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2602.06962 2026-02-09 hep-ph hep-th

Hard thermal contributions to phase transition observables at NNLO

Fabio Bernardo, Mikael Chala, Luis Gil, Philipp Schicho

Comments 42 pages, 5 figures, 1 table

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To construct the high-temperature effective field theory of gauge-Higgs models up to $\mathcal{O}(g^6)$ in the gauge coupling, we integrate out hard modes to three-loop level and use the next-to-next-to-leading order effective potential. For the Abelian Higgs model, we quantify the impact of both higher-dimensional operators and higher-loop corrections on thermodynamic parameters relevant for gravitational-wave observables, finding that one-loop dimension-six effects typically dominate over two- and three-loop corrections to super-renormalizable parameters for the strongest transitions. We derive the three-loop scalar and Debye masses for the ${\rm U(1)}$ and ${\rm SU}(N)$ gauge-Higgs models, as well as the two-loop quartic couplings for the Abelian case, show gauge independence of physical parameters, and demonstrate that no new master integrals are required for the matching, while consistency of 4d and 3d renormalizability points to previously missing contributions in these master integrals.

2602.06961 2026-02-09 gr-qc

The N-Body 2PN Hamiltonian and Numerical Integration of the Equations of Motion

Felix M. Heinze, Gerhard Schäfer, Bernd Brügmann

Comments 15 pages, 5 figures

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To date, the second-order post-Newtonian (2PN) Hamiltonian has been known in closed analytic form only for systems of up to three point masses. In this paper, we present an analytic expression for the general $N$-body 2PN Hamiltonian in the ADM gauge up to a single integral term that, to our knowledge, has no known closed-form analytic solution. We show that the integrals appearing in the 2PN Hamiltonian can be evaluated numerically to machine precision, allowing for cross-validation against analytical results and enabling the full numerical computation of the $N$-body 2PN Hamiltonian. Furthermore, we demonstrate the practical feasibility of the numerical integration of the equations of motion for $N$ bodies at 2PN order using different methods and discuss several strategies for improving computational efficiency.

2602.06957 2026-02-09 hep-ph

Revisiting the Electroweakino Sector of the Baryon Number Violating MSSM at the HL-LHC with Deep Neural Networks

Rahool Kumar Barman, Arghya Choudhury, Subhadeep Sarkar

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We study the projected sensitivity of direct electroweakino production $pp \to \tildeχ_1^{\pm} \tildeχ_2^0$ at the HL-LHC in a simplified framework with wino-like, mass degenerate $\tildeχ_1^{\pm}$ and $\tildeχ_2^0$, and a bino-like lightest neutralino $\tildeχ_1^0$, assuming R-parity violating~(RPV) through the baryon number violating $λ^{\prime \prime}_{112}u^c d^c d^c$ and $λ^{\prime \prime}_{113}u^c d^c b^c$ operators. We consider three channels with the $λ^{\prime \prime}_{112}u^c d^c d^c$ RPV operator: $Wh$ mediated $1\,\ell + 2\,b + \rm E{\!\!\!/}_T$, $Wh$ mediated $1\,\ell + (\geq 2\,j) + 2\, γ+ \rm E{\!\!\!/}_T$, and $WZ$ mediated $3\ell + (\geq 2 j) + \rm E{\!\!\!/}_T$. In each channel, we train benchmark-specific multi-layer perceptrons (MLPs), analogous to signal-region classifiers, on the four-momenta of the final state particles along with a small set of higher-level observables to distinguish the signal from the dominant SM backgrounds. We find that the HL-LHC will be able to probe winos up to $\sim 900~$GeV, $\sim 780~$GeV, and $\sim 880~$GeV in the $Wh$ mediated $1\,\ell + 2\,b + \rm E{\!\!\!/}_T$, $Wh$ mediated $1\,\ell + (\geq 2\,j) + 2\, γ+ \rm E{\!\!\!/}_T$, and $WZ$ mediated $3\ell + (\geq 2 j) + \rm E{\!\!\!/}_T$ channels, respectively, for $m_{\tildeχ_1^0} \sim 50~$GeV, in the presence of $λ^{\prime \prime}_{112}u^c d^c d^c$ couplings, at $2σ$ sensitivity. In case the $λ^{\prime \prime}_{113}u^c d^c b^c$ operator is solely switched on, the projected sensitivity for winos reach up to $\sim 700~$GeV for $Wh$ mediated $1\,\ell + (\geq 1\,b)\, + (\geq 1j)\, + 2\, γ+ \rm E{\!\!\!/}_T$ and $\sim 850~$GeV for the $WZ$ mediated $3\ell + (\geq 1 b) + \rm E{\!\!\!/}_T$ channel.

