Statistical Mechanics · Cross-listed from math.PR
Large deviations, gradient flows and fluctuating hydrodynamics for fractional diffusion
Julien Barre and Hiroshi Horii
This work is a step towards a general understanding of fluctuations for systems of particles described at large scale by fractional
diffusion. First, we derive formally a Large Deviation Principle for the empirical measure of mean-field interacting particles with a Lévy-type noise. In the case of independent particles, this unveils a generalized gradient flow structure at large scales. Second, we derive and solve numerically a
stochastic Partial Differential Equation describing the fluctuating hydrodynamics of this system. The results compare well with direct numerical integration of the particles' dynamics.
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Materials Science
Orientation-Resolved Nanoindentation of Single Crystal Ti-15Mo: Inverted Elastic Anisotropy and Yield-Onset Behavior Beyond Simple CRSS Predictions
Kidus Abebe, David Gaetano, Aurelia Moriyama-Gurish et al. (+4 more)
Ti-15Mo (wt%) is a well-established $\beta$-stabilized
alloy whose mechanical response is strongly governed by phase stability and deformation mechanisms that operate at the single-grain scale. Because these intragranular mechanisms are intrinsically anisotropic, understanding the orientation dependence of the elastic and plastic response is critical to the texture-engineered processing of wrought components. Here, we quantify the nanomechanical anisotropy of single-
crystal Ti-15Mo by combining EBSD with nanoindentation to correlate hardness, indentation modulus, strain rate sensitivity, and indentation yield response with the crystallographic surface normal near $\langle111\rangle,\langle124\rangle,\langle011\rangle,\langle023\rangle$, and $\langle013\rangle$ directions. While the modulus anisotropy is small (~10%), contrary to the prediction for a cubic
crystal with A>1, orientations near $\langle111\rangle$ exhibit the lowest moduli. Yield onset is likewise softest near $\langle111\rangle$ and spans 41%, while hardness spans only 6.6% and follows neither the modulus nor the yield ordering. The
alloy also exhibits yield behavior not captured by the simple CRSS/Schmid-factor models evaluated here. Strain-rate-jump tests yield V*=18-31b$^3$, consistent with kink-pair-nucleation-controlled plasticity; based on V*, the orientations separate into two groups suggestive of glide-dominated versus twin/transformation-participating response. We reveal an inversion of the elastic anisotropy expected for a homogeneous cubic $\beta$-phase and an orientation-dependent yield-onset response that is not reproduced by the simple Schmid-factor models examined here. Retained athermal $\omega$ is proposed as the contributor because $\beta\rightarrow\omega$ collapse occurs on {111}$_\beta$ planes and may provide anelastic compliance through the reversible $\omega\rightarrow\beta$ transformation.
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All authors Kidus Abebe, David Gaetano, Aurelia Moriyama-Gurish, Jana Šmilauerová, Yanfei Gao, Udo D. Schwarz, Amit Datye
Materials Science
High-throughput screening of Heusler alloys for thermoelectrics combining machine-learned densities of states and first-principles transport
Shivam Randive, Rahul Dixit and Himanshu Pandey
Thermoelectrics turn waste heat into electricity, but finding new ones requires transport calculations too costly for whole databases. Searches therefore choose what to calculate from the electronic density of states (DOS), increasingly predicted by machine learning, yet such choices are rarely tested. We test them on all 106,235 Heusler structures in the DXMag database, screening 51,257 on density-functional spectra and 54,978 on neural-network predictions, and judging both by 3,625 band-structure and transport calculations. A DOS-derived Seebeck indicator ranks most compounds passing every transport and stability test within the top 1% of their population, and ten of the eleven established half-Heusler thermoelectrics calculated pass. Predicted spectra lose most band gaps, unnoticed by spectral-similarity metrics, yet still rank passing compounds near the top. The screen certifies 80 computational candidates, 61 without reported measurements. Computed or predicted, the DOS can choose what to calculate; only a band structure shows whether a gap exists.
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Strongly Correlated Electrons
Non-Hermitian Statistical Geometry
Xi Hu, Yan-Qiong Ma and Su-Peng Kou
Particle exchange in two dimensions gives rise to
quantum statistics beyond the
boson-
fermion dichotomy, with central roles in fractional
quantum Hall physics, topological
quantum computation, and strongly correlated
quantum matter. In conventional topological phases, microscopic exchange geometry is compressed into rigid braid and fusion data. We develop a theory of non-Hermitian statistical geometry in which relaxing Hermiticity softens these exchange data into a larger complex space of spectral and relative-
geometric degrees of freedom. For two adjacent braid generators, a single projective exchange spectrum is insufficient: their relative eigenline geometry supplies an additional gauge-invariant modulus. On the generic irreducible two-channel branch, braid consistency locks these coordinates through an exact spectrum-geometry relation. Using Riesz projectors and Kato transport, we realize this geometry in a five-arm Kitaev-Majorana network and test spectral and relative-
geometric responses in an independent two-dimensional four-
vortex Kitaev model. Finite-time dynamics tests the exchange operation, microscopic fusion sewing tests its composition across fusion descriptions, and matched-spectrum controls isolate the role of relative geometry. Nonzero projective Kato
curvature shows that braid-consistent, fusion-coherent exchange can depend on the control path. Non-Hermiticity thus exposes exchange geometry, braid consistency re-locks it, fusion coherence further constrains it, and projective flatness determines when
geometric exchange becomes intrinsically topological.
