High Energy Physics (Phenomenology)
The KM3NeT 220 PeV event: a neutrino messenger from the grand unification scale?
Vernon Barger
The 220~PeV
neutrino KM3-230213A, in tension with IceCube and Auger unless narrow, admits a two-body reading: relic decay $X \to \nu\bar\nu$ with $m_X \approx 4.4\times10^{8}$~GeV. Consistency with
neutrino and $\gamma$-ray bounds sets $\tau/f \approx 10^{29}$–$10^{30}$~s, lifetime over relic fraction. For a flavored $^1S_0$ onium, the operator scale lands in the Majorana-mass range of unified models: one
Higgs insertion gives a singlet mediator, $M/|C_7|^{1/3} \approx 10^{14}$–$10^{16}$~GeV across the allowed relic fraction; two give the seesaw window; Dirac or Majorana
neutrinos select the branch. We give the construction and its decisive tests.
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Adaptation and Self-Organizing Systems
Higher-order interactions for controlling time-delayed Kuramoto model
Narumi Fujii, Martin Moriamé, Maxime Lucas et al. (+2 more)
We propose a framework for controlling the collective dynamics of the time-delayed Kuramoto model based on a delay-free, higher-order approximation of the delayed interactions. By applying the Ott–Antonsen ansatz and the second-order averaging method to the resulting higher-order Kuramoto model, we obtain a one-dimensional reduced equation for the order parameter dynamics. Numerical simulations demonstrate that the higher-order approximation predicts the dynamics of the original delayed system more accurately than the conventional pairwise approximation and enables the realization of bistability and intermediate synchronization states. Our results demonstrate the effectiveness of higher-order interpretations of time delays for the control of oscillator networks with time-delayed interactions.
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All authors Narumi Fujii, Martin Moriamé, Maxime Lucas, Hiroya Nakao, Timoteo Carletti
Computational Physics
Functional Expansion Tallies of Matrix Operators for Prediction for Integrated Autocorrelation Time in Batch Monte Carlo: an Analytic 2D Scattering Chain Benchmark
Jilang Miao, Guillaume L. Giudicelli and William Reed Kendrick
We investigate functional expansion tallies as a reduced-basis representation for predicting inter-cycle correlations in Monte Carlo transport. Using an analytic two-dimensional isotropic scattering-chain
benchmark with reflective boundaries, we compare a conventional discrete-
cell Markov-chain
estimator with a Galerkin reduced-order model built directly from Monte Carlo tallies of basis-function products. The reduced model estimates integrated autocorrelation time without first constructing a large discrete transition
matrix. For the
benchmark problem, the cosine basis converges rapidly to the exact result, while
polynomial bases show systematic convergence with increasing order. Compared with discrete binning, the reduced-basis approach achieves lower bias at comparable or lower solve cost, suggesting that functional-expansion representations can provide an efficient path toward correlation prediction, uncertainty quantification, and future variance-reduction methods in Monte Carlo criticality calculations.
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Mesoscale and Nanoscale Physics
Parity-driven RKKY decoupling and anomalous $1/R$ Dzyaloshinskii-Moriya interaction in odd-parity magnets
Morteza Salehi and Tohid Farajollahpour
Unconventional odd-parity magnets, characterized by an odd-parity momentum-dependent
spin splitting, offer a fundamentally distinct paradigm for non-collinear spintronics. Here, we theoretically investigate the Ruderman-Kittel-Kasuya-Yosida indirect exchange in two-dimensional odd-parity magnets subjected to Rashba
spin-orbit coupling. Using an analytical real-space Green's function formalism, we uncover a parity-driven spatial decoupling in the
magnetic response. Because of the odd-parity exchange field, the out-of-plane Ising interaction is structurally insulated from the macroscopic
magnetic modulation, oscillating isotropically at the shifted
Fermi wavevector. Conversely, the in-plane Heisenberg components exhibit pronounced, directionally tunable spatial beating. Beyond collinear exchange, the hybridized bands generate a highly tunable, three-component Dzyaloshinskii-Moriya interaction alongside symmetric off-diagonal anisotropies. We reveal that the out-of-plane
chiral twisting is driven by the massive, nonrelativistic momentum shift, while the in-plane
chiral components are relativistic. Furthermore, the competition between the nodal geometry and the Rashba gap drives an anomalous, dimension-reducing crossover, in which the in-plane
chiral components follow a 1D-like $1/R$ spatial decay along the nodal lines over an extended intermediate-distance window before ultimately recovering the conventional 2D $1/R^2$ asymptote. We demonstrate that these findings hold universally across the odd-parity class by explicitly generalizing our framework to $f$-wave magnets. Finally, numerical tight-binding calculations verify the striking robustness of this parity-driven decoupling against both scalar and random
magnetic exchange disorder. These findings establish odd-parity magnets as promising platforms for engineering robust, directionally tunable non-collinear
spin textures.
