High Energy Physics (Theory)
Non-relativistic limits of $\mathcal N=4$ supersymmetric Yang-Mills theory and S-duality
Hyungrok Kim and Joseph Smith
We investigate non-relativistic limits of four-dimensional maximally supersymmetric Yang-Mills theory (4d MSYM) and their relation to the nonperturbative $\operatorname{SL}(2;\mathbb Z)$ S-duality of the relativistic theory. We construct a general family of non-relativistic limits using a Type IIB brane set-up with a D3-brane and $(p,q)$-strings and show that the resulting theories are topological deformations of supersymmetric Galilean Yang-Mills theory or
quantum mechanics on the
moduli space of BPS monopoles. The deformations of the Galilean Yang-Mills theory are the familiar $\theta$-term and a coupling to the monopole charge, while in the
moduli space theory the only deformation is a $\theta$-term. This family of theories fit together into a three-dimensional
moduli space with nontrivial
topology, on which $\operatorname{PSL}(2;\mathbb Z)$-valued dualities act in a richer and more complex way than in the relativistic parent theory. In the Abelian case, we establish the duality directly using the path integral, while in the non-Abelian case we support our claim by matching the one-particle spectrum as well as the Galilean spacetime
symmetries and electric/
magnetic invertible one-form
symmetries.
Read the full abstract ▾
Nuclear Theory
Microscopic mechanism of the Fayans pairing for the enhancement of charge radii
Tomoya Naito, Gianluca Colò, Xavier Roca-Maza et al. (+2 more)
The Fayans energy density functional (EDF), and in particular its pairing sector, have been claimed to be able to reproduce the experimental data of charge radii in many instances. A particularly intriguing case is that of the $ \mathrm{Ca} $ isotopes between $ A = 40 $ and $ 48 $, where charge radii exhibit a "bell shape". In our work, we examine the microscopic origin of this behaviour. We prepare in total $ 25 $ paramerizations of the Fayans-like pairing interaction, that are equivalent in fulfilling the same criteria for the reproduction of empirical pairing gaps. We find that both the density and the density-gradient dependence of the pairing interaction are important to reproduce the well-known enhancement of charge radii in the open-shell
nuclei, leading to the "bell shape" behaviour of $ \mathrm{Ca} $ isotopes. In particular, this originates from the repulsive nature of the rearrangement potential, and cannot simply be mocked up by a refit of the pairing strength. At the same time, we notice some drawbacks of the Fayans standard EDFs, that may call for investigating a more general form of it.
Read the full abstract ▾
All authors Tomoya Naito, Gianluca Colò, Xavier Roca-Maza, Hiroyuki Sagawa, Enrico Vigezzi
Chemical Physics
Controlling the phase behaviour of ultraconfined water via bilayer graphene stacking
Yixuan Pu, Benjamin X. Shi, Pavan Ravindra et al. (+3 more)
Water confined within nanoscale capillaries exhibits phase behaviour and transport properties that differ substantially from bulk, and these effects are commonly interpreted as consequences of
geometric confinement and reduced dimensionality. Here we show that confinement
topology alone is insufficient to predict the behaviour of nanoconfined water. Using machine learning interatomic potentials with first-principles accuracy, we compute the density-temperature phase diagram of water confined within
bilayer graphene nanocapillaries and compare AA and AB stacking arrangements, which differ only by a lateral shift of 1.4 Å. Despite this minimal structural change, AA stacking can stabilise different ice polymorphs, can increase the melting temperature by more than 100 K, can enhance
proton transfer, and alters the onset of superionic behaviour relative to AB stacking. We trace these effects to stacking-induced changes in the hydrogen-bond network associated with modifications to the lateral free energy landscape and neighbouring O-O separations. Our results demonstrate that even subtle atomistic variations in the confining walls can qualitatively reshape the physical and chemical behaviour of nanoconfined water, with implications for the interpretation and control of fluids under angstrom-scale confinement.
Read the full abstract ▾
All authors Yixuan Pu, Benjamin X. Shi, Pavan Ravindra, Chris Pickard, Angelos Michaelides, Venkat Kapil
High Energy Physics (Phenomenology)
Accessing the HQET B-Meson Shape Function from a LaMET Quasi-Shape Function
Ao-Sheng Xiong, Jun Ding, Ji Xu et al. (+2 more)
The shape function and the light-cone distribution amplitude of heavy
meson jointly characterize the nonperturbative structure of the heavy
meson on the light-cone, with the former being essential for theoretical predictions of inclusive decays and the latter for exclusive decays. While first-principles
lattice QCD results for the heavy
meson LCDA have become available in recent years,
lattice results for the shape function remain absent. In this work, we establish a two-step factorization scheme – known as the HQLaMET framework – for computing the $B$-
meson shape function on the
lattice, which fully disentangles the effects of the disparate scales $P_B^z$, $m_b$, and $\Lambda_{\textrm{QCD}}$. For illustration, starting from a phenomenological model for the shape function in HQET, we provide a graphical presentation of the entire procedure of this framework. The results of the current work lay the foundation for nonperturbative
lattice QCD determinations of the shape function in the near future.