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Medical Physics · Cross-listed from math.NA
Numerical simulation of biological capsules based on interface-fitted polygonal meshes
Daniele A. Di Pietro, Simon Mendez and Aurelio E. Spadotto
In this work we introduce a numerical framework for the simulation of biological capsules based on meshes that adapt iteration-wise to the shape of the membrane. The discretization leverages a Hybrid High Order method (HHO) to solve a Stokes problem with a source term distributed on the interface between the internal and the external phases. The HHO discretization supports meshes composed of general polygons, permitting to use fitted meshes that can be easily generated by cutting the elements intersected by the interface. Moreover, polygonal meshes allow arbitrarily accurate interface discretizations without introducing bulk degrees of freedom. The presentation of the simulation
algorithm is completed with a proof-of-concept numerical test on a well-established
benchmark: the deformation of an elastic capsule immersed in a shear flow.
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Superconductivity
Effects of the choice of the exchange-correlation functional on high-temperature superconductivity predictions in covalent-cage M(BN)5 family
Zhongyu Wan, Guo-Hua Zhong, Cheng-wei Ju et al. (+2 more)
The recent experimental synthesis of covalent cage
superconductors has ignited hopes for ambient-pressure high-temperature superconductivity, while the computational strategy for discovering new materials poses challenges for accurately estimating superconducting properties. Here, we quantified the response of electron-
phonon coupling (EPC) properties in M(BN)5
superconductors to different exchange-correlation (XC) effects using high-throughput first-principles calculations. We found that the metallic covalent bonds responsible for superconductivity exhibit anomalously high sensitivity to functional selection uncertainty, distinguishing them from conventional
superconductors mediated by metallic bonding. The widely used PBE functional systematically overestimates
lattice volumes, inducing
phonon softening, enhanced EPC, and consequent Peierls instability. In contrast, PBEsol, which is more accurate through enhanced treatment of short-range interactions, eliminates imaginary frequencies in Rb(BN)5 that appear at the PBE level, yielding an outstanding superconducting critical temperature (Tc) of 113 K at ambient pressure and 138 K at 2 GPa. Enhanced electron localization and short-range correlation in covalent bonds manifest through dual mechanisms:
phonon hardening at the
lattice scale and band widening at the electronic scale, which collectively suppress Peierls distortion and delocalize antibonding states. Pressure-dependent analysis reveals that compression attenuates
phonon discrepancies between XC functionals, whereas electronic properties remain notably sensitive to XC-induced perturbations of fine electronic bands near the Fermi level.
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All authors Zhongyu Wan, Guo-Hua Zhong, Cheng-wei Ju, Ruiqin Zhang, Hai-Qing Lin
Optics
Experimental Demonstration of 7-Dimensional N-Vector Model with Dimensional Inflation and Annealing
Daniele Veraldi, Marcello Calvanese Strinati, Paolo Charlesworth et al. (+4 more)
We report the first experimental realization of a physical system described by a high-dimensional
Hamiltonian comprising up to seven dimensions. Our setup is based on a holographic optical computer, which realizes a dimensional inflation by spatial and temporal multiplexing of lower dimensional systems. We demonstrate an $N$-vector model, with applications in field theory and computing. The approach is scalable and enables table-top implementation of high-dimensional theoretical models, and novel methods for combinatorial optimization. We experimentally demonstrate dimensional annealing: by dynamically reducing the number of dimensions, the ground state of an Ising model is found in complex graphs by an adiabatic
evolution from high-dimensional spaces.
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All authors Daniele Veraldi, Marcello Calvanese Strinati, Paolo Charlesworth, Matteo Spaziani, Silvia Gentilini, Davide Pierangeli, Claudio Conti
High Energy Astrophysical Phenomena
Low-frequency spectra and scattering of pulsars towards the Gum Nebula with the MWA
Ting Yu, Zhifu Gao, Zhongli Zhang et al. (+1 more)
Context. The Gum Nebula is a nearby ionised complex with sight-line-dependent
pulsar propagation. Aims. We test whether a smooth ionised structure can explain low-frequency spectral turnovers and pulse broadening, or whether smaller-scale material is required. Methods. We analysed Murchison Widefield Array observations of six
pulsars at 80–240 MHz, combining sub-band flux densities with literature data. We compared power-law, free–free absorption (FFA), and turnover-constrained broken-power-law (BPL) spectra, and modelled scattering through pulse-profile convolution. PSR J0820-4114 and the Vela
pulsar were fitted jointly across frequency. Results. All six spectra depart from a single power law. FFA is favoured for PSRs J0737-3039A and J0820-4114, and BPL for J0742-2822 and J0835-4510; the other two classifications depend on assumed error floors. Conditional FFA solutions imply emission measures of $10^4$–$10^5$ pc cm$^{-6}$ for electron temperatures of $3\times10^3$–$10^4$ K, far exceeding smooth-shell expectations. PSRs J0737-3039A and J0837-4135 have scattering laws consistent with $\tau_{\rm sc}\propto\nu^{-4}$. We obtain $\alpha_{\rm sc}=-3.07\pm0.11$ for J0742-2822 and $-1.59\pm0.44$ for J0820-4114 using a joint two-component model. The Vela
pulsar is best described by an effective thick-screen model with $\alpha_{\rm sc}\simeq-2.74$. Neither tested Galactic electron-density model reproduces both independent distances and low-frequency scattering uniformly. Conclusions. The results favour a structured Gum–Vela magneto-ionic environment in which neighbouring sight lines probe different absorbing and scattering material; these effects need not arise in the same
plasma component.
