same physical signal . Doing so, our analysis provides progressively refined estimates of the chirp mass and coalescence time. We validate our algorithm on the Sangria LISA Data Challenge dataset, successfully detecting all 15 injected MBHBs: 14 of them hours-to-weeks before merger, while one is only detected after the binary coalescence. The algorithm yields chirp mass relative errors below $3\%$ for high-SNR sources and coalescence time uncertainties of up to a few hours. With a computational cost of less than a second to process a 10-day data segment on single core, our approach is suitable for generating real-time alerts, trigger protected observational periods, and provide informative priors for Bayesian parameter estimation.

2602.16791 2026-02-20 astro-ph.SR

Gaia24ccy: An outburst followed the footsteps of its predecessor

Koshvendra Singh, Joe P. Ninan, Zhen Guo, Valentin D. Ivanov, David A. H. Buckley, Devendra K. Ojha, Andrew Monson, Tarak Chand, Saurabh Sharma, Ram Kesh Yadav, Devendra K. Sahu, Pramod Kumar, Vardan Elbakyan, Sergei Nayakshin, Vitor Fermiano, Min Fang, Jura Borissova, Wen Ping Chen, Franz-Josef Hambsch, Radostin Kurtev, Calum Morris, Javier Osses, Vania Rodriguez, Tanvi Sharma, Bandari Srikanth, Thanawuth Thanathibodee, Wei-Hao Wang, Yuting Zhou

Comments Accepted for publication in The Astrophysical Journal

详情
英文摘要

Accretion-driven outbursts in young stellar objects remain poorly understood, largely limited by a statistically small sample of closely followed-up events. This underscores the importance of a thorough exploration of each outbursting object. We studied a peculiar outbursting system, Gaia24ccy, which exhibited two $Δg \sim$ 3.8 mag outbursts in 2019 and 2024. The system consists of two unresolved, nearly identical, and rapidly rotating young stars: Gaia24ccy A (1.1419 days) and Gaia24ccy B (1.7898 days). Periodogram analyses just before the onset of the outbursts suggest Gaia24ccy B to be the outbursting component. Unlike any previously known EXor sources, the two outburst profiles show a very similar evolution: both rose at the same rate for the first 15 days, followed by many 'sub-bursts' on the timescale of 10-20 days. The 2019 outburst lasted 145-255 days, while the 2024 outburst persisted for 367 days. We infer the unstable region to lie at $r_{\rm trigger} \simeq 0.019-0.047$ au ($\sim5-12.3 R_\star$). The accreted mass per event $M_{\rm acc}\sim10^{-5} M_\odot$ can be provided by a compact inner-disk reservoir. The photometric rise/decay timescales and the mid-infrared color evolution favor a thermal-viscous trigger in a hot inner disk, while the appearance of rich emission-line spectra indicates concurrent magnetospheric compression - together best described by a hybrid picture. Finally, we explain the reddening of the mid-infrared color observed during the outburst as a consequence of the competing emission from the viscous disk and the photosphere.

2602.16789 2026-02-20 stat.ME math.ST stat.TH

First versus full or first versus last: U-statistic change-point tests under fixed and local alternatives

Herold Dehling, Daniel Vogel, Martin Wendler

Comments 56 pages: 22 pages main document, 34 pages appendices (containing proofs), one reference list at the end

详情
英文摘要

The use of U-statistics in the change-point context has received considerable attention in the literature. We compare two approaches of constructing CUSUM-type change-point tests, which we call the first-vs-full and first-vs-last approach. Both have been pursued by different authors. The question naturally arises if the two tests substantially differ and, if so, which of them is better in which data situation. In large samples, both tests are similar: they are asymptotically equivalent under the null hypothesis and under sequences of local alternatives. In small samples, there may be quite noticeable differences, which is in line with a different asymptotic behavior under fixed alternatives. We derive a simple criterion for deciding which test is more powerful. We examine the examples Gini's mean difference, the sample variance, and Kendall's tau in detail. Particularly, when testing for changes in scale by Gini's mean difference, we show that the first-vs-full approach has a higher power if and only if the scale changes from a smaller to a larger value -- regardless of the population distribution or the location of the change. The asymptotic derivations are under weak dependence. The results are illustrated by numerical simulations and data examples.

