High Energy Physics (Theory)
$\texttt{SMaSH}$ : Simplify Massive Spinor Helicity
Aakash Kumar, Arnab Rudra and Rahul Shaw
We present $\texttt{SMaSH}$, a $\texttt{Mathematica}$ package to do spinor helicity computations in four spacetime dimensions $\href{https://github.com/aakash-kmr/SMaSH}{\text{(github)}}$. It can handle massive spinor helicity computations with explicit little group indices which is a novel feature. It can also handle massless as well as off-shell spinor helicity variables. It is designed to compute perturbative computations; it comes with predefined three point amplitudes and propagators for any masses and
spins (arXiv:1709.04891). It can implement the high energy limit over an expression, check the discrete $\tt{C,P,T}$ transformations, compute contact terms and impose gauge invariance for any scattering process. We have shown the usage of such functions for computing gauge invariant Weinberg minimal amplitudes (arXiv:2506:12431, arXiv:2504:06343). The package can also generate both real and complex numerical kinematics for any $n$-point scattering for arbitrary masses and energy scales by implementing the $\tt{RAMBO}$
algorithm. It is also rich with basic spinor helicity manipulations like Schouten simplification, Clifford
algebra manipulation, conversion between spinor helicity and Lorentz vectors, derivative w.r.t. spinors and their scalars, helicity scaling etc.
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Cosmology and Nongalactic Astrophysics
Large-scale structures of the Universe: physics, phenomenology, statistics
Cora Uhlemann
In this series of lectures, we seek to describe the
evolution of the
cosmic large-scale structure. We will discover the
cosmic web - the large-scale skeleton of matter traced by
galaxies. It arises from the interplay of the gravitational pull of dark matter and the expansion driven by dark energy. Major large-scale
galaxy surveys map the distribution of matter and
galaxies across most of the sky, spanning over 10 billion years of
cosmic history. I will guide you through some of the principles and challenges behind predicting the statistical properties of the matter and
galaxy distribution in vast
cosmic volumes. In particular we discuss the underlying nonlinear physics and resulting non-Gaussian statistics that need to be predicted to extract fundamental physics from observational data.
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High Energy Physics (Theory)
The two-dimensional disordered $O(N)$ sigma model
Martí Berenguer, Felix M. Haehl and Elisa Tabor
We introduce a two-dimensional $O(N)$ nonlinear sigma model with random Gaussian $p$-body interactions. The model combines the structure of a two-dimensional bosonic SYK-type
quantum field theory with the stabilizing spherical constraint of the nonlinear sigma model. At large $N$ we derive the Schwinger-Dyson equations on a
torus and analyze the solutions using both analytical approximations and numerical methods. We find a phase diagram qualitatively similar to that of the one-dimensional
quantum spherical $p$-
spin model, including a low-temperature transition to a
spin glass phase. This phase is characterized by a finite Edwards-Anderson order parameter, while the dynamical part of the two-point function displays an approximate scaling regime. These results provide a tractable setting for studying approximate conformal behavior and glassy physics in a two-dimensional relativistic field theory with disorder.
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Fluid Dynamics
Effect of an aligned current on the stability of oscillatory incompressible flow past a circular cylinder
Geng Chen, Lian Gan and Philip H. Gaskell
The stability of incompressible flow past a circular cylinder under collinear steady and oscillatory forcing is investigated within a two-dimensional Floquet framework. The flow is parameterised by the Keulegan-Carpenter number $KC \in [4,12]$, the steady-to-oscillatory velocity ratio $m \in [0,1]$, and the oscillatory Reynolds number $Re_m \in [20,100]$. The loci of the leading Floquet multipliers, and hence case-specific bifurcation modes, are examined by progressively reducing $Re_m$ to subcritical values for prescribed $m$. A steady current with $m > 0.5$ gives rise to a period-doubling subharmonic bifurcation that does not occur in purely oscillatory flow, where only synchronous and quasi-periodic modes arise. For $Re_m = 100$, three key features are discernible. First, the neutral stability curve in $(KC,m)$ space is strongly non-monotonic in $m$, separating intrinsically stable regions from those with single unstable modes; a sub-region of striking mode re-stabilisation appears beyond $m \approx 0.9$, where the flow recovers a $Z_2$-symmetric state at peak Reynolds number $\approx 190$, despite the steady and oscillatory components each being individually unstable. Second, a distinct regime supports the coexistence of two unstable modes of different types. Third, complementary direct numerical simulations show that, for a single unstable mode, the linear analysis successfully predicts the saturated nonlinear state even when $Re_m = 100$ substantially exceeds the critical Reynolds number, whereas under mode coexistence the quasi-periodic attractor tends to dominate the developed dynamics.
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Optics
Bound States in the Continuum and Unidirectional Guided Resonances Enabled by Competing Fourier Harmonics near the Fourth Stop Band
Sun-Goo Lee and Wook-Jae Lee
Bound states in the continuum (BICs) and unidirectional guided resonances (UGRs) are singular radiative eigenstates in planar photonic
lattices characterized by complete or directional suppression of out-of-plane radiation, respectively. Here, we show that, near the fourth stop band, the formation of BICs and UGRs can be understood within a unified two-pathway radiation model, in which the Bloch eigenmode radiates through indirect and direct pathways mediated by the first and second
Fourier harmonics of the dielectric modulation, respectively. In vertically symmetric photonic
lattices, when the two radiation components cancel each other out in both the upward and downward directions, BICs emerge. The model yields an analytical BIC condition that can be satisfied by tuning a single
lattice parameter, the duty cycle $\rho$, and is confirmed by finite-element simulations. By contrast, in vertically asymmetric photonic
lattices, the upward and downward radiation-cancellation conditions no longer coincide, allowing UGRs to arise when the cancellation condition is satisfied in only one direction. We introduce a zero-contrast grating (ZCG), in which the upper protruding grating region produces pronounced up-down asymmetry, and show that two off-$\Gamma$ UGRs emerge and can be merged at the $\Gamma$ point by tuning the
lattice parameters.