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All authors Ting Yu, Zhifu Gao, Zhongli Zhang, Weicong Jing
Atmospheric and Oceanic Physics
Linking Horizontal and Vertical Submesoscale Lagrangian Dynamics South of the Ibiza Channel
Sara Cloux, Ismael Hernandez-Carrasco, Alejandro Orfila et al. (+2 more)
Fronts, eddies, jets, and meanders populate the ocean surface and play a key role in organizing transport and mixing across a wide range of scales. From a Lagrangian perspective, frontal structures are conveniently detected as surface filaments that act as barriers to horizontal transport. However, the degree to which these structures maintain coherence below the surface and the relationship between horizontal and vertical motions in their vicinity remain poorly understood. Here we analyze two such filaments in the western Mediterranean Sea, south of the Ibiza Channel, using a high-resolution ocean simulation and Lagrangian diagnostics specifically designed to characterize submesoscale transport. Backward Finite-Size Lyapunov Exponents (FSLE) computed at successive depths reveal nearly vertical, curtain-like structures extending several tens of meters into the water column, with intensity decreasing with depth. Vertical-velocity sections across the filaments show coherent downward motion aligned with the filament cores, while Lagrangian trajectories indicate rapid horizontal convergence of fluid particles accompanied by sustained downward displacement. The barrier effect of Lagrangian Coherent Structures (LCSs) is commonly associated with persistent dynamical features of large-scale flows. Here, however, we demonstrate that FSLE filaments generated by rapidly fluctuating submesoscale dynamics can also act as effective transport barriers. The results demonstrate that the surface signatures of Lagrangian filaments identified through FSLE techniques correspond to three-dimensional transport structures that regulate both lateral aggregation and vertical connectivity in the upper ocean.
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All authors Sara Cloux, Ismael Hernandez-Carrasco, Alejandro Orfila, Emilio Hernandez-Garcia, Cristobal Lopez
Materials Science
Local-resolvent formulation and assessment of linear-scaling Kohn-Sham calculations
Albert Linda
Kohn-Sham density-functional theory is expensive because it needs orbitals that extend over the whole system. For
insulators this can be avoided by using only the diagonal of the one-electron resolvent, $g(\mathbf{r},z)=\langle\mathbf{r}|(z-\hat h)^{-1}|\mathbf{r}\rangle$, at a few complex energies $z$. We call the scheme local-resolvent density-functional theory (LRes-DFT). The density and the band energy are linear in $g$, so neither orbitals nor a kinetic-energy functional are needed. The complex energies are $M$ equally spaced points on a circle that encloses the occupied levels, offset by half a spacing so that no point lies on the real axis. Summing the resolvent over them is equivalent to occupying each level with $1/(1+u^M)$, where $u$ is the level's energy measured from the circle's center in units of its radius. This is a smooth step that is near 1 inside the circle and near 0 outside, and it stays between 0 and 1 for every $M$. If the circle moves with the chemical potential, forces at fixed electron number are exact. Gauss-Legendre and Zolotarev rules need fewer points when the gap is small. In three dimensions we use eigenpairs of small windows around each molecule instead of resolvents. This is divide-and-conquer (DC) with a different occupation function, and it is as accurate as DC with Fermi-Dirac occupations. For H$_2$ molecular
crystals of up to 1024 electrons it agrees with Kohn-Sham to $2.5\times10^{-7}$ Ha per electron. On one core it is slower than dense diagonalization below about 500 electrons and 3.5 times faster at 1024 electrons. It loses accuracy for disordered or compressed systems and for diffuse basis functions.
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Solar and Stellar Astrophysics
MATISSE unveils a dusty disc in the interior of EP Aquarii. First evidence of a misaligned hierarchical triple system with a central AGB star?
J. Alonso-Hernández, C. Paladini, C. Sánchez Contreras et al. (+26 more)
Aims. We have mapped the dust and molecular gas emission distributions in the vicinity (a few stellar radii) of the asymptotic giant branch (AGB)
star EP\,Aquarii, with a previously reported stellar companion at $\sim$50\,au, to search for binary-induced asymmetries. Methods. We present an analysis of new high-angular-resolution ($\gtrsim$4\,mas) images obtained with MATISSE (in the wavelength range $\sim$3–8\,\mum) as well as archival high-angular-resolution ($\gtrsim$20\,mas) ALMA $\rm^{12}$CO\,(c$J$=2-1) line and continuum emission observations ($\sim$230\,GHz), to study the circumstellar morphology and kinematics of the molecular gas on these spatial scales. Results. The MATISSE images display a bright central source and two slightly extended emission features ("blobs") located on opposite sides of the AGB
star (at radial distances of $\sim$4–10\,au). These structures are consistent with previous mid-infrared interferometric observations, suggesting stability over decades. The central source is elongated along the direction defined by the blobs, in both the MATISSE and ALMA continuum images. The ALMA $\rm^{12}$CO\,($J$=2-1) maps display an asymmetric inner wind with a velocity gradient. Conclusions. The observations are consistent with an edge-on dusty equatorial overdensity (disc-like), hinting the presence of a close ($\lesssim$4\,au) companion. The inferred
symmetry axis is almost perpendicular to the CO velocity gradient and the orbital plane proposed for the distant ($\sim$50\,au) companion. EP\,Aqr may represent the first misaligned hierarchical triple system with a central AGB
star.