2602.06952 2026-02-09 astro-ph.HE

Mapping plasma properties of Cassiopeia A with XRISM/Resolve: a Bayesian analysis via UltraSPEX

Manan Agarwal, Jacco Vink, Liyi Gu, Paul P. Plucinsky, Aya Bamba, Toshiki Sato, Daniele Rogantini, Yuken Ohshiro

Comments Submitted version (33 pages, 21 figures). Accepted for publication in ApJ

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Mapping the physical conditions of the shocked plasma of young supernova remnants (SNR) is crucial for understanding their explosion mechanisms, ejecta structure, and large-scale asymmetries. Using $>350$ ks of XRISM/Resolve high spectral resolution observations of Cassiopeia A (Cas A), the youngest known Galactic core-collapse SNR, we present the first microcalorimeter-based plasma parameter maps of any SNR. We tessellate Cas A into $1'\times1'$ regions and fit the broadband spectra as thermal emission from two pure-metal ejecta components -- corresponding to intermediate-mass elements (IMEs) and iron-group elements (IGEs) -- plus nonthermal synchrotron radiation. For robust inference, we introduce UltraSPEX, a Bayesian framework that couples the SPEX plasma code with the UltraNest nested-sampling algorithm, yielding full posterior distributions and exploration of parameter degeneracies. Key findings include enhanced Ar/Si and Ca/Si abundance ratios near the base of the Si-rich jets, and a high Ni/Fe mass ratio ($0.08\pm0.015$) in the base of NE jet. IGEs ejecta exhibit systematically higher Doppler velocities and broadenings than IMEs ejecta in most regions, with maximum differences of $\sim800$ km/s and $\sim1200$ km/s, respectively; Ca shows distinct (faster) kinematics from other IMEs in several SE regions. The ionization timescale and electron temperature show a robust anti-correlation, particularly for IGEs. This relation and measured parameter values could be explained by semi-analytical models with significant ejecta clumping (overdensities of $\sim10$ for IGEs and up to $\sim100$ for IMEs) and reduced historical reverse-shock velocities. Nonthermal emission accounts for a substantial fraction, with at least 47% of the 4--6 keV continuum and dominates in the western regions, where the spectrum hardens.

2602.06951 2026-02-09 hep-th astro-ph.HE gr-qc hep-ph

Gravitational Raman Scattering: a Systematic Toolkit for Tidal Effects in General Relativity

Mikhail M. Ivanov, Yue-Zhou Li, Julio Parra-Martinez, Zihan Zhou

Comments 52 pages, 1 figure

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We present a framework for systematic computations of scattering amplitudes for gravitational Raman scattering, -- the inelastic scattering of massless fields off compact relativistic objects. We focus on the small-frequency (post-Minkowskian, PM) regime relevant for the study of tidal effects, which can be mapped onto gravitational wave observables during the inspiraling phase of a merger. We demonstrate that this setup is ideal for systematic studies of tidal effects, in a way that is free from coordinate, gauge, and field redefinition ambiguities. We use a combination of worldline effective field theory, the background field method, and advanced scattering amplitude techniques to derive phase shifts for scattering of spin-$0,1,2$ fields off generic compact objects at third PM order. We demonstrate that the inclusion of the recoil of the object is crucial for consistency of this calculation. Focusing on a particular case of black holes, we extract the leading static and dynamical Love numbers of the spin-0 field and the static Love number of the spin-1 field in four dimensions by matching our EFT amplitudes and calculations in General Relativity. We show, fully on-shell, that the leading static Love numbers vanish identically, while the dynamical Love numbers are not zero and run logarithmically. The latter resolves the ambiguities of previous off-shell matching calculations. We also extend our results to seven dimensions, where spin-2 Love numbers undergo a renormalization group running at 2PM, which we compute explicitly. In addition, we extract the leading static Love numbers of spin-0 and spin-1 fields in five dimensions, which also run.

2602.06933 2026-02-09 math.AP math-ph math.MP

A global stability result for incompressible magnetohydrodynamics

Livio Pizzocchero, Emanuele Tassi

Comments AUTHOR'S NOTE. Textual overlaps with previous works or ours, namely: Ref. [32], arXiv:1905.13722, arXiv:1511.00533, arXiv:1405.3421, arXiv:1402.0487, arXiv:1310.5642, arXiv:1304.2972, arXiv:1203.6865, arXiv:1104.3832, arXiv:1009.2051, arXiv:1007.4412, arXiv:0909.3707, arXiv:0709.1670. None of these previous works contains the main result of the present manuscript

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We propose a result of global stability for the equations of homogeneous, incompressible magnetohydrodynamics (MHD) on a torus of any dimension $d \in \{2,3,...\}$, with positive viscosity and resistivity. This result applies to the $C^\infty$ global solutions, with a conveniently defined decay property for large times; it is expressed by fully explicit estimates, formulated via $H^p$-type Sobolev norms of arbitrarily high order $p$. The present stability result is similar to that proposed by one of us for the Navier-Stokes (NS) equation \cite{glosta}; it is derived from a suitable formulation of the MHD equations proposed in our previous work \cite{MHD}, emphasizing strong structural analogies with the NS case. A basic tool in the proof of the present stability result is a general theory of approximate solutions of the MHD Cauchy problem, that we developed in \cite{MHD} on the grounds of previous results on the NS equation \cite{smooth} and of the above structural similarities. We also introduce a class of Beltrami-type initial data for the MHD equations; although being arbitrarily large, these data produce global and decaying MHD solutions, fitting the framework of the present stability result. Comparisons with the previous literature on these subjects are performed.