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High Energy Physics (Theory)
A UV-Finite Refinement of the Ryu-Takayanagi Relation in AdS$_3$/CFT$_2$
Philipp Dorau, Albert Much, Leonardo Sangaletti et al. (+1 more)
We establish a refined Ryu–Takayanagi (RT) relation in AdS$_3$/CFT$_2$ using relative
entropy as the central object, in place of the ultraviolet-divergent von Neumann
entanglement entropy. Adapting Hollands' exact result for the
chiral relative
entropy to a diamond region, we express the boundary relative
entropy between the
vacuum and a coherent state as a Schwarzian functional, which the Fefferman–Graham dictionary identifies with the asymptotic data of a Bañados geometry; the
rigidity of three-dimensional
gravity promotes this boundary identification to the bulk. To linear order in the metric perturbation, the relative
entropy then equals the variation of the RT geodesic length divided by $4G_N$. The construction rests only on the Bisognano–Wichmann/Borchers
theorem and the
holographic dictionary, giving a UV-finite, operator-algebraic counterpart to the RT relation.
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All authors Philipp Dorau, Albert Much, Leonardo Sangaletti, Rainer Verch
Strongly Correlated Electrons
Metamagnetism in UTe2: the roles of itinerancy and localization
Theodore I. Weinberger, Daniel Shaffer, Zheyu Wu et al. (+12 more)
The metamagnetic transition in UTe$_2$ plays a key role in stabilizing two enigmatic field-induced superconducting phases. One of these phases (SC2) is truncated by the transition, lying directly below it, while the other (SC3) sits predominantly above it and appears to be stabilized because of it. While numerous pulsed field studies have examined this transition, comparatively few steady field experiments have investigated it. Here we report a suite of measurements of metamgnetism in UTe$_2$, at ambient pressure by torque magnetometry and extraction magnetometry techniques, and of the magnetoconductance under pressure. Our steady field measurements resolve a complex sub-structure within the transition, with separate features that possess different temperature evolutions, pointing to distinct contributions from itinerant and localized moments. The itinerant contribution might relate to a possible
spin-density wave state. We theoretically model the
evolution of Kondo and RKKY interactions and propose that the SC2 state is stabilized under pressure due to the collapse of
magnetic anisotropy, leading to an enhancement of longitudinal
spin fluctuations along the hard $b$ axis, which are pair-forming in the $p$-wave channel.
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All authors Theodore I. Weinberger, Daniel Shaffer, Zheyu Wu, Dmitry V. Chichinadze, Jinxu Pu, Gang Li, Rui Zhou, Yurii Skourski, Dave Graf, Andrej Cabala, Vladimir Sechovsky, Michal Valiska, Michal P. Kwasigroch, F. Malte Grosche, Alexander G. Eaton
Optics
Quantum frequency comb with pump-selectable bin pairing and extraction-aware loading in a lithium niobate microresonator
Mohamad Reza Nurrahman, Hyeon Hwang, Nuri Han et al. (+6 more)
Integrated
quantum photonics requires bright, high-fidelity
photon-pair sources capable of spectral multiplexing, correlation control, and
circuit-compatible extraction. Cavity-enhanced spontaneous parametric down-conversion (SPDC) increases pair generation, but triply resonant operation imposes stringent pump-signal-idler spectral-
alignment constraints. Moreover, the trade-off between intrinsic generation and coincidence-to-accidental ratio (CAR) does not capture the usable output flux, which depends on
photon extraction. Here, we demonstrate a single-pass-pumped, resonator-enhanced
quantum frequency comb (QFC) source based on a periodically poled lithium niobate photonic-
crystal Fabry-P$\'e$rot microresonator. The device yields intrinsic and loaded brightnesses of 69.9 and 1.88 MHz/$\mu$W, respectively, and a maximum CAR of 16,000. Frequency-resolved measurements reveal 461 cavity-defined bins spanning 1495-1570 nm, and loaded spectral brightness approaching $4.29\times10^9$ pairs/(s$\cdot$mW$\cdot$nm). Heralded autocorrelation measurements yield a second-order autocorrelation $g_H^{(2)}(0)$ as low as $4.0\times10^{-4}$ for a selected high-CAR cavity-defined bin pair. In particular, tuning the single-pass pump deterministically selects correlated frequency-bin pairings within the fixed QFC grid while preserving brightness and pairwise coincidence rates. We further separate intrinsic generation from output
photon-pair flux, revealing the loaded-brightness-CAR relation. Together, pump-selectable bin pairing and extraction-aware loading point to tailored SPDC QFCs as chip-integrated nonclassical light resources for multichannel
quantum-state transport and information processing.