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Optics
Three-dimensional excitonic dipole anisotropy enables ultrabroadband polarization photodetection in CrCl3
Satyam Sahu, Jaganandha Panda, Martin Jindra et al. (+9 more)
Simultaneous detection of the spectral and polarization properties of light is highly desirable for integrated imaging and photonic technologies but typically requires complex multi-component architectures. Here, we demonstrate that the intrinsic dielectric anisotropy of layered insulating CrCl3 enables ultrabroadband polarization-resolved photodetection spanning wavelengths from 300 to 1700 nm. The photoresponse is governed by long-lived ligand-field
excitons, whose microsecond-scale lifetime produces a photoconductive gain exceeding 4.5 x 10^4. By combining wavelength-, polarization-, and angle-resolved optoelectronic measurements, we reveal that distinct ligand-field and higher-energy excitonic transitions possess different optical dipole orientations, leading to excitation-energy-dependent rotation of the in-plane polarization axis. Furthermore, oblique illumination activates out-of-plane optical dipoles, while competing excitonic transitions with distinct dipole orientations drive wavelength-dependent rotation and reversal of the polarization anisotropy. Together, these effects produce a highly tunable degree of polarization ranging from -90% to +75%, establishing intrinsic three-dimensional vectorial light-matter interactions in a layered
magnetic van der Waals
insulator. These findings establish dielectric anisotropy and excitonic dipole engineering as powerful design principles for compact ultrabroadband polarization-sensitive photodetectors and multifunctional van der Waals photonic systems.
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All authors Satyam Sahu, Jaganandha Panda, Martin Jindra, Mukesh Kumar Thakur, Farjana J. Sonia, Shankar Khanal, Kornelius Nielsch, Jana Vejpravova, Matěj Velický, Martin Kalbáč, Otakar Frank, Golam Haider
Quantum Physics
Connectivity-induced surface-loss penalty in superconducting qubit-coupler lattices
Xu-Yang Gu, Gui-Han Liang, Ming-Chuan Wang et al. (+7 more)
Recent advances in design and fabrication have increased the energy-relaxation times of isolated superconducting transmon
qubits to the hundreds-of-microseconds regime, with reported values exceeding 500 $\mu$s. However, the same progress has not automatically translated to multiqubit processors, where
qubits are embedded in connected
qubit-coupler
lattices and often exhibit much shorter lifetimes than isolated
qubits. To identify possible sources of this discrepancy, here we use finite-element simulation to investigate how surface participation ratios and the resulting surface dielectric loss change when a
qubit is embedded in a flip-chip
qubit-coupler
lattice. Controlled comparisons show that higher connectivity can indeed lead to larger surface loss: in the simulated
lattice, connecting a
qubit to two and four couplers increases the surface loss by factors of 1.3 and 1.8, respectively. We attribute this change to the combined effects of added edge fields from coupling claws, field redistribution over the larger connected metal network, and hybridization with coupler modes. We further examine how this connectivity-induced surface-loss penalty depends on the
geometric design parameters of both the
qubit electrodes and the coupling claws, and derive guidelines for designing low-loss multiqubit processors.
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All authors Xu-Yang Gu, Gui-Han Liang, Ming-Chuan Wang, Yongxi Xiao, Cheng-Lin Deng, Zheng-He Liu, Tian-Ming Li, Kai Xu, Zhongcheng Xiang, Heng Fan
Applied Physics
Accessing 100 GHz Mechanical Modes in Bulk Crystals at Cryogenic Temperatures
Boxuan Tian, Jiacheng Xie and Hong X. Tang
Sub-terahertz electromechanics offers a promising route to probe mechanical
quantum motion at experimentally friendly Kelvin temperatures. Traditionally, high-frequency mechanical resonators rely on advanced microfabrication to shape complex microstructures, while bulk
crystals have been largely overlooked due to their large inertia and challenging transduction at such frequencies. Here we show that bulk lithium niobate can host mechanically accessible modes near 100 GHz when coupled via plug-and-play three-dimensional microwave cavities. This approach enables efficient, non-contact excitation of centimeter-scale, milligram-mass vibrational modes across 7.0–110 GHz, with mechanical quality factors up to 30,000 at W band. Furthermore, using a frequency-tunable superconducting niobium cavity at 4 K, we demonstrate strong coupling between a microwave cavity mode and multiple mechanical modes, enabling coherent energy exchange between microwave
photons and mechanical
phonons with cooperativity up to 16.6 at 110 GHz. These results establish a versatile platform for accessing massive high-frequency mechanical modes and for precision tests of mechanical
quantum physics at elevated temperatures.
