Computational Physics · Cross-listed from eess.SP
Two-Dimensional Method-of-Moments Analysis of TMz and TEz Scattering from PEC Cylinders
Sabrina Saima
This paper presents a two-dimensional method-of-moments (MoM) solver for electromagnetic scattering from infinitely long perfectly electrically conducting (PEC) cylinders. Both TMz and TEz polarizations are considered. Starting from the scalar Helmholtz equation, the electric field integral equation (EFIE) is derived for TMz scattering and the
magnetic field integral equation (MFIE) is derived for TEz scattering. The induced surface current on the PEC boundary is expanded using pulse basis functions, and the boundary integral equations are discretized using point matching at the segment centers. Circular cylinders with radii $R = {\lambda}$ and $R = 2{\lambda}$ are used as validation cases because analytical series solutions are available. The MoM-computed surface currents, total near fields, scattered near fields, and field-error distributions are compared against the analytical solutions. After validation, the same solver is applied to a square PEC cylinder, for which no simple closed-form analytical solution is used. The results show strong agreement between the MoM and analytical circular-cylinder solutions and demonstrate the geometry-dependent scattering behavior of the square cylinder.
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Quantum Physics
Quantum Primitive for Output-Hiding Function Sharing: QKD and Joint Computation Applications
Olivia R. Hartzell
Applications of the proposed primitive:
Quantum Primitive for Output-Hiding Function Sharing, are discussed for secure
quantum communications and computation protocols. In particular, QKD applications provide notable enhanced security and efficiency properties relative to status-quo protocols. Additionally, we provide examples when parties may wish to encode joint functions, or decisions, which remain information-theoretically hidden from external parties and those internal to the
quantum system, without additional private keys, hidden randomness, or classical communication. In particular these applications may be useful in domains such as; financial transactions, joint signaling or coordination decisions, and
navigation systems, among others.
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Materials Science · Cross-listed from cs.LG
On Surrogate Modeling of Static Response of AM Short-Fiber Thermoplastics Using Graph Neural Networks
Pharindra Pathak, Vipin Kumar, Trenton M. Ricks et al. (+2 more)
Short-fiber thermoplastic (SFT) composites are increasingly employed in lightweight aerospace and automotive structures owing to their favorable strength-to-weight ratio, high production rates, and recyclability. Unlike continuous-fiber systems, the mechanical response of SFTs is governed by mesoscale interactions among fiber orientation, spatial clustering, and manufacturing-induced porosity. These features exhibit significant spatial variability in manufactured components and influence stiffness, damage initiation, and nonlinear deformation. Although mesoscale finite element (FE) models can resolve such heterogeneity, their application to realistic three-dimensional microstructures remains computationally intractable. A data-driven surrogate framework is proposed to predict the mechanical behavior of additively manufactured, compression-molded (AM-CM) SFTs. Microstructures reconstructed from micro-computed
tomography data were discretized into Voronoi-based
cells representing distinct fiber-interaction neighborhoods. Each
cell was homogenized via nonlinear FE simulations incorporating
matrix damage, and the resulting stress-strain responses trained a hybrid Graph Neural Network-Long Short-Term
Memory (GNN-LSTM) architecture encoding microstructural
topology and history-dependent mechanical
evolution. The surrogate accurately predicts stiffness and stress-strain behavior of unseen microstructures, achieving $R^2\approx 0.98$ relative to high-fidelity FE simulations with over two orders-of-magnitude reduction in computational cost. Coupling the framework with experimentally calibrated damage laws demonstrates that fiber orientation, clustering, and porosity collectively govern local effective stiffness. The approach provides a physics-informed, data-efficient pathway to identify mechanically weak microstructural
cells and accelerate digital-twin development for SFT components.
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All authors Pharindra Pathak, Vipin Kumar, Trenton M. Ricks, Suhasini Gururaja, Siddhartha Srivastava
Solar and Stellar Astrophysics
The Long-Period Radio Transient and Cataclysmic Variable ASKAP J1745-5051: Evidence for a 15,000 K White Dwarf and a Sub-Stellar Donor
Christian Knigge, Simone Scaringi, Noel Castro Segura et al. (+2 more)
Long-period transients (LPTs) are
radio sources that exhibit polarized periodic
radio bursts on time-scales of minutes to hours. At least some LPTs are associated with white
dwarfs (WDs) in close binary systems. However, the evolutionary connection between LPTs and accreting WDs (aka “cataclysmic variables” [CVs]) has been unclear. The recent discovery of ASKAP J1745-5051 has been a breakthrough: this system is a bona-fide LPT that is also an X-ray emitting
magnetic CV (mCV) with P_orb ~ 1.3 hrs. Here, we construct the broad-band far-UV through near-IR SED for the system and show that it is well described by two components: a 15,000 K WD (which dominates the far-UV through optical bands) and a sub-
stellar (M_2 ~ 0.05~M_sun, T_eff ~ 1800 K) donor
star (which dominates in the K_s band). Our SED-fitting results differ from those in the discovery paper for four reasons: (i) we fix an issue with the treatment of reddening/extinction; (ii) we discard photometric measurements that are irreparably contaminated by an unrelated
star located just 0.9" from the target; (iii) we add near-infrared brightness measurements obtained from PSF-fitting photometry on archival VISTA/VHS observations; (iv) we fit the data with synthetic spectra based on model atmospheres (rather than with blackbodies). The inferred WD temperature is reasonable for an
accretion-heated primary in a short-period mCV. The sub-
stellar nature of the donor suggests that the system is a "period bouncer" that has already evolved past the CV period minimum. The SED fit also yields a distance of d ~ 320 pc, only ~4x larger than that to the nearest confirmed mCV. Since the fraction of the sky swept out by the
radio beam is likely to be small, systems like ASKAP J1745-5051 could make up a large percentage of mCVs. This may point towards a connection between LPTs and the “missing” population of period bouncers among CVs.