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All authors Mohamad Reza Nurrahman, Hyeon Hwang, Nuri Han, Guhwan Kim, Hong-Seok Kim, Kiwon Moon, Jung Jin Ju, Hansuek Lee, Min-Kyo Seo
High Energy Physics (Phenomenology)
Antideuteron production from beauty-hadron decays: a first phenomenological study
Marta Razza, Nicolò Jacazio and Francesca Bellini
Light antinuclei, such as antideuteron ($\bar{\mathrm{d}}$) and antihelium (${}^{3}\overline{\mathrm{He}}$,${}^{4}\overline{\mathrm{He}}$), provide a link between
collider physics and indirect Dark Matter searches. Despite extensive studies of antinucleus production in high-energy collisions, $\overline{\mathrm{d}}$ production from beauty-
hadron decays remains experimentally unconstrained and has not yet been quantitatively predicted. In this work, we present the first phenomenological study of $\overline{\mathrm{d}}$ production from $\overline{\Lambda}_{b}$
baryon and B$^{-}$
meson decays, providing the first estimates of the corresponding branching ratios. Beauty-
hadron decays are simulated with PYTHIA using realistic input kinematics and three hadronization scenarios. Antideuteron formation is modelled through a
quantum-mechanical coalescence approach based on an $\bar{\mathrm{d}}$ wave function derived from the Argonne $v_{18}$ nucleon-nucleon potential. Depending on the adopted hadronization model, we estimate inclusive branching ratios to be $(5.68 \pm 0.02)\times10^{-4} < BR(\overline{\Lambda}_{b} \rightarrow \overline{\mathrm{d}}+X) < (1.408 \pm 0.004)\times10^{-3}$ and $(7.4 \pm 0.3)\times10^{-6} < BR(B^{-} \rightarrow \overline{\mathrm{d}}+X < (4.34 \pm 0.07)\times10^{-5}$. The predicted rapidity- and transverse-momentum-differential yields populate the kinematic region where $\overline{\mathrm{d}}$ can be identified by the ALICE experiment, motivating dedicated searches for these decay channels. These results provide a quantitative
benchmark for $\overline{\mathrm{d}}$ production from beauty-
hadron decays and establish a phenomenological framework to support future experimental searches, with potential implications beyond
collider physics.
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Quantum Physics
End-to-End Learning of Quantum Control on Latent Dynamical Manifold
Jun-Dong Zhong, Zong-Yuan Ge, Feng-Hua Ren et al. (+1 more)
Traditional
quantum control relies on an iterative "simulate-then-optimize" paradigm, where dynamics simulation and control design are decoupled, leading to substantial computational overhead and limited scalability, particularly in noisy environments. Here, we propose an end-to-end
quantum control framework based on long short-term
memory, in which system dynamics and control strategies are learned jointly in a low dimensional latent
manifold. The model directly maps initial states and environmental parameters to both dynamical trajectories and optimized control pulse in a single forward pass. The framework is validated on adiabatic speedup in a two-level system and state transfer in a one-dimensional
spin chain under noise, achieving accurate dynamical prediction and control optimization. It improves the fidelity for both tasks and significantly reduces the optimization cost by three orders of magnitude compared with conventional iterative methods, while exhibiting strong generalization to multi-parameter, time-varying noise, as well as to different initial states and driving fields. Our work introduces a data-driven control paradigm based on latent
manifold learning, reducing the computational bottleneck of iterative optimization and enabling real-time adaptive control of complex open
quantum systems.
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All authors Jun-Dong Zhong, Zong-Yuan Ge, Feng-Hua Ren, Zhao-Ming Wang
Solar and Stellar Astrophysics
Multivariate Statistical Analysis of Low Mass Ratio Contact Binaries: Definition, Dynamical Stability, and Parameter Relationships
A. Poro, R. Poggiani, A. Foroutanfar et al. (+3 more)
This study explores multiple aspects of W Ursae Majoris (W UMa) contact binary systems with low mass ratios, providing empirical insights into their definition, structure, rotational stability, and parameter relationships. We first examined the range of mass ratios that characterize these systems and, based on an analysis of 818 contact binaries, established an empirical threshold of $q \approx 0.27$ to identify low mass ratio systems. To investigate rotational stability, we conducted a Monte Carlo analysis of the squared gyration radii ($k_1^2$ and $k_2^2$) and assessed the resulting
spin-to-orbital angular momentum ratio ($J_\mathrm{spin}/J_\mathrm{orb}$), finding that while $k_1$ remains nearly constant, $k_2$ and $J_\mathrm{spin}/J_\mathrm{orb}$ decrease slightly with increasing mass ratio, emphasizing the role of the secondary
star's internal structure. Moreover, we compiled a dedicated sample of 115 low mass ratio contact binaries and estimated their absolute parameters using
Gaia DR3 parallaxes. From this
dataset, we derived empirical parameter relationships for low mass ratio systems, which provide a useful reference for future observational and theoretical studies. The resulting
datasets and statistical summaries offer
benchmarks for modeling, stability evaluation, and evolutionary studies of W UMa-type binaries with low mass ratios.
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All authors A. Poro, R. Poggiani, A. Foroutanfar, R. Harzandjadidi, N. Kahali Poor, F. Alicavus
Cosmology and Nongalactic Astrophysics
A hidden reionization prior biases cosmological inference
Zihan Wang and Huanyuan Shan
Precision cosmology assumes that
cosmic reionization was a single smooth transition. We show that this assumption is in tension with current observations: the Planck optical depth, patchy kinetic Sunyaev–Zel'dovich (PkSZ)limits from SPT and ACT, and the Ly$\alpha$ forest endpoint cannot be simultaneously reproduced by any viable monotonic ionization history. Non-parametric reconstructions and Planck EE polarization provide independent support for an additional ionization component at $z \gtrsim 12$. Incorporating this early phase relaxes the upper bound on the summed
neutrino mass to $\sum m_\nu < 0.39$~eV ($95\%$ CL) and shifts $\sigma_8$ toward values preferred by weak-
lensing surveys, both consequences of the standard $A_s$–$\tau_e$ degeneracy. These shifts arise from relaxing a hidden prior on reionization shape rather than from new physics, and identify reionization shape as an implicit prior in cosmological inference. Next generation of CMB and 21~cm experiments will be able to test this directly,which will convert what has been an unflagged systematic on $\sigma_8$ and $\sum m_\nu$ into a quantified statistical uncertainty.
