High Energy Physics (Phenomenology)
Collinearly Improved Balitsky-Kovchegov Evolution of the Gluon Wigner Distribution
Lei Wang
We study how collinearly improved small-$x$
evolution modifies the
elliptic gluon Wigner distribution and its coherent diffractive dijet $\cos2\phi$ signal. Starting from the $SO(3)$-symmetric Gubser initial condition, we compare fixed-coupling leading-order (LO) BK
evolution with the Iancu–Madrigal–Mueller–Soyez–Triantafyllopoulos (IMST) collinearly improved BK prescription, project the evolved dipole to Wigner/GTMD harmonics, and fold the result with
photon wave-function hard factors. Within the $SO(3)$-projected framework, the resummed
evolution moves the
elliptic node and changes the rapidity and hard-scale dependence of $C_2^{\rm coh}=\langle\cos2\phi\rangle$, rather than acting as a simple normalization shift. The effect is largest in node-sensitive windows but remains visible in broader sign-stable bins. Direct daughter-coordinate RHS tests and direct $(r,b,\phi)$
evolution quantify the residual projection ambiguity and check the observed trend. Projection-level EIC-like finite-bin estimates show that balanced high-$\Delta$ candidate bins offer a better compromise between
elliptic signal and denominator weight than the narrow bins with the largest ratio. The unresummed NLO curve is used only as a stability diagnostic; the physical comparison is between LO BK and IMST collinearly improved BK
evolution.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Eikonal Ringing, Shadows, Lensing, Grey-Body Factors, and Binding Energy of Asymptotically Flat Regular Black Holes in Phantom Dirac-Born-Infeld Gravity
Mardon Abdullaev, Gumisbek Allambergenov, Diyorbek Rashidov et al. (+2 more)
We develop a geodesic-optics description of eikonal quasinormal ringing, blackhole shadows, strong
lensing, grey-body factors (GBFs), and the binding energy of massive particles for the asymptotically flat regular black-hole geometry obtained in phantom Dirac-Born-Infeld (DBI)
gravity. The null-orbit structure admits an especially compact analytic treatment. The unstable
photon orbit remains at the Schwarzschild-like coordinate radius throughout the black-hole branch, while the orbital frequency and Lyapunov exponent coincide exactly. Consequently, eikonal quasinormal modes (QNMs), shadow radius, GBFs, and strong-deflection observables are all governed by a single dimensionless function of the core-size parameter. For timelike circular motion, we derive exact expressions for the specific energy and angular momentum, obtain the innermost stable circular orbit (ISCO) condition in closed implicit form, and show that the ISCO binding efficiency decreases as the regular core grows. We present illustrative plots for the exact geodesic invariants, the corresponding grey-body profiles, and the timelike binding-energy curves. The resulting construction provides an exact one-parameter bridge between the regular black-hole metric and its leading geodesic observables.
Read the full abstract ▾
All authors Mardon Abdullaev, Gumisbek Allambergenov, Diyorbek Rashidov, Pakhlavon Jamolov, Javlon Rayimbaev
Quantum Physics
A Quantum Collocation Approach to One-Dimensional Boundary Value Problems with Coherent Amplitude Amplification
Daniel Jaroszewski and Bastian Harrach
We propose a
quantum collocation framework for approximating solutions of one-dimensional linear and nonlinear boundary value problems. The method formulates the search for admissible solutions as a residual-based
quantum search over a discretized ansatz space, where candidate solutions are evaluated through residual conditions imposed at collocation points. A residual-threshold oracle is constructed that acts jointly on spatial and parameter registers. This joint oracle structure leads to amplification dynamics that decompose into a coherent superposition of spatially conditioned amplitude-amplification processes rather than a single global amplification mechanism. We derive the corresponding amplification geometry and show that the success probability is governed by a weighted combination of spatially dependent amplification angles. Furthermore, we prove that the reversible residual oracle can be implemented with gate complexity
polynomial in the logarithm of the number of collocation points, while retaining the quadratic search acceleration associated with amplitude amplification in the parameter space. We analyze how the spatially dependent oracle structure influences the amplification dynamics and corresponding success probabilities. Furthermore, we investigate how discretization, ansatz expressivity, oracle tolerance, and finite-precision effects influence both approximation quality and amplification behavior. Numerical experiments validate the theoretical predictions and illustrate the resulting search dynamics across different discretization and precision regimes.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Lei Wang
The
elliptic small-$x$
gluon Wigner distribution correlates transverse momentum with impact parameter, but it is usually accessed through exclusive diffractive dijets whose
recoil is sensitive to soft radiation. We propose instead an azimuthal energy-flow moment in DIS dijet production. Within leading-power small-$x$ dijet factorization, its normalized $\cos2\phi$ moment is a linear projection of the
elliptic Wigner harmonic after a calculable kinematic subtraction, while the final-state energy weighting is infrared and collinear safe. In conjugate
recoil space a rotationally scalar Sudakov factor evolves the isotropic and
elliptic channels through a fixed $J_0/J_2$ Hankel pair without $W_0\to W_1$ leakage. A proof-of-principle calculation gives a per-mille Sudakov-level moment in an unoptimized conservative window, while auxiliary perturbative-window scans reach several per mille. The observable therefore formulates
elliptic Wigner
tomography as a moment-level energy-flow measurement whose statistical reach can be assessed by simple angular-moment counting.