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Biological Physics
Life in a tight spot: Coupled dynamics of bacteria and soil across scales
Pablo Bravo, Tanumoy Dhar, Eloise Masquelier et al. (+2 more)
Soil harbors much of Earth's bacterial life. The activity of these bacteria governs plant growth, carbon and nitrogen cycling, and the response of land to a changing
climate. Understanding this activity is difficult, however: soil is structurally and chemically heterogeneous and optically opaque, and its bacteria not only respond to their surroundings but continually reshape them, a two-way feedback that most idealized experiments and theories overlook. Here we review how this dynamic feedback governs the physics of bacterial motility, growth, and sensing in soil across three scales – the single pore, the mesoscale of many pores, and the broader landscape.
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All authors Pablo Bravo, Tanumoy Dhar, Eloise Masquelier, Danielle Sclafani, Sujit S. Datta
General Relativity and Quantum Cosmology
Scalar-induced gravitational waves from a box-shaped curvature power spectrum
Zu-Cheng Chen and Lang Liu
We compute the
stochastic background of gravitational waves (GWs) produced at second order in cosmological perturbation theory by a
primordial curvature power spectrum that is flat in $\ln k$ over a finite band $[k_-,k_+]=[k_*e^{-\Delta},k_*e^{+\Delta}]$ and vanishes elsewhere. This logarithmic box interpolates between a monochromatic spectrum as $\Delta\to0$ and a locally scale-invariant plateau as $\Delta\to\infty$, and its sharp boundaries make the geometry of the source convolution unusually transparent. Working in the radiation era, we reduce the convolution to a compact integral over the overlap between the momentum triangle and the box, and evaluate it analytically in two regimes. For a narrow box we show that, to leading order in the width, the spectrum equals the Dirac-spectrum result multiplied by a purely
geometric overlap factor $\Phi_{\rm box}(\kappa,\Delta)$; this factor turns the infrared slope from $k^{3}\ln^{2}k$ into $k^{2}\ln^{2}k$ at a break $k_b=2k_*\sinh\Delta$. For a broad box we separate the lower edge, the scale-invariant interior, and the upper edge, derive the leading behaviour in each (an infrared $k^{3}\ln^{2}k$ rise, a scale-invariant plateau, and a quartic cut-off at the hard endpoint $k=2k_+$), and combine them into a single uniform formula cast as a product of two universal, $\Delta$-independent edge functions. We also provide an integral-free closed-form surrogate for these edge functions for use in parameter scans.
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Physics and Society
Institutional Harm through Threshold Cascades
Piper Harris and Chad M. Topaz
Can a population of people not individually inclined to harm others nonetheless produce harmful collective outcomes, purely because of the institutional structure they inhabit? Social scientists have long argued yes, but existing accounts are largely qualitative and provide no precise condition distinguishing safe institutions from unsafe ones. We develop a threshold cascade model in which
agents have positive activation thresholds, harmful behavior is irreversible, and the institution exerts both standing pressure and peer influence along a weighted network. We give a necessary and sufficient condition, checkable from the institution's structure and its members' thresholds, for resistance to any shock up to a given size. The criterion extends to signed influence, in which some peer effects counteract harm, and yields a convex optimization formulation for least-cost repair. It also reveals a sharp frontier between functionality and safety. An institution can coordinate its members and remain safe if and only if the exposure that coordination creates stays below the weakest member's net threshold. A further tension arises when coordination requires responsiveness to peer influence, which can make it impossible to prevent the most exposed group from cascading. We then analyze a mean-field model of two groups differing in how easily their members are pushed into harm. When one group is unstable in isolation but the system is stable under full mixing, disproportionate within-group influence creates a sharp homophily threshold beyond which the harm-free state becomes unstable. In the model, identical treatment of both groups does not generally equalize their cascade robustness.
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Mathematical Physics · Cross-listed from math.PR
From the Airy line ensemble to the Gaussian free field
Evgeni Dimitrov, Alex Fu and Zhengye Zhou
We study the global fluctuations of the height function associated with the Airy line ensemble. Using its determinantal structure and a steepest-descent analysis of the extended Airy kernel, we prove that, after a suitable rescaling, the centered height function converges to an explicit pullback of the Gaussian free field. The convergence holds in the sense of joint moments of linear statistics against compactly supported continuous test functions.
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Nuclear Theory
From hyperon–nucleon interactions to deuteron–hyperon femtoscopy
Jiaxing Zhao
I investigate the low-energy scattering and femtoscopic correlation functions of the $d-\Lambda$, $d-\Sigma$, and $d-\Xi$ systems within a microscopic folding approach. The effective deuteron–hyperon interactions are constructed by folding the HAL-QCD hyperon–nucleon potentials with the deuteron wave function, while the
spin and isospin structures are treated through Wigner-$6j$ recoupling coefficients. Using the resulting interactions, I calculate the scattering parameters and momentum correlation functions for all
spin channels. No bound states are found for the $d-\Lambda$, $d-\Sigma$, or $d-\Xi$ systems. Nevertheless, the $d-\Lambda$ correlation exhibits a pronounced low-momentum enhancement associated with a large scattering length and a near-threshold pole, whereas the $d-\Sigma$ correlation is suppressed by its predominantly repulsive interaction. The neutral $d-\Xi^{0}$ system shows only a moderate enhancement, while the charged $d-\Xi^{-}$ correlation is strongly amplified by the attractive Coulomb interaction. I further investigate feed-down effects from $\Sigma^{0}$, $\Sigma(1385)$, and $\Xi$ decays using Monte Carlo response
matrices and demonstrate that these decays clearly modify the observable $d-\Lambda$ correlation. The results provide quantitative predictions for future femtoscopic measurements and establish deuteron–hyperon correlations as a sensitive probe of hyperon–
nucleus interactions.