Read the full abstract ▾
All authors Ao-Sheng Xiong, Jun Ding, Ji Xu, Jun Zeng, Shuai Zhao
Fluid Dynamics
Multifractal sets of coherent and incoherent vortices in turbulence
Susumu Goto, Daiki Watanabe and Tsuyoshi Yoneda
We numerically verify multifractal theory (Frisch and Parisi 1985) for
turbulence using simulation data at a high Reynolds number. First, we propose a simple method to directly estimate the multifractal dimension $D(h)$ of vortical structures with a given Hölder exponent $h$. Thus measured $D(h)$ is in good agreement with indirectly measured experimental data. Then, we demonstrate that these structures for $h\ll1/3$ form the hierarchy of coherent eddies, while those for $h\gg1/3$ are featureless.
Read the full abstract ▾
Materials Science
Peripheral Nitrogen Topology as a Defect-Chemical Switch for Electronic and Magnetic States in Graphene: A First-Principles Study of Pyridinic, Pyridazinic, Pyrrolic, and Pyrazolic Configurations
Md. Moktadir Billah Tahmid, Indranil Rudra, Jahid Emon et al. (+1 more)
Defect and heteroatom engineering offer powerful routes for tuning the electronic and
magnetic properties of
graphene, yet the role of specific peripheral nitrogen
topologies around
graphene voids remains insufficiently understood. Here,
spin-polarized first-principles calculations were performed to investigate how four heterocyclic – like peripheral nitrogen configurations – pyridinic, pyridazinic, pyrrolic, and pyrazolic modify the structural stability, charge redistribution, electronic structure, and
magnetic response of
graphene containing a central void. Among the four peripheral N configurations, the pyridinic N provides the most favorable structural-energetic balance among the investigated motifs. Bond-length analysis reveals that nitrogen
topology strongly controls local
lattice reconstruction. Charge-density, charge-density-difference, and Bader analyses demonstrate that the peripheral N atoms act as electron-accumulating centers and reshape the local electronic environment around the vacancy rim.
Spin-resolved band structures show that pyridinic, pyridazinic, and pyrrolic configurations retain metallic or near-metallic defect-state character, whereas pyrazolic
graphene opens a narrow band gap.
Magnetic analysis further reveals that pyrazolic
graphene is
spin-compensated, with zero net magnetization, unlike the other systems, which possess finite
spin-polarized moments.
Spin-density and SPDOS analyses indicate that the magnetism originates from N-modulated vacancy-edge states involving both N 2p and neighboring C 2p orbitals. These findings establish peripheral nitrogen
topology not merely as a structural defect descriptor, but as a deterministic defect-chemical switch, offering a metal-free route to pattern active spintronic and semiconducting domains directly into the
graphene lattice through controlled vacancy-edge nitrogen coordination.
Read the full abstract ▾
All authors Md. Moktadir Billah Tahmid, Indranil Rudra, Jahid Emon, Mohammad Jane Alam Khan
Soft Condensed Matter
Defect Topology in Colloidal Smectics
Chaya Halperin and Hillel Aharoni
Colloidal smectics – layered structures formed in dense suspensions of rod-like particles – often exhibit grain boundaries, across which the layer orientation changes by $90^{\circ}$. Motivated by this feature, we develop a layer-based topological framework that treats orthogonal grain boundaries as constituents of the ground state rather than as exceptional defect structures. Extending the layer-based approach for ordinary smectics, we reduce the smectic structure to layers, half-layers, and domain walls. We classify the
topology of defects and their combination rules based on this structure. In two dimensions, point defects are described by semi-directed cycle graphs. Although the disclination charge remains a valid topological invariant, it does not uniquely classify defects, as distinct graphs may share the same charge. In three dimensions, line defects are classified by their transverse graph structure, while point defects exhibit qualitatively different behavior. In particular, we show that the hedgehog disclination charge is not a topological invariant, but instead varies continuously under smooth deformations of the layer structure.
Read the full abstract ▾
Medical Physics
OpenPINT: Open-source Planning for Isoeffective Nuclear Treatments in BNCT research
Ian Postuma, Sara J. González, Setareh Fatemi et al. (+5 more)
Objective: Present OpenPINT (Open-source Planning for Isoeffective
Nuclear Treatments), an open-source treatment planning system for
nuclear therapies that integrates Monte Carlo dose calculations with modular dosimetric and radiobiological models for
photon-isoeffective dose evaluation. Approach: We describe the software architecture, implementation choices, and data flow from segmented geometry and source configuration to NIfTI dose outputs. We define BNCT-relevant dosimetric metrics and evaluate the workflow with reproducible analytic and voxelized cylindrical-phantom
benchmarks, supplemented by a
geometric patient-positioning example. Main results: The module provides a reproducible and scriptable path for generating MCNP-ready inputs, extracting component-wise BNCT dose maps, and computing analysis-ready outputs for quality checks and decision support. Fine-resolution voxelized configurations reproduced the 1 mm analytic reference within 0.13% for the
brain-limited irradiation-time endpoint, whereas the full voxelized sweep exposed deviations up to 4.42% in coarse 8–10 mm configurations. Patient-wide gamma pass rates were at least 99.60% for the evaluated mesh/interpolation cases, while low-dose DVH-tail quantities remained sensitive to boundary discretization. Significance: This first paper isolates and validates the simulation-preparation and dosimetric-analysis core of an open-source BNCT treatment-planning platform. It establishes a foundation for subsequent work on optimization, biological weighting, and clinical workflow integration.