Read the full abstract ▾
Fluid Dynamics
Mean-Flow Adjoint Sensitivity Analysis of Unsteady Flow Around Porous Cylinders Using a Homogenized Lattice Boltzmann Method
Shota Ito, Johannes L. Grafen, Fedor Bukreev et al. (+2 more)
Adjoint-based sensitivity analysis is an indispensable tool for large-scale fluid-dynamic design and distributed control problems, yet its application to unsteady and turbulent flows is frequently hindered by the prohibitive
memory footprint of transient checkpointing and the divergence of gradients in chaotic regimes. To address these computational bottlenecks, this paper presents a mean-flow adjoint sensitivity analysis framework for unsteady flows around porous cylinders using the homogenized
lattice Boltzmann method (HLBM). Within this framework, solid structures are efficiently modeled as local porous media utilizing a Brinkman penalization approach. We systematically investigate HLBM-based adjoint gradients for drag and energy dissipation objective functionals, transitioning from steady laminar to unsteady, and finally to turbulent flow regimes. For the turbulent case at Re = 3900, a proof-of-concept is conducted where the framework relies on automatic differentiation to automatically generate adjoint kernels containing subgrid-scale (SGS)
turbulence models for large eddy simulations (LES), circumventing manual derivation and allowing for a direct comparison against the frozen
turbulence assumption (FTA).
Read the full abstract ▾
All authors Shota Ito, Johannes L. Grafen, Fedor Bukreev, Adrian Kummerländer, Mathias J. Krause
High Energy Physics (Theory)
Monitoring a de Sitter universe through an anti-de Sitter window
Sarah Hoback, Daniel L. Jafferis and Zixia Wei
We propose that AdS$_3$
gravity coupled to dS$_2$ end-of-the-world branes is dual to a
unitary holographic CFT$_2$ with non-
unitary conformal boundary conditions. These boundary conditions have complex $g$-functions and appear in conjugate pairs. The associated gravitational path integral admits no real saddles, but does admit complex saddles. We show that an AdS$_3$ black hole microstate with a dS$_2$ brane behind the horizon corresponds to the
unitary time
evolution of a pure CFT state prepared by a Euclidean path integral on a cylinder with such boundary conditions. The construction predicts a boundary-condition-changing primary with $h=-c/8$, which resides in the boundary sector rather than the bulk spectrum and is therefore compatible with unitarity of the underlying CFT. This realizes dS holography as state preparation in a
unitary AdS/CFT
Hilbert space.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Unveiling Radio Transients with SKAO Telescopes
James C.A. Miller-Jones, Kaustubh M. Rajwade, Patrick A. Woudt et al. (+1 more)
Transient astrophysics provides a set of unique laboratories for studying fundamental physics. From the launching of powerful relativistic jets to merging
neutron stars, highly-magnetised compact objects, or
stellar explosions, transients probe the Universe at its most extreme. The SKAO will provide an unrivalled set of capabilities for transient observations on timescales from nanoseconds to decades, opening new discovery space. With its sensitivity, broad spectral coverage, wide field of view, and high survey speed, SKAO will allow us to discover and understand rare events that provide powerful new insights into regimes of high energy density, strong
gravity, and intense
magnetic fields. Complemented by a suite of multi-wavelength and multi-messenger facilities, and supported by a network of smaller existing
radio telescopes and new computational capabilities, SKAO will unveil the most powerful and exotic events in our Universe, addressing some of the key questions in modern astrophysics and cosmology.
Read the full abstract ▾
All authors James C.A. Miller-Jones, Kaustubh M. Rajwade, Patrick A. Woudt, Jason W.T. Hessels
High Energy Physics (Phenomenology)
Hadronic exceptional points
Ahmad Jafar Arifi and Kei Suzuki
Exceptional points, where
eigenvalues and eigenvectors coalesce, are a defining feature of non-Hermitian systems and have been extensively observed in photonic, atomic, and condensed matter systems. However, they have received little
attention in
quantum chromodynamics (QCD), which is the fundamental theory of
quarks,
gluons, and
hadrons. We propose that imaginary
magnetic fields provide a simple realization of non-Hermitian dynamics in hadronic systems. Based on two theoretical approaches, a hadronic effective Lagrangian and a constituent
quark model, we compute mass spectra of neutral
mesons and find exceptional points separating the real-spectrum and complex-
eigenvalue regimes. In small fields, the real spectrum exhibits level attraction between hadronic states, whereas in larger fields,
hadrons are deconfined, which is a signature of a field-induced inverted potential. Our findings open a new avenue for studying QCD dynamics in non-Hermitian environments.
