High Energy Physics (Theory)
Multi–black holes in Bertotti–Robinson spacetime
Hideo Furugori, Jun-ichi Sakamoto and Shinya Tomizawa
We construct a new class of exact solutions describing multi-black holes in the Bertotti–Robinson spacetime, using the monodromy-
matrix formalism associated with integrable sigma models. Starting from the extremal Reissner–Nordström black hole in the Bertotti–Robinson background, we derive the corresponding coset and monodromy
matrices and show that they are governed by nilpotent algebraic structures. This property enables an explicit factorization of the monodromy
matrix, allowing for a systematic reconstruction of the underlying gravitational solutions. We extend this construction to multi-center configurations by introducing multiple poles in the monodromy
matrix, leading to Majumdar–Papapetrou–type solutions with Bertotti–Robinson asymptotics. Each center is shown to correspond to a regular extremal black hole with an $\mathrm{AdS}_2 \times S^2$ near-horizon geometry, and the asymptotic end likewise approaches a Bertotti–Robinson geometry. We further generalize the framework to stationary configurations in the Bertotti–Robinson spacetime, as well as to a broader class of Israel–Wilson–Perjés-type solutions, by considering more general nilpotent elements. Our results demonstrate that the monodromy-
matrix approach provides a powerful and systematic framework for constructing multi-black hole solutions in nontrivial backgrounds, and suggest a promising route toward more general configurations.
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Nuclear Theory
Efficient calculation of two-neutrino double-beta-decay nuclear matrix elements
Mihai Horoi
Reliable
nuclear matrix elements (NMEs) are essential for interpreting double-beta-decay experiments and for connecting measured or constrained half-lives to the underlying weak-interaction physics. The two-
neutrino mode ($2\nu\beta\beta$) is allowed by the Standard Model and has been observed in several
nuclei, whereas the neutrinoless mode ($0\nu\beta\beta$) remains the key experimental signature of
lepton-number violation and Majorana
neutrino masses. Recent statistical shell-model studies indicate a strong correlation between the $2\nu\beta\beta$ and $0\nu\beta\beta$ NMEs, making accurate and efficient calculations of the former especially useful for assessing the latter. Direct evaluations of $2\nu\beta\beta$ NMEs usually require summing over many $1^+$ states in the intermediate odd-odd
nucleus, a procedure that becomes expensive and may converge slowly in large model spaces. We present and test an improved strength-function method based on Lanczos iterations that avoids full diagonalization while preserving the accuracy of explicit summation where such
benchmarks are possible. The method is applied to several experimentally important emitters and to different effective
Hamiltonians. We also show that the same framework can be used for the higher-order NMEs entering Taylor-expanded phase-space treatments of $2\nu\beta\beta$ and related decay modes.
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Instrumentation and Methods for Astrophysics
Faraday Tomography with the SKA: A New Era of Cosmic Magnetism Studies
Miguel Carcamo, Anna M. M. Scaife, Jeroen Stil et al. (+3 more)
The Square Kilometre Array (SKA) represents a significant advancement in
radio astronomy, enabling detailed study of
cosmic magnetism through Faraday Rotation and Faraday Measurement Synthesis. This chapter provides a comprehensive review of these techniques, tracing their development and illustrating their crucial role in investigating
magnetic fields across different
cosmic environments. We focus on Array Assembly 4 (AA4), the final deployment stage, featuring 197 dishes (133 SKA, 64 MeerKAT) with 40 km maximum baselines and frequency coverage from 350 MHz to 15.4 GHz (goal: 24 GHz). These capabilities enable high-resolution Faraday
tomography of
magnetic structures in
galaxies, clusters, and the
cosmic web. We also highlight the earlier AA* stage with 144 dishes (80 SKA, 64 MeerKAT). Band 1 (350–1050 MHz) offers the finest Faraday depth resolution among the dish bands (full resolution $\sim$2.5 rad m$^{-2}$) with a maximum observable depth around 174,708 rad m$^{-2}$. Other bands (Band 2, Band 5a, Band 5b) enable multi-scale studies, probing larger structures with lower resolution but higher maximum depths. We discuss synergies between Faraday Measurement Synthesis and Image Synthesis techniques, showing how they complement each other in reconstructing
magnetic field structures. Simulation results demonstrate the SKA's potential for high-resolution observations. We explore possible enhancements beyond the baseline configuration and synergies with other observatories, emphasizing multi-wavelength astronomy. This chapter aims to provide a thorough account of how the SKA's phased deployment from AA* to AA4 will transform our understanding of
cosmic magnetic fields and drive new discoveries in astrophysics.
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All authors Miguel Carcamo, Anna M. M. Scaife, Jeroen Stil, Russ Taylor, Jennifer L. West, Tessa Vernstrom
High Energy Physics (Theory)
Higher dimensional quantum Hall effect and the analog of $W_\infty$-algebra
Dimitra Karabali and V.P. Nair
We show that Abelian and nonabelian gauge transformations are the analog of $W_\infty$ transformations for higher dimensional
quantum Hall effect. The commutator anomaly and the extended
algebra of such transformations on the edge modes of a droplet are obtained by purely topological arguments, basically utilizing the two-cocycle in the descent procedure for anomalies and using the fact that there is anomaly cancellation between the bulk and boundary actions. The method relies on the fact that bulk actions are easily constructed in general using the Dolbeault index
theorem. The resulting
algebras are shown to agree with explicit edge mode calculations for cases where they are available. We also comment on the similarities and differences in the nature of these transformations between two and higher dimensions.