2602.16788 2026-02-20 quant-ph

Quantum Circuits as a Dynamical Resource to Learn Nonequilibrium Long-Range Order

Fabian Ballar Trigueros, Markus Heyl

Comments 6 pages, 4 figures

详情
英文摘要

Equilibrium statistical ensembles impose stringent constraints on phases of quantum matter. For example, the Mermin-Wagner theorem prohibits long-range order in low-dimensional systems beyond the ground state. Here, we show that quantum circuits can learn states of matter with long-range order that are inaccessible in equilibrium. We construct variational quantum circuits that generate symmetry-broken and symmetry-protected topological states with long-range order in one-dimensional systems at finite energy density, where equilibrium states are typically featureless. Importantly, the learned states can exhibit unconventional features with enhanced metrological properties such as a quantum Fisher information close to a GHZ state, but robust against local measurements. Our work establishes coherent quantum dynamics as a powerful resource for engineering nonequilibrium phases of matter, opening a path toward a broader dynamical scope of quantum order beyond the constraints of equilibrium ensembles.

2602.16785 2026-02-20 cond-mat.str-el

Magnetoelectric Raman Force on Shear Phonons in a Frustrated van der Waals Bilayer Magnet

Wolfram Brenig

Comments 13 pages, 9 figures

详情
英文摘要

We show that the concept of coherent phonon generation by second order response to incident electric laser fields, which is a hallmark of pump-probe spectroscopy on conventional solids, can be expanded to include frustrated quantum magnets. For that purpose, we analyze the Raman force on the shear phonons of a frustrated magnetoelectric bilayer spin system. The bilayer is a stacked triangular magnet, motivated by recently emerging type-II van der Waals multiferroic transition metal dihalides and comprises a spin system which allows for incommensurate spiral order. The magnon excitations are treated by linear spin wave theory. In the spiral state, a finite electric polarization is obtained from the spin-current interaction which induces a coupling of the magnons to the electric field. Scattering of the bilayer shear phonons from the magnons is derived from a magnetoelastic energy. In this scenario, a mixed three-point response function for the Raman force is evaluated. We find it to be strongly anisotropic and very sensitive to the magnon lifetime.

2602.16783 2026-02-20 cond-mat.supr-con cond-mat.str-el

3D Unconventional Superconductivity in Bulk LaO

Zhifan Wang, Jingkai Bi, Jiayuan Zhang, Wenmin Li, Yuxuan Liu, Dao-Xin Yao, Zheng Deng, Changqing Jin, Yifeng Han, Man-Rong Li

Comments 35 pages, 14 figures, and 3 tables

详情
英文摘要

Lanthanum-based compounds are cornerstones of superconductivity research, yet the La-5d orbitals typically remain empty spectator states far above the Fermi level (EF). While superconductivity has been induced in LaO up to 5.37 K in tensile epitaxy films, the intrinsic ground state of the bulk phase has remained controversial mostly due to synthetic challenges, with early reports suggesting a metallic nature. Here we report the high-pressure and high-temperature synthesis of pure bulk rock-salt LaO and unveil its intrinsic type-II superconductivity with a transition temperature (TC) of ~6 K at ambient pressure. The bulk TC is further enhanced to 6.9 K in La1-xYxO at x = 0.10, where Y doping leads to lattice contraction (chemical pressing) and a remarkable increase in electron carrier concentration. Strikingly, applying physical pressure further enhances the TC to a maximum of 12.7 K at 20 GPa, the highest TC in lanthanum monochalcogenides LaX (X = S, Se, Te, and O) to date. This pressure dependence is diametrically opposed to the behavior observed in films, and occurs despite a pressure-induced reduction in the density of states at EF - a trend that sharply contradicts the conventional phonon-mediated BCS mechanism. Our first-principles calculations reveal that compressive strain modifies the crystal field splitting to enhance La-5d/O-2p hybridization, fostering a three-dimensional multi-pocket Fermi surface favorable for spin/orbital fluctuation-mediated pairing. This work clarifies the intrinsic superconductivity of bulk LaO and provides a foundation for designing new rare-earth-based superconductors with higher TC