2602.06929 2026-02-09 physics.atom-ph hep-ph nucl-th

Proton-Size Resolution of the Hyperfine Puzzle in Hydrogen

Gerald A. Miller

Comments 3 pages, 2 figures

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Baym and Farrar (arXiv:2601.02300v1) have recently pointed out a puzzle in understanding the role of the hyperfine interaction in the ground state of a hydrogen atom. If one uses a variational wave function in which the Bohr radius, $a_0$ is replaced by a variational radius parameter, $R$, first-order perturbation theory can give a contribution to the energy proportional to $-1/R^3$. This raises the question of why the hyperfine interaction does not lead to collapse of hydrogen. I show that including the effects of the non-zero size of the proton leads to a resolution of the puzzle such that the variational procedure yields a value of $R$ that is indistinguishable from $a_0$.

2602.06923 2026-02-09 cs.LG cs.AI physics.class-ph

From Kepler to Newton: Inductive Biases Guide Learned World Models in Transformers

Ziming Liu, Sophia Sanborn, Surya Ganguli, Andreas Tolias

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Can general-purpose AI architectures go beyond prediction to discover the physical laws governing the universe? True intelligence relies on "world models" -- causal abstractions that allow an agent to not only predict future states but understand the underlying governing dynamics. While previous "AI Physicist" approaches have successfully recovered such laws, they typically rely on strong, domain-specific priors that effectively "bake in" the physics. Conversely, Vafa et al. recently showed that generic Transformers fail to acquire these world models, achieving high predictive accuracy without capturing the underlying physical laws. We bridge this gap by systematically introducing three minimal inductive biases. We show that ensuring spatial smoothness (by formulating prediction as continuous regression) and stability (by training with noisy contexts to mitigate error accumulation) enables generic Transformers to surpass prior failures and learn a coherent Keplerian world model, successfully fitting ellipses to planetary trajectories. However, true physical insight requires a third bias: temporal locality. By restricting the attention window to the immediate past -- imposing the simple assumption that future states depend only on the local state rather than a complex history -- we force the model to abandon curve-fitting and discover Newtonian force representations. Our results demonstrate that simple architectural choices determine whether an AI becomes a curve-fitter or a physicist, marking a critical step toward automated scientific discovery.

2602.06922 2026-02-09 hep-ph astro-ph.CO hep-ex

Parametric-Resonance Production of QCD Axions

Pirzada, Yu Gao, Qiaoli Yang

Comments 5+2 pages ,3 figures

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We demonstrate that dark matter axion production is enhanced through a natural and unavoidable mechanism: primordial temperature fluctuations periodically modulate the axion mass during the QCD phase transition, thereby triggering parametric resonance in axion field evolution. This interplay between parametric resonance and the misalignment mechanism shifts the predicted axion mass window for the observed dark matter abundance to $10^{-4}-10^{-3} \, \text{eV}$, displacing the canonical axion mass window to previously unexplored higher ranges.

2602.06919 2026-02-09 astro-ph.HE astro-ph.GA

Optical spectral characterization of OP 313. Constraining the contribution of thermal and non-thermal optical emission

J. Otero-Santos, M. Nievas Rosillo, J. A. Acosta-Pulido, R. Clavero

Comments Accepted for publication in A&A. 10 pages (+5 pages of Appendix), 13 figures

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The quasar OP 313 was discovered in December 2023 in very-high-energy $γ$ rays above 100 GeV, enabling for the first time a complete characterization of its emission. However, the lack of updated measurements of its accretion disk, broad line region and dusty torus hampers a detailed interpretation of the role of accretion in the observed $γ$-ray production. We intend to characterize, during high-activity states, the external photon fields contributing to the IR-to-UV emission$-$namely dusty torus, broad line region and accretion disk$-$and investigate potential variability and blurring effects on the broad emission lines. We present new spectroscopic observations of OP 313 with the NOT and TNG telescopes to characterize its optical spectrum and variability with respect to archival observations from SDSS. We measure the luminosity of different broad emission lines, characterizing the broad line region, accretion disk and dusty torus. We measure the Mg II emission line, with an average flux of $F_{\mathrm{Mg \ II}} = (0.85 \pm 0.11)\times 10^{-14}$ erg cm$^{-2}$ s$^{-1}$. Its equivalent width and luminosity are consistent with a constant line with a variable non-thermal continuum. From the stable Mg II line we derive a constant luminosity of the thermal components, $\log(L_{\mathrm{BLR}} \ \mathrm{[erg \ s^{-1}]}) = 44.91 \pm 0.19$, $\log(L_{\mathrm{disk}} \ \mathrm{[erg \ s^{-1}]}) = 45.91 \pm 0.19$ and $\log(L_{\mathrm{torus}} \ \mathrm{[erg \ s^{-1}]}) = 44.70 \pm 0.16$, and estimated a BH mass of $\log(M_{BH}/M_{\odot})=8.36 \pm 0.18$, in line with with that derived from the C III] line. These characteristics and the indicator of the accretion rate from the disk/Eddington luminosity ratio $λ=L_{AD}/L_{Edd} = 0.23 \pm 0.10$, along with a high Compton dominance, favour a FSRQ-like nature, contrary to the argued changing-look nature.