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High Energy Physics (Phenomenology)
Neural-Network extraction of TMDs with SIDIS data
Matteo Cerutti
A first global analysis of unpolarized Transverse-Momentum-Dependent (TMD) distributions based on a neural-network (NN) parametrization is presented. Drell-Yan (DY) and semi-inclusive deep inelastic scattering (SIDIS) data are simultaneously included at next-to-next-to-next-to-leading logarithmic (N$^3$LL) accuracy. The results indicate that the inclusion of SIDIS data leads to broader unpolarized TMD PDFs compared to a DY-only NN extraction. The associated uncertainties are reduced with respect to the DY-only case, while remaining larger than the ones obtained using traditional models. These results demonstrate the potential of flexible NN parametrizations in reducing model dependence and provide guidance for future high-precision measurements at Jefferson Lab and the Electron-Ion
Collider.
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High Energy Physics (Phenomenology)
Real poles with opposite-sign residues in the non-perturbative quark propagator
R. Alkofer, M.N. Ferreira, A.S. Miramontes et al. (+2 more)
We investigate the analytic structure of the
quark propagator in the Landau gauge by dynamically coupling the standard gap equation to the non-perturbative
quark-
gluon vertex. Employing the full vertex basis, we demonstrate that for sub-GeV time-like momenta, the proper inclusion of the underlying dynamics leads to a pair of real poles with opposite-sign residues. In particular, in stark contradistinction to the results obtained in widely used approximations, we see no sign of complex conjugate poles. This distinctive analytic structure evades conceptual shortcomings frequently associated with complex conjugate poles while remaining fully compatible with the aspects of color confinement related to positivity violation. Crucially, this novel behavior is governed by a dominant triplet of vertex form factors: the tree-level component, the anomalous chromomagnetic moment, and a component we label as "
spin-momentum
curvature". By gradually tuning the individual strengths of these components, we demonstrate that while they contribute in distinct ways to the
quark propagator, their joint action is vital for stabilizing the system. Together, they place the low-lying poles onto the real axis while producing a robust constituent
quark mass of $350$ MeV.
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All authors R. Alkofer, M.N. Ferreira, A.S. Miramontes, J.M. Morgado, J. Papavassiliou
High Energy Astrophysical Phenomena
SKAO and Gamma-Ray Synergies
Gianluca Castignani, Gavin Rowell, Arnau Aguasca-Cabot et al. (+26 more)
A wide variety of
Galactic and extragalactic sources are known to emitradiation across the entire electromagnetic spectrum, including both transient and steady-state phenomena. A few hundred of these sources (~300) have been detected even at the highest energies, in the TeV range. The number of known TeV emitters is expected to increase substantially in the coming years with the operation of current and next-generation Cherenkov detectors, such as the Large High Altitude Air Shower Observatory (LHAASO) and the Cherenkov
Telescope Array Observatory (CTAO). These sources typically exhibit broad, non-thermal, spectral energy distributions. Explaining such emission requires efficient particle acceleration mechanisms (e.g.
Fermi processes, shock acceleration) and radiative processes involving
magnetic fields (e.g. synchrotron and inverse Compton radiation), often accompanied by polarization signatures. However, the relative contribution of these emission mechanisms and the underlying physical processes are still debated. In this work, we present an overview of the scientific potential arising from the synergy between the Square Kilometre Array (SKA) and current and upcoming gamma-ray facilities. Combined observations across these energy bands will provide crucial insights into the physical mechanisms driving emission from GeV-TeV sources of both
Galactic and extragalactic origin. These include transient events (e.g. gamma-ray bursts,
supernovae, fast
radio bursts,
tidal disruption events,
neutrino and gravitational-wave counterparts), variable sources (e.g. blazars, active
galactic nuclei), and steady emitters (e.g. the
Galactic centre,
supernova remnants,
radio galaxies, and
galaxy clusters). We discuss the prospects for coordinated SKA-gamma-ray observations, including wide-field surveys, monitoring of variable sources, and target-of-opportunity follow-ups.