2602.16782 2026-02-20 hep-th cond-mat.stat-mech gr-qc

Spectral Spacetime Entropy for Quasifree Theories

Joshua Y. L. Jones, Yasaman K. Yazdi

Comments 49 pages, 3 figures

详情
英文摘要

Motivated by the necessity to UV-regularise entanglement entropy, we present a spectral method for calculating the entropy of quasifree states, for both bosonic and fermionic field theories. This construction is defined in spacetime rather than on a hypersurface, enabling the covariant regularisation of entropies, and its calculation in generic spacetime regions. We derive these formulae, which have previously appeared in the literature, in a new manner and highlight certain aspects of them, such as their connection to the density matrix and its eigenvalues. The spacetime nature of the formulation makes it particularly apt in the context of semiclassical and quantum gravity and in connection to black hole entropy. Another useful property of the formulation is its application to settings where no notion of a Cauchy surface exists, such as in the causal set theory approach to quantum gravity. We show example applications of the formulae which demonstrate their ability to reproduce known results. We also show a calculation in a causal set in $1+1$ dimensions which makes use of several of the unique and useful features of the formalism. In this last example, we obtain a novel result of a slightly modified entanglement entropy scaling coefficient, giving a possible signature of spacetime discreteness.

2602.16781 2026-02-20 astro-ph.GA

The CGM with local universe FRBs: evidence of strong AGN feedback in a massive elliptical galaxy

Samuel McCarty, Liam Connor, Ralf M. Konietzka

Comments 15 pages, 8 figures. Comments welcome

详情
英文摘要

Modern cosmology and galaxy formation rely on an understanding of how cosmic baryons are distributed, a significant portion of which exist in the diffuse gas confined to halos. Fast Radio Bursts (FRBs) are a promising probe of the Universe's ionized gas. At low redshift, the contribution to the dispersion measure (DM) from the intergalactic medium (IGM) and intervening halos is subdominant, allowing us to study the circumgalactic media (CGM) of the host galaxies. We select a sample of five local universe FRBs whose host interstellar medium (ISM) DM is negligible and use these to constrain the mass of the CGM in each halo. We find that one of our sources, the only massive elliptical host galaxy, has been evacuated of its baryons ($M_\mathrm{gas}=0.02^{+0.02}_{-0.02}M_\mathrm{h}$, corresponding to $\sim$10$\%$ of the cosmological average $\frac{Ω_b}{Ω_m}$). This galaxy shows evidence of a past episode of AGN activity, consistent with the picture of strong AGN feedback in galaxy group-scale halos. The other sources are consistent with existing multiwavelength data and tentatively support more baryon retention in $L_*$ galaxies compared to group-scale halos. We show that FRBs can measure the halo gas fraction $f_\mathrm{gas}$ in halos of mass $M_\mathrm{h}\sim10^{11-13}M_\odot$, and up to $\sim10^{14}M_\odot$ if galaxy cluster hosts are included, which is a larger range than other gas probes can access. Finally, we demonstrate that a large sample of local universe FRBs, such as those expected from upcoming all-sky radio telescopes, will enable precision measurements of halo gas, which is crucial for understanding the effects of feedback.

2602.16780 2026-02-20 quant-ph cond-mat.dis-nn cond-mat.mes-hall cond-mat.quant-gas hep-th

Controlling energy spectra and skin effect via boundary conditions in non-Hermitian lattices

S Rahul, Pasquale Marra

Comments 5 pages, 4 figures

详情
英文摘要

Non-Hermitian systems exhibit unique spectral properties, including the non-Hermitian skin effect and exceptional points, often influenced by boundary conditions. The modulation of these phenomena by generalized boundary conditions remains unexplored and not understood. Here, we analyze the Hatano-Nelson model with generalized boundary conditions induced by complex hopping amplitudes at the boundary. Using similarity transformations, we determine the conditions yielding real energy spectra and skin effect, and identify the emergence of exceptional points where spectra transition from real to complex. We demonstrate that tuning the boundary hopping amplitudes precisely controls the non-Hermitian skin effect, i.e., the localization of eigenmodes at the lattice edges. These findings reveal the sensitivity of spectral and localization properties to boundary conditions, providing a framework for engineering quantum lattice models with tailored spectral and localization features, with potential applications in quantum devices.