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All authors J. Alonso-Hernández, C. Paladini, C. Sánchez Contreras, J. Drevon, J. P. Fonfría, L. Planquart, T. Khouri, L. Siess, A. Jorissen, B. Aringer, F. Baron, E. De Beck, S. Höfner, J. Hron, F. Lykou, F. Millour, M. Montargès, N. Nardetto, K. Ohnaka, H. Olofsson, V. Răstău, J. Sanchez-Bermudez, L. Velilla-Prieto, W. Vlemmings, M. Wittkowski, G. Weigelt, W. C. Danchi, F. Kerschbaum, B. Lopez
Quantum Physics
Spectrally enhanced gravitational redshift signals in photonic interferometry
Jerzy Paczos, Piotr T. Grochowski, Natalia Bruno et al. (+3 more)
Quantum mechanics and general relativity are remarkably successful, yet their joint predictions remain beyond direct experimental reach. Photonic interferometers operating in a gravitational field offer a promising route to test this regime: gravitational
redshift differentiates
photon propagation between vertically separated arms, leading to a predicted phase shift and reduction in interference visibility. These effects are minute on laboratory scales, motivating existing proposals to consider large interferometer areas to accumulate them geometrically. Indeed, such schemes typically require kilometre-scale optical paths to produce appreciable interferometric signals. Here, we propose a strategy that replaces
geometric accumulation with spectral enhancement by coupling the two interferometer arms to optical scatterers based on ultranarrow atomic transitions. These transitions serve as local spectral references: gravitational
redshift changes the
photon's detuning from each resonance, producing large differences in reflection amplitude and hence substantial visibility loss and interferometric phase shift already for centimetre-scale height differences. We quantify the experimental requirements and assess the feasibility of implementation with current or near-term technology. Our proposal thus opens a route to tabletop optical tests of the interplay between
quantum mechanics and general relativity.
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All authors Jerzy Paczos, Piotr T. Grochowski, Natalia Bruno, Emanuele Distante, Stephan Welte, Magdalena Zych
Quantum Physics
Distance Prediction for Quantum Codes
Nadav Schneider and Eliya Nachmani
The distance of a
quantum code is a fundamental metric that dictates its error-correction capability. While
quantum low-density parity-check (qLDPC) families such as Bivariate Bicycle (BB) codes offer a promising pathway to low-overhead fault-tolerant
quantum computing, computing their distance is challenging. Current exact solvers and even search heuristics that provide a distance upper bound suffer from severe computational bottlenecks, restricting the discovery of optimal codes. In this paper, we construct a
dataset of BB codes with corresponding distance upper bounds obtained through high-budget heuristic searches. We introduce BB-Net, an
attention-based neural network architecture for predicting the distance of BB codes. It achieves 96.39% accuracy on the reference distances in the test set, compared with 94.86% for state-of-the-art heuristics with a budget of up to $10^{4}$ times more computational runtime. On a subset with certified exact distances, BB-Net achieves 98.94%. By relieving the distance-calculation bottleneck, BB-Net enables faster screening of large code spaces, particularly in ML-driven search pipelines, and thereby can accelerate the discovery of novel
quantum error-correcting codes, an important capability for advancing scalable fault-tolerant
quantum computing. Our code is publicly available: https://github.com/NadavSc/BBNet
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Statistical Mechanics
Organisation and aggregation of calcium carbonate ions in water via molecular simulation
Elizaveta Sidler, Rita S Dias and Raffaela Cabriolu
Crystallisation of calcium carbonate (CaCO$_3$) in aqueous solutions is essential for carbon dioxide sequestration and the sustainable production of calcium carbonate materials, which are widely used in industry and increasingly explored for novel applications. While crystallisation is often analysed within the framework of classical nucleation theory, CaCO$_3$ and other ionic
crystals often form through amorphous precursor phases, motivating the need for alternative descriptions. In this work, we investigate the relationship between the formation of the first CaCO$_3$ coordination sphere, a fundamental unit of local ordering, and ionic aggregation using two complementary simulation approaches: on-the-fly probability-enhanced sampling (OPES) and asynchronous and infinite-swap replica exchange transition interface sampling ($\infty$RETIS). OPES was used to explore free-energy landscapes, whereas $\infty$RETIS was used to determine reaction kinetics. We studied systems at two levels of supersaturation, between which the formation of the first coordination sphere exhibited distinct kinetic behaviour. These differences were found to be linked to concentration-dependent ionic aggregation. At lower concentration, aggregation remains limited, whereas higher concentration promotes extensive spinodal-like aggregation. For both concentrations, the first coordination sphere forms within the pre-formed clusters through one of two distinct pathways: either within a cluster close to the minimum size required for its formation, or within larger amorphous aggregates whose size and structure depend on concentration. The coexistence of these pathways at both levels of supersaturation reveals the multifaceted nature of early-stage CaCO$_3$ crystallisation and highlights the importance of differentiating ionic aggregation and organisation.