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Optics
Optical Kerr nonlinearity enhancement in high-index metasurfaces via Mie void lattices
Andrey V. Panov
Recently, research in nanophotonics has turned toward Mie resonances in voids on the surface of high-refractive-index materials. The optical Kerr effect (OKE) in high-index membrane metasurfaces with Mie void
lattices is investigated using three-dimensional finite-difference time-domain (FDTD) simulations, with gallium phosphide (GaP) as a model material. The effective nonlinear refractive index is extracted for empty spherical and truncated-cone (frustum) voids in a high-index slab. Metasurfaces with isolated Mie void resonances yield only modest effective OKE enhancement, up to a factor of ten relative to bulk GaP. Mie void resonances in GaP metasurfaces are observable when the separation between voids exceeds approximately 220 nm; otherwise, modes in the high-index material between the voids prevail. A much stronger response arises from the later modes developing in the high-index regions between closely spaced voids. While the nonlinear figure of merit of Mie-void metasurfaces is limited for applications relying solely on energy-density enhancement, the open-cavity geometry offers advantages for hybrid systems that require access to the confined field, such as
quantum emitters or nonlinear materials infiltrated into the voids.
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General Relativity and Quantum Cosmology
Nonlinear electrodynamics and stability of spherically symmetric space-times in scalar-tensor gravity
Kirill A. Bronnikov, Rustam Ibadov, Feruza Y. Shaymanova et al. (+1 more)
We study linear perturbations of static, spherically symmetric solutions of scalar-tensor theories (STT) of
gravity from the Bergmann-Wagoner-Nordtvedt class, sourced by nonlinear electrodynamics (NED). We obtain a general expression for the effective potential $V_{\rm eff}$ governing the perturbation dynamics for theories with arbitrary scalar-electromagnetic interaction of the form $L(\psi, F)$, where $\psi$ is a scalar field and $F = F_{\mu\nu} F^{\mu\nu}$ the electromagnetic invariant. This consideration includes, in particular, arbitrary scalar self-interaction potentials and scalar fields that can be phantom in some regions of space-time (the so-called trapped ghosts). Only radial (monopole) perturbations are considered here as the most likely ones to cause an instability. It is shown, in particular, that if NED has a correct Maxwell weak field limit, the zero charge limit of $V_{\rm eff}$ does not contain any trace of NED, and the perturbation dynamics is the same as for
vacuum STT solutions. The previously obtained stability results for STT-Maxwell solutions are shown to be extended without change to STT-NED solutions with equal electric and
magnetic charges, implying $F =0$.
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All authors Kirill A. Bronnikov, Rustam Ibadov, Feruza Y. Shaymanova, Najibullokhon M. Shukurullokhon
High Energy Physics (Phenomenology)
Migdal Ionization as a Probe of Light Dark Matter from Nuclear Transition
Yuanchao Lou, Liangliang Su and Lei Wu
Nuclear reactors serve as a key artificial source of light dark matter. Direct detection of reactor-produced dark matter faces substantial obstacles, since quenching effects suppress conventional elastic scattering signals below detector thresholds. We present a new search strategy utilizing the Migdal effect in germanium detectors to probe light dark matter produced via
nuclear de-excitation from reactors. Using ON-OFF residual spectra from the TEXONO experiment, we set a new stringent limit on the dark matter and
nucleus interaction over the mass range $0.01\,\text{MeV}\le m_\chi \lesssim 2.6\,\text{MeV}$, which provides a complementary bound to existing cosmological and astrophysical limits.
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Quantum Physics
Nonlocal nonstabilizerness for slightly entangled quantum many-body states
Lei-Yi-Nan Liu and Jian Cui
Nonlocal nonstabilizerness quantifies the irreducible magic resource encoded in bipartite
entanglement, but its evaluation is generally hindered by a highly nonconvex optimization over local
unitary transformations. Here we propose a Schmidt-reference-state framework that replaces this optimization by a direct construction from the sorted Schmidt spectrum. We
conjecture that the nonlocal stabilizer Rényi
entropy (SRE) is given by the SRE of the corresponding reference state, and support this
conjecture through analytical and numerical evidences. Our framework makes nonlocal nonstabilizerness efficiently accessible for weakly entangled many-body states whenever the
entanglement spectrum is available. Applying it to Haar-random states, critical
spin chains, and PXP dynamics, we show that nonlocal SRE captures nonstabilizer structures in the
entanglement spectrum that are invisible to conventional
entanglement measures. Our results establish
entanglement spectra as a powerful window into irreducible nonstabilizer correlations, opening a broadly applicable route to studying nonlocal magic resources of
quantum many-body systems in and out of
equilibrium.