Read the full abstract ▾
Physics Education
Notes from the Physics Teaching Lab: Rubidium Atomic Spectroscopy
Kenneth G. Libbrecht
We describe a series of rubidium spectroscopy experiments that can be done using the Teachspin Diode
Laser Spectroscopy instrument, which is commercially available and is already being used in physics teaching labs at over 150 universities. Our goal here is to provide a detailed examination of the capabilities of this instrument, including numerous examples of measurements and data analysis, presented as a supplement to the Teachspin users manual. Our hope is that instructors using this product or similar diode-
laser-based Rb spectroscopy systems will find the experiments described here useful for designing and implementing the curricula in their own physics teaching labs.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Strain-Tunable Harmonic Responses in Valley-Polarized Bilayer Graphene
Narjes Kheirabadi and Aliasghar Shokri
We theoretically investigate the linear and second-order nonlinear optical responses of valley-polarized
bilayer graphene under uniaxial strain. Employing a low-energy effective
Hamiltonian that incorporates trigonal warping and strain-induced anisotropy, we calculate the optical susceptibilities within the
quantum kinetic formalism. We show that, while the second-order response vanishes in valley-balanced
bilayer graphene owing to the cancellation of contributions from opposite valleys, a finite valley polarization lifts this cancellation and enables a net second-harmonic generation (SHG) signal. Uniaxial strain substantially modifies the nonlinear response by distorting the low-energy electronic structure and altering the pseudospin texture, producing a highly anisotropic SHG spectrum. Pronounced resonant enhancements occur at
photon energies $\hbar\omega \approx E_f$ and $\hbar\omega \approx 2E_f$, associated with two-
photon and one-
photon interband resonances, respectively. Remarkably, changing the sign of the strain parameter reverses the direction of the induced second-harmonic current, providing a mechanically controlled switching mechanism for nonlinear optical transport. These results establish strain engineering as an effective route for manipulating valley-dependent nonlinear optical phenomena in
bilayer graphene and suggest new opportunities for tunable mid-infrared photonic and valley-optoelectronic applications.
Read the full abstract ▾
Quantum Physics
Relativistic Gravity-Induced Entanglement via Frame Dragging
Eyuri Wakakuwa, Luciano Petruzziello, Trinidad B. Lantaño et al. (+2 more)
Gravity-induced
entanglement has been proposed as a method for testing the non-classical nature of
gravity via tabletop experiments. While most existing proposals are restricted to the Newtonian limit, the frame dragging effect offers access to genuinely post-Newtonian features of the gravitational interaction and remains comparatively less explored. Here, we study
gravity-induced
entanglement generated by frame dragging in an interferometric setting and compute the
entanglement phase between the rotational degrees of freedom of a source mass and the paths of a particle in two complementary ways: (i) via Schrödinger
evolution with a quantized Lense-Thirring
Hamiltonian in the large angular momentum limit, and (ii) via the on-shell action of linearized
quantum gravity within the stationary phase approximation. Both approaches yield the same
entanglement phase, consistent with the proper time difference between the interferometer arms. The path integral derivation further reveals how gravitational retardation modifies the
entanglement phase, thereby making the local, relativistically causal linearized-
gravity description explicit. Under the standard locality/mediator assumptions used in existing arguments, the resulting
entanglement would witness non-classicality of the gravitational interaction.
Read the full abstract ▾
All authors Eyuri Wakakuwa, Luciano Petruzziello, Trinidad B. Lantaño, Susana F. Huelga, Martin B. Plenio
Astrophysics of Galaxies
AGN Feedback: The impact of galactic-scale radio jets on the interstellar medium in starbursting obscured AGN
M. Polletta, C.J. Lonsdale, P. Pallavi et al. (+4 more)
A highly
star-forming
galaxy at z ~ 2 hosting an obscured, luminous active
galactic nucleus (AGN) and a relativistic
radio jet sets the stage for a
cosmic crime scene. The victim is
star formation, the suspect is AGN feedback. These systems offer a rare opportunity to catch this process in the act. We propose SHARP@ELT integral-field spectroscopic observations of heavily obscured, luminous AGN with resolved
radio emission to witness the onset of feedback and its impact on the host interstellar medium (ISM). Such objects trace a short-lived (< 10^5 yr) evolutionary phase in which a recent starburst, newly triggered
radio jets, and a deeply embedded AGN coexist. In this phase, feedback is expected to suppress
star formation while clearing the dusty
nuclear regions. Using SHARP/VESPER, we will derive spatially resolved maps of
stellar ages,
star formation rate density, gas density, and ionization state, alongside the kinematics of
stars and ionized gas. By directly comparing these properties with the
radio structures, we will quantify the effects of both jet-driven and radiative feedback on the ISM. Our sample consists of eleven luminous, obscured AGN at 1.5 < z < 2.5 with resolved
radio emission on scales of ~1-15 kpc. Exploiting the VESPER multi-Integral Field Selector capability, we will obtain resolved continuum and emission-line maps for at least 110
galaxies at
cosmic noon, enabling a comprehensive characterization of their environment, multiphase ISM, and
nuclear activity within 55 h of integration time. SHARP will thus reveal AGN feedback at the epoch when it is most effective, providing a decisive step toward understanding its role in
galaxy evolution.
Read the full abstract ▾
All authors M. Polletta, C.J. Lonsdale, P. Pallavi, G. Vietri, A.E. Kimball, P. Franzetti, C.J. Lonsdale
Astrophysics of Galaxies
Fueling and feedback mechanisms at the nodes of the cosmic web
M. Polletta, G. De Lucia, A.R. Gallazzi et al. (+1 more)
The environment plays a key role in shaping how
galaxies form and evolve.