Read the full abstract ▾
All authors Ian Postuma, Sara J. González, Setareh Fatemi, Cristina Pezzi, Carolina Ruzzon, Oreste Nicrosini, Valerio Vercesi, Silva Bortolussi
General Relativity and Quantum Cosmology
The WDM Time-Frequency Transform in Gravitational-Wave Data Analysis I: Formalism
Aaron Johnson, Katerina Chatziioannou and Jake Summers
For slowly-varying noise, time-frequency methods offer a natural middle ground between the efficiency of the frequency domain and the generality of the more expensive time domain. Despite growing adoption, such methods remain less well documented and less familiar in the gravitational-wave literature, compared to the ubiquitous frequency domain. Aimed at gravitational-wave analysts, in this paper we present a self-contained account of time-frequency methods, detail derivations for a specific basis, namely the Wilson-Daubechies-Meyer (WDM) basis, and share intuition and lessons learned. We document key concepts: the orthogonality and good time-frequency localization of the basis, the edge effects at the DC and Nyquist frequencies, the forward and inverse transforms and their practical implementation, and the noise covariance
matrix and likelihood in the time-frequency domain.
Read the full abstract ▾
Quantum Physics
Quantum work statistics and coherence effects in quenched bosonic Josephson junctions
Mattia Orlandini, Stefano Gherardini, Lorenzo Buffoni et al. (+1 more)
We investigate the non-
equilibrium work statistics originating from a sudden quench in a bosonic Josephson junction. In particular, by employing the Holstein-Primakoff approximation, the work statistics are analytically characterized in the weak-interaction regime, where the dynamics map onto a time-dependent
quantum harmonic oscillator. For a junction initialized in the ground state of the pre-quench
Hamiltonian, we demonstrate that the work statistics are governed by a negative binomial distribution, as occurs in fully-connected models driven across a critical point. Furthermore, we also consider initial superposition states containing
quantum coherences in the energy basis. To characterize the corresponding work distributions, we employ Kirkwood-Dirac quasiprobabilities (KDQ). Even in the simplest case, when the junction is initialized in a superposition of the ground and second excited states, the KDQ distribution of work exhibits negative or complex values, reflecting non-classical features. Moreover, the coherence content of the initial state can be optimized to enhance the extractable work extracted from the quench, beyond classical bounds. Finally, we propose an experimental interferometric protocol to directly measure the characteristic function of the work distribution in experimentally accessible settings.
Read the full abstract ▾
All authors Mattia Orlandini, Stefano Gherardini, Lorenzo Buffoni, Beatrice Donelli
Mesoscale and Nanoscale Physics
Hyperfine versus exchange interaction in the spin dynamics of spatially indirect excitons in CsPbI$_{3}$ perovskite nanocrystals
Timur S. Shamirzaev, Nataliia E. Kopteva, Dmitry S. Smirnov et al. (+7 more)
We study the dynamics of recombination, optical orientation, and optical
alignment of
excitons in ensembles of CsPbI$_{3}$ nanocrystals (NCs), synthesized in a glass
matrix. In large NCs with size exceeding 16 nm, the low-energy photoluminescence is contributed by the emission of indirect in real space
excitons formed by spatially separated electrons and holes, which are localized at the NC/glass interface. The recombination dynamics of an ensemble of such
excitons extends from tens of nanoseconds to microseconds and exhibits a power-law dependence. Their optical
alignment and optical orientation reveal a peculiar
spin dynamics caused by
excitons influenced by the exchange interaction, varying by orders of magnitude. We develop a theory of the polarized photoluminescence of triplet
excitons, taking into account the interplay between the electron-hole exchange interaction, their Zeeman effect, and their hyperfine interaction with the
nuclei. This model reveals that for the
excitons with the smallest exchange splitting we reach the regime, where the
exciton fine structure becomes dominated by the hyperfine interaction with the random
nuclear spin fluctuations in the NCs.
Read the full abstract ▾
All authors Timur S. Shamirzaev, Nataliia E. Kopteva, Dmitry S. Smirnov, Dmitri R. Yakovlev, Elena V. Kolobkova, Maria S. Kuznetsova, Eugeniyus L. Ivchenko, Yan E. Maidebura, Evgeny A. Zhukov, Manfred Bayer
Materials Science
Machine learning metallic glass critical cooling rates through elemental and molecular simulation based featurization
Lane E. Schultz, Benjamin Afflerbach, Paul M. Voyles et al. (+1 more)
We have developed a machine learning model for critical cooling rates for metallic glasses based on computational properties. We compare results for features derived from easy-to-compute functions of elemental properties to more complex physically motivated properties using ab initio, machine-learning potentials, and empirical potential molecular dynamics methods. The established approach enables property acquisition across a diverse range of
alloys. Analysis of various features for 34
alloys from 20 chemical systems shows that the best model for critical cooling rates was learned from one elemental property-based feature and three simulated features. The elemental property-based feature is an ideal
entropy value based on
alloy stoichiometry. The simulated features were acquired from estimates of energies above the convex hull, changes in heat capacity, and the fraction of icosahedra-like Voronoi polyhedra. Models were assessed through a demanding cross validation test based on repeatedly leaving out full chemical systems as test sets and had an $R^2$ of 0.78 and a mean average error of 0.76 in units of $[log_{10}(K/s)]$. We demonstrate with Shapley additive explanation analysis that the most impactful features have physically reasonable influence on model predictions. The established methodology can be applied to other high-throughput studies of material properties of diverse compositions.