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Materials Science
Symmetry-Selective Strain Control of Spin-Momentum Locking and Spin Transport in Two-Dimensional Pentagonal Altermagnets
ShuaiYu Wang, Sheng Chen, Xiao-Ping Li et al. (+1 more)
Altermagnets are compensated magnets featuring momentum-dependent nonrelativistic
spin splitting generated by nontrivial operations connecting opposite-
spin sublattices. A direct
symmetry-based route to control this
spin splitting is to modify the real-space operations that define the altermagnetic
spin-momentum locking (SML). Here, we develop a strain-resolved
symmetry framework for two-dimensional pentagonal altermagnets, classifying whether uniaxial and shear strain tensors preserve, reconstruct, or eliminate the SML. Using the above criterion combined with first-principles screening, we identify 94 stable altermagnetic candidates from 3330 materials. These candidates cover all type-III
spin Laue groups of orthorhombic
lattices and are classified into three strain-response types: Type-I preserves the SML; Type-II reconstructs the SML through partial
symmetry breaking while retaining essential altermagnetic features; and Type-III destroys the altermagnetic SML. Representative materials further demonstrate this classification: ferroelastic $\alpha$-CoS$_2$ exhibits ferroelastically switchable SML and reverses the sign of the off-diagonal
spin conductivity; shear-strained \(\alpha\)-CoP\(_2\) undergoes a \(g\)- to \(d\)-wave reconstruction of the SML, activating off-diagonal
spin conductivity; and uniaxially strained FeSSe realizes strain-selected
spin-valley transport. This work provides theoretical and material guidance for strain-controlled transport in two-dimensional orthorhombic altermagnets.
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All authors ShuaiYu Wang, Sheng Chen, Xiao-Ping Li, Lei Wang
Computational Physics
Mosaic: A Benchmark Suite for Differentiable Physics Solvers
Andrin Rehmann, Heiko Zimmermann and Dion Häfner
Differentiable partial differential equation (PDE) solvers underpin solver-in-the-loop MLtraining, gradient-based optimal control, and inverse problems, yet the practical cost of obtaining correct, usable gradients from a given solver on a given problem is largely undocumented. Integration effort, computational cost,
memory, gradient accuracy, and numerical stability vary widely across solvers and are discoverable only by trial and error. We introduce Mosaic, an extensible benchmarking framework for differentiable PDE solvers that standardizes access to solver gradients. Each solver is packaged as a containerized component (Tesseract) exposing a uniform gradient API regardless of
language or automatic differentiation (AD) strategy, enabling researchers to evaluate, compare, and build on non-trivial physical solvers. Our evaluation of 14 solvers across fluid dynamics, structural mechanics, and heat transfer demonstrates that the
benchmark surfaces practically relevant differences: order-of-magnitude variation in computational cost and
memory, alongside setup incompatibilities and instabilities that rule out solvers for specific tasks. Despite this variation, all solvers that produce gradients converge to similar optima on our tasks, indicating that the practical barriers are
memory limits, numerical stability, and setup compatibility rather than gradient accuracy alone. Mosaic is open-source and available at github.com/pasteurlabs/mosaic.
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Quantum Physics
Non-equilibrium quantum thermometry with bosonic samples
Marek Winczewski, Michał Horodecki and Ricard Ravell Rodríguez
We study low-temperature non-
equilibrium quantum thermometry with a bosonic probe: a
quantum harmonic oscillator strongly coupled to a bosonic bath at temperature $T$ through a Drude–Ohmic spectral density. We treat the probe–bath dynamics both exactly, using the quadratic solution of Boyanovsky and Jasnow, and within a renormalized Gorini–Kossakowski–Lindblad–Sudarshan (GKLS) master equation. From the time-dependent covariance
matrix we extract the
quantum Fisher information (QFI) for general single-mode Gaussian probe states, including squeezed ones. In the strong-coupling, non-Markovian regime the QFI is non-monotonic in time, displaying bath-
memory revivals that make a finite interrogation time $t^*>0$ strictly optimal. By contrast, we prove that the Markovian QFI rises monotonically to its stationary value and develops no interior optimum, so that its optimum is always pinned to the boundary $t^*\to\infty$; this complements existing Markovian precision-rate bounds, which concern $(\mathcal F(t)/t)$ rather than the single-shot QFI $(\mathcal F(t))$. Squeezed initial states yield a large transient advantage that thermalisation eventually erases, establishing squeezing and interrogation time as complementary thermometric resources. At
equilibrium, strong coupling replaces the exponential Boltzmann suppression of the low-temperature relative error by a far milder
polynomial divergence. As the model maps directly onto
circuit quantum electrodynamics, these protocols appear within current experimental reach.
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Optics
Vibrational high-harmonics and period-doubling bifurcation probed by time-resolved electron diffraction
Alexander Schröder, Kai Nettersheim, Ferdinand Evers et al. (+1 more)
Nanoscale mechanical oscillators exhibit a plethora of nonlinear phenomena with promising applications for the sensing and clocking of processes down to atomic length scales. Oscillator dynamics are typically probed by electrical or optical means, providing only limited access to the spatial profile of the oscillator motion. Here, we introduce event-based convergent beam electron diffraction for the spatio-temporal mapping of nanoscale mechanical resonators in ultrafast transmission electron microscopy. Employing an optically driven silicon membrane resonator at various driving strengths, we gain access to nonlinear processes with increasing complexity, ranging from a simple Duffing behavior to nonlinear multimode coupling and period-doubling bifurcations. The time-resolved diffraction probing approach supports a spatial resolution down to a few nanometers and a temporal resolution of 5 ns and provides quantitative information on the local membrane bending. Because the diffraction signal responds to local displacement gradients, which become more pronounced as resonators shrink, this approach offers a route toward probing nonlinear nanomechanics at the atomic scale.