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Quantum Physics
Local error correction prolongs time-crystalline memory
Benedikt Fauseweh
Discrete time
crystals are non-
equilibrium phases of matter with spatiotemporal order and a response that breaks the time-translation
symmetry of a periodic external drive. Interactions, spatial disorder and correlated random driving can in theory stabilize this order. In experiments, however, coupling to the environment limits the time
crystal lifetime. Here we use
stochastic local bit-flip error correction to prolong the time-crystalline response of a driven, spatially disordered two-dimensional Ising model on a superconducting
quantum processor, using a repetition code with distances three and five on a honeycomb
lattice with up to 68 physical
qubits. Even though ancilla
qubits, midcircuit syndrome measurements and decoding increase the required
quantum and classical resources, the
stochastic drive increases the
memory decay time by a factor of up to two. At late times we observe that recovery stabilizes spatial order across the
lattice. The
spin-configuration distributions explain this separation, as recovery suppresses disagreeing bonds while broadening occupies completely reversed states. Syndrome measurements without correction accelerate the
memory decay, demonstrating the importance of conditional correction. Our results show that local bit-flip error correction can preserve time-crystalline
memory over more drive cycles than the bare dynamics.
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Optics
Chirality Inversion and Giant Optical Activity in Scalable Self-Assembled Metamaterials
Antonio Carone, Aso Rahimzadegan, Birgül Kalkan et al. (+8 more)
Chiral materials manipulate light in ways that hold promise for sensing, imaging, and photonics, but producing such materials with strong and reproducible optical activity at large scale remains challenging. Here, we develop a scalable strategy to assemble hierarchical helicoidal metamaterials from metallic nanoparticles and chitin nanocrystals, a biosourced polysaccharide. Spontaneous co-assembly produces ordered chiral structures with strong plasmonic optical activity, reaching a dissymmetry factor of 0.55. The unprecedented ability to vary the helicoidal pitch allows control of the optical response, enabling inversion of optical handedness without changing the handedness of the template, effectively decoupling geometrical chirality from optical chirality. Remarkably, the gold nanoparticles can also be recovered from dry films and redispersed as colloids, introducing an appealing circularity concept for sustainable chiral plasmonic materials.
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All authors Antonio Carone, Aso Rahimzadegan, Birgül Kalkan, Thomas G. Parton, Tony Jin, Zihao Lu, Clemens Schmitt, Emeline Raguin, Bruno Frka-Petesic, Kevin Vynck, Silvia Vignolini
Earth and Planetary Astrophysics
3D Global Climate Simulations of Synthetic Mars Warming
Tom N. Landefeld and Harald Lesch
Artificial warming via engineered aerosols presents a novel pathway to bypass volatile scarcity on modern Mars. Utilizing the Generic Planetary
Climate Model, we evaluate the physical feasibility of aerosol-induced terraforming over a full Martian year (669 Sols). Unlike previous approaches that added aerosols to background dust or assumed continuous nanoparticle injection, we simulate the complete substitution of natural dust with a single-injection profile of radiatively active aluminium nanoparticles without continuous dumping. This tests whether initial infrared greenhouse forcing can overcome the severe ice-albedo cooling induced by a massive regional water-ice sheet ($3400 \text{ kg/m}^2$) localized in the Hellas Basin. Comparing this scenario against an unperturbed control run, we analyze surface temperature dynamics, sublimation fluxes, and water vapour concentration. Our 3D global
climate simulations quantify the radiative-dynamical feedback thresholds and determine whether engineered aerosol forcing can trigger a self-sustaining water-vapour greenhouse effect or remains fundamentally limited by regional ice-albedo suppression in Hellas.
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General Relativity and Quantum Cosmology
Kantowski Sachs Cosmological Model with Radiation and Generalized Chaplygin Gas
G. Oliveira-Neto and R. Hincho Laucata
In the present paper we study the
evolution of a homogeneous and anisotropic Kantowski Sachs cosmological model coupled with radiation and a generalized Chaplygin gas. Our main objective is verifying if this model evolves to a homogeneous and isotropic Friedmann Robertson Walker cosmological model, which is the more accepted model to describe our present Universe. If this is the case, we may imagine that the Kantowski Sachs cosmological model could had been an early stage of our Universe.
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Solar and Stellar Astrophysics
Dynamical and thermal evolution of localized reconnecting current sheets under varying guide-fields in the solar corona
Saksham Pande, Abhishekh Kumar Srivastava, Fabio Bacchini et al. (+9 more)
Although
magnetic reconnection in coronal current sheets (CSs) is a fundamental energy release mechanism in the solar corona, the role of guide-fields in governing its formation and self-consistent
evolution is not fully understood. Through 2.5D resistive magnetohydrodynamic (MHD) simulations, we investigate how guide-fields affect the formation and
evolution of a localized reconnecting coronal CS. Strong guide-fields prevent oppositely directed field lines from approaching sufficiently to form a CS, delaying and suppressing its subsequent
evolution. The reconnection rate exhibits a rising phase resembling a power-law, with exponent $\delta_1$ decreasing with rising guide-fields, indicating slower temporal growth of the reconnection rate. The aspect ratio of the CS follows a similar power-law trend with the exponent $\alpha_1$ decreasing with rising guide-fields. A subsequent slower growth phase of the reconnection rate shows a power-law exponent $\delta_2$ that increases with rising guide-fields, as does the corresponding aspect-ratio exponent $\alpha_2$. As the CS evolves, the latter phase is achieved due to a sharp decremental transition of the guide-field within the CS after a time when the increasing inflows are inefficiently resisted by the guide-field itself. In the reconnection regime during prior phases, the power-law exponents of the maximum temperature and the outflow velocities also decrease with rising guide-fields demonstrating that stronger guide-fields suppress the growth of these indicators also. This study suggests that a self-consistently formed CS displays phases of efficient and inefficient quenching of the reconnection mechanism, promoted by non-zero guide-fields. We also quantify this behavior for indicators of the reconnection process and discuss their applicability to observations of apparent CSs and probing background coronal conditions.