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All authors Gianluca Castignani, Gavin Rowell, Arnau Aguasca-Cabot, Gemma E. Anderson, Csaba Balazs, Pol Bordas, Andrea Botteon, Jess W. Broderick, Gianfranco Brunetti, Ettore Carretti, Roland M. Crocker, Shi Dai, Filippo D'Ammando, Philip G. Edwards, Sabrina Einecke, Miroslav D. Filipovic, Marcello Giroletti, Adelle J. Goodwin, James A. Green, Sanja Lazarevic, Giulia Migliori, Monica Orienti, Josep M. Paredes, Elena Pian, Alak Ray, Lauren Rhodes, Zachary J. Smeaton, Nick Tothill, Martin White
High Energy Physics (Theory)
Non-primary square roots in massive gravity
Alexey Golovnev
Non-linear dRGT massive and bimetric gravities are complicated theories constructed in terms of square roots of
matrices. Apart from the technical issues of successfully working with such square roots, there is also a problem of their non-uniqueness. There are claims in the literature that one should better use the principal root. This is a very reasonable conclusion. However, the motivation they give for it is that otherwise there would be non-primary square roots violating the general covariance. In this paper, I would like to show that, if properly understood, the non-primary square roots are also perfectly covariant. At the same time, I recall the relatively old observation that the real problem with such square roots lies in perturbation theory around them. In terms of
matrices, it simply does not exist. In terms of the elementary symmetric
polynomials used in the Lagrangian density, it is not analytic. Moreover, the non-principal square roots are more prone to getting into the complex domain.
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Mesoscale and Nanoscale Physics
Interlayer electric multipole Hall effect in twisted multilayers
Chengxin Xiao, Cong Xiao, Dawei Zhai et al. (+1 more)
Electrons in layered van der Waals materials possess a layer pseudospin characterizing their wave-function distribution among layers. In twisted structures, this pseudospin forms nontrivial textures, leading to intriguing phenomena such as the layer
Hall effect (LHE), where distinct layer
Hall currents flow despite the presence of time-reversal
symmetry. In
chiral bilayers, LHE manifests as an interlayer electric dipole
Hall effect with
Hall counterflows and a concomitant in-plane
magnetic dipole. Multilayers host richer layer-dependent
Hall currents, generating interlayer electric multipole
Hall effects and in-plane
magnetic multipoles. We start from exploring the interlayer electric quadrupole
Hall effect in mirror-symmetric twisted trilayers. At small twist angles, interlayer translation efficiently tunes layer
Hall current magnitudes. At large angles and low doping, the currents can be well accounted for by adding the contributions from the two individual twisted interfaces. This decomposition allows obtaining layer-resolved
Hall currents in large-angle twisted multilayers even without well-defined periodicity.
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All authors Chengxin Xiao, Cong Xiao, Dawei Zhai, Wang Yao
Quantum Physics
Hybrid Quantum-Classical Neural Networks for Recognizing Quantum Phases
Colin Scarato, Johannes Knörzer, Markus K. Hoffmann et al. (+11 more)
Identifying
quantum phases of matter is key to understanding strongly correlated materials, but remains a challenging task for both conventional computers and current
quantum processors. Here, we introduce and implement a hybrid
quantum-classical neural network for
quantum phase recognition by combining a hardware-efficient parameterized
quantum circuit and a feedforward neural network. We jointly train both components with superconducting
quantum hardware in the optimization loop, to experimentally demonstrate a classifier for the
quantum phases of surface code
lattices with up to 4x4 sites in a
magnetic field. To learn nonlocal features of the topological phase, we train the hybrid neural network to distinguish topological ground states of the surface code from a featureless ensemble of product states. This allows the trained classifier to distinguish topological ground states from randomly chosen product states, even when subjected to any single-
qubit Pauli error. The classifier reaches accuracies above 85% in single-shot measurements, and above 99% when averaging over ten measurements. We expect hybrid neural networks such as the one presented here to be a promising approach for characterizing
quantum states in scenarios where classical methods exhibit an unfavorable scaling of sample complexity.
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All authors Colin Scarato, Johannes Knörzer, Markus K. Hoffmann, Leon C. Sander, Luca Hofele, Shengpu Wang, Kilian Hanke, Ashay Sathe, Dominic Hagmann, Alexander Flasby, Michael J. Hartmann, Petr Zapletal, Andreas Wallraff, Christoph Hellings
Quantum Physics
Hybrid quantum-classical neural network for sample-efficient recognition of topological phases
Markus K. Hoffmann, Leon C. Sander, Colin Scarato et al. (+4 more)
With increasing maturity of
quantum computers, standard methods for characterizing global properties of their output
quantum states via direct measurements and classical post-processing are becoming increasingly impractical due to large measurement costs. Although
quantum neural networks could directly process
quantum states to identify underlying characteristics with reduced measurement efforts, they often require deep
quantum circuits that cannot be implemented on existing devices. To overcome these challenges, we introduce a hybrid
quantum-classical neural network that consists of a shallow parameterized
quantum circuit, measurements, and a classical neural network. The parameterized
quantum circuit performs a nonlocal transformation of the measurement basis, which is jointly trained with the classical neural network to maximize the statistical distance between data obtained by measuring different
quantum states. Using supervised learning, we demonstrate that the hybrid neural network distinguishes the topological phase of the surface code from a
symmetry-enriched topological phase and random product states. Moreover, this hybrid neural network reduces both inference and training sample complexities of recognizing the topological phase by approximately one order of magnitude compared to a classical neural network trained on randomized Pauli measurements. As this hybrid neural network features a shallow
quantum circuit that can be readily implemented on existing
quantum computers, it enables the efficient characterization of complex
quantum states.