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All authors Christian Knigge, Simone Scaringi, Noel Castro Segura, Domitilla de Martino, Martina Veresvarska
Nuclear Theory
Ab initio $\alpha$-$\alpha$ scattering with high-fidelity chiral interactions
Avik Sarkar, Serdar Elhatisari, Timo A. Lähde et al. (+1 more)
Low-energy $\alpha$-$\alpha$ scattering underlies
stellar helium burning and sharply tests
nuclear forces in the reaction regime. We present its first calculation using the high-fidelity N3LO
chiral NLEFT interaction, incorporated through wave function matching, on a fine
lattice, using the adiabatic projection method. On the fine
lattice, the two-cluster norm
matrix becomes severely ill-conditioned, and its direct inversion is unstable. We address this with Tikhonov regularization, extrapolating the regulator to zero, and confirm the result with an independent truncated singular-value decomposition. The S- and D-wave phase shifts agree with empirical analyses, extending the validation of this interaction from bound states and charge radii to scattering and providing a practical route to ab initio
nuclear reactions on fine
lattices
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All authors Avik Sarkar, Serdar Elhatisari, Timo A. Lähde, Ulf-G. Meißner
Materials Science
Structural properties of one-dimensional $\mathrm{Cs}_2\mathrm{CoCl}_4$ confined within single-walled carbon nanotubes
Jaskaran S. Mangat, Yu Lei, Matthew Weyland et al. (+9 more)
Crystals under one-dimensional (1D) confinement are well-known to exhibit drastic changes in
metallicity,
magnetic properties and chemical state, however, the intermediate phase space between binary metal halides and ternary metal halide perovskites remains poorly explored, especially in the context of the rich polymorphism exhibited by both families in the one-dimensional limit. Through aberration-corrected (scanning) transmission electron microscopy and multislice simulations, it is shown that the metal halide $\mathrm{Cs}_2\mathrm{CoCl}_4$ crystallizes in the tetragonal $\wp4/mcc$ and orthorhombic $\wp{mcm}$ rod groups under radial compression within single-walled carbon nanotubes (SWCNTs) of increasingly small diameter, with a massive re-entrant orthorhombic strain towards the $1$ $\mathrm{nm}$ extremum. The persistence of $\mathrm{Co}^{2+}$ is determined from fits to the d.c. magnetization, with a surprisingly small increase in the effective moment ($4.607(3)$ to $4.788(3) \mathit{{\mu}}_\mathrm{B}/\mathrm{f.u.}$) and Weiss constant ($-7.9(3)$ to $-4.09(7) \mathrm{K}$) after confinement in the SWCNTs, suggesting that the confined structure topologically preserves the core
magnetic properties of the bulk. Both unconventional polymorphs observed are noticeably different to the high-pressure piezochromic polymorph previously shown to undergo a tetrahedral-to-octahedral coordination transition, highlighting 1D confinement as a unique tool for structural manipulation.
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All authors Jaskaran S. Mangat, Yu Lei, Matthew Weyland, Yisong Han, Kiran Bal, Martin R. Lees, Craig I. Hiley, Piotr Dłużewski, Sławomir Kret, Peng Wang, Richard I. Walton, Jeremy Sloan
Other Condensed Matter
Electromagnetic response of two interacting topological insulator spheres in external fields
J. Cornejo Gómez, M. Ibarra-Meneses, L. Medel Onofre et al. (+1 more)
We study the static electromagnetic response of two spherical topological
insulators embedded in a dielectric medium and subjected to a uniform external electric field. The gapped surface states are described by a piecewise constant
axion field, which induces a topological magnetoelectric coupling localized at the spherical interfaces. {More generally, the same formalism applies to isotropic magnetoelectric media characterized by an effective scalar magnetoelectric response.} The electrostatic problem is solved at zeroth order using bispherical coordinates, allowing for an exact treatment of both parallel and perpendicular orientations of the external field relative to the center-to-center axis. The resulting mode expansions are determined by three-term recurrence relations, which are solved perturbatively for nonoverlapping spheres. The { magnetoelectric}-induced response is then computed to leading order in the fine-structure constant {(or, more generally, in the effective coupling strength)}. The induced sources are purely interfacial and generate distinct magnetostatic field configurations in the parallel and perpendicular geometries. Closed-form series representations for the induced vector potential and
magnetic field are obtained in terms of the zeroth-order electrostatic coefficients. These results provide an analytically controlled description of {interaction-induced magnetostatics in coupled spherical magnetoelectric systems}.