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General Relativity and Quantum Cosmology
Regular black holes with Minkowskian cores: energy-condition obstruction and optical screening
Francisco Tello-Ortiz, Y. Gómez-Leyton, Alejandro Rueda et al. (+2 more)
We construct an asymptotically flat black-hole geometry with a Minkowskian core using gravitational decoupling and analyze its static and rotating extensions. Rather than imposing global energy-condition viability, we show that the vanishing central density required by the Minkowskian core produces a local null-energy-condition obstruction for the present static closure class. The exact mass profile can be written in terms of the regularized incomplete gamma function, which makes transparent both the horizon structure and the exponential localization of the deformation. This localization yields an analytic optical-screening mechanism: on the black-hole branch, deviations of the critical impact parameter from Schwarzschild are controlled by the exponentially suppressed mass deficit at the
photon sphere. We also clarify the status of the rotating extension:
curvature invariants remain finite on the physical domain $r\geq0$, but this local statement does not by itself establish a globally regular analytic extension through the Kerr disk. These results separate local core regularization from global completeness and explain why strong modifications of the interior can coexist with very small changes in exterior optical observables.
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All authors Francisco Tello-Ortiz, Y. Gómez-Leyton, Alejandro Rueda, Kazuharu Bamba, Manuel González-Espinoza
Quantum Physics
MDQEC-QAS: Meta-Decoding for Quantum Error Correction with Hardware-Aware VQC Search and Confidence-Gated Recovery
Prashant Kumar Choudhary, Nouhaila Innan, Muhammad Shafique et al. (+1 more)
We propose a unified meta-decoding framework for
quantum error correction that learns syndrome-to-recovery mappings across multiple stabilizer codes and noise settings, without requiring separate decoders for each configuration. The
benchmark includes FiveQubit, Steane, Planar3x3, and Planar5x5 codes, four noise families, and five evaluation regimes: interpolation, unseen-p transfer, unseen-noise transfer, few-shot unseen-code adaptation, and few-shot held-out-size adaptation. We compare a classical Meta-MLP teacher-trained baseline with variational
quantum circuit (VQC) meta-decoders selected through hardware-aware
quantum architecture search over
qubit count,
circuit depth, and entangling
topology. The Meta-MLP achieves teacher-label accuracies of 0.9993, 0.9118, 0.9342, 0.6304, and 0.7548 across the five regimes, while the hardware-aware VQC achieves 0.9400, 0.8495, 0.8415, 0.5678, and 0.7143. However, logical-level evaluation shows that high teacher-label accuracy alone is insufficient in the most challenging Planar5x5 setting. During interpolation, the raw logical-failure ratios relative to the teacher are 12.08 and 25.91 for the Meta-MLP and VQC, respectively, whereas confidence-gated fallback reduces them to 1.71 and 1.11. These results support confidence-aware selective recovery rather than unconditional teacher replacement.
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All authors Prashant Kumar Choudhary, Nouhaila Innan, Muhammad Shafique, Rajeev Singh
Quantum Physics
Passive spectral-admittance bounds and exact continuum certificates for multiresonator quantum-memory interfaces
Maxim V. Churilov
Broadband
quantum-
memory interfaces are often assessed by center-frequency impedance matching or by a sampled efficiency curve. Neither supplies an operational continuous-band certificate, and absorption is not automatically reversible storage. We model a passive one-port multiresonator interface by a positive-real spectral admittance with explicitly identified controlled output channels. If their one-
photon subspace is mapped isometrically into long-lived registers, the write probability for a normalized spectrum $f$ supported in a band $\mathcal{B}$ is $1-\int_{\mathcal{B}} |r(i\omega)|^2 |f(\omega)|^2\,d\omega$, and the worst-case write efficiency is $1-\|r\|_{L^\infty(\mathcal{B})}^2$. We prove that a finite passive rational interface cannot have zero reflection on a nonzero interval and derive the Bode–Fano floor $\|r\|_\infty \geq \exp[-\pi\kappa/(2B)]$ for a band of half-width $B$. At fixed pole locations, minimax synthesis is a quasiconvex semi-infinite problem in the oscillator strengths. We then give an exact computer-assisted certificate: after a decimal design is converted into an explicit rational system, the continuum reflection bound becomes positivity of one univariate
polynomial and is proved by Sturm root counting; exact Routh–Hurwitz determinants certify stability and minimum phase. In units $\kappa=2$ and $B=1$, an 11-mode design obeys $0.064112405 \leq \|r\|_\infty < 0.0641125$, implying a conditional uniform write guarantee above $0.995889587$. This is a reproducible certificate for a specified interface, not a claim of global movable-pole optimality or of an experimentally complete
memory.