Read the full abstract ▾
All authors Lane E. Schultz, Benjamin Afflerbach, Paul M. Voyles, Dane Morgan
Soft Condensed Matter
Nonlocal Sensing Drives Hybrid Phase Separation in Brownian Matter
Benchang Wu, Ziluo Zhang, Shutong Guo et al. (+2 more)
Matter can organize not only through forces, but also through the information its constituents acquire from their surroundings. Here we use perceptive Brownian particles as a minimal model to isolate nonlocal sensing as an organizing principle for nonequilibrium matter. The particles undergo purely Brownian motion, with no mechanical interactions, self-propulsion,
alignment, or auxiliary fields. Their only coupling is informational, through diffusivity regulated by density measured over a finite perception zone. Whereas local sensing, when unstable, produces conventional long-wavelength demixing, nonlocal perception restructures the instability spectrum, introducing finite-wavelength patterning and nonlinear bubbling instabilities. More fundamentally, it reshapes the ordering pathway by assembling a cascade of instabilities: macroscopic demixing creates dense domains, finite-wavelength modes pattern them internally, and nonlinear feedback hollows them into void bubbles. This produces hybrid phase separation, where a macroscopic dense phase coexists with a dilute background while retaining ordered internal microstructure, whose
symmetry, anisotropy, and length scales are selected by the perception kernel. These results establish information acquisition as a constitutive principle of nonequilibrium matter, capable of governing both phase stability and the dynamical pathways through which order emerges.
Read the full abstract ▾
All authors Benchang Wu, Ziluo Zhang, Shutong Guo, Hepeng Zhang, Zhihong You
High Energy Physics (Theory) · Cross-listed from math.QA
Non-commutative calculus and Getzler-Gauss-Manin connections for Open-closed Homotopy Algebras
Zekai Yu
We establish the calculus structure on Hochschild invariants of open-closed homotopy
algebras. We further define the Getzler-Gauss-Manin connection and show that it is flat up to chain homotopy on the open-closed periodic cyclic chain complex.
General Relativity and Quantum Cosmology · Cross-listed from math.DG
On toric self-dual Einstein gravitational instantons
Bernardo Araneda, James Lucietti and Virinchi Rallabhandi
We consider the classification of toric self-dual Einstein gravitational instantons with negative cosmological constant. As is well known, any Killing vector field on a self-dual Einstein
manifold defines a local conformal Kähler structure. We prove that if the conformal Kähler structure associated to one of the
torus Killing fields is global and extends to an ALE
manifold with no additional fixed points, then the corresponding self-dual Einstein instanton is precisely given by the infinite class of multipole solutions constructed by Calderbank, Pedersen and Singer.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Spin qubit operations by conveyor-mode shuttling
M. De Smet, Y. Matsumoto, D. Fernández-Fernández et al. (+8 more)
Dynamic
qubit routing is emerging as a promising architectural path for
semiconductor quantum processors. Charge carriers can be rapidly moved around on a chip using traveling-wave potentials known as conveyors, preserving the
spin state with high fidelity. Originally developed for
spin transport, conveyor-mode shuttling may also offer opportunities for performing
qubit operations directly controlled by the motion itself. Here, we demonstrate coherent single- and two-
qubit control by conveyor-mode electron shuttling, using two conceptually different approaches. First, conveyor electric-dipole
spin resonance (conveyor EDSR) achieves high-fidelity rotations by resonantly shuttling
spins through transverse
magnetic-field gradients at their mean Larmor frequency. Second, conveyor diabatic gates exploit quantization-axis tilts for tunable bang-bang control. Combining diabatic conveyor transport with exchange activation controlled by the motion directly yields a variety of effective two-
qubit interactions selectable via the shuttling speed and distance. These experimental results motivate an architectural paradigm of reconfigurable and transport-driven
spin qubits.
Read the full abstract ▾
All authors M. De Smet, Y. Matsumoto, D. Fernández-Fernández, L. Tryputen, S.L. de Snoo, D.J. Michalak, H.G.J. Eenink, G. Platero, S. Bosco, G. Scappucci, L.M.K. Vandersypen
Instrumentation and Detectors
Test of the JUNO 20-inch PMTs during Installation
Haojie Dong, Zhaoyuan Peng, Zhonghua Qin et al. (+13 more)
Photomultiplier tubes (PMTs) are widely used in
neutrino experiments. As a new-generation
neutrino observatory, JUNO requires an excellent energy resolution of 3% at 1 MeV. This will be realized with a 20 kton
liquid scintillator detector instrumented with more than 20000 20-inch PMTs and 25600 3-inch PMTs. These PMTs were successfully installed in JUNO from October 2022 to December 2024. During the installation, seven test campaigns were performed to validate the PMT functionality, including measurements dark count rate, gain, waveform, and charge spectrum. In this paper, we present the implementation of these tests and the corresponding results for the 20-inch PMTs throughout the installation process.
