Peer Revenue Fully funded

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics

Watch Physics

Monday 20 July

Solar and Stellar Astrophysics

Solar, Heliospheric and Ionospheric Physics: Pathfinders, Precursors and SKAO Perspective

Pietro Zucca, Rohit Sharma, Divya Oberoi et al. (+5 more)

The Solar, Heliospheric and Ionospheric (SHI) Physics Science Working Group of the Square Kilometre Array Observatory (SKAO) addresses the full chain of plasma processes linking the solar corona to the terrestrial environment. This overview chapter synthesises 16 topical contributions to Advancing Astrophysics with the SKA-II, spanning the quiet and active solar atmosphere, eruptive phenomena, heliospheric turbulence and solar-wind diagnostics, ionospheric science, stellar-solar connections, and the observational frameworks required to deliver these science goals. The primary focus is on the capabilities of Array Assembly 4 (AA4), the design baseline for both SKA-LOW (50-350,MHz) and SKA-MID (0.35-15.4,GHz), which together provide continuous spectral coverage, sub-arcsecond angular resolution, full-Stokes polarimetry, and sensitivity gains of an order of magnitude over existing facilities. From resolving fine-scale coronal heating events to mapping coronal mass ejection magnetic fields and characterising multi-scale heliospheric turbulence, SKAO will deliver transformative advances in solar and space-weather science. We frame these contributions as a single end-to-end Sun-to-Earth system. We identify cross-cutting themes and gaps not fully addressed by individual chapters and outline the staged roadmap from early operations through to the full AA4 capability.
Read the full abstract

All authors Pietro Zucca, Rohit Sharma, Divya Oberoi, Eduard Kontar, John Morgan, Peter Gallagher, Sven Wedemeyer, Biagio Forte

Cosmology and Nongalactic Astrophysics

Magnetically assisted primordial scalar perturbations: Scalar-Induced Gravitational Waves

Arko Bhaumik, Theodoros Papanikolaou and Anish Ghoshal

Primordial magnetic fields (PMFs) provide a well-motivated source of cosmological perturbations through their anisotropic stress and may leave observable imprints in both the scalar and tensor sectors. In this work, we study scalar metric perturbations sourced by a PMF evolving through a finite post-inflationary epoch characterized by a constant equation-of-state (EoS) parameter $w$. Working in a gauge-invariant framework, we derive the sourced evolution equation for the Bardeen gravitational potential in a general constant-$w$ background. Our analysis indicates faster (slower) growth of PMF-sourced scalar perturbations on superhorizon scales for a stiffer $w>1/3$ (softer $w<1/3$) background compared to the marginal radiation-dominated scenario with $w=1/3$. We then derive the scalar-induced gravitational wave (SIGW) background induced at second order by the magnetically generated scalar perturbations. Our analysis indicates a narrow viable parametric region for a kination-like post-inflationary era and a nearly scale-invariant PMF that may give rise to a PMF-sourced SIGW signal dominating over the direct PMF-generated tensor background. Simultaneously, the induced tensor modes are found to be perturbatively small compared to the magnetic sector, which, in turn, exerts negligible backreaction on the background. Interestingly enough, for an inflationary scale $H_{\rm inf}\sim10^3-10^9$ GeV and duration of reheating in $e$-folds $N_{\rm reh}\sim8-10$, the dominant PMF-sourced SIGW signal may be detectable by next-generation terrestrial and space-based interferometric GW detectors spanning the mHz$-$kHz frequency range.
Read the full abstract

High Energy Physics (Theory)

Dynamical Timelike Entanglement Entropy in an Evaporating Schwarzschild–AdS Black Hole

Digen Das and Prabwal Phukon

Timelike entanglement entropy (tEE) has recently emerged as a novel probe of temporal quantum correlations in gravitational systems. Existing studies are largely restricted to static backgrounds. In this work we extend the construction of tEE to an evaporating Schwarzschild–AdS black hole. The evaporation is modeled through an effective Stefan–Boltzmann description of Hawking radiation coupled to an external absorptive bath, yielding a time-dependent horizon radius ($r_h(t)$) and surface gravity $\kappa(t)$. We derive, from the near-horizon Rindler structure of the evolving horizon, an adiabatic generalization of the static Kruskal construction, obtaining the accumulated thermal phase $\Phi(t)=\int_0^t\kappa(t')\,dt'$ as the natural replacement for the static phase $\kappa t$. The validity of this construction is governed by an explicit adiabatic parameter $\mathcal A(t)$, which we verify numerically remains small ($\lesssim0.012$) throughout the regime of interest. It vanishes exactly where the horizon crosses the critical radius $r_h=l/\sqrt3$ identified independently from the static thermodynamics. Using $\Phi(t)$, we construct a dynamical timelike entanglement entropy that continuously tracks the evaporation process and derive the corresponding dynamical Page-like times. Unlike the uniformly spaced Page-like times of the static geometry, evaporation induces non-uniform temporal spacing, together with a progressive phase delay and amplitude modulation of the oscillatory tEE. Because the dynamical entropy depends on the full accumulated history of $\kappa(t)$ rather than its instantaneous value alone, it retains a memory of the entire evaporation process. These results establish a first-principles dynamical framework for investigating temporal quantum correlations in evaporating black holes.
Read the full abstract

Quantum Physics

Entanglement geometry separates circuit cutting, classical hardness, and trainability