Galaxies in dense nodes of the
cosmic web are thought to grow and quench earlier, and faster and become more massive than those in the field. To understand the physical drivers of this environmental effect, we must probe the most crowded regions of the Universe at the epoch when growth was at its peak and the transition to quiescence was triggered, around 10 billion years ago (z ~ 2). This period saw the downturn of the
cosmic star-formation and black-hole
accretion histories, the quenching and morphological transformation of massive
galaxies, and the virialisation of the first clusters. Several processes might be at play:
stellar and AGN feedback, reduced gas
accretion, disk instabilities, morphological quenching, interactions, and ram-pressure stripping. The ELT/SHARP instrument, with its sensitivity, spectral resolution, wavelength coverage, and multiplexing capabilities over a wide field, is ideally suited to study these mechanisms by targeting multiple members of dense structures simultaneously. Cluster and protocluster cores at z ~ 2 span roughly 1 arcmin and host about ten massive (Mstar > 10^10.5 Msun)
galaxies. VESPER can deliver spatially resolved gas and
stellar kinematics, map recent and past
star formation, identify companions, inflows,
outflows, shocks, and AGN activity for the most massive core members. With 80 hr of VESPER time, we can obtain this type of data for about 60
galaxies selected from the densest regions of five clusters at 1.5 < z < 1.7 and five protoclusters at 2 < z < 2.5 spanning the evolutionary phases of maximal growth and rapid decline. Such a sample would permit to trace the
evolution from protoclusters to virialised clusters and identify the environmental processes responsible for their rapid transformations.
Read the full abstract ▾
All authors M. Polletta, G. De Lucia, A.R. Gallazzi, C. Mancini
Materials Science
Optimizing Ti substitution for the enhanced densification, ionic conductivity, and microstructure of garnet-type Li$_7$La$_3$Zr$_2$O$_{12}$ solid electrolytes
Neha, A. V. Deshpande, Muktai Aote et al. (+1 more)
Garnet-type lithium lanthanum zirconium
oxide Li$_7$La$_3$Zr$_2$O$_{12}$ (LLZO) is a favorable solid electrolyte for all-solid-state Li-ion batteries due to its wide electrochemical stability, compatible ionic conductivity, and good safety. However, further improvement in ionic conductivity is required for its practical applications. In this work, titanium (Ti) is doped into LLZO to enhance its Li-ion transport properties and structural stability. The series Li$_7$La$_3$Zr$_{2-x}$Ti$_x$O$_{12}$ has been successfully synthesized using conventional solid-state reaction method. The content of Ti has been varied from 0 to 0.20 atoms per formula unit (a.p.f.u). The conducting cubic phase has been confirmed by the X-ray diffraction technique (XRD). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) have been used for structural analysis, and elemental distribution. Density measurements have been carried out for all the samples. Electrochemical impedance spectroscopy revealed that the high ionic conductivity of $8.08\times 10^{-5}$ Scm$^{-1}$ is offered by the Li$_7$La$_3$Zr$_{1.9}$Ti$_{0.1}$O$_{12}$ sample, which has the lowest activation energy of 0.37 eV. The DC polarization analysis verified that the main contribution to conductivity in the 0.10 Ti sample comes from ions. A one order of magnitude increase in room temperature ionic conductivity is observed for the 0.10 Ti sample, making it a strong candidate for solid electrolyte applications.
Read the full abstract ▾
All authors Neha, A. V. Deshpande, Muktai Aote, Abhishek Pradhan
Quantum Gases
Suppressing Parametric Instabilities in Driven Bosonic Lattices through Multi-tone Control
Robbie Cruickshank, Samuel Lellouch, Marin Bukov et al. (+3 more)
Periodically driven
quantum systems offer remarkable flexibility in tailoring effective
Hamiltonians and synthetic band structures. However, such driving also induces heating and dynamical instabilities that limit the coherence and lifetime of many-body states. Here, we demonstrate that these instabilities can be suppressed by employing multi-tone driving schemes. Using a Bose-Einstein condensate of cesium atoms in an optical
lattice, we experimentally explore two approaches: pulsed driving composed of odd harmonics and two-tone driving with tunable amplitude and relative phase. We show that both methods allow independent control of the effective tunneling amplitude and Peierls phase factor, while significantly reducing
phonon excitation and the resulting rapid decay of the condensate. Numerical simulations and theoretical modeling based on Bogoliubov-de Gennes equations confirm the suppression of unstable modes under optimized driving conditions. Our results establish multifrequency drives as powerful tools for stabilizing driven many-body systems and pave the way toward robust Floquet engineering with interactions.
Read the full abstract ▾
All authors Robbie Cruickshank, Samuel Lellouch, Marin Bukov, Eugene Demler, Nathan Goldman, Elmar Haller
Disordered Systems and Neural Networks
Activated dynamics in the quantum random field Ising model
Ivan Balog, Lovro Šaravanja and Andrei A. Fedorenko
We study the critical dynamics of the
quantum random-field Ising model using the nonperturbative functional renormalization group (NP-FRG). The static critical behavior is found to be controlled by the zero-temperature fixed point of the classical random-field Ising model, where both thermal and
quantum fluctuations are dangerously irrelevant. Considering a family of
quantum dynamical universality classes defined by a bare dynamical kernel $F_\Lambda(\omega)\sim |\omega|^\sigma$, we show how this fluctuationless fixed point nevertheless controls the
quantum dynamics by computing the full Matsubara-frequency dependence of the running dynamical kernel $F_k(\omega)$. This is essential at zero temperature: a naive treatment of the dynamical kernel flow leads to a divergence at a finite length scale, resulting in apparent localization. In contrast, keeping the full frequency dependence of the dynamical kernel and choosing a regulator adapted to its running scale yields a controlled flow. The resulting dynamics is of activated form, with a relaxation time given by $\ln \tau \sim \xi^\Psi$. The exponent $\Psi$ is determined by the static RFIM fixed-point exponents and by $\sigma$. At finite temperature, the flow crosses over to the classical thermally activated scaling of the random-field Ising model. These results provide a quantitative field-theoretic realization of the heuristic activation scenario proposed earlier for the
quantum random-field model and establish a framework for analyzing the dynamics of other disordered
quantum systems that may exhibit similar tentative localization-like singularities.