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All authors Alexander Schröder, Kai Nettersheim, Ferdinand Evers, Sascha Schäfer
Plasma Physics
Electrons with Anomalous Energy Generated in Gas-Filled and Vacuum Diodes
Victor F. Tarasenko, Vasily Yu. Kozhevnikov, Andrey V. Kozyrev et al. (+2 more)
It is shown that, when high-voltage pulses (with a voltage amplitude exceeding 100 kV in centimeter gaps) with a leading edge duration of 1 ns or shorter are applied to gas-filled and
vacuum electric discharge diodes, electrons with kinetic energies nominally exceeding the amplitude of the applied voltage are detected. In the experiments, electron beam attenuation curves were measured in absorbers consisting of Al foil of varying thicknesses. These curves were used to reconstruct the electron beam energy spectrum by regularizing the solution of an integral equation based on deep machine learning. The obtained spectra contain electrons with anomalously high energies, the proportion of which, depending on the conditions, can reach 25 percent. A control experiment with a long voltage pulse on a large-area
vacuum diode (voltage 150 kV, pulse duration 35 microseconds,
vacuum gap 12 cm, electrode area 75 x 15 cm2) showed that the proportion of electrons with anomalous energies is less than 0.2 percent. Experiments have shown that the main mechanism for generating electrons with anomalous energy is the spatio-temporal synchronism of the motion of fast electrons in the enhanced field formed in the gap by space charge.
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All authors Victor F. Tarasenko, Vasily Yu. Kozhevnikov, Andrey V. Kozyrev, Evgenii Kh. Baksht, Maxim S. Vorobyov
Materials Science
Unlocking Cryogenic Energy Storage by Constructing Dipole Glass with Unit-cell-level Polar Disorder
Yangyang Si, Denan Li, Yijie Li et al. (+21 more)
Cryogenic energy storage is vital for frontier technologies including deep-space exploration and
quantum computing, yet conventional electrochemical energy systems fail below ~230 K due to frozen ion migration. While relaxor-based dielectric capacitors provide high efficiency at room temperature, the intrinsic freezing/growth of polar nanodomains at extended cryogenic regime limits their applications with deteriorated hysteresis losses. Here, we realize superior cryogenic energy-storage performance by designing unit-
cell-level disordered dipole-glass state in Pb0.6Sr0.4ZrO3 thin films with composition near antiferroelectric-paraelectric phase boundary. The antiferroelectric-derived dipole-glass introduces enhanced unit-
cell-level complexity of dipole interaction that suppresses long-range ferroelectric order. This enables ultralow-hysteresis operation (efficiency > 88%) down to 4 K, delivering record-high energy density (211 J/cm^3) at 9 MV/cm, stability over 10^8 charge/discharge cycles and microsecond-scale charge/discharge capability. This work establishes a dipole-glass paradigm for cryogenic dielectric capacitors, opening a new avenue to highly-efficient energy-storage systems with broad applications in frontier nanoelectronics.
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All authors Yangyang Si, Denan Li, Yijie Li, Changsheng Chen, Jingxuan Li, Chao Zhou, Hao Xiong, Tianfu Zhang, Wenjin Liao, Zhongqi Ren, Huaicheng Yuan, Dong Li, Jing-Kai Qin, Cheng-Yan Xu, Ye Zhu, Yunlong Tang, Sujit Das, Jieun Kim, Junling Wang, Hao Pan, Fei Li, Zhen Chen, Shi Liu, Zuhuang Chen
Instrumentation and Methods for Astrophysics
On-sky Fibre-Target-Alignment of the 4MOST instrument: calibration and performance
Roland Winkler, Weijia Sun, Daniel Sablowski et al. (+9 more)
The 4-metre Multi-Object Spectroscopic
Telescope (4MOST) is a new wide-field, fibre-fed spectroscopic survey facility for the VISTA
telescope at ESOs Paranal Observatory. The instrument enables the simultaneous acquisition of 2436 spectra across a 4.2 square deg field of view, using a tilting spine fibre positioner feeding three dedicated spectrographs. In this paper, we describe the calibration process, and performance verification of the Fibre-Target-
Alignment (FTA) process for 4MOST. We show the complete FTA process, including calibration of the individual hardware- and software components. Namely the Metrology camera system, the Fibre Positioner AESOP, a spine based Secondary Guiding System, the sky to focal surface projection software, and residual minimization via raster scans. In total, the FTA system required one special tool, a large calibration target for the focal surface, and approximately 1 month of accumulated calibration work on the
telescope. The FTA process reached approx. 24 um (0.4 arc sec) RMS distance between fibres and targets on sky about 3 weeks after installation of the final hardware components of 4MOST, which is when 4MOST had its first light event. By the time of writing this paper, i.e. 6 months later, we reach approx. 16 um (0.27 arc sec) RMS. Currently, we far exceed our requirements in terms of accuracy, and are doing trade-off studies to maximize scientific returns.