Maria Gragera Garces, Sabina Drăgoi and Lirandë Pira

Circuit cutting promises to scale quantum computations beyond current hardware, but variational quantum advantage also requires low cutting overhead, classical hardness, and trainability. We show that these properties are strongly constrained by entanglement geometry. Matrix product state (MPS) and tree tensor network (TTN) circuits with constant seam bond dimension can be cut with \(O(1/\varepsilon^2)\) sampling overhead, but remain efficiently classically simulable, ruling out asymptotic quantum advantage within these families. By independently controlling seam and intra-block entanglement, we construct a two-block circuit family that remains cheaply cuttable while requiring a super-polynomial global MPS bond dimension, as supported numerically up to \(n=100\). However, MPS hardness and trainability require incompatible depth regimes, \(d=\omega(\log n)\) and \(d=O(\log n)\), respectively. Using magic rather than entanglement as the hardness resource avoids this conflict: shallow Clifford+\(T\) circuits remain cuttable and trainable while their stabiliser-simulation cost grows exponentially with the \(T\)-count.
Read the full abstract

Statistical Mechanics

On the use of the Belopol'skaya-Daletskii representation of a diffusion on a Riemann manifold to construct path integrals

Paolo Muratore-Ginanneschi

We show that the Belopol'skaya-Daletskii formulation of stochastic differential equations on a Riemann manifold offers an elementary way to construct equivariant representations of finite-dimensional approximations to the path measure of a diffusion. The key ingredient is the use of the exponential map to describe increments of the diffusion.
Read the full abstract

Astrophysics of Galaxies

Spatio-kinematical structure of the Galactic Nuclear Stellar Disk revealed in VLBI astrometry of circumstellar masers

Hiroshi Imai, Kohei Kurahara, Huib J. van Langevelde et al. (+2 more)

SKA-VLBI astrometry will enable us to measure up to thousands of three dimensional motions of OH masers associated with circumstellar envelopes (CSEs) of OH/IR stars in the Nuclear Stellar Disk (NSD) and sites of high mass star formation in the Central Molecular Zone (CMZ) of the Galactic Center (GC). It is expected that the spatio-kinematical distribution of those OH masers should indicate the existence of a ring structure in the NSD, which has formed as a result of outward propagation of star-formation activities in the GC. This is likely visualized clearly by a group of OH/IR stars, some of which should have stellar pulsation periods of >400 days and the corresponding ages of <500 Myr, and some sites of ongoing star formation. These OH/IR stars should host 1612-MHz OH masers, some of which should become targets of huge-sample VLBI astrometry, in moderate accuracy, in SKA-MID Band 2 (~1.6 GHz). The data of maser source proper motions will exhibit a stream motion in the stellar ring structure. Furthermore, the information of accurate distances (error <100 pc) of the maser sources are necessary to directly find the major-axis direction of a possible elliptical ring of stars at ~8 kpc. These distances may be yielded through trigonometric parallaxes measurable in SKA-MID Band 5a (5–7 GHz) and/or photometric parallaxes derived from the pulsation period–luminosity relation of long period variable stars hosting the maser sources.
Read the full abstract

All authors Hiroshi Imai, Kohei Kurahara, Huib J. van Langevelde, Maria J. Rioja, Richard Dodson

High Energy Astrophysical Phenomena

Black hole spin-mass correlation and vector resonant relaxation in gaseous star clusters: the origin of GW231123?

Zacharias Roupas

During the formation of a star cluster a spin-mass correlation of stellar black holes is generated as they grow via accretion of the residual gas. Moreover, the black hole spin tends to be anti-aligned with its orbital angular momentum in the cluster. We show that GW231123, reported by the LIGO-Virgo-KAGRA (LVK) collaboration, lies on our predicted high-mass, high-spin plateau of the spin-mass correlation with positive Bayesian evidence over the LVK prior. Furthermore, vector resonant relaxation (VRR) equilibrium is favored over the isotropic LVK prior in reproducing the distribution of the relative spin tilt. The joint Bayes factor suggests strong evidence for the favored cluster models. GW231123 is thus consistent with our proposed channel that generates correlated black hole masses and spins, and drives the spins' orientations.
Read the full abstract

Exactly Solvable and Integrable Systems

Integrable Volterra hierarchies over nonabelian algebras

J. P. Wang, S. Carpentier and A. V. Mikhailov

Known integrable systems with noncommutative dependent variables are typically formulated over free associative algebras, quantum algebras, or Grassmann algebras. For differential-difference integrable equations, we identify a new class of noncommutative algebras that is compatible with the dynamics and can be positioned between quantum and free algebras. In this brief communication, we consider reductions of the nonabelian Volterra hierarchy to new algebras. This approach extends to a broad class of integrable systems, including the Toda lattice, the Ablowitz-Ladik system, and many others.
Read the full abstract

Mesoscale and Nanoscale Physics

Physics-constrained machine learning for decoding multi-nanobubble configurations in graphene

Jihye Kim, Taegeun Song and Nojoon Myoung

Identifying multiple graphene nanobubbles from electronic spectra is challenging because their strain-induced features overlap. We develop a physics-constrained machine-learning framework that decodes nanobubble configurations from density-of-states (DOS) spectra. For spatially separated nanobubbles, previous full quantum-transport calculations established that the multi-bubble DOS is numerically equivalent to the normalized sum of the constituent single-bubble spectra. We encode this validated additive relation in a compact neural decomposition model. For each target spectrum, the basis coefficients are optimized independently, and the resulting weights directly identify the constituent geometries. The method accurately reconstructs configurations of increasing complexity and remains robust to repeated constituents, incomplete basis dictionaries, and simulated measurement noise. The framework provides an interpretable route for characterizing strain-engineered graphene nanostructures and may extend to other quantum materials with additive spectral responses.
Read the full abstract

Fluid Dynamics

Physically Consistent Outflow Boundary Conditions for Global Stability Analysis of Bluff Body Wakes