2602.16779 2026-02-20 astro-ph.SR astro-ph.EP

Bridging Solar and Stellar Physics: Role of SDO in Understanding Stellar Active Regions and Atmospheric Heating

Shin Toriumi

Comments 25 pages, 7 figures, 3 tables, accepted for publication in Solar Physics

详情
英文摘要

The solar-stellar connection provides a unique framework for understanding magnetic activity and atmospheric heating across a broad spectrum of stars. Solar Dynamics Observatory (SDO) of NASA, equipped with the Helioseismic and Magnetic Imager, Atmospheric Imaging Assembly, and Extreme ultraviolet Variability Experiment, has enabled detailed Sun-as-a-star studies that bridge solar and stellar physics. Integrating spatially resolved solar observations into disk-integrated datasets, these studies provide insights into magnetic activity occurring in distant stars. This review highlights key results from recent analyses that employed all three SDO instruments to characterize active regions, quantify universal heating relationships, and reconstruct stellar X-ray and ultraviolet spectra. We discuss how these findings advance our understanding of stellar magnetic activity, provide predictive tools for exoplanetary environments, and outline future directions for applying solar-based frameworks to diverse stellar populations.

2602.16778 2026-02-20 astro-ph.GA

ELVES-Field: Isolated Dwarf Galaxy Quenched Fractions Rise Below $M_* \approx 10^7$ $M_\odot$

Scott Carlsten, Jiaxuan Li, Jenny Greene, Alex Drlica-Wagner, Shany Danieli

Comments Accepted to ApJL. Comments welcome

详情
英文摘要

We use a new sample of low-mass ($M_* < 10^9$ $M_\odot$) isolated galaxies from the Exploration of Local VolumE Survey - Field (ELVES-Field) to examine the star formation properties and sizes of field dwarf galaxies in the Local Volume (LV; $D<10$ Mpc). This volume-limited sample was selected from nearly 3,000 square degrees of imaging, relying on surface brightness fluctuations to determine distances to the majority of the systems and is complete to $M_* \approx 10^6$ $M_\odot$. Across the surveyed area, we catalog over 2300 candidate LV dwarfs, of which we confirm 95 as genuine LV members and reject over 1600 as background contaminants, with the remaining 600 candidates still requiring a distance measurement. Of the confirmed LV dwarfs, 46 are either new discoveries or confirmed via a distance measurement for the first time here. We explore different environmental criteria to select isolated dwarfs but primarily focus on dwarfs that are $>2\times R_{\mathrm{vir}}$ in projection from any known group with $M_\star > 10^9$ $M_\odot$. We find that, at higher dwarf masses ($M_\star \gtrsim 10^7$ $M_\odot$), essentially all field dwarfs are star-forming as has been found before. In contrast, at $M_\star \lesssim 10^7$ $M_\odot$, $\sim30\%$ of field dwarfs appear to be quenched. Finally, we find that isolated dwarfs are noticeably smaller ($\sim 20\%$) than satellite dwarfs of the same stellar mass, regardless of quenched status.

2602.16775 2026-02-20 astro-ph.GA

Causal Reversal in the $M_\unicode{x25CF}\unicode{x2013}σ_0$ Relation: Implications for High-Redshift Supermassive Black Hole Mass Estimates

Benjamin L. Davis, Saakshi More, Zehao Jin, Mario Pasquato, Andrea Valerio Macciò, Feng Yuan

Comments Unedited manuscript (17 pages, 7 figures, and 2 tables) accepted by The Astrophysical Journal on February 17, 2026