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All authors Roland Winkler, Weijia Sun, Daniel Sablowski, Thomas Liebner, Ole Streicher, Steffen Frey, Ingo Stilz, Alexander Pramskiy, Scott Smedley, Thomas Szeifert, Diogo Rio Fernandes, Gerard Zins
High Energy Physics (Phenomenology)
Prospects for probing neutral vector-like leptons via pair production at a muon collider
Chong-Xing Yue, Mei-Shu-Yu Wang, Xin-Yang Li et al. (+1 more)
Vector-like
leptons (VLLs) are well-motivated candidates for physics beyond the standard model. We investigate the sensitivity of the $6$ TeV
muon collider to the neutral doublet VLL (denoted by $N$) via its pair production in an SU(2)$_L$ doublet model with hypercharge $Y=-\frac{1}{2}$. Assuming mixing with
muons, we study the subsequent decay $N\rightarrow W^+ \mu^-$ and analyze two representative signals, namely $4j2\mu$ and $2\ell2\mu E\mkern-10.5 mu/$, arising from the hadronic and leptonic decays of the $W$
boson, respectively. The signal and background events are simulated within a Monte Carlo framework, and a cut-based analysis is performed at the $6$ TeV
muon collider with an integrated luminosity $\mathcal{L}=4$ ab$^{-1}$ for the unpolarized and polarized beam configurations, $(P_{\mu^+},P_{\mu^-})=(0,0)$ and $(P_{\mu^+},P_{\mu^-})=(-1,1)$. We consider VLL masses in the range of $1300-2980$ GeV and evaluate the corresponding search sensitivity. Our results show that the $6$ TeV
muon collider could provide strong sensitivity to neutral doublet VLLs through the $4j2\mu$ and $2\ell2\mu E\mkern-10.5 mu/$ signals, particularly for the idealized fully polarized beam configuration, under the detector, polarization, luminosity and background assumptions adopted in this analysis.
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All authors Chong-Xing Yue, Mei-Shu-Yu Wang, Xin-Yang Li, Si-Yu Zhang
General Relativity and Quantum Cosmology
Comparing accretion disk profiles of Bogush-Galt'sov naked singularity and Kerr black hole
R. Kh. Karimov, R. N. Izmailov, A. A. Potapov et al. (+1 more)
It is well known that the Einstein-scalar system of general relativity can in principle yield non-unique exact spinning naked singularities, which lead to unique Kerr black hole when the scalar field is switched off. It is a challenging task to observationally distinguish these two types of objects. Since
accretion process could be a viable diagnostic for this distinction, the purpose of the present work is to explore whether there could be features in the
accretion profiles distinguishing the singularity from a Kerr black hole. Here we study the Novikov-Thorne thin
accretion to a new spinning naked singularity with a scalar charge $\sigma$ recently reported by Bogush and Gal'tsov (BG). Our study reveals that: (1) The conversion efficiency $\epsilon$ of the BG naked singularity is independent of $\sigma$ and (2) The maxima of emissivity profiles for the BG singularity tend to shift towards the inner disk ISCO boundary $r=r_{ms}$ and peak at a value significantly larger than those of a Kerr black hole with the increase of $a$, $\sigma$ and relative shrinking of $\sqrt{-g}$. All these effects are quantitatively tabulated, which reveal, for instance, that the flux from the naked singularity could be as high as $10^{5}$ times larger than that of a Kerr black hole. Since these distinguishing features are known to be shared also by other models of naked singularity, it is tempting to speculate that such behavior could be hallmark of naked singularities.
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All authors R. Kh. Karimov, R. N. Izmailov, A. A. Potapov, K. K. Nandi
Disordered Systems and Neural Networks
A stochastic model of a nuclear reactor with directed percolation. Overjump and maximum power
V. V. Ryazanov
A
stochastic risk model is applied to simulating the behavior of a
nuclear reactor in a situation where the
neutron chain length is described by a distribution with heavy "tails," such as the Pareto distribution. Probabilities of a fluctuation exceeding a critical threshold are obtained, and risk bounds for power-law distributions of jumps are estimated. Functionals of the reactor power maximum, the instant of first reaching the maximum, and the distribution of the overjump magnitude are considered. A relationship between the shape parameter and the physical constants of reactors is obtained, as well as the relationship with the noise spectrum and physical constants. The finite dimensions of a real reactor are taken into account. The autocorrelation function of the truncated Lévy process and its relationship with the frequency filters of the
neutron flux monitoring equipment are considered.
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Atmospheric and Oceanic Physics
Ocean-atmosphere interaction at the Gulf Stream sea surface temperature front: variability and impacts on midlatitude atmospheric circulation
Luca Famooss Paolini
Sea surface temperature (SST) gradients associated with western boundary currents affect the atmospheric circulation across a range of spatial and temporal scales. Yet, several aspects of ocean-atmosphere interactions linked to oceanic fronts remain unclear. This PhD thesis analyses such interactions for the Gulf Stream SST front (GSF). The first part assesses the atmospheric response to the interannual GSF meridional shifts and its dependence on model horizontal resolution, using ERA5 reanalysis and atmosphere-only simulations forced by observed SST. Results show that the response is strongly resolution dependent, with only simulations finer than 50km resembling observed anomalies. Locally, diabatic heating near the GSF is mainly balanced by vertical motion and transient eddy heat transport. At large-scale, the GSF shifts is associated with a homo-directional shift in the North Atlantic eddy-driven jet and storm track, mediated by changes in low-level baroclinicity. The second part assesses the North Atlantic Oscillation (NAO)-GSF interaction and the mechanisms through which the NAO forces the GSF shifts on decadal timescale, using atmosphere and ocean reanalyses. The NAO and GSF covary on decadal timescales only during 1972-2018. This non-stationarity is also reflected in their lead-lag relationship: the NAO leads the GSF shifts by 3 years during 1972-1990 and by 2 years during 1990-2018. The lag is interpreted as the joint effect of the fast response of wind-driven oceanic circulation, the lagged response of deep oceanic circulation, and the propagation of Rossby waves. However, Rossby wave propagation is evident only before 1990, suggesting that its non-stationarity may explain the different NAO-GSF time lag before and after 1990. Overall, the thesis improves understanding of GSF variability and its role in North Atlantic and extratropical
climate variability.