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All authors J. Cornejo Gómez, M. Ibarra-Meneses, L. Medel Onofre, A. Martín-Ruiz
Optics
Continuous modal spectrum in nonreciprocal cavities
Filipa R. Prudêncio, David E. Fernandes and Mário G. Silveirinha
Nonreciprocal systems enable asymmetric energy transport and suppress backscattering, giving rise to unconventional wave phenomena. Here, we show that nonreciprocal cavities based on unidirectional waveguides exhibit a continuous modal spectrum, in contrast to conventional cavities with discrete eigenmodes. Using a ferrite-loaded microwave cavity as an example, we demonstrate that enforcing unidirectionality, by tailoring the waveguide geometry, drives a transition from discrete to continuous spectra, accompanied by strong spatial localization of electromagnetic fields. Our results reveal that dissipation alone fails to regularize these singular responses, highlighting the need for additional mechanisms to control localization in nonreciprocal systems.
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Mesoscale and Nanoscale Physics
Synchronic scattering and geometric dephasing in microwave-induced resistance oscillations
Jesus Iñarrea
We present a novel
quantum transport model for microwave-induced resistance oscillations (MIRO) where we prove that the instantaneous scattering rate is directly modulated by the velocity of the driven coherent state. This interaction peaks exactly at $\omega t = 2n\pi$, where the wave packets sweep through the
impurity landscape at maximum speed, breaking time-reversal
symmetry to generate a net direct current. Additionally, we introduce a dephasing architecture to explain amplitude saturation: a non-linear
geometric dephasing ($\exp(-A/R_c)$) triggered when the displacement amplitude $A$ of the oscillating coherent state, approaches the cyclotron radius $R_{c}$. This perfectly captures the linear-to-sublinear power crossover at high intensities, offering a fully coherent description of non-
equilibrium transport.
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Mathematical Physics
Cohomological beta function
Oleksandr Gamayun, Maxim Gritskov and Andrey Losev
We propose a cohomological approach to computing the conformal anomaly. Using the example of current-current deformations of two-dimensional conformal field theories, we reproduce the well-known Cardy formula for the leading contribution to the perturbative beta function as the coefficient of the cocycle that realizes the obstruction to deforming the conformal
algebra module structure on the state space. In addition to offering a novel conceptual perspective on the conformal anomaly, the proposed approach is anticipated to provide an efficient tool for computing higher-order coefficients of perturbative beta functions.
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Mathematical Physics · Cross-listed from math.AP
Noncommutative Anisotropic Diffusion in Hilbert Space. I. The Consistent A-Geometry, Mosco Stability, and the Weak Bridge
E. Yu. Shchetinin, A. A. Shevchuk and S. I. Salpagarov
This first part of the series builds the analytic layer of noncommutative anisotropic
diffusion in a separable
Hilbert space. Let $\mu_0=\mathcal{N}(0,Q)$ be the reference Gaussian measure, with $Q\in L^1(\mathcal{H})$, and let $D(x)$ be a positive, state-dependent anisotropy. We do not assume that $[D(x),Q]=0$. Consequently, for the forward SDE with $\sigma(x)=D(x)^{1/2}Q^{1/2}$, the correct energy form is given not by the expression $\langle D\nabla u,\nabla v\rangle$ but by the consistent form $\Gamma_A(u,v)= \langle Q^{1/2}D(x)^{1/2}\nabla u, Q^{1/2}D(x)^{1/2}\nabla v\rangle$. We prove closability of the form, well-posedness of the forward dynamics, Galerkin convergence, stability of the $A$-LSI under a Mosco limit, the chain rule for relative
entropy, and a general weak-bridge
theorem. The main result of Part~I is a functional-analytic
theorem: if $A$-consistency, a uniform $A$-LSI, and representability of the right-hand side of the backward weak form in the negative energy space all hold, then a backward weak drift $v=\mathsf{A}\nabla\Phi$ exists and the basic
entropy dissipation estimate holds. In addition, we single out a three-dimensional tensor class of anisotropies, formulate a condition for the absence of
diffusion degeneracy, and obtain a rate estimate for the homogenization limit, first on cylindrical subspaces and then on compact-tail classes, which yields strong resolvent convergence and convergence of the forward SDEs. The statistical closure, an independent isotropic
benchmark, and an approximation
theorem for $A$-adapted networks are treated in Part~II.
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Quantum Physics
Tracking Entanglement Transfer: Emergence of Thermodynamics from Quantum Information
Debraj Debata, Abhirup Mukherjee and Siddhartha Lal
We study
entanglement transfer in a minimal model of two
qubits that are coupled with one another through an
antiferromagnetic Heisenberg exchange ($\tilde{J}$), and where one of them is additionally coupled to a fermionic environment through another
antiferromagnetic Heisenberg exchange ($J_{K}$). By tuning the coupling ratio $J_{K}/\tilde{J}$, the system undergoes a
quantum phase transition at $T=0$, accompanied by a redistribution of
entanglement from the $d'-d$
qubit-subsystem to the environment. Remarkably, the resulting physics exhibits properties that bear analogy with a
quantum-information theoretic perspective of the physics of black hole thermodynamics. Carefully selected bipartite and tripartite mutual information measures displays behaviour analogous to the dynamical
evolution of black hole
entropy, Hawking
entropy, and the Page curve expected during the process of evaporation. An effective temperature scale is obtained from the variation of the ground state energy with respect to changes in the bipartite mutual information between the subsystem and the bath. A steady growth of this temperature with the coupling ratio resembles that of the Hawking temperature with the inverse mass of the black hole. Concomitantly, the emergence of non-
Fermi liquid behaviour observed near the
quantum critical point and in the strong-coupling phase resembles strange-metal-like physics expected near the event horizon from a
holographic duality perspective. Our results establish the minimal model as a platform for studying
entanglement transfer and information scrambling within a fully
unitary quantum framework, and offer new insights into a resolution of the black hole information paradox.