Guangyao Cui, Amit Sigawi and Michael Karp

Global linear stability analysis of bluff body wake flows is performed using the matrix-forming method based on finite-difference discretization. Particular emphasis is placed on the influence of outflow boundary conditions, with the aim of minimizing the required computational domain size without degrading accuracy or inducing spurious oscillations near the outlet. This study focuses on incompressible wakes behind bluff bodies such as cylinders and airfoils at high angle of attack, especially in regimes where global modes exhibit downstream spatial amplification. It is shown that below the critical Reynolds number – where the global mode remains linearly stable – significant spatial growth can persist far downstream, even when the wake is nearly absent. This behavior underscores the importance of imposing a physical boundary condition at the outlet. Several commonly used outflow boundary conditions are evaluated, including Dirichlet, Neumann, extrapolation, stress-free, sponge layer, and the Robin condition that incorporates predictions from local linear stability analysis at the outlet. The results demonstrate that, for different $Re$ cases, the Robin condition enables robust convergence of global modes within substantially truncated domains, thereby improving the efficiency of global stability analysis. These findings highlight the broader applicability of the matrix-forming approach for complex stability analyses, including Floquet analysis of time-periodic flows and extensions to compressible configurations.
Read the full abstract

Soft Condensed Matter

Molecular chirality controls droplet division and helical fiber formation in liquid crystal emulsions

Simon Čopar, Mariana V. M. Rodriguez, Peter Marinko et al. (+9 more)

Molecular chirality is a source of broken mirror symmetry, but using it to control mesoscale structures with a tunable length scale remains challenging. Here, we demonstrate that adding a chiral dopant to nematic liquid crystal droplets bounded by a deformable two-surfactant interface controls their morphogenesis: the ratio of droplet diameter to cholesteric pitch determines whether droplets divide asymmetrically or symmetrically upon cooling, and whether they transform into single- or double-strand helical fibers. The fiber periodicity and thickness both scale linearly with the cholesteric pitch, which varies by less than 2% with temperature across the self-shaping window. Numerical simulations reveal that chirality-driven elastic stresses at the interface destabilize the droplets and trigger cusp-mediated shape transformations. These results establish cholesteric pitch as a design variable to precisely control droplet division and decouple the dimensions of spontaneously formed mesoscale structures from temperature dependence.
Read the full abstract

All authors Simon Čopar, Mariana V. M. Rodriguez, Peter Marinko, Seyed Reza Seyednejad, Jan Dolinar, Miha Škarabot, Karthik Peddireddy, Khoa V. Le, Samo Kralj, Slobodan Žumer, Miha Ravnik, Venkata S. R. Jampani

Quantum Physics

High-frequency dual-channel lock-in detection via rapidly oscillating driving

Kangze Li, Xu Zhao, Liantuan Xiao et al. (+1 more)

Here we propose a general protocol for dual-channel lock-in detection of high-frequency ac signals. We find that the effect of a high-frequency target signal can be modulated through the application of rapidly oscillating driving fields. Based on this mechanism, we develop a quantum dual-channel lock-in detection protocol for high-frequency signals, which not only extends the accessible frequency range of quantum sensing but also enables the simultaneous estimation of the signal amplitude and initial phase. Furthermore, we present a feasible implementation scheme of the protocol based on nitrogen-vacancy centers in diamond. Numerical simulations demonstrate that the proposed protocol can effectively filter out background noise and significantly improve the signal-to-noise ratio. Our results provide a promising approach for realizing noise-resistant detection of weak signals in the high-frequency regime.
Read the full abstract

All authors Kangze Li, Xu Zhao, Liantuan Xiao, Gerardo Adesso

High Energy Physics (Experiment)

First Observation of an Exotic Reggeon

G. D. Alexeev, M. G. Alexeev, C. Alice et al. (+181 more)

We present new \compass high-statistics measurements of the peripheral production of $\eta \pi^-$ and $\eta^\prime \pi^-$ pairs in the reactions $\pi^- p \to \eta^{(\prime)}\pi^- p$. For the first time, we perform an unbinned analysis of the high-mass region of the $\eta\pi^-$ and $\eta^\prime\pi^-$ systems, which allows us to disentangle the exchange mechanisms governing their production. We report the first observation in high-energy scattering of an exotic Reggeon with high significance exceeding $5\,\sigma$ for both channels, which is, most likely, related to the exotic $\pi_1(1600)$.8
Read the full abstract