2602.06908 2026-02-09 hep-ph

QED Effects in PDFs -- A Les Houches Comparison Study

Thomas Cridge, Juan Cruz Martinez, Joey Huston

Comments 12 pages, 7 figures, 5 tables. This work was initiated at the Les Houches 2025 ("Physics at TeV colliders and Beyond the Standard Model'') Standard Model Session

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In the last decade, and even more so in the last few years, our knowledge of the internal structure of the proton has become more accurate and precise thanks to the large amount of data available and developments in theory and methodology. The reduction of the uncertainties associated to these developments has brought previously neglected effects into focus as their typical magnitude are competitive with the size of the uncertainties. One such effect is the inclusion of QED into PDF fits. Typically this is a percent effect, and thus while theoretically important, it has had a relatively limited impact on phenomenological studies up to this point. In this proceeding we study some of the effects which, while peripheral to the inclusion of QED in the proton, can considerably change the relative size and shape of the QCD+QED fit with respect to the QCD only determination. These may become important in the future as precision continues to increase. After a comparison of the QCD+QED PDFs with the QCD only PDFs of various global PDF fitting groups, we focus largely upon NNPDF4.0, which shows the biggest effect when including QED. Focusing largely on a single set of PDFs also enables more subtle effects to be analysed, making it an ideal candidate for this study.

2602.06904 2026-02-09 astro-ph.CO

Non-spherical BUFFALOs: a weak lensing view of the Frontier Field clusters and associated systematics

A. Niemiec, A. Acebron, B. Beauchesne, M. Jauzac, J. M. Diego, D. Eckert, D. Harvey, A. M. Koekemoer, D. J. Lagattuta, M. Limousin, G. Mahler, N. Patel, S. Tam, J. F. V. Allingham, R. Cen, A. Faisst, D. Perera, M. Sereno

Comments 19 pages, 12 figures, 5 tables

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Galaxy clusters are tracers of the large scale structures of the Universe, making the time evolution of their mass function dependent on key cosmological parameters, such as the cosmic matter density or the amplitude of density fluctuations $σ_8$. Accurate measurements of cluster's total masses are therefore essential, yet they can be challenging, particularly for clusters with complex morphologies, as simple mass profiles are often adopted to fit the measurements. In this work, we focus on the Frontier Fields galaxy clusters: a sample of six extremely massive systems, that, in most cases, exhibit highly complex mass distributions. The BUFFALO survey extended the Hubble Space Telescope observations for the Frontier Fields galaxy clusters, providing high-resolution multi-band imaging within a few Mpc. Combining this high-quality imaging dataset with ancillary spectroscopy, we produce weak-lensing catalogues with very high source densities, about 50 sources/arcmin$^2$. This allows us to robustly estimate the individual weak-lensing cluster masses and quantify the sensitivity of these measurements on different factors, such as the cluster centring, the uncertainty on the redshift distribution or the foreground contamination and boost factor correction. This provides a data-driven analysis of the different sources of systematics that can impact such measurements. We find that the largest sources of systematic bias arise for the most disturbed clusters, such as the multi-modal, merging galaxy cluster Abell 2744. This analysis sets a comprehensive framework for assessing the impact of systematics on the weak-lensing estimates of cluster masses, and in particular, in the case of unrelaxed clusters. This can play a key role in forthcoming cosmological analyses based on wide-field surveys such as Euclid and the Legacy Survey of Space and Time of the Rubin Observatory.

2602.06901 2026-02-09 hep-th

Anomaly Induced Current in Boundary Lifshitz Field Theory

Chong-Sun Chu, Himanshu Parihar

Comments 19 pages, no figures

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We study quantum transport phenomena induced by anisotropic Lifshitz scale anomaly in a boundary Lifshitz field theory (BLFT) coupled to an external electromagnetic background. In this context, we obtain the anisotropic scale anomaly in Lifshitz field theories coupled to a background $U(1)$ gauge field and subsequently compute the anomaly induced near boundary current in a BLFT. Focusing on 5D BLFTs, we find that the temporal and spatial components of the induced current exhibit distinct power law dependencies on the distance from the boundary, reflecting the intrinsic time-space anisotropy of the theory. We further derive this anomalous current holographically from the bulk dual of BLFT and find that the temporal component is independent of the boundary conditions while the spatial component depends explicitly on them. The distance dependence is in exact agreement with the dual field theory result.