Read the full abstract ▾
Chemical Physics
Contrastive Regularization of Machine Learning Potentials
Dimitrios Tzivrailis, Georgios Sotiropoulos, Alberto Rosso et al. (+1 more)
Machine learning models are increasingly trained as regressors and then deployed as generators, from
language models to learned simulators. In this setting, accuracy on held-out data says little about the distribution a model produces when it is sampled. We study this problem where the correct distribution is fixed by first principles, in machine learning interatomic potentials (MLIPs) trained by minimizing the mean squared error (MSE) on density functional theory (DFT) energies and forces, then used to run molecular simulations. The MSE never constrains the Boltzmann distribution that the potential defines, so an MLIP can match held-out DFT data and still drift, when sampled, into spurious minima that corrupt its thermodynamics. Building on the variational principle of statistical physics, we introduce Contrastive Regularized MSE (CRMSE), a post-training step in which the potential acts as its own energy-based model and learns to reproduce the distribution it generates, without any new DFT data. On molecules from the MD17
benchmark, CRMSE restores physical sampling and recovers DFT free-energy profiles, while keeping energy and force errors within chemical accuracy. Our results suggest that a model meant to be sampled must be trained on the distribution it produces, not only for pointwise accuracy.
Read the full abstract ▾
All authors Dimitrios Tzivrailis, Georgios Sotiropoulos, Alberto Rosso, Eiji Kawasaki
Quantum Gases
Universal scaling of many-body effects in quantum tunneling
Hongmian Shui, Chi-Kin Lai, Chengyang Wu et al. (+6 more)
Quantum tunneling is fundamental to diverse phenomena and underpins a wide range of modern technologies. In the study of superconducting
quantum computation and high-temperature superconducting materials, tunneling on multi-particle scale is central. Recently, several cold atom experiments successfully simulated the tunneling process in a many-particle ensemble. However, the many-body nature remains largely unexplored. Here, we observe the universal scaling of many-body effects in
quantum tunneling process, using a hexagonal-triangular
quantum simulator with independent control of barrier, temperature and interaction. In the weak-interaction regime, the critical tunneling coefficient scales parabolically with temperature under various conditions, in contrast to the linear scaling of single-particle tunneling. By further increasing the interactions beyond the mean-field regime, the scaling exponent decreases, consistent with
quantum field theory predictions. Our results address the fundamental question of how many-body effects renormalize
quantum tunneling, with direct implications for correlated
quantum matter and devices.
Read the full abstract ▾
All authors Hongmian Shui, Chi-Kin Lai, Chengyang Wu, Lorenzo Pizzino, Chi Zhang, Guohao Shen, Thierry Giamarchi, Hepeng Yao, Xiaoji Zhou
Space Physics
Cometary ion dynamics at a weakly outgassing comet
Victor Steinwand, Peter Stephenson, Zoe Lewis et al. (+3 more)
The ESA/Rosetta mission escorted comet 67P/Churyumov-Gerasimenko for two years, exploring its
plasma environment across diverse outgassing conditions.
Plasma density observations from the Rosetta
Plasma Consortium (RPC) are broadly categorized into two regimes for the ion dynamics, linked to the presence of a diamagnetic cavity at Rosetta's location. With a diamagnetic cavity present, ions detected by Rosetta are accelerated with respect to the neutral coma. Without a diamagnetic cavity present, at lower outgassing, and nearer the
nucleus, ions co-move with the neutrals. We examine the transition between regimes following Rosetta's last detection of the cavity in February 2016. During this transition, global 3D
plasma models of the cometary ionosphere underestimate
plasma densities. To investigate this underestimation, we assess the sensitivity of cometary ion densities to different parameters using a 3D collisional ion test particle model, driven by electromagnetic fields from hybrid modeling. We show that considering cometary electron cooling is necessary to model cometary ion dynamics within 100 km of the surface. Electron temperatures derived from collisional electron modeling affect ion dynamics via the ambipolar electric field, increasing ion number densities. We further show that the cometary electron cooling exobase organizes Rosetta
plasma density observations; different ion dynamics regimes are linked to the position of Rosetta relative to the exobase. These findings demonstrate that Rosetta was below this exobase for much of the post-perihelion period. They justify the absence of ion acceleration in
plasma density assessments and the use of uniform electron-impact ionization frequencies between Rosetta and the surface during post-perihelion.