All authors G. D. Alexeev, M. G. Alexeev, C. Alice, A. Amoroso, V. Andrieux, V. Anosov, K. Augsten, W. Augustyniak, C. D. R. Azevedo, B. Badelek, R. Beck, J. Beckers, Y. Bedfer, V. Benesova, J. Bernhard, F. Bradamante, A. Bressan, W.-C. Chang, C. Chatterjee, M. Chiosso, S.-U. Chung, A. Cicuttin, M. L. Crespo, D. D'Ago, S. Dalla Torre, S. S. Dasgupta, S. Dasgupta, F. Delcarro, I. Denisenko, O. Yu. Denisov, S. V. Donskov, N. Doshita, Ch. Dreisbach, W. Dunnweber, R. R. Dusaev, D. Ecker, P. Faccioli, M. Faessler, M. Finger, M. jr Finger, H. Fischer, K. J. Flothner, W. Florian, J. M. Friedrich, V. Frolov, L.G. Garcia Ordonez, O. P. Gavrichtchouk, S. Gerassimov, J. Giarra, D. Giordano, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, M. Gruner, A. Guskov, P. Haas, D. von Harrach, M. Hoffmann, N. d'Hose, C.-Y. Hsieh, S. Ishimoto, A. Ivanov, T. Iwata, V. Jary, E. Jelinkova, R. Joosten, E. Kabuss, F. Kaspar, A. Kerbizi, B. Ketzer, G. V. Khaustov, T. Klasek, J. H. Koivuniemi, V. N. Kolosov, K. Kondo Horikawa, I. Konorov, A. Yu. Korzenev, A. M. Kotzinian, O. M. Kouznetsov, A. Koval, F. Kunne, K. Kurek, R. P. Kurjata, G. Kurten, A. Kveton, K. Lavickova, S. Levorato, Y.-S. Lian, J. Lichtenstadt, P.-J. Lin, R. Longo, V. E. Lyubovitskij, A. Maggiora, N. Makke, G. K. Mallot, A. Maltsev, A. Martin, J. Marzec, J. Matousek, T. Matsuda, C. Menezes Pires, F. Metzger, W. Meyer, M. Mikhasenko, E. Mitrofanov, D. Miura, Y. Miyachi, R. Molina, A. Moretti, A. Nagaytsev, D. Neyret, M. Niemiec, J. Novy, W.-D. Nowak, G. Nukazuka, A. G. Olshevsky, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, H. Pekeler, J.-C. Peng, M. Pesek, D. V. Peshekhonov, M. Peskova, S. Platchkov, J. Pochodzalla, V. A. Polyakov, P. Pucci, C. Quintans, G. Reicherz, C. Riedl, D. I. Ryabchikov, A. Rychter, A. Rymbekova, V. D. Samoylenko, A. Sandacz, S. Sarkar, I. A. Savin, G. Sbrizzai, H. Schmieden, A. Selyunin, S. Seriubin, L. Sinha, D. Spulbeck, A. Srnka, M. Stolarski, M. Sulc, H. Suzuki, S. Tessaro, F. Tessarotto, A. Thiel, F. Tosello, A. Townsend, V. Tskhay, B. Valinoti, B. M. Veit, J.F.C.A. Veloso, A. Vijayakumar, M. Virius, M. Wagner, S. Wallner, K. Zaremba, M. Zavertyaev, M. Zemko, E. Zemlyanichkina, M. Ziembicki, for the COMPASS Collaboration, C. Fernandez-Ramirez, M. Mikhasenko, L. Bibrzycki, G. Foti, N. Hammoud, V. Mathieu, G. Montana, R. J. Perry, A. Pilloni, A. Rodas, V. Shastry, W. A. Smith, A. P. Szczepaniak, D. Winney, for JPAC Collaboration

High Energy Physics (Theory)

Leading Yukawa terms in the three-loop anomalous dimension and four-loop $\beta$-function of ${\cal N}=1$ supersymmetric theories for various renormalization prescriptions

Ratmir Jumanov and Konstantin Stepanyantz

For an arbitrary renormalizable ${\cal N}=1$ supersymmetric theory with a single gauge coupling regularized by higher covariant derivatives we calculate the three-loop contribution to the anomalous dimension of the matter superfields proportional to the sixth powers of Yukawa couplings for a wide class of renormalization prescriptions. Next, taking into account that in the case of using the higher covariant derivatives supplemented by minimal subtractions of logarithms the NSVZ relation is valid in all orders, we calculate the corresponding four-loop contribution to the gauge $\beta$-function and investigate its scheme dependence. In particular, we construct the so-called “minimal” renormalization prescription for which the renormalization group functions have the simplest possible form provided that the exact equations for the gauge and Yukawa $\beta$-functions following from supersymmetry remain valid.
Read the full abstract

Nuclear Experiment

Study of $\chi_{\mathrm{c}}$ production in pPb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV

CMS Collaboration

Production of prompt P-wave charmonium states $\chi_\mathrm{c1}$(1P) and $\chi_\mathrm{c2}$(1P) is studied in proton-lead (pPb) collisions at a center-of-mass energy per nucleon pair of $\sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}$ = 8.16 TeV. The analysis is based on data corresponding to an integrated luminosity of 175 nb$^{-1}$ collected by the CMS experiment at the CERN LHC. The $\chi_\mathrm{c}$ states are measured via their decay $\chi_\mathrm{c}$ $\to$ J$/\psi\,\gamma$. The J$/\psi$ meson is reconstructed via its decay to a muon pair, while the photon is reconstructed through its conversion to an electron-positron pair. The ratio of production cross sections times branching fractions for the two charmonium states, [$\sigma(\chi_\mathrm{c2}) \mathcal{B}(\chi_\mathrm{c2}$ $\to$ J$/\psi \, \gamma$)] / [$\sigma(\chi_\mathrm{c1}) \mathcal{B}(\chi_\mathrm{c1}$ $\to$ J$/\psi \, \gamma)$], is reported in the rapidity range $\vert y($J$/\psi)\vert$ $\lt$ 2.4 for the transverse momentum range 6.5 $\lt$ $p_{\mathrm{T}}$(J$/\psi$) $\lt$ 30 GeV. The $\chi_\mathrm{c2}$-to-$\chi_\mathrm{c1}$ ratio is found to be independent of event charged-particle multiplicity, as well as of the rapidity and $p_\mathrm{T}$ of the J$/\psi$. The consistency of this ratio with proton-proton measurements at $\sqrt{s}$ = 7 TeV indicates an absence of strong relative modification for $\chi_\mathrm{c}$ states in pPb collisions, in contrast to the behavior observed in the $\psi$(2S)-to-J$/\psi$ ratio.
Read the full abstract

Nuclear Theory

Dissipative properties of a Fermi system within the diffusion approximation of kinetic theory