Read the full abstract ▾
All authors Haojie Dong, Zhaoyuan Peng, Zhonghua Qin, Wan Xie, Haoqi Lu, Jun Hu, Lei Fan, Xiaoshan Jiang, Chao Chen, Xiaolu Ji, Fei Li, Shenghui Liu, Xiaochuan Xie, Mei Ye, Hongzhao Yu, Zeyuan Yu
Materials Science
Bulk Photovoltaic Effect in Two-Dimensional Perovskite Oxides
Chunmei Zhang, Jian Zhou and Liang Si
Perovskite
oxides ABO$_3$ host a rich interplay of charge,
spin,
lattice, and orbital degrees of freedom, giving rise to diverse
quantum phenomena. In low-dimensional ABO$_3$, reduced
symmetry can induce exotic
quantum effects such as the two-dimensional electron gas and unconventional superconductivity. Using first-principles density functional theory, tight-binding modeling, and
symmetry analysis, we show that ultrathin two-dimensional (2D) ABO$_3$ films – exemplified by SrTiO$_3$ – naturally break inversion
symmetry, producing a spontaneous out-of-plane bulk photovoltaic (BPV) effect. This differs from previous studies on in-plane BPV current signals and is more applicable and experimentally detectable. Such an effect is highly tunable via thickness, strain, surface termination, crystallographic orientation, and Moiré twisting. These findings are broadly applicable to a wide range of 2D perovskite and other layer-resolved
oxides.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Relativistic effects in extreme-mass-ratio inspirals within scalar clouds: Eccentric and inclined orbits
Qi-Xuan Xu, Richard Brito, Riccardo Della Monica et al. (+2 more)
We study extreme-mass-ratio inspirals (EMRIs) evolving in a scalar cloud environment that may form through superradiant instabilities, using a fully relativistic perturbative framework that allows for eccentric and inclined orbits. EMRIs, consisting of a
stellar-mass compact object inspiraling into a supermassive black hole, are key sources for space-based gravitational-wave detectors such as LISA. Previous relativistic studies of EMRIs in scalar clouds have been restricted to circular, equatorial motion. Here, instead, we focus on a Schwarzschild black hole background to incorporate eccentricity and orbital inclination. By computing the scalar energy and angular momentum scattered off to spatial infinity and absorbed at the event horizon, we show that orbital eccentricity can induce a dense spectrum of resonances near the last stable orbit, associated with strong relativistic apsidal precession. We further find that orbital inclination can significantly modify the orbital energy and angular momentum losses. In particular, we identify a critical inclination angle below which, at sufficiently small orbital radii, there is a net transfer of energy from the scalar cloud to the orbit. Moreover, for sufficiently large eccentricities, resonances associated with relativistic apsidal precession persist across the full range of inclinations, although their structure changes significantly between prograde and retrograde orbits. These results provide a foundation for future studies of EMRIs in scalar cloud environments on fully generic orbits around spinning black holes.
Read the full abstract ▾
All authors Qi-Xuan Xu, Richard Brito, Riccardo Della Monica, Rodrigo Vicente, Chen Yuan
Optics
Induced Directional Switching of Platicon Microcombs in Photonic Crystal Ring Resonators
Erwan Lucas, Su-Peng Yu, Jizhao Zang et al. (+1 more)
Microcombs in normal-dispersion photonic
crystal ring resonators (PhCRs) are versatile building blocks for next-generation integrated photonic
circuits, but their inherent backward-propagation bias necessitates optical circulators or complex filtering for comb extraction, creating a significant bottleneck for full on-chip integration and precluding self-injection locking schemes. In this work, we introduce Side-mode Induced Forward Forcing (SIFF), a robust method to control and reverse this directionality. By engineering auxiliary mode splittings on resonances adjacent to the pump, we steer the nonlinear dynamics to favor stable, forward-propagating platicon states. We identify an optimal coupling condition that ensures forward-comb dominance across a wide parameter range. Our findings, validated numerically and experimentally, enable circulator-free, integrated normal-dispersion microcombs compatible with self-injection locking, offering a scalable architecture for compact telecommunications and sensing systems.
Read the full abstract ▾
All authors Erwan Lucas, Su-Peng Yu, Jizhao Zang, Scott B. Papp
Nuclear Theory
Is the coexistence of strange quark stars and hadronic stars favored by astrophysical data? A Bayesian analysis
Luca Passarella, Mirco Guerrini, Giuseppe Pagliara et al. (+2 more)
Hadronic
stars and strange
quark stars could coexist within the so-called two-families scenario. In this respect, hadronic matter and strange
quark matter correspond to two distinct
equilibrium phases described by two different equations of state. We perform here the first detailed
Bayesian analysis that makes use of astrophysical and laboratory data in order to constrain the equations of state adopted within the two-families scenario for hadronic and strange
quark matter. In particular, in hadronic matter we consider the possible formation of hyperons and delta resonances (beside nucleons) within a class of non linear relativistic mean field models and in
quark matter we consider the possible formation of a color-superconducting phase within a bag-like model. Results of the analysis indicate that while at the moment both the one-family and the two-families scenarios are compatible with the data, by comparing the Bayes factors of both models, the two-families scenario is favored with respect to the one-family scenario. Specifically, the two-families framework naturally relieves the tension between the intermediate-density softness of the equation of state required by small-radius objects and the high-density stiffness needed to support massive
pulsars. Ultimately, future detections of even more massive compact objects, very compact ordinary-mass objects, or precise measurements of two distinct masses with the same radius, will provide strong indications in favor of the two-families scenario.