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All authors Saksham Pande, Abhishekh Kumar Srivastava, Fabio Bacchini, Sripan Mondal, Akash Bairagi, Balveer Singh, Kartika Sangal, Sudheer K. Mishra, Xinping Zhou, Ding Yuan, R. -Y. Kwon, B. N. Dwivedi
Instrumentation and Methods for Astrophysics
Charge Response Simulation of Liquid Argon Compton Cameras for Precise MeV Gamma-Ray Event Reconstruction
Shota Arai, Hirokazu Odaka, Satoshi Takashima et al. (+5 more)
We studied the detector response for a
liquid-argon time-projection chamber (LArTPC) Compton camera targeting MeV gamma-ray astronomy by a Geant4-based Monte Carlo simulation. The simulation, implemented within ComptonSoft, incorporates electron-ion recombination, charge
diffusion, and induction on the electrode pixels. We evaluated the angular resolution measure (ARM) and the energy reconstruction error as functions of electronic noise, pixel pitch, and the recombination correction method. An electronic noise level of 4 keV and a pixel pitch of 1 mm yield an ARM (FWHM) of about 3 degrees at 1332.5 keV and an energy reconstruction error better than 4% for incident energies of 1173.2 keV and above. Recombination correction using both scintillation light and charge signals improves the ARM and the energy error by factors of 1.7–2.3 and 2.2–5.4, respectively, compared to the charge-only correction, although the uncertainty of the recombination-fluctuation model remains. Since this simulation relies on idealized assumptions such as the use of the Monte Carlo truth in the event reconstruction, these values represent the best cases achievable under these detector conditions; nevertheless, they show that a large-scale LArTPC is a promising Compton camera for
cosmic MeV gamma-ray observations.
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All authors Shota Arai, Hirokazu Odaka, Satoshi Takashima, Masashi Tanaka, Ryutaro Tatsumi, Hodaka Kawamura, Kouichi Hagino, Aya Bamba
Nuclear Theory
Finite-Temperature Equations of State for Neutron-Star Mergers within the Quark Mean-Field Model
Shuochong Han, Xiangdong Sun, Zhenyu Zhu et al. (+1 more)
We extend the
quark mean-field (QMF) model to finite temperature and systematically investigate the thermodynamic properties of uniform nuclear matter, using the relativistic mean-field (RMF) model as a reference. For each model, we consider two parameter sets calibrated to the same selected nuclear-matter saturation properties but with different nucleon Dirac effective-mass ratios at saturation. We examine the effective nucleon mass and the composition of $\beta$-
equilibrium matter, together with the free energy, energy density, pressure,
entropy, and heat capacities of symmetric nuclear matter, pure
neutron matter, and $\beta$-
equilibrium matter. The QMF and RMF models exhibit similar qualitative trends, but their predictions increasingly differ at high density, where the effective masses have distinct density dependences. These differences are particularly evident in the thermal pressure and thermal index. For the two parameter sets considered in this work, we further provide compact analytical representations of the thermal index, $\Gamma_{\rm th}(\rho_{\rm b},T,\beta)$ over baryon densities of 0.08-1.0 $\rm fm^{-3}$, temperatures of 5-100 MeV, and isospin asymmetries of 0-1. The fits reproduce the numerical results with an accuracy better than $2\%$ and can be directly implemented in binary
neutron-
star merger simulations. This study establishes a finite-temperature extension of the QMF framework and provides a basis for future assessments of how a
quark-structure-based description of nuclear matter affects thermal support and post-merger dynamics in binary
neutron-
star mergers.
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All authors Shuochong Han, Xiangdong Sun, Zhenyu Zhu, Ang Li
Chemical Physics
QUPEX: A Streamlit-Based Framework for Visualizing Quantum-Mechanical Property Spaces of Organic Molecules
Mirtha Pillaca Quispe, Alejandra Hinostroza Caldas and Leonardo Medrano Sandonas
The growing availability of
quantum-mechanical (QM)
datasets offers new opportunities to investigate structure-property and property-property relationships in drug-like molecules using data-driven methods. However, interactive tools that integrate molecular visualization, statistical analysis of QM properties, clustering, and machine learning (ML) remain limited, despite their value in facilitating
dataset exploration and interpretation. To address this gap, we introduce QUPEX (
QUantum Property EXplorer), an open-source Streamlit-based framework for the interactive exploration of QM property spaces in molecular systems. As a demonstration, we apply QUPEX to a subset of the QM7-X
dataset comprising 41,537
equilibrium molecular structures containing up to seven non-hydrogen atoms (C, N, O, S, and Cl) and their 24 associated QM properties. In addition to property-space analysis, QUPEX incorporates an XGBoost regression pipeline for predicting PBE0 dipole moments from tight-binding-derived electronic descriptors, together with model evaluation and SHAP-based interpretability functionality. By combining interactive molecular visualization, data analysis, and predictive modeling, QUPEX provides an accessible and extensible environment for investigating molecular
datasets and identifying patterns in their structural and electronic properties. These capabilities can support the exploration of chemical space and inform the rational design of drug-like molecules with targeted QM properties.