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General Relativity and Quantum Cosmology
Vincenzo Branchina, Salvatore Capozziello, Filippo Contino et al. (+1 more)
We investigate whether the classical equivalence of general relativity, its teleparallel equivalent, and its symmetric teleparallel equivalent extends to false-
vacuum decay at leading semiclassical order. For a real scalar field minimally coupled to
gravity, we compare the tunnelling exponent $B=S_{\rm b}-S_{\rm fv}$, which determines the exponential suppression of the decay rate, $\Gamma\sim e^{-B}$, with the Euclidean bounce, $S_{\rm b}$, and false-
vacuum actions, $S_{\rm fv}$. The three formulations admit the same $O(4)$-symmetric Coleman-De Luccia bounce, but the boundary terms relating their actions can contribute to $B$. We explicitly evaluate the torsion and non-metricity boundary contributions at the regular origin, $r=0$, and at the asymptotic endpoint, $r\to\infty$. For regular configurations with consistently matched bounce and false-
vacuum boundary data, these contributions vanish in both TEGR and STEGR. We therefore obtain $B_{\rm GR}=B_{\rm TEGR}=B_{\rm STEGR}$, establishing that the three formulations predict the same leading semiclassical suppression of false-
vacuum decay within the class of configurations and boundary conditions considered.
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All authors Vincenzo Branchina, Salvatore Capozziello, Filippo Contino, Carmen Ferrara
Quantum Physics
A High-Performance Pauli-Algebra Framework for Large-Scale Quantum Simulations
Xiaopeng Li, Zhijie Sun, Yi Fan et al. (+3 more)
Efficient manipulation of Pauli-algebraic objects is a key bottleneck in the classical emulation and benchmarking of
quantum algorithms for chemistry and many-body physics. This bottleneck appears in
Hamiltonian construction, variational ansatz preparation, expectation-value and gradient evaluation, and real-time propagation, all of which require repeated Pauli-
algebra operations. Here, we present a high-performance Pauli-
algebra framework tailored to
quantum many-body and
quantum-chemical simulations. The framework combines compact binary
symplectic encoding, canonical coefficient reduction, and grouped sparse operator representations that exploit shared bit-flip patterns among Pauli strings. The resulting Julia/C++ implementation accelerates Pauli multiplication,
Hamiltonian construction, and operator–state multiplication in sparse and
symmetry-adapted many-electron spaces.
Benchmarks demonstrate efficient
Hamiltonian construction, large-active-space VQE and ADAPT-VQE calculations, and real-time variational dynamics on modern multicore CPU and GPU architectures. These results show that structure-aware Pauli-
algebra engines provide a scalable classical backend for developing and benchmarking
quantum algorithms in
quantum chemistry and many-body simulation.
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All authors Xiaopeng Li, Zhijie Sun, Yi Fan, Jie Liu, Zhenyu Li, Jinlong Yang
Nuclear Experiment
Dineutron clusters
Takashi Nakamura, Kouichi Hagino and Yosuke Kondo
The dineutron is a spatially compact two-
neutron cluster, which is expected to appear in a low-density part of
nuclei. In recent years, there has been rapid progress in experimental and theoretical research on dineutron clusters, particularly on
neutron-rich rare isotopes. Experimentally, evidence for dineutron in two-
neutron halo nuclei, such as $^{11}$Li, has been obtained using Coulomb breakup, measurements of charge radii, and quasi-free
proton scattering. Specific unbound
nuclei just beyond the
neutron drip line, which decay by emitting two
neutrons, are also candidates for having a dineutron correlation. For instance, the dineutron structure has recently been investigated for $^{16}$Be, focusing on its decay into the core and the two
neutrons. Theoretically, it is shown that the dineutron is partially due to the admixture of different-parity configurations for the two valence
neutrons. Few-body theories, including dynamical effects of the decay process, play important roles in interpreting three-body decays. We also discuss the four-
neutron clusters, showing the experimental results of recent tetraneutron experiments and observation of $^{28}$O. Possible relevance of these states to dineutron correlation is discussed. Finally, we discuss future perspectives on dineutron clusters in
neutron-rich
nuclei and their relation to the universal features in few-body physics.
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Mathematical Physics
The heat-kernel master field on $\mathbb{Z}^d$ at strong coupling
Thibaut Lemoine
We solve large-$N$ Yang–Mills theory on $\mathbb{Z}^d$, for every $d\geq2$, at strong coupling, for structure group $\mathrm U(N)$ and for the heat-kernel action. More precisely, we prove that normalized Wilson loop expectations have infinite-volume large-$N$ limits, factorize at leading order, and admit an all-order $1/N$-expansion with exponentially local coefficients, whose leading order characterizes the master field. We also prove an area-law upper bound for the heat-kernel master field, with a stronger coefficientwise version. The proof is based on a rooted heat-kernel master loop equation. Unlike the Wilson-action equation or the two-dimensional Makeenko–Migdal equation, this equation does not close on Wilson loop observables alone; it closes on an extended space of loop observables coupled to compactly supported plaquette decorations. We prove a strong-coupling, order-truncated rooted trajectory expansion and then identify its leading term with the master field. The main inputs are the universal finite-$N$ duality formulas developed in the companion paper \cite{Lem26a} and large-$N$ heat-kernel estimates from \cite{LemMai25,LM2}.