Read the full abstract ▾
All authors Luca Passarella, Mirco Guerrini, Giuseppe Pagliara, Andrea Lavagno, Alessandro Drago
High Energy Astrophysical Phenomena
The Fundamental Planes of Black Hole Activity for High-Synchrotron-Peaked BL Lacertae Objects
Qing-Chen. Long, Ai-Jun. Dong and Qi-Jun.Zhi
The
radio–X-ray correlation and Fundamental Plane (FP) of black hole activity can serve as a diagnostic tool for the origin of X-ray emissions. There was a scaling relation between
radio and X-ray emissions for High-synchrotron-peaked BL Lacertae objects (HBLs), i.e., $L_{\rm{R}}\propto L_{\rm{X}}^{0.64}$, which can be explained by ADAF-dominated mode or synchrotron cooling (Syn-c). However, many results of studying blazar physics show that the X-ray emissions of HBLs are mainly produced by the synchrotron process of jets. Therefore, Syn-c appears to provide a plausible explanation for this relation. To further clarify the origin of X-ray emissions of HBLs, we constructed a sample containing 69 HBLs in this paper to re-investigate their
radio–X-ray correlation and FP. Considering the Doppler beaming effect, we find that the intrinsic
radio–X-ray correlation and FP of HBLs are $L_{\rm R,int}\propto L_{\rm X,int}^{0.68}$ and $\log L_{\rm R,int}=(0.57\pm0.06)\log L_{\rm X,int}+(0.33\pm0.11)\log M_{\rm BH}+(12.65\pm2.00)$, respectively. Our results agree with the scaling relation mention above, which suggests these scaling relations are not artificial. By employing the theoretical model of Syn-c, we find that these shallow
radio–X-ray correlations and FP are caused by Syn-c, which implies that the X-ray emissions of HBLs may be produced by rapidly cooling, high-energy electrons accelerated at a shock. This is consistent with results of the recent X-ray polarization observations of HBLs. Our results provide the observational evidence of $L_{\rm R}\propto L_{\rm X_{\text{Syn-c}}}^{0.6\sim0.7}$.
Read the full abstract ▾
Plasma Physics
Geometric numerical discretization of a quasineutral hybrid model of drift-kinetic electrons and fully kinetic ions
Nishant Narechania, Guo Meng, Emil Poulsen et al. (+1 more)
We extend the
geometric electromagnetic particle-in-
cell (PIC) framework, GEMPICX, to solve the quasineutral hybrid Vlasov-Maxwell equations with drift-kinetic electrons and fully kinetic ions. A structure-preserving finite difference method that employs dual grids is used. The discrete action principle for the hybrid model is derived, using the dual nature of the grids. The dynamical system for this hybrid quasineutral model does not explicitly involve the temporal
evolution term for the electric field. A curl-curl equation is therefore used to implicitly obtain the component of the electric field that is parallel to the background
magnetic field, at every timestep. The perpendicular component of the electric field is obtained using the quasineutral Ampere's equation without the displacement current, combined with the definition of the current in the drift-kinetic model. The discretized versions of the electric field equations are large, sparse linear systems. A fully explicit time-stepping scheme as well as two implicit-explicit (IMEX) schemes are tested. The numerical model is validated by verifying the various waves obtained from the dispersion relation.
Read the full abstract ▾
All authors Nishant Narechania, Guo Meng, Emil Poulsen, Eric Sonnendruecker
Solar and Stellar Astrophysics
XP-TEAL: Gaia XP Tool for Emission and Absorption Lines II. Gaia-HELIX catalogue of H$\alpha$ emitters in Gaia BP/RP spectra
S. Malhotra, M. Weiler, F. Anders et al. (+8 more)
Context: With
Gaia's third Data Release (DR3), low-resolution BP/RP (XP) spectra became available for more than 219 million sources. In previous work, we developed a fast method for detecting absorption and emission lines while measuring their equivalent widths directly from the XP spectral coefficients. Aims: We conduct a systematic search for H$\alpha$ emitters in the
Gaia DR3 XP spectra. Methods: We measured the equivalent width of the Balmer H$\alpha$ line for all sources with
Gaia XP spectra and selected an initial sample of 556100 sources depicting an H$\alpha$ emission-like feature at $2\sigma$ level or above. Using a semi-supervised classifier complemented by manual spectral labelling, we removed sources that merely masqueraded as emission-line
stars. Results: We find that 95% of the initial candidates are most likely cool M-type
stars, where a molecular absorption band gives rise to a local maximum that can mimic H$\alpha$ emission. Subsequently, 28394 sources were flagged as bona fide H$\alpha$ emitters using the
Gaia DR3 XP spectra. The majority are Be-like candidates (26287), M-type emission-line
stars (717), Herbig Ae/Be candidates (525), quasi-
stellar objects (204), Wolf-Rayet
stars (177), cataclysmic variables (51), and carbon
stars (18), among other sources. Our equivalent widths and
stellar classifications agree well with results from higher-resolution studies and recent
Gaia XP spectra-based catalogues. Ground-based spectroscopic follow-up for some of the newly found H$\alpha$ emitters reinforces our confidence in the catalogue.