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Astrophysics of Galaxies
Radio ghosts: Radio polarimetry study of newly discovered cluster minihalo candidates or radio tailed galaxies
Sam Taziaux, Christopher J. Riseley, Stefan W. Duchesne et al. (+5 more)
Extended diffuse
radio emission in the central regions of
galaxy clusters is commonly associated with non-thermal processes in the intracluster medium (ICM), but its origin and the mechanisms responsible for sustaining it remain uncertain. We present the discovery and multi-wavelength analysis of two diffuse
radio sources, MKTJ0355-4237 and MKTJ0355-4230, to assess their nature and investigate their
radio spectral and
magnetic field properties through
radio polarimetric analysis. We use deep MeerKAT L-band (1.28 GHz) observations to perform spectral analysis of the diffuse emission and study its polarisation properties via rotation measure synthesis. These are complemented by eROSITA X-ray data and DESI photometric
redshift catalogues to characterise the host cluster environments. MKTJ0355-4237 is confirmed as cluster-scale minihalo with extent of $\sim 400$ kpc, while the other diffuse source MKTJ0355-4230 remain uncertain and could be either associated with a
radio minihalo or
radio tailed
galaxy. Both show steep spectra ($\alpha \approx -0.7$ to $-0.8$) that steepen toward the outskirts ($\alpha \lesssim -2.5$), consistent with spatial variations in electron ageing and re-acceleration. Polarised emission is detected in both systems, with fractional polarisation $\sim1\,\%$ in the centres and increasing in the outer regions of MKTJ0355-4237. MKTJ0355-4230 is associated with a previously uncatalogued cluster and shows an X-ray morphology offset from the brightest cluster
galaxy, indicative of dynamical activity. MKTJ0355-4237 exhibits a sharply bounded internal
radio deficit without a corresponding X-ray counterpart, within current sensitivity limits. The spectral steepening supports turbulent re-acceleration as the origin of the diffuse emission.
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All authors Sam Taziaux, Christopher J. Riseley, Stefan W. Duchesne, Francesca Loi, Alec J. M. Thomson, Aritra Basu, Timothy J. Galvin, Dominik J. Bomans
Instrumentation and Methods for Astrophysics · Cross-listed from cs.NI
Developments in Building Towards the Indian SKA Regional Centre
Rohit Sharma and Yogesh Wadadekar
The SKA Regional Centre Network (SRCNet) is a
federated global network designed to archive, distribute, and process SKAO data products. This paper examines the evolving SRCNet architecture-focusing on the transition to version 0.2 (v0.2) requirements, including computation, orchestration, and multi-tiered storage-and details the strategy for establishing its proto-SRC infrastructure. We outline the prototype developments for the major and minor nodes in the context of v0.2. We describe the minor node compute and storage demands, establishing a pathway toward a fully operational Indian SKA Regional Centre (INSRC).
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High Energy Physics (Theory)
Supersymmetric Observables from Surface Defect Anomalies in 4d and 6d SCFTs
Zi-Xiao Huang, Ma-Ke Yuan and Yang Zhou
We study the contributions of half-BPS surface defects to supersymmetric Casimir energy and the universal logarithmic term of supersymmetric Rényi
entropy in four- and six-dimensional SCFTs. Using equivariant integration of defect anomaly
polynomials and its extension to supersymmetric Rényi backgrounds, we obtain closed expressions for these observables in terms of defect 't Hooft anomalies. For Gukov–Witten defects preserving transverse rotations in four-dimensional $\mathcal{N} = 4$ super Yang–Mills theories, both observables depend on a single R-
symmetry anomaly. For $\mathcal{N} = (0, 4)$ defects in six-dimensional $\mathcal{N} = (1, 0)$ theories, additional terms arise from the gravitational anomaly. We provide complementary checks using chiral
algebras, five-dimensional localization, and holographic probe branes at large $N$, while localized chiral
fermions reproduce the gravitational-anomaly contributions. The framework also recovers Wilson-surface results in six-dimensional $\mathcal{N} = (2, 0)$ theories.