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Physics and Society
A Structural Comparison of Indian Epics
John D.P. Evans
The Mahabharata and Ramayana constitute the two major Sanskrit epics of ancient India. Traditionally they are viewed quite differently, with the former being seen as more historical and the latter more poetic. We perform network analysis on both texts in an attempt to gather quantitative information on interrelationships between characters, thereby offering quantitative insight into such separate classifications. We also compare with the Iliad in an attempt to see if structural similarities exist that underlie several narrative similarities.
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Solar and Stellar Astrophysics
Rediscussion of eclipsing binaries. Paper 32. The eccentric F-type system EY Cephei
John Southworth
EY Cep is a detached eclipsing binary containing two F0 V
stars in an orbit with a period of 7.97 d and an eccentricity of 0.440. We determine the physical properties of the system using light-curves from the Transiting
Exoplanet Survey Satellite and published spectroscopic measurements. We find masses of 1.523 +/- 0.008 Msun and 1.494 +/- 0.014 Msun, radii of 1.491 +/- 0.004 Rsun and 1.446 +/- 0.004 Rsun, and temperatures of 7070 +/- 170 K and 6990 +/- 150 K. We calculate the system's distance to be 300.3 +/- 3.8 pc, in excellent agreement with the
Gaia DR3 parallax, and estimate its age to be 220 Myr. We find no evidence for pulsations, but there are hints of variation in the eclipse times potentially attributable to a third body on a longer-period eccentric orbit.
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Fluid Dynamics
Secondary Flows and Near-Wall Turbulence in Channel Flow with Longitudinal Ribs
Ranjan Kushwaha, S. Sarkar and Gautam Biswas
This study employs the Large Eddy Simulation (LES) to investigate secondary flows and near-wall
turbulence induced by two types of surface-mounted longitudinal ribs, namely rectangular and triangular, in a channel flow. The friction Reynolds number, based on friction velocity and channel height H, is set at 220. The rib aspect ratio W/h, where W and h represent the width and height of the rib, is 2, and the rib spacing, S is 0.6H. The results indicate formation of two counter-rotating
vortices between the adjacent ribs for both the cases considered. The roughness function is higher with the rectangular rib as compared to that of the triangular rib. At the location of the mid-plane on the rectangular ribs, the wall shear stress is relatively lower as compared to that of the location of mid-plane between the ribs. Conversely, for the case of triangular rib, the opposite pattern is observed. Normal Reynolds stress exhibits strong anisotropic behaviour near the wall for both the cases, overlapping above 0.4H. Between 0.4H and 0.8H, the variation in normal Reynolds stresses is linear. Near the wall, higher production of turbulent kinetic energy (TKE) and normal Reynolds stresses are observed with the triangular rib as compared to those of the rectangular rib. The ratio of production to dissipation is unity in the log-law region.
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Data Analysis and Statistics
Quantification of Electron Energy-Loss Spectra
Pavel Potapov and Giulio Guzzinati
This manuscript summarizes the recent developments in EELS quantification flow as will be implemented in the CEOS Panta Rhei and TEMDM software. This should serve as a technical reference for the
algorithms used in the software.
Mathematical Physics · Cross-listed from math.AP
Singular mean-field limits via a multiscale mollification metric
Quoc Hung Nguyen and Sylvia Serfaty
We consider a general class of first order ODE systems for the
evolution of $N$ interacting particles (in Euclidean space $\mathbb{R}^d$) in a mean-field regime. The class of interactions treated includes singular interactions of inverse power type up to power $d+1$, attractive or repulsive, and not necessarily deriving from a potential – unlike, for instance, the modulated energy method. We introduce a new method to prove quantitative convergence of the discrete system to solutions of the mean-field equation. It relies on studying the
evolution of a metric encoding a multiscale control of the difference between the empirical measure and its limit, via mollification by heat kernels. We prove that the desired convergence holds (i) up to the maximal time of existence of the smooth solution to the limiting equation if the singularity is sub-coulombic in any dimension, or coulombic in dimensions 1 and 2 (where, to do so, we introduce a notion of weak solution to the ODE system), or (ii) for short time in the case of Coulomb singularity in dimension 3 and above and (iii) up to a short $N$-dependent timescale for super-coulombic interactions in all dimensions. The latter two results are demonstrated to be optimal as we prove that collisions occur within the same timescale for a class of attractive interactions.