Read the full abstract ▾
All authors S. Malhotra, M. Weiler, F. Anders, J. M. Carrasco, G. Garcia-Moreno, C. Jordi, N. Blagorodnova, A. Castro-Ginard, J. Castañeda, F. Boix, X. Luri
Plasma Physics
Geometric numerical discretization of electromagnetic quasineutral models
Nishant Narechania, Emil Poulsen and Eric Sonnendrucker
In this work, the
geometric electromagnetic Particle-in-
Cell (PIC) framework, GEMPICX, is extended to solve the quasineutral, fully kinetic Vlasov-Maxwell equations on dual grids using mimetic finite differences. The discrete action principle is derived, taking into account the duality between the grids. The temporal derivative of the electric field does not directly appear in the dynamical system for the quasineutral model. Hence, a discretized curl-curl equation is used to implicitly obtain the electric field at every time-step. This also circumvents the need to obtain electric potentials. A Lagrange multiplier is used to maintain the discretized divergence of the current density at machine zero.
Read the full abstract ▾
Optics
Blind Gradient-Ascent Phase Alignment for Multi-Aperture Coherent Digital Combining Under Aperture-Dependent Phase Disturbance
Cheng Chen, Tong Luo, Jiayin Xue et al. (+5 more)
Multi-aperture reception can provide spatial diversity in free-space optical (FSO) communication by collecting signal replicas at separate apertures. When the branches are accurately phase-aligned, their received optical fields can also be added constructively to obtain coherent-combining gain. In this paper, we propose blind gradient-ascent phase
alignment (BGAPA), which iteratively adjusts one phase correction per aperture by directly maximizing the combined output power. Closed-form analytical gradients provide a deterministic update that requires no symbol decisions, unlike the
stochastic perturbation-based estimate of SPGD or the decision-directed feedback of DD-LMS. To isolate phase-tracking capability, the numerical model includes independent aperture-dependent phase disturbance but excludes amplitude scintillation and polarization-dependent distortion. Under this controlled phase-only setting, BGAPA obtains an SNR improvement closer to the ideal 6.02~dB coherent-combining gain than block-wise cross-correlation, SPGD, DD-LMS, and CMA/RDE-based equalization when the aperture count is increased by a factor of four. In particular, increasing the aperture count from 64 to 256 yields an SNR improvement of about 5.7~dB. In a separate amplitude-tolerance test with $N=16$ and $f_{\max}=1$~MHz, the first observed BGAPA trial above the HD-FEC threshold of $3.8\times10^{-3}$ occurs at an actual phase RMS of approximately 278~rad, whereas DD-LMS becomes unreliable at substantially smaller phase excursions. The reported step size is optimized separately at each operating point. BGAPA is fully blind and updates its phase parameters directly from the received aperture fields without training symbols, pilots, or decision-directed feedback.
Read the full abstract ▾
All authors Cheng Chen, Tong Luo, Jiayin Xue, Siyu Gong, Qun Zhang, Linsheng Fan, Qi Wu, Yanfu Yang
Materials Science · Cross-listed from math.NA
An FFT-based solver with general boundary conditions for stationary diffusion problems based on Chebyshev collocation
Juan M. Quecedo and Javier Segurado
An efficient and robust FFT-based solver is proposed for
diffusion-type problems with general Neumann and Dirichlet boundary conditions, based on a Chebyshev collocation framework. The method combines Chebyshev
polynomial approximations with FFT-based operators to provide a
matrix-free implementation of the discrete differential operator at the Chebyshev-Gauss-Lobatto points. The linear system of equations resulting from the Chebyshev discretization is solved using LGMRES. To overcome convergence problems on fine grids, a hierarchical refinement strategy based on modal prolongation is proposed, enabling the solution of very large 3D problems. The methodology is applicable to homogeneous and heterogeneous domains, as well as to linear and nonlinear constitutive equations. The accuracy of the proposed method is analyzed by solving the Poisson equation in homogeneous 1D and 3D domains with general boundary conditions, using manufactured analytical solutions as references. Convergence to the analytical solution is achieved in a few iterations, with smaller errors than those obtained using DCT/DST approaches. Discretizations of up to $256^3$ are achieved thanks to the hierarchical refinement strategy. In the case of heterogeneous domains, the accuracy and efficiency obtained are similar to those of a standard periodic FFT approach. It is found that the computational complexity of the method preserves the FFT scaling, of order $n\log n$, in all the cases studied.