详情
英文摘要

The nascent methodology of applying the principles of causal discovery to astrophysical data has produced affirming results about deeply held theories concerning the causal nature behind the observed coevolution of supermassive black holes (SMBHs) with their host galaxies. The key results from observations have demonstrated an apparent causal reversal across different galaxy morphologies$\unicode{x2014}$SMBHs causally influence the evolution of the physical parameters of their spiral galaxy hosts, whereas SMBHs in elliptical galaxies are passive companions that grow in near lockstep with their hosts. To further explore and ascertain insights, it is necessary to utilize galaxy simulations to track the time evolution of the observed causal relations to learn more about the temporal nature of the changing SMBH/galaxy evolutionary directions. We conducted experiments with the NIHAO suite of cosmological zoom-in hydrodynamical simulations to follow the evolution of individual galaxies along with their central SMBH masses ($M_\unicode{x25CF}$) and properties, including central stellar velocity dispersion ($σ_0$). We reproduce the causal results from real galaxies, but add clarity by observing that the SMBH/galaxy causal directions are noticeably inverted between the epochs before and after the peak of star formation. The implications for causal reversal of the $M_\unicode{x25CF}\unicode{x2013}σ_0$ relation portend larger concerns about the reliability of SMBH masses estimated at high redshifts and presumptions of overmassive black holes at early epochs. Toward this problem, we apply updated causally-informed scaling relations that predict high-$z$ black hole masses that are approximately two orders of magnitude less massive, and thus not overmassive with respect to local $z=0$ SMBH$\unicode{x2013}$galaxy mass ratios.

2602.16774 2026-02-20 cond-mat.str-el cond-mat.mes-hall cond-mat.quant-gas quant-ph

Singular three-point density correlations in two-dimensional Fermi liquids

Pok Man Tam, Charles L. Kane

Comments Main: 4 pages, 2 figures; Supp: 3 sections

详情
英文摘要

We characterize a singularity in the equal-time three-point density correlations that is generic to two-dimensional interacting Fermi liquids. In momentum space where the three-point correlation is determined by two wavevectors $\mathbf{q}_1$ and $\mathbf{q}_2$, the singularity takes the form $|\mathbf{q}_1\times\mathbf{q}_2|$. We explain how this singularity is sharply defined in a long-wavelength collinear limit. For a non-interacting Fermi gas, the coefficient of this singularity is given by the quantized Euler characteristic of the Fermi sea, and it implies a long-range real space correlation favoring collinear configurations. We show that this singularity persists in interacting Fermi liquids, and express the renormalization of the coefficient of singularity in terms of Landau parameters, for both spinless and spinful Fermi liquids. Implications for quantum gas experiments are discussed.

2602.16772 2026-02-20 quant-ph cond-mat.quant-gas cond-mat.stat-mech cond-mat.str-el

Finite-Temperature Dynamical Phase Diagram of the $2+1$D Quantum Ising Model

Lucas Katschke, Roland C. Farrell, Umberto Borla, Lode Pollet, Jad C. Halimeh

Comments $11+2$ pages, $4+3$ figures

详情
英文摘要

Mapping finite-temperature dynamical phase diagrams of quantum many-body models is a necessary step towards establishing a framework of far-from-equilibrium quantum many-body universality. However, this is quite difficult due, in part, to the severe challenges in representing the volume-law entanglement that is generated under nonequilibrium dynamics at finite temperatures. Here, we address these challenges with an efficient equilibrium quantum Monte Carlo (QMC) framework for computing the finite-temperature dynamical phase diagram. Our method uses energy conservation and the self-thermalizing properties of ergodic quantum systems to determine observables at late times after a quantum quench. We use this technique to chart the dynamical phase diagram of the $2+1$D quantum Ising model generated by quenches of the transverse field in initial thermal states. Our approach allows us to track the evolution of dynamical phases as a function of both the initial temperature and transverse field. Surprisingly, we identify quenches in the ordered phase that cool the system as well as an interval of initial temperatures where it is possible to quench from the paramagnetic (PM) to ferromagnetic (FM) phases. Our method gives access to dynamical properties without explicitly simulating unitary time evolution, and is immediately applicable to other lattice geometries and interacting many-body systems. Finally, we propose a quantum simulation experiment on state-of-the-art digital quantum hardware to directly probe the predicted dynamical phases and their real-time formation.