Read the full abstract ▾
All authors Victor Steinwand, Peter Stephenson, Zoe Lewis, Esa Kallio, Arnaud Beth, Marina Galand
Soft Condensed Matter
Mesoscopic simulations of linear and ring polymer solutions with explicit hydrodynamics under good and poor solvent conditions
Ashish Kumar Singh and Angelo Rosa
We employ large-scale Dissipative Particle Dynamics simulations to investigate dilute solutions of linear
polymers and unknotted, non-concatenated ring
polymers in explicit solvent. By systematically varying solvent quality, we examine the interplay between hydrodynamic interactions, chain architecture, and intermolecular association. Under good solvent conditions, both linear and ring
polymers remain expanded and well dispersed, displaying center-of-mass dynamics consistent with normal
diffusion. In poor solvents, attractive
polymer-
polymer interactions drive the formation of irregular aggregates characterized by partial chain collapse, substantial interpenetration, and slower dynamics. Despite their different
topologies, the two
polymer architectures exhibit remarkably similar structural and dynamical responses across the solvent conditions considered. These results indicate that solvent quality largely determines the organization and transport properties of dilute
polymer solutions, whereas topological effects remain comparatively weak in the investigated regime.
Read the full abstract ▾
Strongly Correlated Electrons
Local magnon modes studied by dynamic magnetic pair-density function analysis
Shin-ichi Shamoto, Yukio Yasui, Kazuki Iida et al. (+4 more)
The dynamic
magnetic pair-density function (DymPDF) $D_{\rm M}(r, E)$ is obtained via the
Fourier transform of the dynamic
magnetic structure factor, $S_{\rm M}(Q, E)$, which is measured using nonpolarized inelastic
neutron scattering. While there is a long history of
magnetic excitation studies with $S_{\rm M}(Q, E)$, there are no reports on $D_{\rm M}(r, E)$. In this study, we examine simple magnet models and representative magnet examples, such as FeTiO$_{3}$ and YBa$_{2}$Cu$_{3}$O$_{6}$, to investigate the real-space dynamics of $D_{\rm M}(r, E)$. We derive the $D_{\rm M}(r, E)$ equations for simple magnet models in a low energy limit. By comparing these equations to the simulations, we demonstrate the characteristic energy dependence of real-space local
magnon modes, including the transition of the
magnon mode from acoustic to optical. Our novel analysis reveals the local
magnon modes accompanied by a sign change in each
spin-pair correlation at a given energy in nanoscale real space even under non-periodic conditions. This method is unique for studying local
magnetic dynamics.
Read the full abstract ▾
All authors Shin-ichi Shamoto, Yukio Yasui, Kazuki Iida, Yasuhiro Inamura, Motoyuki Ishikado, Mitsutaka Nakamura, Lieh-Jeng Chang
Astrophysics of Galaxies
First-star imprints in a metal-poor galaxy overdensity near the end of reionization
Zihao Li, Koki Kakiichi, Lise Christensen et al. (+24 more)
The first generation of
stars, known as Population III (Pop III), formed from
primordial gas consisting solely of hydrogen and helium and is believed to have emerged only a few hundred million years after the Big Bang. Detecting the chemical enrichment of metal-poor circumgalactic gas offers a promising way to trace the enrichment signature of Pop III
stars. Along the sightline to the
quasar SDSS J0100+2802, a metal absorber at $z = 5.945$, showing over-abundant carbon and silicon compared to
solar, has been reported to be consistent with the enrichment pattern of Pop III
stars. With the James Webb Space
Telescope, we report the discovery of an unusually metal-poor
galaxy overdensity of 17 members (mean
metallicity $\approx 3\%$
solar) near this metal absorber, which is $\sim 0.4$ dex more metal-poor than coeval
galaxies in similarly overdense environments. This less chemically evolved system may have provided favorable conditions for preserving the absorption signatures of Pop III enrichment. We infer a minimum dark matter
halo of $\log(M_{\mathrm{h,min}}/M_{\odot})=10.68^{+0.93}_{-1.72}$, supporting late-time Pop III formation at the outskirts of atomic hydrogen cooling
halos. Our findings open a promising observational pathway to identify the chemical imprints of the first
stars and constrain the conditions for their formation.