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Quantum Physics
Standard-quantum-limit-surpassing vector polarimetry using Rydberg atoms in an SU(1,1) interferometer
Weiqiang Guan, Yuetao Chen, Jun Zhou et al. (+3 more)
Vector polarimetry is an important application frontier for Rydberg-atom-based sensing. While prior research has largely concentrated on developing novel measurement schemes, high-sensitivity vector polarimetry remains an open question. Here we propose a theoretical framework for high-sensitivity detection of
radio-frequency (RF) electric field polarization direction, which is particularly suitable for weak-field detection. Under a static
magnetic field, the asymmetry in coupling between the Zeeman sublevels of the Rydberg atom and the RF field's polarization components enables the polarization angles to be determined from the atomic absorption index, which is retrieved via homodyne detection by incorporating the Rydberg atom system into an SU(1,1) interferometer. We derive the sensitivity of the polarization angles along with the corresponding standard
quantum limit (SQL) and
quantum Cramér–Rao bound (QCRB). Our results demonstrate a sensitivity surpassing the SQL across wide angular ranges using either dual coherent states or a coherent state combined with a squeezed
vacuum state as input. Significantly, the optimal sensitivity reaches below \SI{e-6}{\degree}, with sensitivities better than \SI{e-3}{\degree} maintained over most of the angular domain. This work establishes a foundation for high-precision vector polarimetry, thereby advancing the development of Rydberg-atom-based
quantum sensing and contributing to a deeper understanding of light–matter interactions.
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All authors Weiqiang Guan, Yuetao Chen, Jun Zhou, Keyi Li, Yu Huang, Shaoyan Gao
Statistical Mechanics
Quantum enhancement of information-mediated energy transfer
Shotaro Oki, Yuki Kadono, Kaito Tojo et al. (+2 more)
Thermodynamics of information identifies information flow as a thermodynamic resource, but whether
quantum coherence and collective coupling can enhance it at low
entropy-production cost remains unresolved. We address this question for interacting open
quantum systems by deriving a thermodynamic uncertainty relation that bounds information flow in terms of
entropy production in nonequilibrium steady states. We construct a
quantum engine in which N-fold degenerate ground and excited states are collectively coupled to heat baths. Collective jumps enhance heat currents and information flow linearly with N, while
entropy production remains independent of N, realizing a high-power, low-dissipation autonomous
quantum Maxwell's demon that leverages collectively enhanced information flow to pump heat against a temperature gradient. Beyond steady states, collective interactions amplify the
unitary component of
quantum information flow, yielding a quadratic enhancement of the free-energy charging power of
quantum batteries. Our results reveal scalable advantages of
quantum coherence and collective effects in
quantum engines.
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All authors Shotaro Oki, Yuki Kadono, Kaito Tojo, Takahiro Sagawa, Ken Funo
Physics and Society
Extracting behavioural properties from face-to-face interactions temporal networks: a measure of egonet persistency
Gabriel Maurial, Elisa Klüger and Mathieu Génois
Understanding how individuals repeat social interactions over time is a central problem in the analysis of temporal networks. In social systems, repeated interactions shape processes such as information
diffusion, collective coordination, and the emergence of social structure. Existing measures of egonet persistence often conflate genuine behavioural regularities with structural effects such as node degree, making it difficult to distinguish meaningful temporal correlations from random mixing. In this work, we introduce the Neighbourhood Persistency Criterion (NPC), a statistically grounded framework for quantifying egonet persistence across time. NPC combines classical similarity measures with tailored null models controlling for network
topology and interaction weights. We apply this framework to high temporal resolution face-to-face interaction networks collected at four Computational Social Science conferences using the SocioPatterns platform. Our results reveal a common behavioural structure across events, characterised by an exploration$\unicode{x2013}$exploitation trade-off in social interactions. While many individuals alternate between both strategies, others exhibit stable interaction patterns throughout the event. Importantly, these behaviours show little systematic association with socio-demographic attributes, suggesting that interaction strategies are shaped primarily by contextual factors rather than stable individual traits. NPC thus provides a flexible and interpretable tool for studying egonet persistence in temporal networks and social systems.