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All authors Markus K. Hoffmann, Leon C. Sander, Colin Scarato, Christoph Hellings, Johannes Knörzer, Michael J. Hartmann, Petr Zapletal
Solar and Stellar Astrophysics
An Adjoint Projection Formulation for Enforcing the divergence-free Constraint in Smoothed Particle Magnetohydrodynamics
Yusuke Tsukamoto
We present a projection method for controlling numerical \(\nabla\cdot\B\) errors in smoothed particle magnetohydrodynamics (SPMHD). The method corrects the
magnetic field after an MHD update by solving an
elliptic projection problem constructed from the same discrete divergence operator used to measure the error. A key ingredient is to use the adjoint gradient associated with a volume-weighted metric. With this choice, the projection gives an energy-minimizing correction, does not increase the discrete
magnetic energy, and leads to a symmetric positive semidefinite linear system that can be solved by the conjugate-gradient method without explicitly assembling the
matrix. We test the method using two-dimensional Dedner-type divergence tests and three-dimensional magnetized collapse calculations. With sufficiently many iterations, the projection reduces the divergence error to the floating-point roundoff level in both test problems. In realistic collapse runs, practical stopping criteria designed to reduce the divergence error generated by the underlying SPMHD update suppress the normalized divergence error well below that obtained in the divergence-cleaning run, with a projection cost of only about \(1\)–\(10\%\) of the SPMHD update cost. The density and
plasma-\(\beta\) structures remain consistent when the projection interval is varied, whereas the divergence-cleaning run shows quantitative differences. These results indicate that the projection method is a robust and attractive alternative to divergence cleaning for controlling \(\nabla\cdot\B\) errors in SPMHD and related particle or meshless MHD schemes.
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Mesoscale and Nanoscale Physics
Role of the Casimir force in the capacitive radio-frequency microelectromechanical switches
G. L. Klimchitskaya, A. S. Korotkov, V. V. Loboda et al. (+1 more)
We determine the role of the fluctuation-induced Casimir force acting between a membrane of cylindrical shape and a bottom electrode in microelectromechanical capacitive switches. For this purpose, the Casimir force is computed taking into account the real properties of both a membrane and a bottom electrode materials with account of surface roughness. The obtained results are compared with those found for the smooth surfaces using the idealization of ideal metal. It is shown that an account of both the real material properties and surface roughness is crucial for obtaining the correct values of the Casimir force. According to our results, at the shortest separations, when the switch membrane is in contact with the transmission line, the magnitudes of the Casimir force may exceed the magnitudes of the electric one depending on the value of the operating voltage. The obtained values of the Casimir force can be used for determining the thickness of the switch membrane, which ensures the necessary magnitude of the restoring elastic force required for a stable cyclic functioning of the micromechanical switch with no pull-in.
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All authors G. L. Klimchitskaya, A. S. Korotkov, V. V. Loboda, V. M. Mostepanenko
High Energy Physics (Theory)
Quantum anomalies from three-point on-shell bootstrap
Hiren Kakkad, Rémy Larue and Alexander Ochirov
We bootstrap
quantum anomalies using on-shell techniques in the simplest setting: at three points. The necessary field-theoretic input includes the local or global classical
symmetry, which the anomaly may break, and the
symmetries of the effective action — though not its explicit form. We use massless helicity spinors together with an on-shell representation of the discrete C, P, and T transformations. Our approach determines the Weyl,
chiral (global and local), diffeomorphism, and Lorentz anomalies up to real constant prefactors and terms that vanish on shell. In particular, we recover gauge-anomaly cancellation conditions, as well as find that the Weyl anomaly should not involve Pontryagin densities.
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Astrophysics of Galaxies
J. Moldon, A. Alberdi, M. Perez-Torres et al. (+11 more)
The appearance of
galaxies is strongly dominated by two physical phenomena:
star formation and
accretion of material onto compact objects, primarily supermassive black holes. Nearby
galaxies offer a unique window to study these processes in detail and with high spatial resolution. The $\mu$Jy sensitivity, sub-arcsecond angular resolution and broadband coverage provided by SKA AA4 configuration will enable us to separate morphologically and spectrally the contribution from SMBH
accretion and
star formation processes, from the most compact
nuclear region out to the most diffuse,
galaxy-wide components. Disentangling thermal and non-thermal emission using multi-scale spectral index maps (traced by SKA-Mid) and absorption processes (traced mainly by SKA-Low) will allow us to account for the present and past
star-formation rate, the AGN activity and the ISM properties. SKA observations of a wide range of
galaxy types in the nearby Universe, including quiescent, AGN-dominated and starburst
galaxies, will provide a broad view of how
star formation and
accretion regulate
galaxy evolution, while time-domain and spectral-variability information further isolate compact
accretion and transient phenomena.