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Applied Physics
Vertical $\beta$-Ga$_2$O$_3$ Schottky Diodes with Deep-Etch Field Termination using Plasma-free Ga-assisted Etching
Saleh Ahmed Khan, Ahmed Ibreljic and Anhar Bhuiyan
A deep-etch field termination strategy using a Ga-assisted
plasma-free etching technique in a low-pressure chemical vapor deposition (LPCVD) system is demonstrated for $\beta$-Ga$_2$O$_3$ Schottky barrier diodes (SBDs). The thermally activated etching method provides a
plasma-free approach for forming deep mesa terminations while maintaining excellent device integrity. The fabricated diodes exhibit excellent forward conduction characteristics with a turn-on voltage of 1.14~V, a Schottky barrier height (SBH) of 1.15~eV, an ideality factor of 1.20, and a specific on-resistance of 3.72~m$\Omega\cdot$cm$^2$, all closely matching those of the unetched planar devices. Capacitance-voltage analysis further confirms a uniform carrier concentration of $2\times10^{16}$~cm$^{-3}$ and an SBH of 1.23~eV, indicating stable electrical characteristics after deep mesa formation. Temperature-dependent electrical measurements from 25 to 250$^\circ$C demonstrate stable thermionic-emission transport behavior, with a gradual increase in on-resistance at elevated temperatures due to
phonon-limited carrier mobility. Over this temperature range, the SBH decreases from 1.16 to 1.12~eV, while the ideality factor increases from 1.21 to 1.33. The leakage current remains low throughout the entire temperature range, and the rectification ratio remains above $10^{5}$ even at 250$^\circ$C. Under reverse bias, the diodes exhibit an increase in breakdown voltage from 287V to 500V, confirming the effectiveness of
geometric electric-field redistribution achieved by the deep-etched mesa structure. Silvaco TCAD simulations corroborate these experimental observations by showing significant suppression of electric-field crowding near the anode edge. These results establish Ga-assisted
plasma-free etching as a reliable, damage-free field termination technique for high-performance $\beta$-Ga$_2$O$_3$ power devices.
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Materials Science
Selenium direct doping obtained high-performance-n-type Bi2Te3-based thermoelectric materials with a wide temperature range
Zhiyuan Liu, Junjie Ma, Zhaopeng Zeng et al. (+5 more)
The article reports on a series of n-type Bi2Te3-based thermoelectric materials prepared via a high-temperature melting combined with annealing process. The effects of Se doping content and annealing process on the carrier concentration, suppression of the bipolar effect, and thermoelectric performance of the materials were systematically investigated. The experimental results provide valuable reference for researchers in this field.
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All authors Zhiyuan Liu, Junjie Ma, Zhaopeng Zeng, Ni Ma, Qian Ba, Di Zhang, Zhe Tao, Ailin Xia
General Relativity and Quantum Cosmology
Quadrupole and quadratic-in-spin effects in quasicircular, spinning, asymmetric binaries
Mostafizur Rahman, Misbah Shahzadi, Adam Pound et al. (+1 more)
Next-generation gravitational-wave detectors will require significant improvements in current theoretical waveform models, particularly in the case of asymmetric-mass binaries. Here we provide one such improvement by calculating fully relativistic finite-size effects for small mass ratios – primarily, fluxes of energy – including quadratic-in-secondary-
spin terms,
spin-induced quadrupole terms, and tidally induced quadrupole terms, for quasicircular inspirals of a small companion into a Kerr black hole. We formulate these calculations within a multiscale waveform-generation framework in self-force theory, which could be used, with an energy-balance law we derive, to develop self-contained waveform models for asymmetric binaries involving
stars orbiting black holes. Our results could additionally be used to improve other families of waveform models across all mass ratios. We present results both as complete numerical data sets on a Chebyshev grid and as analytical post-Newtonian expansions (to sixth PN order relative to the leading term in each contribution to the flux).
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All authors Mostafizur Rahman, Misbah Shahzadi, Adam Pound, Josh Mathews
Mesoscale and Nanoscale Physics
Optically Switched Phonon Superradiance of Surface Acoustic Wave in Diamond
Zhiwei Chen, Changyong Lei and Jie Ren
Surface acoustic wave (SAW)
phonon coupling with nitrogen-vacancy (NV) center
spins in diamond offers a promising platform for on-chip
quantum phononic manipulations. Although an ensemble of NV centers coupled to a common SAW
phonon mode enables superradiance and collective
quantum control, achieving a tunable superradiant phase transition remains challenging. Here, we show that optically driving NV centers level transitions enhances the effective
spin-
phonon coupling, triggering a SAW
phonon superradiant phase transition in the weak-coupling regime. We also demonstrate that above a critical threshold, the driving light rapidly switches on the
phonon superradiance–a dynamic effect that persists in finite-number NV ensembles. Our results provide a controllable route to coherent
phonon-NV
spin manipulation in solid state
quantum devices.