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General Relativity and Quantum Cosmology
Corrections to inflationary models induced by non-minimal coupling between scalar field and curvature
I. V. Fomin, S. V. Chervon, E. S. Dentsel et al. (+1 more)
In this paper, we consider possible corrections to the characteristics of inflationary models based on a specific parametrization of the non-minimal coupling between the scalar field and
curvature. At the inflationary stage, these corrections lead to a deformation of the scalar field potential and a corresponding deviation in the determination of the cosmological perturbation parameters. At the same time, it is shown that the proposed parametrization yields a description of the reheating stage dynamics completely analogous to the case of Einstein
gravity with minimal coupling between the scalar field and
curvature. For a model-independent analysis of inflationary corrections induced by a non-minimal coupling, a classification of inflationary scenarios based on the expansion in series of the dependence of the tensor-to-scalar ratio on the spectral index of scalar perturbations is considered. It is also shown that this approach allows for the inclusion of well-known inflationary models as special cases.
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All authors I. V. Fomin, S. V. Chervon, E. S. Dentsel, B. Mishra
High Energy Physics (Phenomenology)
Do primordial quark pellets solve the dark matter puzzle?
Domenec Espriu
We show that
primordial quark pellets (PQPs) - ultra-dense
quark-matter mini-
stars formed at $T\sim 1$ GeV - could naturally arise in a radiation dominated early universe if rare
baryon overdensities are produced by contracting Peccei-Quinn domain walls or similar super-horizon structures. Solving the Tolman-Oppenheimer-Volkoff equation with a hot
quark equation of state, we find stable solutions with a maximum theoretical mass of $10^{-2}$
solar masses and radii of order 100 m, although the formation mechanism favours much lighter objects that would indeed be dominant. Once formed, PQPs cool and evolve into either mini
neutron stars or stable strange-matter nuggets, depending on the QCD ground state. The mechanism we present could suffice to reproduce the present dark matter density without altering Big Bang Nucleosynthesis or requiring a posterior
entropy injection. PQPs may evade current microlensing constraints if their masses are below $10^{-8}$
solar masses, a range that in view of their mass function could easily accommodate a large fraction of dark matter. PQPs thus potentially constitute a conservative Standars-Model based, and observationally testable candidate.
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Solar and Stellar Astrophysics
SN 2025aico: Early observations of a faint Type IIb supernova with a low-mass envelope
J.-W. Zhao, A. Pastorello, B. Kumar et al. (+45 more)
We aimed to investigate the physical properties and the underlying explosion mechanisms of the Type IIb SN 2025aico. Through a comprehensive analysis of early-phase optical light curves and spectroscopic data, we aim to constrain the fundamental explosion parameters and evaluate the physical state of the event. We present early multi-band optical imaging and low-resolution optical spectroscopic follow-up observations of the Type IIb SN 2025aico, spanning approximately 70 days from the explosion. We constrain the properties of SN 2025aico by utilizing a hybrid model that combines shock-cooling emission and radioactively powered
diffusion, as well as by analyzing the spectroscopic
evolution. We use various approaches to constrain the 56Ni mixing from early data, and also compared our spectra with models to constrain the properties of the progenitor. The explosion epoch of SN 2025aico is estimated to be MJD 61032.69, while the rise time in the r_M-band is 22.30 +/- 0.70 days. The peak pseudo-bolometric luminosity in the optical bands is L_opt = (4.07 +/- 0.10) x 10^41 erg/s. The fitting yields a moderate to relatively low 56Ni mass of M_Ni = 0.033 +0.006/-0.004 M_sun and an ejecta mass of M_ej = 2.79 +0.21/-0.18 M_sun. The photospheric velocity near the bolometric peak, measured from the Fe II lambda 5169 line, is 6450 +180/-160 km/s. The derived envelope properties suggest a compact He-
star progenitor possessing an H-rich envelope of M_env approx. 0.01 M_sun and a radius of R_env approx. 6-10 R_sun. The derived physical properties of SN 2025aico indicate an origin from a moderate-mass, stripped He-
star in a compact binary system, characterized by a minimal residual hydrogen envelope. The explosion itself demonstrates weak to moderate 56Ni mixing throughout the ejecta.