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General Relativity and Quantum Cosmology
Quantum fluxes and $\langle\hat{\Phi}^2\rangle$ for a non-minimally coupled scalar field: ringdown and tail on approaching the polar Kerr inner horizon
Maria Alberti, Noa Zilberman, Marc Casals et al. (+1 more)
We compute $\langle\hat{\Phi}^{2}\rangle_\text{ren}$ as well as the energy fluxes $\langle \hat{T}_{uu}\rangle_\text{ren}$ and $\langle \hat{T}_{vv}\rangle_\text{ren}$ (where $u$ and $v$ are the standard Eddington-Finkelstein coordinates) associated with a
quantum massless real scalar field $\hat{\Phi}$, with a general
curvature coupling constant $\xi$, near the inner horizon (IH) of a Kerr black hole, along the axis of rotation. The
quantum field is in the Unruh state, corresponding to an evaporating black hole. We renormalize these quantities by the state-subtraction method. We drop the assumption of minimal coupling to the
curvature, thereby generalizing the results of arXiv:2203.08502 for the fluxes at the IH. This requires understanding the asymptotic behavior of $\langle\hat{\Phi}^{2}\rangle_\text{ren}$ neat the IH. State subtraction allows us to push the computation of $\langle\hat{\Phi}^{2}\rangle_\text{ren}$ along the axis of rotation in the Kerr interior in arXiv:2409.17464 deeper into the near-IH region, exposing their final asymptotic behavior on approaching the IH. For $\langle\hat{\Phi}^{2}\rangle_\text{ren}$ (a $\xi$-independent quantity in the Kerr case), we find that the approach to its finite asymptotic IH value is given, per $\ell$-mode, by a ringdown phase (namely exponentially damped oscillations), followed by an inverse-power tail, both in the tortoise coordinate $r_{*}$ (which diverges at the IH). Interestingly, in the regime where the ringing dominates, the ringing's complex frequencies are (numerically) found to match twice the well-known classical quasinormal-mode frequencies in Kerr, and the inverse-power tails are found to be $r_{*}^{-2\ell-3}$ (resembling Price's law in the classical black hole exterior, upon replacement $t\to r_*$). [Abridged]
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All authors Maria Alberti, Noa Zilberman, Marc Casals, Adrian C. Ottewill
Cosmology and Nongalactic Astrophysics
Inferring Cosmology and Astrophysics from the High-redshift 21cm Signal with SKA-Low
Anshuman Acharya, Satadru Bag, Sabrina Berger et al. (+29 more)
The Square Kilometre Array's low frequency
telescope (SKA-Low) will enable inference of astrophysical and cosmological parameters from the redshifted 21 cm signal, probing the
Cosmic Dawn and Epoch of Reionisation. While the power spectrum is the primary target for initial detection, the inherently non-Gaussian nature of the 21 cm signal, driven by the patchy
evolution of ionised regions and
spin temperature fluctuations, encodes rich information accessible through higher-order statistics and morphological measurements. Extracting these constraints requires diverse inference tools, encompassing both sophisticated modelling frameworks (analytical, semi-numerical, numerical, and emulators) used to predict the 21 cm signal, and advanced inference techniques (
Bayesian, simulation-based, field-level) to connect statistics to the underlying physics. This chapter reviews these tools and explores the constraining power of different statistical probes accessible with SKA-Low, including the power spectrum, statistics beyond order two, moments of the signal distribution, and morphological measures. Combining these complementary statistics is crucial for breaking parameter degeneracies and unveiling the properties of the early Universe. We specifically assess the potential of the initial SKA-Low configuration (AA*) to measure
galaxy and IGM properties, demonstrating its capability for early science results. This chapter forms part of a comprehensive set detailing the Epoch of Reionisation and
Cosmic Dawn science case for the SKA-Low
telescope.
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All authors Anshuman Acharya, Satadru Bag, Sabrina Berger, Michele Bianco, Daniela Breitman, Lilian Crascall-Kennedy, Saswata Dasgupta, Abhirup Datta, Marian Douspis, Ivelin Georgiev, Sambit K. Giri, Adélie Gorce, Caroline Heneka, Julien Hiegel, Ian Hothi, Akanksha Kapahtia, Nicholas Kern, Yashrajsinh Mahida, Barun Maity, Suman Majumdar, Romain Mériot, Rajesh Mondal, Steven G. Murray, Leon Noble, Samit Kumar Pal, Aurel Schneider, Benoit Semelin, Abinash Kumar Shaw, Hayato Shimabukuro, Emilie Thélie, Anshuman Tripathi, Cathryn M. Trott
General Relativity and Quantum Cosmology
Testing generalized spacetimes for black holes using the Hod function representation of the hoop conjecture
K. K. Nandi, R. N. Izmailov, R. Kh. Karimov et al. (+3 more)
The hoop
conjecture, due to Thorne, is a fundamental aspect of black holes in classical general relativity. Recently, generalized classes of regular spherically symmetric static black holes with arbitrary exponents coupled to nonlinear electrodynamics have been constructed in the literature. The
conjecture in those spacetimes could be violated if only the asymptotic mass $M_{\infty}$ is used. To avoid such violations, Hod earlier suggested the appropriate mass function and stated the
conjecture in terms of what we call the Hod function. The
conjecture can then be applied to any given static spacetime to test whether or not it represents black holes. It is shown here that the
conjecture is protected in the above constructed class of generalized spacetimes thus supporting them as black holes. However, it is argued that there are factors, including violation of the
conjecture, that militate against the proposed new class of solutions to be qualifying as black holes. Finally, we exemplify that the Hod mass $M(r\leq R)$ in the
conjecture is exactly the matter counterpart of the Misner-Sharp geometrical quasilocal mass $m(r\leq R)$ of general relativity. Thus any conclusion based on Hod function is strictly a conclusion of general relativity.
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All authors K. K. Nandi, R. N. Izmailov, R. Kh. Karimov, G. M. Garipova, R. R. Volotskova, A. A. Potapov
Quantum Physics
Simulating the Dynamics of Markovian Quantum Processes by Quantum Collision Models on Quantum Computers
Zeqing Wang, Julian D. Teske, Anshuman Bhardwaj et al. (+2 more)
Hamiltonian dynamics have been widely implemented on noisy intermediate-scale
quantum devices in recent years. In contrast, experimental demonstrations of Markovian
quantum dynamics remain limited, because implementing nonunitary
evolution on
quantum computers is challenging.
Quantum collision models provide a natural approach to this problem by coupling the system to ancillas to realize dissipation. However, previous implementations of
quantum collision models on
quantum computers have typically been restricted to one or two system
qubits and fewer than 12 time steps, owing to noise,
circuit depth, the overhead of ancilla reset, and limited
qubit resources. In this work, we experimentally simulate Markovian
quantum processes with local and nonlocal dissipation on both trapped-ion and superconducting
quantum computers. By employing hardware-specific ancilla strategies, we realize simulations with up to seven system
qubits, corresponding to 13
qubits in total, and 40 time steps. Our results demonstrate that, even for the same physical model, the optimal implementation strategy depends strongly on the hardware characteristics of the
quantum computer.
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All authors Zeqing Wang, Julian D. Teske, Anshuman Bhardwaj, Masahiro O. Takahashi, Seiji Yunoki