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High Energy Physics (Phenomenology)
Effects of Mirror Dark Matter on Neutron-Star Structure and Tidal Deformability
Jin-Cheng Jiao and Cheng-Ming Li
Mirror dark matter (MDM) can modify
neutron-
star structure and
tidal response through gravitational coupling. In this work, we construct an ordinary-matter equation of state (EOS) by comparing hadronic matter described by the relativistic mean-field NL3\(\omega\rho\) model, and
quark matter in the framework of the Nambu–Jona-Lasinio (NJL) model. The stable branch is determined through a Maxwell construction, which serves to connect distinct phases of matter. For the parameter sets considered here, \(m_u=5.2~{\rm MeV}\) is the lowest light current-
quark mass in the scanned range that satisfies the \(2M_\odot\) maximum-mass requirement, while \(m_u>5.2~{\rm MeV}\) all yield stable
neutron-
star configurations without a resolved macroscopic
quark core. The small-radius inferences for PSR J0437–4715 and XTE J1814–338, together with the
tidal-deformability constraint from GW170817, are sensitive to the dark-matter mass fraction \(f_D\). The commonly used GW170817 interval \(70\lesssim\Lambda_{1.4}\lesssim580\) corresponds approximately to \(0.12\lesssim f_D\lesssim0.88\) in the present model. These results indicate that, even without a macroscopic
quark core, MDM can provide an important mechanism for reducing the visible radius and modifying the
tidal response of
neutron stars.
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Solar and Stellar Astrophysics
Evidence of global periodicity in PSP data: can they be linked to long-period oscillations in solar active regions?
G. Dumbadze, B.M. Shergelashvili, M. Khodachenko et al. (+4 more)
The presence of coherent oscillatory signatures in Parker
Solar Probe SWEAP
datasets, identified through a series of spectral analyses, is addressed, and their possible connection to oscillatory phenomena in HMI/SDO
datasets of active regions is questioned. The goal of the work is to perform a systematic analysis of oscillation spectra applied to SWEAP/PSP time series of various physical quantities. We apply the Lomb-Scargle spectral analysis method to the original, unevenly sampled PSP
datasets and to wavelet analyses corresponding to the interpolated, evenly sampled time series. Furthermore, the statistical analysis uses spectra developed for 17 PSP encounters to obtain statistically proven characteristic periodicities. It has been found that, similarly to previously studied spectra in
solar active regions with periods above 2 hours, the
solar wind
datasets manifest sequences of statistically significant periods in the same range in
datasets of different physical quantities. It has been found that, similarly to previously studied spectra in
solar active regions with periods exceeding 2 hours, the
solar wind
datasets exhibit sequences of statistically significant periods in the same range across
datasets of different physical quantities. Based on the analysis, it is concluded that the spectra exhibit coherent, fixed periodicities in the range of 2-20 hours, with the highest statistical confidence in periods between 4 and 8 hours. It is also vital that the signature of such periods is systematically absent in
datasets of PSP orbital trajectory far from the encounter sites. The coherent signal is detectable at the place of the orbital perihelion (when PSP moves almost horizontally with respect to the
solar surface) and during approaching and receding phases when PSP flies almost radially.
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All authors G. Dumbadze, B.M. Shergelashvili, M. Khodachenko, L. Westrich, H. Fichtner, A. Reza, S. Poedts
Nuclear Theory
Investigating forward-backward asymmetry in D-meson production and anisotropic flow in p-Pb collisions at the LHC
Siyu Tang, Chao Zhang, Liang Zheng et al. (+3 more)
We investigate the forward–backward asymmetry in the production and
elliptic flow of
prompt D0
mesons in
proton–lead (p–Pb) collisions at$\sqrt{s_{\mathrm{NN}}}=8.16$ TeV using the heavy-
flavor improved string-melting version of the AMPT model. The model calculations provide a simultaneous description of
nuclear modification factor $R_{\mathrm{pPb}}$ and $v_2$ in forward and backward rapidities. We find that the observed asymmetry arises from the interplay of initial-state cold
nuclear matter effects and final-state partonic interactions, with the competition between coalescence and fragmentation playing a critical role in shaping the transverse momentum and rapidity dependence of both observables. This work suggests that a partonic medium is formed in high-multiplicity p-Pb collisions at LHC energies.
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All authors Siyu Tang, Chao Zhang, Liang Zheng, Renzhuo Wan, Zi-Wei Lin, Guo-Liang Ma
Astrophysics of Galaxies
Insights into Jet-Induced Cloud Disruption in NGC 1316: ALMA Reveals a Spatially Extended Molecular Gas
Kana Morokuma-Matsui, Alexander Y. Wagner, Filippo M. Maccagni et al. (+14 more)
We present ALMA CO($J=1-0$) observations of a nearby
radio galaxy NGC1316 at a 100-pc resolution to investigate the impact of AGN jets on the molecular gas. The molecular gas exhibits complex spatial and kinematic distributions, with broad CO line widths ($>50$ km s$^{-1}$) observed in several regions. The interferometric CO flux is only 34%-38% compared to single-dish data, indicating a large fraction of spatially extended molecular gas, especially in the central regions. We identified 24
Giant Molecular Clouds Associations (GMAs) primarily within the “NW Shell” and the “SE Blob”; these GMAs show velocity dispersions approximately twice as high as those in typical
star-forming
galaxies for their sizes. Analysis of archival ALMA CO($J=2-1$) and CO($J=3-2$) data reveals elevated line ratios ($R_{21} \sim 1$ and $R_{31} \sim 1$) in gas near the jet, whereas, away from the jet, typical values ($R_{21} \sim 0.7$, $R_{31} \sim 0.3$). A multi-wavelength comparison reveals a $\sim$5 kpc warm ionized gas shell that encompasses the molecular NW Shell. The observed energetics and bubble morphology are consistent with an expanding bubble model driven by the jet assuming a jet power of $1.6\times10^{43}$~erg~s$^{-1}$. We propose that the high extended gas fraction results from the destruction of molecular clouds due to interactions with the jet
plasma. NGC1316 may be a good example of jet-induced negative feedback through the ablation, dispersal, and rarification of dense molecular clouds through jet-ISM interactions.