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All authors J.-W. Zhao, A. Pastorello, B. Kumar, Y.-Z. Cai, A. Dutta, D. K. Sahu, A. Reguitti, R. S. Teja, H. Das, T. J. Moriya, N. Pyykkinen, K. Valeckas, G. Valerin, X.-Z. Zou, C. Ashall, S. Bijavara Seshashayana, G.-W. Du, G. C. Anupama, A. L. Bouquin, S. Campana, K. Chatterjee, X.-L. Chen, X.-L. Du, N. Elias-Rosa, Y. Fang, M. Fraser, W. Hoogendam, E. Hsiao, E. Kankare, E. P. Lagioia, W.-Y. Li, X.-K. Liu, P. Lundqvist, K. Matilainen, J. Martikainen, K. Medler, N. Morrell, Y. Pan, C. Pfeffer, G. Rameshan, T. M. Reynolds, M. D. Stritzinger, V. Vuolteenaho, Z.-Y. Wang, H.-F. Xiao, J.-H. Zhang, X.-W. Liu, Y.-P. Yang
Plasma Physics
Electrohydrodynamic wind generation in planar DBDs: role of electrode symmetry and geometry
Farshad Sohbatzadeh, Saeed Ranjbar Malekshah, Hamed Soltani Ahmadi et al. (+4 more)
This study experimentally and numerically investigates the electrohydrodynamic (EHD) interaction produced by a surface dielectric barrier discharge (SDBD)
plasma actuator at atmospheric pressure. The non-thermal dielectric barrier discharge generates ionic wind, which is characterized using a symmetric annular actuator composed of concentric ring and disk electrodes. Unlike conventional linear SDBD actuators that primarily produce tangential airflow, this annular configuration generates a predominantly vertical ionic-wind jet. The effects of electrode diameter D and thickness delta on the induced wind velocity perpendicular to the electrode plane are systematically examined. The experimental results show a maximum wind velocity of 3.42 m s^{-1} for an optimized electrode configuration with D = 32 mm and delta = 0.06 mm. Numerical
plasma-fluid simulations support the experimental trends and provide spatial distributions of airflow velocity, electrohydrodynamic volumetric force, electron temperature, and gas pressure in the
plasma region. Additional diagnostics based on ozone concentration measurements and Schlieren imaging show that electrodes with larger diameters, particularly 22 and 32 mm, enhance the height and development of the vertical flow, while increasing electrode diameter also promotes ozone production. The results demonstrate an important trade-off between ionic-wind performance and reactive byproduct generation. These findings provide practical guidance for optimizing annular dielectric barrier discharge
plasma actuators for active flow control, air purification, ozone-assisted disinfection, and biomedical
plasma applications.
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All authors Farshad Sohbatzadeh, Saeed Ranjbar Malekshah, Hamed Soltani Ahmadi, S Mirzanejhad, Ramin Mehrabifard, Samira Mavaddati, Zdenko Machala
Superconductivity
Soft point-contact Andreev reflection spectroscopy in a palm-type cubic anvil-pressure cell
Qingxin Dong, Fengrui Shi, Yan Zhang et al. (+11 more)
We have implemented soft point-contact Andreev reflection spectroscopy (PCARS) in a palm-type cubic anvil pressure
cell by combining a substrate anchoring strategy with an external wire-splitting technique. This design enables the stable formation of multiple point contact junctions under hydrostatic pressures up to 15 GPa.
Benchmark measurements on the elemental
superconductor Nb demonstrate high reproducibility and yield a zero-temperature superconducting gap with a gap ratio of 3.3. We further apply this technique to the Kagome metal
superconductor CsCr3Sb5 and the
bilayer nickelate
superconductor La2PrNi2O7. Pronounced zero-bias conductance peaks are observed, and their
evolution with temperature,
magnetic field and applied pressure is investigated, together with the superconducting gap magnitude and possible pairing
symmetries. These measurements provide spectroscopic evidence consistent with unconventional superconductivity in these materials. Our work establishes a robust experimental platform that bridges macroscopic electrical transport and microscopic spectroscopic probes, opening a new avenue for investigating pairing
symmetry in a wide range of pressure-induced unconventional
superconductors.
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All authors Qingxin Dong, Fengrui Shi, Yan Zhang, Tong Shi, Yi Liu, Shaoheng Ruan, Zhongjin Wu, Jianping Sun, Zhaoming Tian, Yoshiya Uwatoko, Guanghan Cao, Xin Lu, Bosen Wang, Jin-Guang Cheng
Materials Science · Cross-listed from cs.CV
Answer-Conditioned Chain-of-Thought Distillation for Few-Shot Industrial Vision with Small VLMs
Shubham Rao
Deploying AI-based visual inspection in manufacturing is hard because requirements change often, new defect types appear, and large labeled
datasets are rarely available. We propose answer-conditioned chain-of-thought (CoT)
distillation for rapidly adapting small
vision-
language models (VLMs) to new industrial tasks using minimal labeled data. A frontier VLM receives each training image along with its correct label and generates a justified visual explanation. A 3B-parameter model is then fine-tuned on these
reasoning-augmented examples via LoRA. By conditioning on correct answers, we ensure all training
reasoning is directed toward the correct conclusion, which is critical because frontier models score as low as 24.1% on our hardest task. We validate on four industrial classification tasks spanning three image modalities using only 18 to 30 labeled images per task. Across 4 seeds per task (32 training runs), our method outperforms direct fine-tuning on all 16 seed-task combinations, with mean improvements of +1.7 to +4.4 percentage points. A controlled equal-budget experiment confirms the improvement comes from
reasoning quality, not additional training steps. An unconditioned baseline demonstrates that with out answer-conditioning, wrong
reasoning degrades performance by 17.8 percentage points. On weld radiograph classification, the fine-tuned 3B model outperforms GPT-4.1 by 10.0pp using just 24 training images.
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