2602.06896 2026-02-09 physics.optics physics.app-ph

Dissipative Kerr Soliton Self-Balancing from Kerr-Induced Synchronization

Pradyoth Shandilya, Kartik Srinivasan, Curtis R. Menyuk, Grégory Moille

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Integrated frequency comb sources are a key enabling technology for frequency metrology applications. Their on-chip integration promises to bring metrology capacity outside of the lab, particularly since they can operate at low continuous-wave pump laser power in the dissipative Kerr soliton (DKS) regime. Yet, such small foot-print and low power comes at a cost: higher noise and overall lower comb power. In particular, this translates to highly challenging detection and locking of the carrier-envelope offset, necessary for complete stabilization of the comb. Recently, Kerr-induced synchronization (KIS) of a DKS to a reference laser has been demonstrated as a tool for passive all-optical stabilization of DKS microcombs, with fundamental modification to the DKS and microcomb properties. Here, we demonstrate that the combination of additional power from the reference laser (now part of the DKS) and the KIS phase locking that pins the repetition rate together fundamentally alter the DKS, forcing an energy redistribution to maintain its center of mass. We demonstrate this self-balancing effect theoretically, which in a pure quadratic dispersion resonator leads to reference-dependent recoil. With higher-order dispersion through which the DKS yields phase-matched dispersive waves (DWs), we demonstrate that self-balancing increases the DW radiation, experimentally showing a 22 dB increase of comb teeth at 780 nm in an octave-spanning microcomb for efficient deployable carrier-envelope offset detection.

2602.06892 2026-02-09 hep-ph hep-ex hep-lat

Study of $B \to K_0^*(1430)\,\ell^+ \ell^-$ Decay in the Standard Model and Scalar Leptoquark Scenario

M. Dadashzadeh, K. Azizi

Comments 15 Pages, 2 Figures and 3 Tables

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This study examines the rare decay $B \to K_0^*(1430)\,\ell^+ \ell^-$ as a possible probe for new physics beyond the standard model (SM). We first analyze this channel within the SM and then include scalar leptoquark (LQ) contributions. We provide predictions for key observables, like differential decay rate, branching ratio, ratio of branching fractions at different channels, forward-backward asymmetry and different lepton polarizations, and assess their sensitivity to leptoquark scenarios, highlighting $q^2$ regions less affected by the long-distance charmonium effects. The results can be useful for future Belle II and LHCb measurements.

2602.06890 2026-02-09 astro-ph.EP astro-ph.IM

Astrometric follow-up of near-Earth asteroid 2024 YR4 during a Torino scale level 3 alert

Marco Micheli, Maxime Devogèle, Larry Denneau, Eileen V. Ryan, William H. Ryan, Petr Pravec, Kamil Hornoch, Hana Kučáková, Petr Fatka, Melissa J. Brucker, Cassandra Lejoly, Nicholas Moskovitz, Mikael Granvik, Zuri Gray, Grigori Fedorets, Anlaug Amanda Djupvik, Carson Fuls, David Rankin, Kacper Wierzchoś, Bill Gray, Tim Lister, Richard J. Wainscoat, Robert Weryk, Olivier R. Hainaut, Federica Spoto, Peter Veres, Andrew S. Rivkin, Bryan J. Holler, Artem Y. Burdanov, Julien de Wit, Davide Farnocchia, Regina Rudawska, Eduardo Alonso Peleato, Francisco Ocaña, John Tonry, Jeroen Audenaert, Laura Faggioli, Francesco Gianotto, Marco Fenucci, Luca Conversi, Richard Moissl

Journal ref J Astronaut Sci 73, 8 (2026)

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The discovery of 2024 YR4 presented the planetary defense community with the most significant impact threat in almost two decades, reaching level 3 on the Torino scale. The community, now mature and well-organized, responded with a global observational effort. Astrometric measurements, forming the basis for orbital refinement and impact prediction, were a central component of this response. In this paper, we present the astrometric data collected by the international community, from the time of discovery until the object became too faint for all existing observational assets, including JWST. We also discuss the coordination role played by the International Asteroid Warning Network, and the importance of publicly available image archives to enable precovery searches.

2602.06881 2026-02-09 nlin.CD

Using correlation diagrams to study the vibrational spectrum of highly nonlinear floppy molecules: The K-CN case

H. Párraga, F. J. Arranz, R. M. Benito, F. Borondo

Journal ref Physical Review E 101, 062215 (2020)

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The correlation diagrams of vibrational energy levels considering the Planck constant as a variable parameter have proven as a very useful tool to study vibrational molecular states, and more specifically in relation to the quantum manifestations of chaos in such dynamical systems. In this paper, we consider the highly nonlinear K-CN molecule, showing how the regular classical structures, i.e., Kolmogorov-Arnold-Moser tori, existing in the mixed classical phase space appear in the quantum levels correlation diagram as emerging diabatic states, something that remains hidden when only the actual value of the Planck constant is considered. Additionally, a quantum transition from order to chaos is unveiled with the aid of these correlation diagrams, where it appears as a frontier of scarred functions.