Sergiy V. Lukyanov

The dissipative properties of a Fermi system are studied within the diffusion approximation of kinetic theory for a model of a spherical atomic nucleus. An analytical solution of the nonlinear diffusion equation in energy space with constant kinetic coefficients is used to show that the distribution function asymptotically approaches the equilibrium Fermi distribution. It is found that the deviation from equilibrium at finite times decays with an effective relaxation time of $\tau_\mathrm{eff}\approx 1.0\times10^{-23}$ s, whereas the asymptotic regime is characterized by an exponential decay with a relaxation time of $\tau_\text{eq}\approx 3\,\tau_\text{eff}$. These results explain the difference between the relaxation times extracted from integral characteristics of the relaxation process and from the asymptotic long-time evolution.
Read the full abstract

Fluid Dynamics

A coupled Eulerian Lagrangian approach for fluid and particle dynamics

Snehanshu Maiti and Rajaraman Ganesh

We present a one-way coupled Eulerian-Lagrangian computational framework for simulating fluid and particle dynamics in two-dimensional incompressible flows. The framework extends the GPU-accelerated GHD2D Fourier pseudospectral Navier-Stokes solver \cite{Mukherjee2018,Biswas2024} by incorporating passive tracer and finite-inertia particle modules. The Eulerian fluid equations are integrated using a second-order Adams-Bashforth scheme, while particle trajectories are advanced with a classical fourth-order Runge-Kutta method. Coupling between the Eulerian and Lagrangian descriptions is achieved through spatial and temporal interpolation of the fluid fields using bilinear, bicubic Catmull-Rom, and bicubic B-spline schemes. The framework is verified using analytical solutions and benchmark problems for the fluid solver, tracer transport, and inertial-particle dynamics. Bilinear interpolation produces transport statistics nearly identical to higher-order schemes while providing greater computational efficiency, and particle-number convergence demonstrates statistical robustness. Simulations of tracer and inertial particles in decaying two-dimensional turbulence capture long-time transport, turbulent dispersion, vortex trapping, coherent-structure interactions, preferential concentration, and inertia-dependent transport. The solver exhibits stable scaling with grid resolution and particle number while maintaining efficient single-GPU performance. The modular architecture and computational efficiency make the framework suitable for Eulerian-Lagrangian studies of turbulent transport and particle-laden incompressible flows.
Read the full abstract

Materials Science · Cross-listed from eess.SY

Multisine electrochemical impedance spectroscopy for Li-ion battery characterisation

Noël Hallemans, Heiko Seel-Mayer, Peter Keil et al. (+2 more)

Electrochemical impedance spectroscopy (EIS) is a valuable tool for non-invasive battery characterisation, providing a compact representation of physical processes over a wide range of time scales. Commonly, sinusoids at different frequencies are injected sequentially (single-sines). Alternatively, a multisine excitation (a sum of sines) is advantageous for reducing experiment time and allowing impedance to be measured during operation. In this work, we demonstrate high-fidelity multisine EIS measurements on Li-ion cells over a wide frequency range (20 mHz to 1 kHz), taken with a commercial potentiostat modified to give access to the underlying current and voltage time-series data, and compare these to single-sine EIS. We show how this allows the conditions of linearity and stationarity to be verified directly, which is not possible with impedance data alone. We then measure broadband impedance during charging and discharging, temperature change, and relaxation. Because impedance is a linearisation of the response about an operating point, each of these conditions probes a state that classical EIS excludes by definition: kinetics linearised about a non-zero current, thermally activated reaction rates, and relaxing concentration gradients, respectively. Operando multisine EIS is therefore not simply a faster measurement approach, but one that resolves behaviour that steady-state EIS cannot.
Read the full abstract

All authors Noël Hallemans, Heiko Seel-Mayer, Peter Keil, Stephen R. Duncan, David A. Howey

High Energy Physics (Phenomenology)

A Gauge Model for Quasi-Dirac Neutrinos

Zhao-Xing Fan and Chun Liu

In a model with $L_{\mu} - L_{\tau}$ Abelian gauge symmetry, anomaly-free chiral fermions, which are Standard Model singlets, are introduced as the origin of right-handed neutrinos. This $\mathsf{U} (1)$ symmetry keeps the right-handed neutrinos Majorana massless. Tiny nonvanishing Dirac masses of neutrinos are due to higher-dimensional operators with natural coupling constants. After gauge symmetry breaking, a quasi-Dirac neutrino scenario naturally appears, and realistic neutrino physics can be produced. Phenomenological and cosmological aspects of the model are discussed.
Read the full abstract

Solar and Stellar Astrophysics

Fast and periodic propagating disturbances along coronal loops detected with EUI on board Solar Orbiter

A. Dolliou, S. Mandal, K. Barczynski et al. (+9 more)

Recent high-resolution observations from the Solar Orbiter mission can help detect the indirect signatures of heating at the smallest scales. In this work we measure the properties and investigate the physical origin of propagating disturbances (PDs) in the intensity at the smallest resolvable scales with Solar Orbiter/EUI along coronal loops. We used two sequences of EUI/HRIEUV at high spatial (down to 125 km per pixel) and temporal resolutions (5 s of cadence). We placed slits along 13 active region (AR) coronal loops. We measured the plane-of-sky (PoS) velocities and the intensity perturbation damping along the slits of PDs. We also measured the periodicity of PDs in one slit by using a Fourier analysis. We report the detection of PDs that have high PoS velocities ranging between 500 and 2000 km/s (which we call "fast" PDs). They are only visible in the upper part of the coronal loops. The intensity increase associated with these fast PDs is on the order of 4% to 8% of the HRIEUV intensity, and we measured little to no damping of their intensity with distance. We also measured a peak in the Fourier power spectra at 2 min above the 95% confidence limit that is associated with fast PDs. The fast PDs are detected in the same coronal loops as PDs with a lower PoS velocity (70 to 90 kms/s), which we refer to as "slow" PDs. Unlike the fast PDs, these slow PDs are only visible in the lower part of the coronal loop, and they show clear intensity damping. Slow PDs show properties consistent with slow magneto-acoustic modes or upflows. On the other hand, fast PDs cannot be explained by slow magneto-acoustic modes. Instead, they show properties consistent with fast flows induced by magnetic reconnection, current sheet generated by propagating transverse oscillations, and fast magnetohydrodynamics modes or Alfvén waves.
Read the full abstract