2602.16771 2026-02-20 hep-ph

On the Run from the Dark Side of the Muon

Pouya Asadi, Austin Batz, Samuel Homiller, Tien-Tien Yu

Comments 8 pages, 5 figures

详情
英文摘要

We present an analysis strategy for probing physics beyond the Standard Model via modifications to the parton distribution functions (PDFs) in a muon beam, which measurably alter the kinematics of all hard processes at a future muon collider. High-energy muon colliders represent an opportunity to probe new physics using precision measurements and novel search strategies. At sufficiently high energies, light particles act as ``constituents'' of the muon described by PDFs. As a concrete case study, we apply this framework to an $L_μ - L_τ$ gauge boson and demonstrate that, for masses in the range of approximately 50--100 GeV, this indirect PDF-based approach outperforms traditional searches relying on direct gauge boson production. These results highlight muon PDF probes as a powerful and promising avenue for beyond the Standard Model physics searches at a future muon collider.

2602.16770 2026-02-20 hep-th cond-mat.str-el math-ph math.MP math.QA quant-ph

From Multipartite Entanglement to TQFT

Michele Del Zotto, Abhijit Gadde, Pavel Putrov

Comments 43 pages, 17 figures

详情
英文摘要

At long distances, a gapped phase of matter is described by a topological quantum field theory (TQFT). We conjecture a tight and concrete relationship between the genuine $(d+1)$-partite entanglement -- labelled by a $d$-dimensional manifold $M$ -- in the ground state of a $(d-1)+1$-dimensional gapped theory and the partition function of the low energy TQFT on $M$. In particular, the conjecture implies that for $d=3$, the ground state wavefunction can determine the modular tensor category description of the low energy TQFT. We verify our conjecture for general (2+1)-dimensional Levin-Wen string-net models.

2602.16769 2026-02-20 astro-ph.EP

On Eccentric Protoplanetary Disks I -- How Eccentric are Planet-Perturbed Disks?

Cory Padgett, Jeffrey Fung

Comments Accepted for publication in The Astrophysical Journal

详情
英文摘要

Protoplanetary disks can become eccentric when planets open deep gaps within, but how eccentric are they? We answer this question by analyzing two-dimensional hydrodynamical simulations of planet-disk interaction. The steady state eccentricity of the outer disk (outside of the planet's orbit) is described as a balance between eccentricity excitation by the 1:3 eccentric Lindblad resonance and eccentricity damping by gas pressure. This eccentricity scales with $q(\frac{h_p}{r_p})^{(-1)}(\frac{r_{gap}}{r_p})^{(a-\frac{b}{2}-2)}$, where $q$ is the planet-to-star mass ratio, $\frac{h_p}{r_p}$ is the disk aspect ratio, $\frac{r_{gap}}{r_p}$ is the radial position of the outer gap edge divided by the planet's position, and $a$ and $b$ are the negative exponents in the disk's surface density and temperature power law profiles, respectively. We derive a semi-analytic eccentricity profile that agrees with numerical simulations to within 30%. Our result is a first step to quantitatively interpret observations of eccentric protoplanetary disks, such as MWC 758, HD 142527, IRS 48, and CI Tau.

2602.16768 2026-02-20 astro-ph.CO

C3NN-SBI: Learning Hierarchies of $N$-Point Statistics from Cosmological Fields with Physics-Informed Neural Networks

Kai Lehman, Zhengyangguang Gong, David Gebauer, Stella Seitz, Jochen Weller

Comments 17 pages, 6 figures

详情
英文摘要

Cosmological analyses are moving past the well understood 2-point statistics to extract more information from cosmological fields. A natural step in extending inference pipelines to other summary statistics is to include higher order N-point correlation functions (NPCFs), which are computationally expensive and difficult to model. At the same time it is unclear how many NPCFs one would have to include to reasonably exhaust the cosmological information in the observable fields. An efficient alternative is given by learned and optimized summary statistics, largely driven by overparametrization through neural networks. This, however, largely abandons our physical intuition on the NPCF formalism and information extraction becomes opaque to the practitioner. We design a simulation-based inference pipeline, that not only benefits from the efficiency of machine learned summaries through optimization, but also holds on to the NPCF program. We employ the heavily constrained Cosmological Correlator Convolutional Neural Network (C3NN) which extracts summary statistics that can be directly linked to a given order NPCF. We present an application of our framework to simulated lensing convergence maps and study the information content of our learned summary at various orders in NPCFs for this idealized example. We view our approach as an exciting new avenue for physics-informed simulation-based inference.