Read the full abstract ▾
All authors Zihao Li, Koki Kakiichi, Lise Christensen, Zheng Cai, Valentina D'Odorico, Jorryt Matthee, Daichi Kashino, Rongmon Bordoloi, Ruari Mackenzie, Trystyn A. M. Berg, Irene Vanni, Stefania Salvadori, Alessandra Venditti, Shiwu Zhang, Sarah E. I. Bosman, Eduardo Bañados, Frederick B. Davies, Xiaohui Fan, Hyunsung D. Jun, Xiangyu Jin, Mingyu Li, Sofía Rojas-Ruiz, Feige Wang, Jinyi Yang, Siwei Zou, Huanian Zhang, Yongda Zhu
Statistical Mechanics
Effects of confinement in a Brownian gas with simultaneous stochastic resetting and dynamically emergent correlations
Gabriele de Mauro, Satya N. Majumdar and Gregory Schehr
We study $N$ non-interacting Brownian particles in an external potential under simultaneous
stochastic resetting to the origin. Although they do not interact directly, common resets generate strong dynamically emergent correlations (DEC). We analyze how confinement modifies these correlations and the nonequilibrium stationary state for $V(x)=\kappa |x|^\alpha$, $\alpha\geq0$, focusing mainly on two analytically tractable cases: harmonic confinement (HC), $\alpha=2$, and box confinement (BC), $\alpha\to\infty$. In both cases the stationary state is controlled by the competition between confinement and resetting lengths. We derive exact results for the stationary joint distribution, density, correlations, extreme value statistics (EVS), and gap statistics. While the density behaves similarly in HC and BC, the normalized correlation coefficient differs sharply. In BC it is non-monotonic and overshoots the unconfined value, as hard walls suppress decorrelating trajectories. In HC it instead increases monotonically toward the unconfined limit. For general $\alpha$, the behavior is monotonic for $0<\alpha<\alpha_c=1+\sqrt{5}$ and non-monotonic for $\alpha>\alpha_c$. The difference between HC and BC is also visible in edge observables. In HC, the maximum scales as $M_1=O(\sqrt{\ln N})$ and has a limiting distribution with bounded support and a shape transition controlled by the ratio of the two length scales. In BC, the maximum is at distance $O(1/N)$ from the boundary, as in
equilibrium, but its fluctuations have a broad power-law tail with logarithmic corrections. The first gap shows a similar contrast: BC gives a smaller typical gap but stronger anomalous fluctuations than HC. Finally, we extend the EVS analysis to general $\alpha$ and identify, via simulations and scaling arguments, three universality classes: $0\leq\alpha\leq1$, $1<\alpha<\infty$, and the singular limit $\alpha\to\infty$.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Beating micromagnetic limits on skyrmion stability by long-range frustration
Shiwei Zhu, Moritz A. Goerzen, Changsheng Song et al. (+1 more)
Skyrmion stability is commonly assumed to scale with skyrmion size or exchange stiffness within micromagnetic models. Here, we demonstrate that long-range exchange frustration can break this paradigm, enhancing the collapse energy barrier without increasing skyrmion size or
magnetic energy scale. By mapping the continuum model onto a
spin-
lattice Hamiltonian, we find that skyrmions with identical micromagnetic parameters can exhibit significantly different energy barriers, depending on their underlying atomistic exchange interactions. We attribute this behavior to saddle point textures, whose pronounced noncollinearity captures long-range frustration beyond the micromagnetic approximation. We further develop an exchange optimization framework to predict that long-range frustration can double the energy barrier in physically realistic conditions, possibly valid for ultrathin films or van der Waals magnets. These results hold across different
lattice symmetries, revealing an intrinsic limitation of micromagnetics and establishing long-range frustration engineering as a promising route toward highly stable nanoscale skyrmions.
Read the full abstract ▾
All authors Shiwei Zhu, Moritz A. Goerzen, Changsheng Song, Dongzhe Li
Cosmology and Nongalactic Astrophysics
Ultralight dark matter mixed with primordial black holes
Xing-Yu Yang
Dark matter candidates span many orders of magnitude in mass, from ultralight bosonic fields to massive compact objects. In this work, we connect these two extremes by investigating ultralight dark matter (ULDM) mixed with
primordial black holes (PBHs). We study mixed ULDM-PBH
halos by separating the continuum PBH contribution from the shot-noise fluctuation generated by discrete PBHs. The continuum contribution enters the averaged Schrödinger-Poisson background, while the discreteness contribution is treated as a perturbation that induces ULDM eigenmode transitions and
soliton heating. The two contributions have distinct parametric dependencies: continuum effects scale with PBH fraction, whereas discreteness-driven transition rates scale with the product of PBH fraction and individual PBH mass in the perturbative regime. For a fiducial mixed
halo with ULDM particle mass $10^{-22}\,\mathrm{eV}$, virial mass of order $10^{10}\,M_{\odot}$, and PBH fraction $1\%$, the continuum PBH component modifies the background density, gravitational potential, and low-lying ULDM
eigenvalues only at the sub-percent level. Nevertheless, this percent-level continuum PBH contribution produces a tens-of-percent response in the coherent
soliton region, changing the radial mode participation by about $20\%$. For
stellar-mass PBHs, the discrete shot-noise fluctuation induces extremely slow ULDM mode transitions, with the fastest low-lying multiplet transition having a timescale of order $10^9\,\mathrm{Gyr}$ for
solar-mass PBHs. In this regime, the leading PBH effect is the continuum contribution, while discrete PBH shot noise is dynamically negligible on
galactic timescales.