All authors A. Dolliou, S. Mandal, K. Barczynski, T. Van Doorsselaere, D. Berghmans, C. Froment, F. Auchère, P. Antolin, H. Eklund, Y. Zhu, E. Kraaikamp, C. Verbeeck

Optics

Photonic Memory as a Dynamical Phase for Neuromorphic Computing: A Unified Framework with Experimental Realization

Isaac Yorke

Photonic memory underpins optical information processing, neuromorphic photonics, and photonic computing. Existing studies typically treat dispersive, nonlinear, and driven-dissipative memory as distinct physical phenomena, despite all being governed by the evolution of the optical field. This work proposes a unified phase-based framework in which photonic memory is interpreted as a dynamical phase, with transitions between memory regimes governed by optical phase evolution, Kerr nonlinearity, and the balance between delayed feedback and dissipation. Within this framework, dispersive memory arises from frequency-dependent phase accumulation, nonlinear memory emerges through intensity-dependent phase evolution leading to bistability and hysteresis, and driven-dissipative memory is established through attractor convergence and memory stabilization. The proposed framework is validated through theoretical analysis and numerical simulations, demonstrating a continuous progression from linear dispersive memory to nonlinear and ultimately driven-dissipative memory. Experimental validation is performed using a silicon photonic waveguide incorporating chirped Bragg gratings. Group delay measurements reveal distinct linear and nonlinear memory responses, while the reconstructed memory distribution demonstrates the coexistence of dispersive, nonlinear, and driven-dissipative memory within a single integrated photonic device. To the best of the author's knowledge, this constitutes the first experimental demonstration supporting the coexistence of all three photonic memory regimes in a single photonic platform. These results establish optical phase as the unifying physical quantity underlying photonic memory and provide a common framework for designing future neuromorphic photonic systems, reservoir computers, and integrated photonic processors.
Read the full abstract

Lattice Field Theory

Renormalization of meson susceptibilities and RG-invariant symmetry ratios in QCD

Ting-Wai Chiu

We analyze the ultraviolet divergence structure of meson susceptibilities in finite-temperature QCD, for lattice formulations with exact chiral symmetry. The bare susceptibility separates into additive divergences and a multiplicative renormalization $Z_\Gamma^{2}$. The additive divergences are temperature-independent, and are removed by the temperature subtraction. They consist of the leading power divergence $\alpha_\Gamma/(2a^2)$ from the identity operator, together with a mass-dependent logarithmic term $\propto m^2\ln(1/(am))$. Exact chiral symmetry forbids all mass-dependent power divergences of the susceptibility. The multiplicative factor $Z_\Gamma^{2}$ has a logarithmic dependence on the lattice spacing, controlled by the operator anomalous dimension. We show that the symmetry ratio $\kappa_{AB} = (\chi_A^{\rm reg} - \chi_B^{\rm reg})/ (\chi_A^{\rm reg} + \chi_B^{\rm reg})$, built from temperature-subtracted susceptibilities of symmetry partners, is exactly renormalization-group invariant and scheme-independent. The additive divergence is removed by the subtraction, and the multiplicative factor cancels through the equality $Z_A = Z_B$. This equality holds for any number of flavors and any quark masses in a mass-independent scheme, unaffected by spontaneous symmetry breaking or the $U(1)_A$ anomaly. We derive the complete $Z$-factor chains for all meson channels and contrast the divergence structure with that of Wilson fermions, for which the explicit chiral-symmetry breaking induces a chiral-odd power-divergent mixing and spoils the equality $Z_A = Z_B$ on which the construction relies.
Read the full abstract

Astrophysics of Galaxies

Revealing a multi-zone circumnuclear dust response in UGC 11487 through phase-resolved WISE W1–W2 diagnostics

I.O. Izviekova, O.V. Kompaniiets, I.B. Vavilova et al. (+1 more)

Mid-infrared (MIR) flares provide a direct probe of dust reprocessing in obscured tidal disruption event (TDE) candidates when the primary optical or ultraviolet flare is weak, missed, or strongly attenuated. We present a phase-resolved analysis of the WISE/NEOWISE W1-W2 evolution of the MIR-selected TDE candidate UGC 11487/WTP14adeqka over 2014-2024. We combine timing, colour, and flux diagnostics with phenomenological modelling, hydrodynamically motivated clumpy dust-echo calculations, and an aperture-matched ultraviolet-to-radio spectral energy distribution of the host. The decade-long flare shows a delayed and broader W2 response, colour hysteresis, and cooling from approximately 900 K to 500-600 K. Positive-fluence centroids yield a preferred delay of $224 +/- 45$ d, corresponding to $0.188 +/- 0.038$ pc. The effective infrared luminosity peaks at approximately $3 x 10^{43}$ erg s$^{-1}$, and the integrated infrared energy is $(2.9-3.8) x 10^{51}$ erg. A single self-similar MIR response is strongly disfavoured, with Delta BIC = 281.7, while the preferred compact description is a two-component phenomenological model. Representative hydro-clumpy calculations reproduce the empirical diagnostics in a structured, multi-zone dust-response scenario. The host is a moderately star-forming isolated barred disc without a dominant persistent active galactic nucleus component. These results support an obscured TDE-like accretion transient reprocessed by structured circumnuclear dust and show that phase-resolved WISE diagnostics can recover characteristic sub-parsec response scales in obscured accretion-powered nuclear transients.
Read the full abstract