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All authors J. Moldon, A. Alberdi, M. Perez-Torres, G. Lucatelli, R. Beswick, M. Sargent, E. Brinks, R. D. Baldi, S. Dey, F. S. Tabatabaei, K. Rubinur, N. Seymour, M. Pandey-Pommier, C. Bot
Superconductivity
Imaging geometry- and phase-controlled spectra in a surface-state Andreev cavity
Adrian Greichgauer, Yoichi Ando and Jens Brede
Andreev cavities provide a setting in which superconducting proximity spectra are shaped by phase-coherent electron-hole motion along extended trajectories. While such Andreev physics is well established in transport, local spectra in two-dimensional cavities remain largely unexplored in real space. Here we use scanning tunnelling spectroscopy to study confined Cu(111) surface states coupled to superconducting Nb(110). The in-plane
magnetic-field scale for the collapse of the resolved low-energy spectrum is controlled by the transverse extent available to Andreev trajectories, while the zero-field excitation energy evolves with the characteristic trajectory length. These trends, together with spatial variations within individual islands and the response to
vortex phase textures, are captured by a minimal semiclassical phase-accumulation picture. Our results identify geometry-defined Andreev trajectories as a design principle for phase-coherent superconducting cavities accessible by local spectroscopy.
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Materials Science
Moiré Phonons and Emergent Exciton-Phonon Coupling in a Moiré Heterobilayer
Can B. Uzundal, Woochang Kim, Zhiyuan Cui et al. (+13 more)
Moiré superlattices have emerged as a new platform for engineering electronic and optical properties in van der Waals
heterostructures, enabling control over correlated and excitonic phenomena. Yet the impact of moiré superlattices on
exciton-
phonon coupling remains largely unexplored. Here we demonstrate emergent, layer-selective coupling between moiré
phonons and moiré
excitons in angle-aligned WS2/WSe2 heterobilayers. Using a broadband terahertz
phonon transducer, we coherently launch moiré
phonons that resonantly perturb the excitonic states. We show that the
exciton-
phonon coupling is intrinsically modified by the moiré superlattice in a layer-selective manner. A driven oscillator model captures the dynamics, revealing three moiré
phonon resonances with distinct coupling to the moiré
excitons. First principles calculations show that many moiré
phonon modes can arise with distinct strongly hybridized in-plane and out-of-plane vibrations in the moiré unit
cells. The calculations further identify the three experimentally observed moiré
phonons and their emergent characteristic coupling to the moiré
excitons.
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All authors Can B. Uzundal, Woochang Kim, Zhiyuan Cui, Yuxuan Wei, Zheyu Lu, Qixin Feng, Francis L. Hong, Indrajit Maity, Takashi Taniguchi, Kenji Watanabe, Manish Jain, Mit H. Naik, Yoseob Yoon, Michael F. Crommie, Steven G. Louie, Feng Wang
Computational Physics · Cross-listed from math.NA
A fast sum-of-Gaussians algorithm for the high-dimensional fractional Fokker-Planck equation
Shidong Jiang, Dong Wang and Qi Zhou
We present a fast, high-order
algorithm for the free-space fractional Fokker-Planck equation (FFPE) in arbitrary spatial dimension. Its fundamental solution, corresponding to a Dirac-delta initial condition, is obtained from the explicit
Fourier representation by applying a sum-of-Gaussians (SOG) approximation to the nonseparable stretched exponential, using its complete monotonicity as the Laplace transform of a one-sided $\alpha$-stable density. Each Gaussian term is an ordinary heat kernel and therefore factorizes across spatial coordinates. On a tensor-product grid, the separated form can be assembled in $O(MdN)$ work and storage, rather than forming all $O(N^d)$ grid values, where $M$ is the number of Gaussian terms and $N$ is the number of points per dimension. We prove an a~priori error estimate for the pure-fractional fundamental solution and give a parameter-selection procedure for prescribed accuracy over specified ranges of space and time. In numerical experiments the method achieves more than ten digits of relative accuracy, with $M$ growing only logarithmically in the inverse tolerance, and maintains this accuracy in dimensions up to $d=10^{5}$. This exceeds the dimensions reached in comparable radial-quadrature tests, where the integrand becomes increasingly oscillatory as the dimension grows. Because the method represents the fundamental solution as a separated sum of heat kernels, any initial datum given as a finite sum of tensor products can be evolved in closed form using only one-dimensional convolutions. This yields a computable class of high-dimensional solutions that is amenable to error analysis, and tensor neural networks provide one possible way to construct such separated representations for more general data.
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Nuclear Theory
Universal EOS-Radius Inverse Mappings Govern Precision-Dependent Inference of the Neutron Star Equation of State
Bao-An Li
Bayesian inference of the
neutron star (NS) equation of state (EOS) generally assumes that improved observations primarily reduce posterior uncertainties while leaving inferred EOS parameters unchanged. Using mock measurements of the radius of a canonical $1.4\,M_\odot$ NS with identical central values but varying observational precisions, we show that the inferred posterior means of EOS parameters can shift systematically as the measurement uncertainty changes. We demonstrate that this behavior originates from previously unidentified nearly universal inverse mappings between the NS radius $R_{1.4}$ and empirical EOS parameters. Across a broad range of observational precisions, posterior samples collapse onto nearly unique functions. These mappings are largely independent of observational precision and define a low-dimensional EOS
manifold underlying
Bayesian inference. We show that the precision dependence of inferred EOS parameters arises from nonlinear filtering of the posterior radius distribution through these mappings. In the narrow-distribution limit this effect reduces to a Jensen-type correction proportional to the local
curvature of the inverse mapping, while for presently realistic uncertainties the full nonlinear-filtering relation accurately reproduces the posterior means. Our results reveal a
geometric origin of precision-dependent inference in NS EOS studies and provide a new framework for connecting astrophysical observations directly to microscopic
nuclear many-body theories.