2602.06878 2026-02-09 astro-ph.IM

Antenna for the detection of electromagnetic audio-band disturbances on-board LISA

D. Serrano, A. Pérez-Ortega, D. Roma-Dollase, J. Salvans-Tort, J. Ho-Zhang, J. Ramos-Castro, M. Nofrarias

Comments 27 pages, 10 figures, 1 table

Journal ref Class. Quantum Grav. 42 (2025) 245006

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The LISA mission will be the first observatory to detect gravitational waves from space within the millihertz frequency band. Magnetic forces have an important impact on the instrument's sensitivity below the millihertz. Hence, monitoring the magnetic environment within each of the LISA spacecrafts is of utmost importance. In this Letter we present the characterization of the coils that were used in LISA Pathfinder (LPF) when operating as magnetic sensors in the audio frequency band. The necessity of implementing this type of magnetometer is presented in order to monitor high frequency magnetic signals from the electronics on-board. We show that the LPF coils have a performance one order of magnitude better than the current requirements set by the LISA mission at the low end of the audio-band frequency. The LPF coils are able to measure a magnetic noise level of 1.45 $\rm pT/\sqrt{\rm{Hz}}$ at 50 Hz and 0.17 $\rm pT/\sqrt{\rm{Hz}}$ at 500 Hz. Additionally, the LPF coils can reach a magnetic noise floor of 0.1 $\rm pT/\sqrt{\rm{Hz}}$ at frequencies above 1 kHz.

2602.06876 2026-02-09 math.PR math-ph math.MP

Bulk heights of the KPZ line ensemble

Duncan Dauvergne, Fardin Syed

Comments 28 pages

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For $t > 0$, let $\{\mathcal{H}^{(t)}_n, n \in \mathbb{N}\}$ be the KPZ line ensemble with parameter $t$, satisfying the homogeneous $\mathbf{H}$-Brownian Gibbs property with $\mathbf{H}(x) =e^x$. We prove quantitative concentration estimates for the $n$th line $\mathcal{H}^{(t)}_n$ which yield the asymptotics $\mathcal{H}^{(t)}_n = n \log n + o(n^{3/4 + ε})$ as $n \to \infty$. A key step in the proof is a general integration by parts formula for $\mathbf{H}$-Brownian Gibbs line ensembles which yields the identity $\mathbb{E} \exp(\mathcal{H}^{(t)}_{n + 1}(x) - \mathcal{H}^{(t)}_n (x)) = n t^{-1}$ for any $n, t, x$.

2602.06861 2026-02-09 hep-ph

Direct Detection and Cosmological Constraints of Dark Matter with Dark Dipoles

Takumi Kuwahara, Jun-Chen Wang, Shu-Run Yuan

Comments 30 pages, 5 figures

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We study a fermionic dark matter candidate that couples to the standard model particles exclusively through electric and magnetic dipole operators mediated by a massive dark photon. Such dipole portals naturally arise in dark sectors where the dark matter is neutral under a hidden $U(1)_D$, and they lead to phenomenology distinct from conventional vector-current interactions. We consider the direct-detection signals arising from dark matter-nucleus scattering including the Migdal effect, dark matter-electron scattering, and semiconductor targets, which allow sensitivity to sub-GeV dark matter masses, together with the cosmological bounds from such as thermal relic abundance, cosmic microwave background, big-bang nucleosynthesis, and cosmic-rays. We find that the dark dipole coupling can be largely constrained by direct detection (in particular, electric dipole coupling). However, the cosmological observations have already constrained most of the parameter space, in particular for magnetic dipole interactions of $U(1)_D$ for sub-GeV dark matter. For the dark matter mass below 10 MeV, the semiconductor (in particular, using skipper-CCD) experiments can play a crucial role in probing the dark dipole interactions: future low-threshold experiments utilizing the semiconductor targets can further extend the constraints. Our results have demonstrated that the sub-GeV dark matter with dark dipole interactions can be still safe from the direct-detection constraints, and the future low-threshold semiconductor experiments may play a significant role in constraining the dark dipole interactions.

2602.06856 2026-02-09 hep-th

Holomorphic D-brane embeddings in D-brane backgrounds

James Ratcliffe, Ronnie Rodgers, Sangsoo Ryu

Comments 42 pages + appendices, 1 figure

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We describe families of probe D$q$-brane embeddings in the extremal black D$p$-brane backgrounds of type IIA and type IIB supergravity, specified by an arbitrary holomorphic function of a complex coordinate on the worldvolume of the D$q$-branes. These embeddings preserve one-quarter of the supersymmetry of the D$p$-brane background, or sometimes one-half of the supersymmetry when $p = q$. We discuss the holography of two example families of holomorphic probe branes in the near-horizon limit of the D3-brane background. The first is probe D5-branes, dual to defect hypermultiplets with a holomorphic mass, which in the infrared flow to Wilson lines located at the zeros of the mass. The second is probe D3-branes, holographically dual to states in the presence of Gukov--Witten surface defects in the dual $\mathcal{N}=4$ supersymmetric Yang--Mills theory.