All authors I.O. Izviekova, O.V. Kompaniiets, I.B. Vavilova, D.V. Dobrycheva

Other Condensed Matter

Spin relaxation in $X$-wave magnets with $X=p, d, f, g, i$

Lijie Liu, Mingbo Dou, Xu Chen et al. (+4 more)

Spin relaxation results in the spin decoherence and a finite spin lifetime, which are detrimental to spintronic devices. To achieve a long spin lifetime desirable for spintronic devices, elucidating the spin relaxation mechanism and factors influencing the spin lifetime is of vital importance. Here, we investigate the spin relaxation in $X$-wave magnets ($X=p, d, f, g, i$) with Rashba spin-orbit coupling within the framework of D'yakonov-Perel' mechanism. We calculate the general matrix of the spin relaxation time for an arbitrary Néel vector direction of the $X$-wave magnet. As an illustration, we study the spin relaxation for the Néel vector along the $[001]$ direction. It is found that the reciprocal spin-relaxation-time matrices are anisotropic and diagonal for the $d$-, $f$-, $g$- and $i$-wave magnets. For the $p$-wave magnet, we derive the analytical expressions for the temporal evolution of spins. Moreover, the spin relaxation rate is proportional to the momentum relaxation time, Rashba and altermagnetic spin-split strengths for all $X$-wave magnets. Our results shine more light on the fundamental understanding of the spin relaxation mechanism in $X$-wave magnets.
Read the full abstract

All authors Lijie Liu, Mingbo Dou, Xu Chen, Xianjie Wang, M. Ye. Zhuravlev, A. V. Nikolaev, L. L. Tao

Quantum Physics

Stochastic Pauli-path simulator for large-scale quantum optimization

Kaining Zhang, Xinbiao Wang, Kunsheng Li et al. (+4 more)

Pauli-based simulators offer a promising route to large-scale classical simulation of quantum circuits in the low-magic regime. Yet their applicability remains largely limited to forward simulation, making them inadequate for optimization-driven quantum tasks such as variational state preparation and parameter initialization. Existing approaches either lack native support for gradient-based optimization or suffer from severe gradient bias. Here we propose the stochastic Pauli-path simulator (SPPS), a computational framework for large-scale quantum optimization that enables unbiased stochastic gradient estimation via Pauli-path sampling across optimization iterations. Our theoretical analysis shows that the proposed simulator yields unbiased gradient estimates and admits provable convergence guarantees. We systematically evaluate our proposal, including quantum eigensolver benchmarks with up to 100 qubits and quantum neural network benchmarks with up to 40 qubits. Across these tasks, SPPS faithfully tracks optimization dynamics, converges within minutes, and broadens the role of Pauli-based simulation from forward estimation to large-scale quantum optimization.
Read the full abstract

All authors Kaining Zhang, Xinbiao Wang, Kunsheng Li, Qixin Zhang, Yuxuan Du, Min-Hsiu Hsieh, Dacheng Tao

Mesoscale and Nanoscale Physics

Impurity-induced Inverse Faraday Effect

A. A. Kopasov, A. A. Bespalov and A. S. Mel'nikov

We provide a quantum-mechanical description of the photoinduced dc current states and magnetic fields around nonmagnetic point impurities in a two-dimensional (2D) electron gas irradiated by a circularly polarized electromagnetic wave. Based on the solution of the corresponding time-dependent Schrodinger equation within the second-order perturbation theory in the electromagnetic wave amplitude we find that the resulting dc magnetic field component perpendicular to the plane of the 2D system is distributed like in a set of random magnetic fluxes bound to the positions of impurities. As a result, the spatially averaged dc magnetic field does not vanish far from the sample edges and, thus, our scenario of the inverse Faraday effect in disordered systems differs strongly from the standard one based on the relaxation time approximation within the hydrodynamic or kinetic equation approaches which would give only the photoinduced currents flowing along the sample edges. The predicted mechanism for formation of rectified currents flowing around the impurity centers is shown to be generic both for 2D and three-dimensional systems. The internal dc magnetic field can give rise to the photoinduced Hall effect and Faraday rotation for a probing electromagnetic signal.
Read the full abstract

Optics

Real-time THz ptychography using an optically modulated aperture

Diksha Garg, Anil Kumar, Ian R. Hooper et al. (+6 more)

Ptychography allows ordinary cameras to perform both quantitative phase and intensity imaging. However, the requirement for relative object to probe motion and high measurement count significantly limits imaging speed and application scope. In this work, we introduce optically modulated aperture ptychography, using a silicon photomodulator as a rapidly reconfigurable aperture, deployable across the microwave, millimeter wave and terahertz bands. We demonstrate experimentally at ~ 0.1 THz real-time ptychographic image capture, without moving parts. Furthermore, a reconfigurable aperture facilitates diverse and spatially multiplexed probes. We use a multiplexed known-probe reconstruction strategy that improves signal-to-noise ratio and increases the information content per measurement, enabling the capture of fluid dynamics at 16 fps. Our optical modulation approach enables high-throughput ptychographic imaging of dynamic samples, for applications such as non-destructive evaluation and in-vivo biomedical imaging.
Read the full abstract