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Soft Condensed Matter
Universality of Bubble Coalescence in Electrolytic Media
Afsal Chakkam Palliyalil, Gaurav Tomar and Susmita Dash
Bubble coalescence phenomenon in electrolytic media finds applications in technologies from mineral flotation to electrochemical energy conversion. However, the underlying governing physics still remains unresolved, with longstanding disagreement over the extent to which Marangoni stresses affect the coalescence time by modulating the interfacial mobility. Here, we show that the thin film morphology governs drainage more strongly than the interfacial boundary conditions. We demonstrate experimentally that thin film drainage during bubble coalescence proceeds through three distinct regimes. An initial visco-capillary stage that exhibits a power-law thinning, followed by an exponential decrease in film thickness with time induced by rim stabilisation. The final regime is governed by disjoining pressure and is marked by an exponential relaxation of the film to the
equilibrium thickness. We show that, irrespective of the electrolyte type and concentration, film
evolution exhibits universal behavior by collapsing onto a single curve when rescaled with the characteristic film thickness and time scale, demonstrating that electrolyte effects act only to renormalize timescales rather than alter the underlying dynamics.
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Instrumentation and Methods for Astrophysics
Radiation tolerance of a diamond radiation detector for space use
Yoshiyuki Ando, Shutaro Ueda, Ryota Heibatake et al. (+13 more)
We present a study of the radiation tolerance of two types of diamond radiation detectors for space use. We plan to launch a 3U-size CubeSat, KSAT3-X, developed by Kanazawa University in 2027. The KSAT3-X mission is aimed to observe inflows and
outflows of charged particles such as electrons and
protons, particularly in the 10 - 40 keV energy range, in the Earth's magnetosphere. As the mission instrument, we have developed two diamond radiation detectors. The first is composed of a microwave
plasma chemical vapor deposition (MPCVD) diamond fabricated by Element Six, and the second is based on a MPCVD diamond produced in-house at Kanazawa University. We irradiate both diamonds with 100 MeV
protons and evaluate their spectroscopic performance as an indicator of radiation tolerance using characteristic X-rays from radioisotope sources. We find no significant degradation in their spectroscopic performance up to at least the 10-year equivalent irradiation under the orbital environments of KSAT3-X. We additionally irradiate the Element Six diamond with 100 MeV
protons up to the 100-year equivalent. As a result, no significant degradation in the spectroscopic performance is observed. These results indicate that the two diamond radiation detectors have sufficiently high radiation tolerance. We also discuss possible physical origins of the observed difference in the spectroscopic performance between the two detectors.
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All authors Yoshiyuki Ando, Shutaro Ueda, Ryota Heibatake, Kaito Ozawa, Makoto Arimoto, Tatsuya Sawano, Daisuke Yonetoku, Kimiyoshi Ichikawa, Norio Tokuda, Taichi Miyazaki, Shoya Matsuda, Yasuhiro Shoji, Satoshi Hatori, Kyo Kume, Shinko Sando, Satoshi Mizushima
Quantum Physics
Vacuum Fluctuation-Induced State Switching in Degenerate Optical Parametric Oscillators
Yihao Huang, Seou Choi, Rom Simovitch et al. (+5 more)
Bistable driven-dissipative systems near bifurcations can exhibit noise-activated switching between steady states. Here, we investigate how
quantum vacuum fluctuations induce such switching in a biased optical parametric oscillator (OPO), a nonlinear system with intrinsic bistability. We show how microscopic
quantum fluctuations driving macroscopic transitions can be controlled with an external bias field that reshapes the OPO steady-state metapotential. We derive analytical expressions for the average switching time and validate them through simulations of the OPO field distribution and inter-state probability flow under bias injection. We further examine how switching depends on bias strength, pump gain, and optical nonlinearity. Our findings clarify how
quantum noise can shape macroscopic dynamics and provide a foundation for noise-assisted photonic machine learning and probabilistic
quantum gates.
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All authors Yihao Huang, Seou Choi, Rom Simovitch, Jamison Sloan, Charles Roques-Carmes, Michael Horodynski, Marin Soljačić, Yannick Salamin
Optics
Direct Observation of X-ray Double-Slit Interference in Momentum Space
Fugui Yang, Xiaoxiao Liang, Tianchong Zhang et al. (+1 more)
Young's double-slit experiment is conventionally deemed a spatial phenomenon emerging from free-space transport. In this Letter, we invert this perspective to demonstrate that Young's interference can be accessed directly as a pure momentum-space observable. Using a perfect-
crystal diffraction to project the field's reciprocal-space profile immediately downstream of the aperture, we resolve the complete hard X-ray double-slit fringe structure without any propagation arm, focusing optics, or imaging detector. This direct capture of the field's invariant momentum marginal establishes a compact, lensless, and propagation-free approach to coherence diagnostics, proving that the fundamental physics of wave interference can be detached from real-space propagation.