2602.06852 2026-02-09 quant-ph cs.AI

The Quantum Sieve Tracer: A Hybrid Framework for Layer-Wise Activation Tracing in Large Language Models

Jonathan Pan

Comments 4 pages, 4 figures

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Mechanistic interpretability aims to reverse-engineer the internal computations of Large Language Models (LLMs), yet separating sparse semantic signals from high-dimensional polysemantic noise remains a significant challenge. This paper introduces the Quantum Sieve Tracer, a hybrid quantum-classical framework designed to characterize factual recall circuits. We implement a modular pipeline that first localizes critical layers using classical causal tracing, then maps specific attention head activations into an exponentially large quantum Hilbert space. Using open-weight models (Meta Llama-3.2-1B and Alibaba Qwen2.5-1.5B-Instruct), we perform a two-stage analysis that reveals a fundamental architectural divergence. While Qwen's layer 7 circuit functions as a classic Recall Hub, we discover that Llama's layer 9 acts as an Interference Suppression circuit, where ablating the identified heads paradoxically improves factual recall. Our results demonstrate that quantum kernels can distinguish between these constructive (recall) and reductive (suppression) mechanisms, offering a high-resolution tool for analyzing the fine-grained topology of attention.

2602.06848 2026-02-09 gr-qc

Chaos as a Possible Probe for Scalar Hair in Horndeski Gravity

Yang Yu, Ruo-Ting Chen, Shulan Li, Dan Zhang, Jian-Pin Wu

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英文摘要

The detection of black hole scalar hair, a possible deviation from general relativity's "no-hair" theorem, requires sensitive probes beyond conventional methods. This study proposes chaotic dynamics as a novel indicator for scalar hair in Horndeski gravity. We investigate the motion of a spinning test particle in a static, spherically symmetric hairy black hole spacetime. Our results show that increasing scalar hair systematically suppresses orbital chaos, as evidenced by regularized precession, reduced Lyapunov exponents, and contracted Poincare sections. Furthermore, scalar hair enhances the correlation between the two gravitational wave polarization modes, restoring phase coherence. These findings demonstrate that chaotic observables and gravitational wave signatures can jointly serve as sensitive probes for black hole hair, offering a complementary approach to testing gravity in strong-field regimes.

2602.06847 2026-02-09 quant-ph cs.NI

Consensus Protocols for Entanglement-Aware Scheduling in Distributed Quantum Neural Networks

Kuan-Cheng Chen, Samuel Yen-Chi Chen, Mahdi Chehimi, Felix Burt, Kin K. Leung

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英文摘要

The realization of distributed quantum neural networks (DQNNs) over quantum internet infrastructures faces fundamental challenges arising from the fragile nature of entanglement and the demanding synchronization requirements of distributed learning. We introduce a Consensus-Entanglement-Aware Scheduling (CEAS) framework that co-designs quantum consensus protocols with adaptive entanglement management to enable robust synchronous training across distributed quantum processors. CEAS integrates fidelity-weighted aggregation, in which parameter updates are weighted by quantum Fisher information to suppress noisy contributions, with decoherence-aware entanglement scheduling that treats Bell pairs as perishable resources subject to exponential decay. The framework incorporates quantum-authenticated Byzantine fault tolerance, ensuring security against malicious nodes while maintaining compatibility with noisy intermediate-scale quantum (NISQ) constraints. Our theoretical analysis establishes convergence guarantees under heterogeneous noise conditions, while numerical simulations demonstrate that CEAS maintains 10-15 percentage points higher accuracy compared to entanglement-oblivious baselines under coordinated Byzantine attacks, achieving 90 percent Bell-pair utilization despite coherence time limitations. This work provides a foundational architecture for scalable distributed quantum machine learning, bridging quantum networking, distributed optimization, and early fault-tolerant quantum computation.

2602.06845 2026-02-09 quant-ph

Comment on "Relativistic covariance and nonlinear quantum mechanics: Tomonaga-Schwinger analysis''

Lajos Diósi

Comments 2pp, Comment on arXiv:2511.15935 [Phys.Lett.B872,140053(2026)]

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英文摘要

Contrary to the central claim (Hsu, 2026) published in Physics Letters B, the Tomonaga--Schwinger equation remains covariant despite the nonlinear modification of it. The proof of covariance becomes simple after the loopholes and mistakes in Hsu's arguments are identified.

2602.06833 2026-02-09 gr-qc hep-th

Timelike Entanglement Entropy of Hawking Radiation

Yahya Ladghami, Francisco S. N. Lobo, Taoufik Ouali

Comments 10 pages, 2 figures

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英文摘要

We introduce the concept of timelike entanglement entropy of Hawking radiation as a novel probe of the black hole information paradox. By analytically continuing black hole spacetimes to Euclidean signature, we define timelike correlations that reveal a sequence of timelike Page times at which the entanglement entropy equals the Bekenstein-Hawking entropy. Applying this framework to Schwarzschild, Reissner-Nordström, static higher-dimensional and braneworld solutions, four-dimensional Kerr, and higher-dimensional rotating Myers--Perry black holes, we demonstrate that timelike entanglement exhibits periodic or quasi-periodic behavior, with the recurrence times sensitive to surface gravity, charge, rotation, and spacetime dimensionality. Extremal and near-extremal black holes display effectively frozen thermal oscillations with persistent rotational modulation, reflecting their near-horizon geometries. Unlike conventional approaches based on islands or firewalls, our framework encodes information entirely in the Hawking radiation, preserving unitarity while avoiding violations of horizon smoothness. These results establish timelike entanglement as a robust and physically transparent mechanism for information recovery and provide a versatile tool for exploring quantum gravitational dynamics across a wide range of black hole spacetimes.