All authors Diksha Garg, Anil Kumar, Ian R. Hooper, Nicholas E. Grant, John D. Murphy, John E. Cunningham, Nick Stone, Euan Hendry, Harry Penketh

Instrumentation and Methods for Astrophysics

DESTINY: a new binding-energy-resolved astrochemical framework. Self-Consistent Competitiveness using Branched Absorbing Markov Chains

Maria Groyne, Cedric Baijot and Michaël De Becker

Under cryogenic interstellar conditions, the amorphous structure of interstellar ice results in binding-energy distributions (BEDs) per species. However, only few studies attempted their inclusion in astrochemical models. This paper introduces DESTINY, a deterministic astrochemical framework designed to incorporate BEDs while self-consistently accounting for the competition among activated surface processes. The framework is currently constrained to a monolayer. Surface processes initiated by surface species are reformulated using a trial-frequency-capped formalism represented through branched absorbing Markov chains. The ordinary differential equations (ODE) system is redefined based on normalized effective probabilities. Preliminary results based on a reduced surface network are discussed. To isolate the effects of the probabilistic reformulation from those induced by BED discretizations, DESTINY is benchmarked against Nautilus, a single-BE rate-equation based open source code. In the single-BE limit, DESTINY reproduces the behavior of Nautilus for most species. The largest deviations are obtained for CH$_{x = [2,4]}$ ; these are traced to a different treatment of the H$_2$ encounter effect, impacting both H$_2$ surface exploration and desorption efficiencies within the DESTINY framework. Introducing BEDs redistributes species among adsorption sites of different depths, altering the balance between diffusion, desorption, and reactions. Significant effects are found for H, H$_2$, NH$_x$, NO, CH$_x$, CO and H$_x$CO. Preliminary results showed that the self-consistent treatment of the H$_2$ encounter effect coupled with the explicit treatment of BEDs can substantially modify grain-surface chemistry. Further framework extensions are expected in the near future.
Read the full abstract

Mathematical Physics · Cross-listed from math.AP

Minimizers and Weak Solutions for Singular Born–Infeld Type Functionals

Tengyang Liu and Ruifeng Zhang

We investigate the relation between minimizers and weak solutions for a class of singular functionals arising from Born–Infeld type theories $\mathcal{L}(s)$. In the setting of an electrostatic field $s=\frac{1}{2}|\nabla\phi|^2$, $\mathcal{L}(s)$ satisfies $\lim_{s\to(1/2)^-}\mathcal{L}(s)=+\infty$, which naturally enforces the finite gradient bound $|\nabla\phi|\le 1$, also called the truncation threshold. For a prescribed extended charge density $\rho$, we consider the relation between the weak solution of the system \begin{equation} \begin{cases} -div\left(b\left(\frac12|\nabla\phi|^2\right)\nabla\phi\right)=\rho,& \text{in }\mathbb{R}^N,\\ b(s)=\mathcal{L}'(s),\quad\lim_{s\to\frac12^-} b(s)=+\infty,\\ \lim_{|x|\to\infty}\phi(x)=0 \end{cases} \end{equation} and the minimizer $\phi_0$ of the singular functional. We propose a monotonic approximation method to handle the intrinsic singularities of $\mathcal{L}(s)$. We prove that the gradient of the minimizer never touches the singular boundary $|\nabla\phi|^2=1$; this structural result yields a key integrability property, the existence and uniqueness of the minimizer, and the corresponding variational inequality. Under the additional assumption that $\rho$ is radially distributed, we show that the minimizer is the unique weak solution. Furthermore, we establish the $C^1$ and $C^2$ regularity of the minimizer under suitable integrability conditions on $\rho$, and provide a uniform estimate for the strict spacelikeness condition $|\nabla\phi_0|\le 1-\epsilon$, where the parameter $\epsilon>0$ is explicitly characterized in terms of the spatial dimension, the spatial region, and $\rho$. Our results extend the classical Born–Infeld theory to a general class of singular Born–Infeld type theories, thereby providing a unified framework for the variational analysis and regularity of such singular functionals and systems.
Read the full abstract

Quantum Physics

Geometry-Resolved Projection of RF Imbalance to Ion Micromotion in a Same-Phase Dual-RF Blade Trap

Chun-Yang Luan, Haiyu Ding, Cheng-Kang Pan et al. (+8 more)

Common-mode metrics of a high-$Q$ helical resonator do not determine the residual ion-side field in a dual-electrode drive. We combine a two-node differential RF model with single-electrode finite-element bases to obtain a computation-only, geometry-resolved projection for a same-phase blade trap. For a 3.5 pF external load per branch, the model gives a total effective branch capacitance of 7.640 pF and an HWHM-equivalent full branch-difference scale of 12.7 fF at $Q_{\mathrm{loaded}}=600$. The seven-segment geometry gives center and axial-RMS differential field coefficients of 640 V m$^{-1}$ and 635 V m$^{-1}$ per differential peak volt. A representative 10 fF mismatch with an effective 0.1 pF balance scale projects to 44.5/44.1 nm center/RMS $^{171}\mathrm{Yb}^{+}$ micromotion at 100 V common peak voltage. Supplementary thermal, bypass-admittance, and tested numerical cases characterize model sensitivity. All reported displacements are projections; no RF-bench or ion-side validation is claimed.
Read the full abstract

All authors Chun-Yang Luan, Haiyu Ding, Cheng-Kang Pan, Xiangjie Li, Lin Cheng, Gangxi Wang, Yuting Lei, Peilin Zheng, Shixin Hu, Xiang Zhang, Fei Wang