Read the full abstract ▾
High Energy Astrophysical Phenomena
A New Scaling of Neutron Star Tidal Deformability for Directly Probing the Central Equation of State Parameter
Jian-Hao Shi, Bao-Jun Cai, Bao-An Li et al. (+1 more)
The dimensionless
tidal deformability, $\Lambda$, of
neutron stars (NSs), inferred from gravitational-wave (GW) observations, has thus far been used primarily to constrain the pressure of dense matter near twice
nuclear saturation density, leaving the core equation of state (EOS) largely inaccessible to inspiral-phase GW observations. We show that a fundamental central EOS parameter can be probed directly through $\Lambda$ using a perturbative analysis of the dimensionless
stellar-structure and
tidal-response equations formulated in terms of scaled intrinsic variables, without invoking any specific EOS model. We uncover a remarkable EOS-insensitive scaling relation between $\Lambda$ and the central EOS parameter $\rm{X}\equiv P_{\rm c}/\varepsilon_{\rm c}$, where $P_{\rm c}$ and $\varepsilon_{\rm c}$ denote the central pressure and energy density, respectively. The relation is validated against a broad ensemble of physically viable EOSs. Applying it to
tidal deformabilities inferred from events such as GW170817 enables a direct determination of $\rm{X}$. By adopting the previously established effective upper bound $\rm{X}\lesssim0.381$, we infer a tight lower bound, $\Lambda_{\rm{TOV}}\gtrsim9.1^{+0.5}_{-0.5}$, for maximum-mass NSs along stable mass-radius sequences, quantitatively demonstrating that even the most compact stable NSs remain distinctly separated from black holes, for which $\Lambda_{\rm{BH}}=0$. These findings reveal a previously unrecognized connection between inspiral-phase
tidal deformability and the central EOS parameter $\rm{X}$, establishing a direct link between GW observables and the microphysics of ultradense matter in the strong-
gravity regime. The resulting scaling establishes inspiral-phase
tidal deformability as a direct and largely model-insensitive probe of the central EOS parameter $\rm{X}$, and hence of key properties of NS cores.
Read the full abstract ▾
All authors Jian-Hao Shi, Bao-Jun Cai, Bao-An Li, Yu-Gang Ma
Fluid Dynamics
Enhanced Heat Transfer through Density- and Pressure-Driven Flow at Fracture Intersections With Dead-Ends
Lisa Maria Ringel, Yves Méheust, Caroline Darcel et al. (+2 more)
Heat transport in fractured media is governed by coupled thermal-hydraulic (TH) processes. This study evaluates TH processes at fracture intersections, focusing on T-intersections where one horizontal fracture is subjected to a pressure gradient while the other forms a vertical dead-end fracture. Using numerical simulations, we investigate the influence of the inlet velocity, thermal Péclet, and Rayleigh numbers, and the impact of a pressure gradient along the T-intersection, on the resulting heat transport. The model domain consists of a fluid and a solid region. Fluid flow and heat transport in the fractures are described by the conservation equations for mass, momentum, and energy. The rock
matrix is considered impermeable, therefore, it is governed by heat conduction. The simulations consistently show that heat transfer from the fluid to the
matrix is enhanced when fluid flow occurs within the dead-end fracture, since such fluid flow maintains a higher temperature difference between the
matrix and the fluid. This flow arises either from buoyancy-driven natural convection due to temperature-dependent fluid density or from a pressure gradient imposed by the orientation of the dead-end fracture with respect to the flow direction in the horizontal fracture. Natural convection dominates at high flow rate, Rayleigh, and Péclet numbers, whereas pressure-driven flow becomes the controlling mechanism for an increasing deviation from the orthogonal configuration of the two fracture planes and under higher flow rates. At low flow rates, Péclet, or Rayleigh numbers, no flow develops in the dead-end fracture, and heat transport in the dead-end fracture becomes conduction-dominated.
Read the full abstract ▾
All authors Lisa Maria Ringel, Yves Méheust, Caroline Darcel, Philippe Davy, Maria Klepikova
Materials Science · Cross-listed from cs.LG
Atomistic Language Models Understand and Generate Materials
Sathya Edamadaka, Krithik Ramesh, Ju Li et al. (+1 more)
Atomistic structure and natural
language have long been modeled separately, with
language models either calling atomistic models as tools or being fine-tuned on lossy textual encodings that discard atomistic information. We introduce Atomistic
Language Models (ALMs) to pursue native multimodality, in which a single
language backbone understands atomistic structures, generates materials from natural
language, and optimizes
crystal structures as instructed by text. By unifying a pretrained atomistic encoder, large
language model, and denoising
diffusion model through purely continuous projectors and staged training, ALMs achieve state-of-the-art results on
crystal structure prediction and de novo generation. ALMs are enabled by a continuous bridge that maps
language model
embeddings directly into the steering space of atomistic
diffusion, and are assisted by Text-to-
Crystal Feynman-Kac (T2C-FK), a particle-based sampler that scores partial denoising trajectories to enforce stoichiometric targets at inference time. To evaluate the ability of ALMs to optimize and generate materials from natural-
language prompts and 3D atom-coordinate inputs, we introduce ALM Bench, the first
benchmark for text-conditioned
crystal generation and optimization. Code, training data, and model weights will be released soon.
Read the full abstract ▾
All authors Sathya Edamadaka, Krithik Ramesh, Ju Li, Rafael Gómez-Bombarelli