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All authors Fugui Yang, Xiaoxiao Liang, Tianchong Zhang, Xiaowei Zhang
Cosmology and Nongalactic Astrophysics
HIcosmo: a differentiable JAX-based framework for cosmology inference
Jing-Zhao Qi, Jing-Fei Zhang and Xin Zhang
The Stage IV cosmological surveys, such as Euclid, LSST, DESI, and SKA, will deliver observational data of unprecedented volume, calling for efficient and reliable inference tools. This paper presents HIcosmo (High-performance Inference for Cosmology), an open-source JAX-based framework for cosmology inference. In HIcosmo, the forward model, distance integrals, likelihood evaluations, posterior sampling, and Fisher forecasts are all built from JAX primitives, so that gradients and Hessians of the log-likelihood are obtained directly by automatic differentiation, without any finite-difference approximation. The framework implements the $\Lambda$CDM, $w$CDM, $w_0 w_a$CDM, and interacting dark-energy models, and provides likelihoods for Type Ia
supernovae (Pantheon+, DES-SN5YR, Union3),
baryon acoustic oscillations (DESI DR1/DR2, SDSS), Planck 2018 distance priors, local $H_0$ measurements, and strong-
lensing time delays. Its scope is restricted to background cosmology, with Boltzmann solvers and full perturbation-level likelihoods left to external tools. We validate HIcosmo against the reference implementation of each likelihood and against Cobaya. $\chi^2$ values agree to absolute differences of $10^{-6}$-$10^{-2}$, and the marginalized constraints from the two codes differ by less than $0.2\sigma$ in every analysis tested. Leveraging just-in-time compilation and automatic differentiation, HIcosmo achieves about $8.7\times$ the end-to-end sampling throughput of Cobaya on CPU. As the
dataset grows to survey scale, GPU acceleration over CPU reaches up to $20\times$. As applications, we present multi-probe $\Lambda$CDM joint constraints, dark-energy equation-of-state constraints, and Fisher forecasts for six 21 cm intensity-mapping surveys, including SKA1, MeerKAT, BINGO, Tianlai, and CHIME.
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General Relativity and Quantum Cosmology
Gravitational-wave responses and noise correlations in geometric time-delay interferometry
Rui Luo, Pan-Pan Wang, Lin-Lin Yang et al. (+2 more)
Space-based gravitational-wave observations will probe the formation and growth of massive black holes and the
evolution of compact binaries in the millihertz band. We develop a
geometric-link representation of time-delay interferometry using six round-trip and six non-round-trip two-link blocks. Starting from the one-way Doppler response, we derive the elementary block responses and a dictionary that expresses 45 known second-generation combinations in terms of these blocks and residual one-way measurements. Representative Michelson and Relay observables admit compact forms, from which analytical sky-averaged tensor responses are obtained for a fixed, equal-arm constellation. We also derive the noise covariance of the blocks, retaining cross-spectra between blocks that share measurement streams. The resulting noise spectra agree with direct one-way assembly. We apply this formulation to a narrowband compact-binary signal in an equal-arm LISA instrument model. For the Relay example, neglecting the shared-link cross-spectrum changes the low-frequency noise scaling and overestimates the conditional Fisher uncertainties in amplitude or distance by factors of 10.71 at 1~mHz and 3.37 at 3~mHz.
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All authors Rui Luo, Pan-Pan Wang, Lin-Lin Yang, Xin-Lei Zhao, Cheng-Gang Shao
Cosmology and Nongalactic Astrophysics
Searching for primordial features with radio surveys: synergy between the power spectrum and bispectrum
Dionysios Karagiannis, Mario Ballardini and Roy Maartens
We present a comprehensive
forecasting framework to assess the detection of
primordial oscillatory features by exploiting the synergy between future neutral hydrogen (HI) intensity mapping (IM) surveys and
cosmic microwave background (CMB) measurements. Focusing on next-generation single-dish (SKAO) and interferometric (HIRAX)
radio configurations, we perform a joint analysis of the
redshift-space power spectrum and bispectrum, consistently incorporating scale-dependent bias,
redshift-space distortions, and non-Gaussian covariance. We investigate phenomenological templates with linear and logarithmic
primordial oscillations, together with a physically motivated sharp-feature model. We find that including the large-scale structure bispectrum improves marginalised constraints on feature amplitudes by $30$–$40\%$ relative to the power spectrum alone and helps break parameter degeneracies. In several cases, the bispectrum contains more information on the power-spectrum feature parameters than the power spectrum itself. Much of this gain arises from the late-time gravitational contribution, which inherits the oscillatory structure of the
primordial feature signal and acts as an independent source of information. While the CMB angular power spectrum is crucial for constraining low oscillation frequencies, joint interferometric IM analyses ($P+B$) outperform CMB amplitude constraints by up to $75\%$ in the linear regime. We also show that, despite non-Gaussian covariance degrading the independent constraining power of the bispectrum by $55$–$90\%$, the combined HI+CMB probe achieves percent-level precision on the frequency of
primordial features, providing a powerful test of non-slow-roll inflation.