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All authors Kana Morokuma-Matsui, Alexander Y. Wagner, Filippo M. Maccagni, Lauranne Lanz, Fumiya Maeda, Jin Koda, Akihiko Hirota, Yutaka Fujita, Kotaro Kohno, Tomoki Morokuma, Tsutomu T. Takeuchi, Kouichiro Nakanishi, Fumi Egusa, Kenji Bekki, Daniel Espada, Bärbel Koribalski, Jing Wang
High Energy Astrophysical Phenomena
Late-time evolution of the interacting stripped-envelope supernova 2017dio
C. Humina, C. P. Gutiérrez, H. Kuncarayakti et al. (+14 more)
The discovery of stripped-envelope
supernovae (SNe) interacting with dense circumstellar medium (CSM) challenges our current understanding of massive
star evolution. We present late-time observations of the interacting Type Ic SN 2017dio and investigate its mass-loss mechanism and progenitor channel. We analysed late-time spectra and light curves (LCs) that are dominated by ejecta-CSM interaction. We examined the CSM and the source of the infrared (IR) excess by modelling the radiation produced by the ejecta-CSM interaction and the IR echo from circumstellar
dust. In addition, we studied the
evolution of spectral features, with a particular emphasis on the Halpha emission line. From the combined analysis of the LCs and spectral properties, we infer that the peak mass-loss rate for the CSM reaches ~0.2 $M_{\odot}/yr$ and that the typical value over most epochs is ~0.06 $M_{\odot}/yr$. The nearby CSM was formed over a period of 4 to 65 years before the explosion. The CSM radius begins at ~$1.3\cdot10^{15}$ cm. The IR excess identified in the LCs is consistent with the radiation from
dust with a mass increasing from ~0.001 to ~0.005 $M_{\odot}$ in the case of carbon
dust or ~0.005 to ~0.02 $M_{\odot}$ in the case of silicate
dust. From IR echo modelling, we estimate an upper limit on the
dust mass of $4\cdot10^{-5} M_{\odot}$, which implies an SN progenitor mass-loss rate of $2.4\cdot10^{-5} M_{\odot}/yr$ at the
dust evaporation radius determined by the SN peak luminosity (0.017 pc for carbon
dust, corresponding to mass loss ~170 years before the explosion). This implies a very rapid increase in the mass-loss rate ahead of the explosion. Although the progenitor of SN 2017dio has lost its helium envelope, it interacted with a hydrogen-rich CSM formed shortly before the explosion, suggesting that this material originated from a companion
star rather than the progenitor itself. [Abridged]
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All authors C. Humina, C. P. Gutiérrez, H. Kuncarayakti, T. Nagao, S. González-Gaitán, T. Kangas, T. Kravtsov, K. Maeda, S. Mattila, T. M. Reynolds, L. Tartaglia, S. Benetti, M. Fraser, C. Gall, P. Lundqvist, A. Morales-Garoffolo, M. Stritzinger
High Energy Astrophysical Phenomena
Tracing the Orbital Motion of the Accreting White Dwarf in EX~Hydrae with XRISM/Resolve
Yuken Ohshiro, Yukikatsu Terada, Taichi Ichikawa et al. (+7 more)
Measuring the masses of accreting white
dwarfs (WDs) is crucial for understanding their
evolution and the physics of
accretion. High-resolution X-ray spectroscopy can trace the WD motion through Doppler shifts of emission lines formed close to the WD. We report an 83~ks XRISM/Resolve observation of the intermediate polar EX~Hydrae and measure the orbital modulation of individual Fe K-shell line centroids. The Fe~xxv K$\alpha$ components show coherent orbital modulation, yielding $K_1 = 58.1 \pm 8.5\ \mathrm{km\ s^{-1}}$. This is the first detection of orbital modulation in individual Fe K-shell lines from an accreting WD, made possible by the high spectral resolution of Resolve and its frequent in-orbit gain calibration. The measured $K_1$ is consistent with optical/UV $K_1$ measurements, providing a cross-check that these distinct tracers follow the WD orbital motion. Combining this X-ray measurement with literature orbital parameters, we derive a WD mass of $M_1 = 0.79 \pm 0.04\ M_\odot$. These results demonstrate that high-resolution X-ray spectroscopy can use individual Fe K-shell line centroids to trace WD orbital motion in accreting WDs.