2602.06815 2026-02-09 nucl-th astro-ph.HE hep-th

Many-body effects on dense matter with hyperons at finite temperature

Rafael Bán Jacobsen, Ricardo Luciano Sonego Farias, Veronica Dexheimer

Comments 42 pages, 20 figures, 6 tables

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英文摘要

In this work, we present the first extension of the Many-Body Forces (MBF) Model to finite temperature. The MBF Model describes nuclear matter in a relativistic quantum hadrodynamics formalism that takes many-body forces into account through a field dependence of the nuclear interaction coupling constants. Assuming nuclear matter to be charge neutral, beta-equilibrated, and populated by the baryon octet, electrons, and muons, we explore the parameters of the model, three different hyperon coupling schemes (also introduced here for the first time in MBF), and temperature effects to describe basic properties of nuclear matter, including the speed of sound, compressibility, and adiabatic index. We also investigate the mass-radius relation of compact stars by solving the Tolman-Oppenheimer-Volkoff equations at zero and finite temperature, including scenarios with fixed entropy per baryon. Our original results at finite temperature open the path to a new description of proto-neutron stars.

2602.06812 2026-02-09 quant-ph

Hybrid Coupling Topology with Dynamic ZZ Suppression for Optimizing Circuit Depth during Runtime in Superconducting Quantum Processor

Uday Sannigrahi, Amlan Chakrabarti, Swapnil Saha, Shrinjita Biswas

Comments 6 pages, 8 figures

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英文摘要

To reduce circuit depth when executing Quantum algorithms, it is necessary to maximize qubit connectivity on a near-term quantum processor. While addressing this, we also need to ensure high gate fidelity, suppression of unwanted ZZ cross-talk, a compact layout footprint, and minimal control hardware complexity to support scalability. In current superconducting quantum chips, fixed coupling is used as it is easier to scale, but it is limited by unwanted static ZZ interaction during single qubit operations, which degrades system performance. To overcome these challenges, we have introduced a first-of-its-kind hybrid tunable-coupling architecture that connects four fixed-frequency transmon qubits using a single coupler. This hybrid coupler uses off-resonant Stark drives to tune ZZ strength between qubit pairs. Experimentally backed simulation results indicate that our proposed hybrid design maximizes the qubit connectivity while reducing control overhead. This design achieves a near 20% reduction in circuit depth compared to IBM's Heavy-Hexagonal layout, showing its potential for scalability.

2602.06803 2026-02-09 physics.plasm-ph

Collision of two radial rarefaction waves in unmagnetized ambient plasma: effects of the ambient plasma density

Margaux François, Mark E. Dieckmann, Lorenzo Romagnani, Xavier Ribeyre, Emmanuel d'Humières

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英文摘要

The expansion of two circular rarefaction waves in vacuum or in a thin ambient plasma is examined with particle-in-cell simulations that resolve two spatial dimensions. In the simulation with no ambient plasma, the rarefaction waves interpenetrate near the symmetry line between both rarefaction wave centers. The exponential density decrease of rarefaction waves with distance implies that the sum of their density does not lead to a density maximum near the symmetry line. The absence of a density maximum, which would yield a repelling electric potential for the inflowing rarefaction wave ions near the symmetry line, and the high interpenetration speed of the ion beams lead to ion-ion instabilities rather than shocks in the overlap layer. The simulations with ambient plasma show that the rarefaction waves pile up the ions of the ambient plasma near the symmetry line. A localized piston of hot ambient ions forms. If its density is large enough, its thermoelectric field allows reverse shocks to grow in the rarefaction waves. These reverse shocks move slowly in the simulation frame and enclose a slab of downstream plasma. A decrease in the speed of the rarefaction wave ions upstream of the shocks with time leads to their collapse.

2602.06796 2026-02-09 quant-ph physics.optics

Phase-sensitive characterization of a quantum frequency converter by spectral interferometry

Mateusz J Olszewski, Kasper Hecht Alexander, Michael T M Woodley, Leah R Murphy, Peter J Mosley, Alex O C Davis

Comments 14 pages, 17 figures

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英文摘要

We introduce an experimental technique for complete phase-sensitive characterization of arbitrary unitary spectral-temporal transformations of optical modes. Our method recovers the complex spectral transfer function, or Green's function, of a frequency converter by analyzing spectral interference in the response to a tunable bichromatic probe. We perform a proof-of-concept experiment on a frequency conversion module based on Bragg-scattering four-wave mixing in photonic crystal fiber. Our results validate our technique by recovering useful information in the phase of the Green's function, revealing the relative positions of regions of active frequency conversion and passive dispersive propagation within the module. Our work introduces a new approach to characterizing the performance of a variety of active devices with diverse applications in emerging quantum technologies.