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Mathematical Physics · Cross-listed from math.SP
Optimization Inverse Spectral Problem for the Schrödinger Operator on a Compact Graph
Valeev Nur
We study the optimization inverse spectral problem (OISP) for the first $m$
eigenvalues of the Schrödinger operator on a compact metric graph. We prove the existence of a solution for every strictly increasing finite set of prescribed
eigenvalues. On a graph without cycles, we obtain a representation of the optimal correction as a linear combination of squared eigenfunctions, provided that the selected
eigenvalues are simple and separated from the next
eigenvalue. On a graph with cycles, under the same simplicity and separation assumptions, we obtain a strong limiting representation of the optimal potential in terms of eigenfunctions of approximating operators. For a graph with a cycle, we give a counterexample with simple
eigenvalues and linearly dependent squared eigenfunctions. We also prove that linear dependence of the squares of nonzero restrictions to an edge of eigenfunctions corresponding to distinct
eigenvalues forces the potential on that edge to have an analytic representative
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Solar and Stellar Astrophysics
Simulating Ionospheric Distortions in Mock SKA-Low Solar Radio Observations
Rohit Sharma and Mitin
The Square Kilometre Array Observatory (SKAO) will provide unprecedented angular resolution for low-frequency solar
radio imaging, enabling access to fine-scale coronal structures. However, the improved spatial resolution of SKA-Low also increases the sensitivity of solar images to ionospheric propagation effects. We investigate the impact of ionospheric fluctuations on simulated SKA-Low solar observations at 50, 100, 150, and 200 MHz using the Karabo simulator and turbulent, moving ionospheric phase screens. We quantify the resulting image distortions using spatial power spectral density (PSD) analysis and compare the SKA response with corresponding MWA simulations. The results show that ionospheric distortions are strongly scale- and frequency-dependent, with the maximum fractional PSD distortion decreasing with observing frequencies. SKA resolves ionospheric fluctuations over spatial scales that are largely smoothed by the MWA instrumental response, with significant distortions occurring on scales comparable to solar active-region structures. These results demonstrate that ionospheric propagation effects should be considered when interpreting high-resolution SKA-low solar
radio images, particularly at the lower end of the frequency band.
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Optics
Imaging the building blocks of ant pheromone communication
Laure Anne Poissonnier, Erwan Amichot, Julien Brevier et al. (+2 more)
Organisms have evolved diverse strategies to communicate. Beyond acoustic and visual signals, many species rely on chemical communication, including pheromones: volatile compounds involved in reproduction, defense, and coordination. Ant trail systems, a paradigm of pheromone use, have inspired decades of research in collective behavior, self-organization and optimization
algorithms. Yet, despite their central role, individual pheromone deposits have never been directly visualized or quantified, limiting our understanding of how deposition events scale into collective trail formation. Here, we use interferometric imaging to reveal and quantify single pheromone deposits in the ant Lasius niger. This label-free, non-invasive approach enables precise measurement of single deposit volume (~1 pL, with x20-fold variability), morphology, and temporal dynamics. We uncover a two-phase volume loss process: most of secreted volume evaporates within seconds, forming a dried droplet, which then partially sublimates (~10%) over one hour. These findings challenge the assumption of homogeneous deposition and bring previously inaccessible properties of ant pheromone trails within experimental reach. Our method establishes a quantitative framework for studying the spatiotemporal dynamics of insect chemical communication, linking individual signaling to collective patterns.
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All authors Laure Anne Poissonnier, Erwan Amichot, Julien Brevier, Thibault Liard, Pierre Bon
Materials Science
Tellurium trioxide as an n-type wide-gap semiconductor with ultrahigh work functions from first principles
Tianwei Wang, Teruya Nagafuji, Kota Hanzawa et al. (+2 more)
The exploration of next-generation wide-gap
semiconductors with extreme work functions is highly desirable for the continued advancement of electronic and optoelectronic devices. By using first principles calculations, we show that e̱ta}-TeO3, with a wide band gap exceeding 3 eV, emerges as a promising n-type
semiconductor exhibiting ultrahigh work functions of up to ~8 eV. Intentionally or unintentionally incorporated interstitial H, Li, Na, Cu, Mg, and Zn impurities and substitutional F impurities are identified as shallow donors, whereas O vacancies act as minor carrier-compensating defects that locally trap electrons at neighbouring Te sites. The work function is evaluated across a series of low-index nonpolar surfaces. The presence of ordered O vacancies is energetically favoured on these surfaces and tends to reduce the corresponding work functions. These findings underscore the significance of precise control over the O chemical potential to suppress surface O-vacancy formation, thereby preserving the exceptional electronic performance of e̱ta}-TeO3 associated with ultrahigh work functions. Collectively, the results highlight the potential of e̱ta}-TeO3 for hole injection/extraction/transport layers as well as transparent electrodes for applications such as light-emitting devices and photovoltaic
cells, while providing useful guidance on carrier doping and surface tuning for these practical applications through elucidating the effects of the point-defect and surface configurations on the electronic properties.
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All authors Tianwei Wang, Teruya Nagafuji, Kota Hanzawa, Hidenori Hiramatsu, Fumiyasu Oba
Soft Condensed Matter
Evolution of dense liquid marbles under light tapping
Amaelle Sprocq, Théo Dhoudain, Alexis Duchesne et al. (+1 more)
Liquid marbles interface is composed by a dense network of grains trapped by capillarity at their surface. The mix of capillarity and granular character make their interfaces remarkable, allowing non wetting, high mobility and strong robustness which are a basis for numerous applications. A canonical experiment showing out of
equilibrium nature of granular material is the so called tapping experiment, where a dry granular medium under vertical vibration reorganize an evolve toward a denser final state function of the vibration amplitude In this paper we explore the out of
equilibrium nature of densely covered
liquid marbles by measuring their shape, compaction and stresses
evolution under vertical vibration. We show that
liquid marble do indeed reorganize when submitted to taps, leading to higher internal pressure and lower effective surface tension.
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All authors Amaelle Sprocq, Théo Dhoudain, Alexis Duchesne, Guillaume Lagubeau