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All authors Yuken Ohshiro, Yukikatsu Terada, Taichi Ichikawa, Yugo Motogami, Manabu Ishida, Koji Mukai, Masayoshi Nobukawa, Takayuki Hayashi, Mariko Kimura, Mai Takeo
Materials Science · Cross-listed from cs.LG
MALOQ: Massively Accelerated Learning of Operators for Quantum Transport
Manasa Kaniselvan, Alexander Maeder, Denghui Lu et al. (+2 more)
Machine-learned (ML) operator models can be trained to predict density functional theory (DFT)
Hamiltonian/density
matrices at significantly reduced computational cost, thus extending electronic-structure calculations to previously unfeasible scales. Here, we introduce MALOQ (Massively Accelerated Learning of Operators for
Quantum Transport), an application built to train on and predict electronic-structure
matrices for systems made of few to 100k atoms, described by large basis sets, and covering a wide range of atomic elements. Based on a state-of-the-art, SO(2)-equivariant backbone architecture, MALOQ provides (i) custom data-processing kernels to handle high-rank
Hamiltonian matrix data and (ii) a scalable edge-wise distribution of atomic graph(s). Trained on the largest molecular
Hamiltonian datasets available today, it reduces time-per-epoch by over 30% compared to a molecule-wise-distributed framework, and enables inference on material graphs of arbitrary size. We demonstrate scalable training and inference for 3,000-12,000 atoms on the Alps supercomputer, up to 192 GPUs and 256 GPUs, respectively.
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All authors Manasa Kaniselvan, Alexander Maeder, Denghui Lu, Alexandros Nikolaos Ziogas, Mathieu Luisier
Fluid Dynamics
Premixed flames in a stagnation point flow under Darcy's law
Prabakaran Rajamanickam and Joel Daou
Premixed flames in stagnation point flows are traditionally described using Navier–Stokes equations where inertia and density variations play an important part in determining the flame structure. However, in porous media or Hele-Shaw configurations, Darcy's law replaces the momentum balance, shifting the governing physics to a balance between pressure and viscous forces. This study investigates non-adiabatic strained premixed flames under Darcy's law, pertinent in particular to confined flames in Hele-Shaw burners, accounting for non-unity Lewis numbers and volumetric heat losses. The flame is established in a planar counterflow formed by impinging a cold unburnt gas and a hot burnt gas maintained at the adiabatic flame temperature. We show that the jump in the strain rate across the flame is associated with a jump in viscosity, rather than, as in the classical Navier–Stokes case, a jump in density. Furthermore, the ratio of viscosity to the density-permeability product $\mu/\rho \kappa$, i.e., kinematic viscous resistance, is identified as a key coordinate stretching factor in the mathematical description of the flame structure. This ratio increases significantly across the flame. As a result: (1) the burnt gas acts as a strong viscous barrier, (2) for an increasing strain rate, flame migration towards the burnt gas is hindered, (3) for a decreasing strain rate, migration towards the unburnt gas is promoted, and (4) streamline refraction is augmented. By analysing the burning rate across varying strain rates and heat-loss parameters, we identify distinct extinction and ignition regimes that fundamentally differ from classical combustion theory, thereby providing new insights into flame stabilisation in friction-dominated environments and under confinement.
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Superconductivity
Theory of High-Tc Superconductivity in Cuprates
E. C. Marino
The essential physical processes underlying the phenomenon of High-Tc superconductivity in cuprates occur in the $CuO_2$ planes, found in these materials. The dynamics of the active electrons belonging to such planes is well described by the Three Bands Hubbard Model (3BHM). The complexity of such model, however, led the researchers to look for simpler and yet relevant alternatives. In the attempts to circumvent the complexity of this model,two main simplified versions of the (3BHM) were considered. In the first alternative, one eliminates the doped holes and their respective sub-
lattices by tying them to the $Cu^{++}$ electrons, thereby forming the so called Zhang-Rice singlets. The remaining dynamics consists in doping a Mott-Hubbard
insulator and is described by the t-J Model. The second alternative maintains that the $Cu^{++}$ electrons form a square
lattice of localized
spins, while the doped holes move along the oxygen sub-
lattices and undergo a Kondo like
magnetic interaction with the localized
spins, besides the Hubbard-like electric repulsion. This scenario is described by the
Spin-
Fermion-Hubbard Model. Most of the researchers in the field chose to follow the first road, while, I chose the second one. In this article I review in detail the reasons why that choice has led to a successful theory for High-Tc superconductivity in hole doped cuprates.
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Materials Science · Cross-listed from cs.CV
Projection-based coupling of infrared thermography and stereocorrelation-based digital image correlation
Jendrik-Alexander Tröger, Lutz Müller-Lohse and Stefan Hartmann
Full-field measurement techniques such as digital image correlation and infrared thermography are prevalent in experimental solid mechanics. Digital image correlation is used to analyze surface deformation, while infrared thermography quantifies surface temperature fields. However, sophisticated procedures are necessary to express both
datasets in the same Lagrangian frame, especially when analyzing non-flat surfaces. In this study, we propose an external projection-based coupling that uses the pinhole camera model to relate two-dimensional temperature data measured by infrared thermography to three-dimensional point coordinates from stereocorrelation-based digital image correlation. Unlike existing multiview approaches, we utilize two independently calibrated industrial-grade systems and augment the experimental evaluation with the pinhole camera model. The projection
matrix of the camera model is calibrated using a single image of a reference object. Through this projection, temperature fields are accurately represented at material points. Our method is particularly suited for, but not restricted to, curved surfaces and is straightforward to embed in existing experimental protocols, as the image registration is kept as is. Additionally, we use radial basis functions as a global interpolation ansatz in both space and time to compute in-plane temperature gradients and even temperature rates on curved surfaces, thereby providing an extensive and information-rich full-field
dataset.
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