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Earth and Planetary Astrophysics
Demographics of planet-forming disks with the SKAO
Antonio Garufi, Sebastián Pérez, John D. Ilee et al. (+21 more)
Understanding how solid material in
planet-forming disks evolves from micron-sized
dust to planetary cores is a central challenge in modern astrophysics. This study has advanced dramatically in the past decade, largely driven by ALMA and high-contrast imaging facilities. However, major uncertainties remain regarding the presence,
evolution, and role of centimeter-sized grains (the pebbles) in
planet formation. The SKAO will fill this gap by enabling the first large-scale, high-resolution survey of disk emission at centimeter wavelengths. This chapter presents the scientific rationale and observational strategies to detect and characterize pebbles in the
planet-forming disks of nearby
star-forming regions. By resolving their spatial distribution, spectral properties, and evolutionary trends, SKA will offer essential constraints on
dust growth and disk dynamics. This work provides observational strategies, target selection, and predictions on the detectability of hundreds of nearby disks. The chapter also explores SKA's potential to uncover the actual
dust mass in disks, protoplanets and their circumplanetary disks, and other aspects of the
planet formation. Together, these capabilities will establish SKAO as a cornerstone facility for
planet formation science in the coming decade.
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All authors Antonio Garufi, Sebastián Pérez, John D. Ilee, Daniel J. Price, Paola Pinilla, Marion Villenave, Eleonora Bianchi, Luca Cacciapuoti, Greta Guidi, Giovanni Sabatini, Yinhao Wu, Asmita Bhandare, Claudio Codella, Nicolás Cuello, Liton Majumdar, Mayank Narang, Linda Podio, Danae Polychroni, Isaac Radley, Jessica Speedie, Leonardo Testi, Claudia Toci, Diego Turrini, David Wilner
Quantum Physics
Time Evolution on Hybrid Tensor Networks – A Novel and Parallelizable Algorithm
Tobias V. Bauer, Richard M. Milbradt and Christian B. Mendl
We develop a novel time-
evolution algorithm for
matrix product states based on the recently introduced hybrid tensor network (hTN) framework. We retain the tensors close to the boundary on the classical computer and offload the highly entangled inner ones to the
quantum computer. In our variant, we employ the Basis Update and Galerkin (BUG) integrator to time-evolve the classical tensors, and we develop a coupling scheme between the classical and
quantum parts. Our framework admits modular combination with any
quantum time-
evolution method, such as (classically pre-optimized) Trotterization. The ratio of classical and
quantum tensor degrees of freedom can be dynamically adjusted during the time
evolution, which can be advantageous when the classical
memory requirements become prohibitive. The
quantum and classical components can run in parallel during a single time step and are not constrained by synchronization barriers or mid-
circuit measurements. We describe the detailed steps and pseudocode for our
algorithm specialized for tensor networks originating from the
matrix product state Ansatz.
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High Energy Physics (Phenomenology)
Pion and Kaon PDFs via Infrared-Safe Evolution augmented by $J/\psi$ Data Constraints
Yanbing Cai, Chengdong Han and Xurong Chen
Probing the partonic structure of the pion and the kaon provides essential insights into the non-perturbative dynamics of QCD, yet their parton distribution functions (PDFs) remain poorly constrained due to the scarcity of high-precision experimental data, especially for the
gluon distributions. We present an improved determination of pion and kaon PDFs within the dynamical parton model combined with the maximum
entropy method (MEM) framework. Our analysis features two key advancements: firstly, we employ an infrared-safe QCD
evolution scheme, allowing the
evolution to be reliably extended down to very low $Q^2$, approaching the hadronic scale; secondly, we incorporate pion- and kaon-induced $J/\psi$ hadroproduction data as crucial constraints in the global fit. We find that our approach yields a good description of the available Drell-Yan data, deep-inelastic scattering structure functions ($F_2$), and $J/\psi$ production across various energies and targets. The results provide significantly improved constraints on the
gluon distributions at moderate and large $x$ in both the pion and the kaon, offering a more complete picture of their internal structure.
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Lattice Field Theory
Spectral densities from Euclidean correlators via integral transforms: theoretical framework
Leonardo Giusti, Matteo Saccardi and Diego Toniolo
Spectral densities link experimental measurements to dynamical properties of a
quantum field theory which, in turn, can be resolved non-perturbatively from the Euclidean time-dependence of correlation functions. By making extensive use of integral transforms, we present analytic formulae to carry out the inverse Laplace transform so as to extract spectral densities from either the continuum or the discrete sampling of correlation functions in the Euclidean time. Formulae extend to regulated and/or smeared spectral densities as well. We explicitly show that the proposed
lattice solution tends to its continuum counterpart up to $O(a^2)$ effects in the
lattice spacing $a$ if the
lattice correlator is $O(a)$-improved. In practical computations,
lattices have necessarily a finite Euclidean temporal extent, a lack of knowledge which suggests to introduce incomplete integral transforms and the corresponding incomplete smeared spectral densities. The contribution from the unknowns to a smeared spectral density can then be rigorously bound and kept under control if the integral transform of the smearing function decays fast enough with the conjugate variable. Conversely, the bound can be used to plan
lattices so as to achieve a given target precision on the reconstructed spectral density of interest. The formulae presented here in the context of
lattice field theory can be easily applied or extended to other areas of research.
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