Read the full abstract ▾
Astrophysics of Galaxies
A big step forward with SHARP: spatially resolved stellar population properties in passive galaxies at z > 1.5
A. Gargiulo, C. Mancini, F. R. Ditrani et al. (+6 more)
Understanding when and how massive quiescent
galaxies (log(M*/Msun) > 10.5) assembled their
stellar mass and quenched remains a central challenge in
galaxy evolution. Spatially resolved
stellar population measurements at z > 1.5 offer a uniquely powerful avenue to address this problem, as they can provide information on the radial variations in
stellar age,
metallicity, and enrichment histories in passive
galaxies as they first emerge. In this work, we present a feasibility study quantifying the transformative capabilities of the proposed IFU SHARP/VESPER at the ELT for performing such radial mapping of
stellar population gradients in passive
galaxies at 1.5 < z < 3. Using the COSMOS-Web catalogue, we define a realistic population of massive quiescent systems at 1.5 < z < 3 and model representative compact and extended
galaxies across this
redshift range. Through detailed simulations with the official SHARP ETC, we derive the exposure times required to reach S/N = 10-15 per resolution element at key rest-frame optical wavelengths. Our results show that SHARP will routinely measure
stellar population gradients out to 2Re for the majority of the population at z < 2.5 with integrations of about 20h, and that will reach at least Re in about 30h at z = 3. Thanks to MORFEO's MCAO and to its spatial resolution of 30mas SHARP/VESPER will also resolve the inner < 1kpc at all
redshifts considered, enabling for the first time, direct tests of quenching mechanisms linked to central mass build-up, bulge growth, and structural transformation. These findings demonstrate that SHARP/VESPER will open an entirely new observational window on the early
evolution of massive quiescent
galaxies, providing, for the first time, statistically meaningful, spatially resolved
stellar population constraints during the epoch when their
stellar cores were assembled.
Read the full abstract ▾
All authors A. Gargiulo, C. Mancini, F. R. Ditrani, S. Bisogni, P. Franzetti, G. Vietri, A. Gallazzi, M. Longhetti, S. Zibetti
Instrumentation and Methods for Astrophysics
Multi-Scale Contrastive Attention for Light-Curve Representation Learning
Torsha Majumder, Konstantin Malanchev and Emille E. O. Ishida
Current and next-generation time-domain surveys demand automated techniques capable of analyzing millions of light curves, observed in multiple filters, without relying on exhaustive human annotation or scarce spectroscopic follow-up. We present Astra-CLR, an
attention-based, self-supervised contrastive learning framework which enables the representation of raw light curves into a highly discriminative latent space. Pre-trained on $\sim$2.1 million unlabeled Zwicky Transient Facility light curves, the framework utilizes partial light curves as input sequences to generate asymmetric, multi-scale temporal views (explicitly contrasting shorter sequences against longer ones) forcing the network to learn a robust "local-to-global" mapping strategy. Furthermore, we introduce a novel multi-view late fusion architecture that extends the model to efficiently handle longer light curves with larger numbers of observations while accommodating the different cadences associated with each filter. The discriminatory power of the resulting representations was evaluated by using them as input to a Multinomial Logistic Regression classifier, trained to identify 12 broad classes of variability. Final accuracy achieved $\sim 0.70$. When applying a label-efficient, partial top-layer fine-tuning strategy, the topological structure of the latent space is significantly refined, boosting results to $\sim$0.77. Astra-CLR is the first publicly available multi-filter time-series
Transformer trained exclusively on real ZTF light curves. Results presented here demonstrate that it provides an ideal foundation for the development of end-to-end pipelines, taking into account color
evolution and respecting the inhomogeneous nature of astronomical light curve sampling.
Read the full abstract ▾
Chemical Physics
An Additive Reference Correction Scheme for the Transcorrelated Method
Johannes Hauskrecht, Kristoffer Simula, Yifan Cheng et al. (+3 more)
We introduce an additive reference correction for the transcorrelated (TC) method and its three-body mean-field approximation (xTC), to improve energy differences computed in small orbital basis sets. The correction is motivated by the observation that, for xTC atomization energies, the dominant error in double-{\zeta} bases originates from the reference contribution rather than from the correlation energy. In the proposed reference-corrected scheme (RC-xTC), the small-basis correlation energy is retained, while the corresponding TC reference energy is replaced by its value from a larger basis.
Benchmark calculations for the non-relativistic HEAT set with the Dunning basis-set family show that RC-xTC substantially improves both total and atomization energies relative to standard xTC in double-{\zeta} bases. At the CCSD(T) level, RC-xTC yields better atomization energies than CCSD(T)-F12a in the double-{\zeta} regime, while preserving the favorable total-energy accuracy of xTC. At the CCSD level, RC-xTC improves atomization energies relative to F12a throughout the full basis-set sequence. As the basis set is enlarged, xTC and RC-xTC become progressively identical, as expected from the construction of the correction.
Read the full abstract ▾
All authors Johannes Hauskrecht, Kristoffer Simula, Yifan Cheng, Evelin Martine Corvid Christlmaier, Daniel Kats, Ali Alavi
Mathematical Physics
Serre Relations in Yangian Doubles
A. Liashyk, S. Pakuliak and E. Ragoucy
Following the approach of B.~Enriquez~\cite{E} we exhibit the analytical properties of the products of the currents in the Yangian doubles restricted to the category of the highest weight representations. We will demonstrate that the Serre relations for the simple root currents in the Drinfeld's 'new' realization of the Yangian doubles \cite{Dnew,KhT-DY,LP1} can be reformulated as quadratic commutation relations between composed currents for the Yangian doubles associated with Lie
algebras of the classical series.
Read the full abstract ▾
Mathematical Physics
Stability of the Hydrogen Molecule and Related Issues
Jean-Marc Richard
We review the collaboration that led to the first rigorous proof of the stability of the hydrogen molecule within
quantum mechanics and discuss several related issues concerning few-charge systems. Particular emphasis is placed on the role of
symmetry breaking, the stability domains of Coulombic few-body systems, and some applications to exotic
hadrons in the
quark model.
Read the full abstract ▾