Materials Science · Cross-listed from cs.LG
Interpretable Inverse Design of Metal-Organic Frameworks with Large Language Model Agents
Kyungmin Nam, Seunghee Han and Jihan Kim
Inverse design of metal-organic frameworks (MOFs) requires navigating combinatorial spaces with costly property labels and opaque machine-learning models. We introduce LLM4MOF, a closed-loop multi-
agent framework that converts a natural-
language target into chemical hypotheses, constraints, diagnostic tests, and feedback. One
agent proposes interpretable hypotheses over metal nodes, linkers, pore geometry, and functionality. Another converts them into constraints selecting MOFs defined by a node, linker, and
topology. The Matchmaker forms four beams to attribute gains to geometry, chemistry, or metal choice: full hypothesis, chemistry, metal only, and random baseline. Blind to database landscapes, LLM4MOF enriches top performers across six adsorption, separation, and electronic-structure tasks within 400 evaluations. It also designs and live-simulates de novo MOFs spanning H2 storage, SF6 capture, and C2H6/C2H4 separation, deriving a distinct design rule for each objective. Under an identical nominal evaluation budget it consistently outperforms random search,
Bayesian optimization, and genetic
algorithms, and the outcome is insensitive to the
language-model backend. All of this uses not a single property-labeled training structure, whereas generative alternatives train on thousands to hundreds of thousands. A new objective requires only a natural-
language request: interpretable inverse design at a fraction of the data cost of existing approaches.
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Materials Science
Bilinear Flexo-Antiferrodistortive Coupling in Ferroelastics: Polar Twins, Antiphase Boundaries and Fingerprints of Alterelectricity
Eugene A. Eliseev, Anna N. Morozovska, Akash Saha et al. (+1 more)
Using the Landau-Ginsburg-Devonshire approach we show that the linear gradient-type coupling between the electric polarization vector and antiferrodistortive long-range order parameter pseudovector, that has the form of Lifshitz invariant and named "bilinear flexo-antiferrodistortive coupling", can emerge in all antiferrodistortive ferroelastics, since it is
symmetry-allowed. Using the four sublattices model we reveal that the bilinear flexo-antiferrodistortive coupling can induce the sublattice-sensitive polarization at the twin walls and antiphase boundaries in antiferrodistortive ferroelastics without any ferroelectric or antiferroelectric ordering. Since the induced polarization is perpendicular to the antiferrodistortive long-range order parameter and counter-directed in neighboring sublattices with checkerboard-type direction of antiferrodistortive long-range order parameter, such structure of polarization may correspond to the alterelectric-type quadrupolar electric order. However, physical manifestations of the bilinear flexo-antiferrodistortive coupling are invisible in most nanostructured antiferrodistortive ferroelectrics and antiferroelectrics due to the domination of piezoelectric and/or omnipresent linear flexoelectric couplings.
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All authors Eugene A. Eliseev, Anna N. Morozovska, Akash Saha, Venkatraman Gopalan
High Energy Physics (Theory)
Gluon mass and small-x dynamics in hadrons
Stanisław D. Głazek
Precise derivation of the logarithmically scale-dependent
Hamiltonian eigenstate picture for
hadrons in the space of virtual
quark and
gluon states of the canonical front form of QCD requires addressing first the problem of divergences stronger than logarithmic, and especially the small-x divergences in the dynamics of
gluons. We propose to facilitate the regularization and cancellation of these divergences using a
gluon mass parameter and an auxiliary color-octet scalar field corresponding to the longitudinally polarized
gluons. The auxiliary field decouples from the hadronic constituent dynamics when the mass parameter tends to zero, as required in the gauge theory. The same method applies in the cancellation of the quadratic ultraviolet transverse divergences in the self-interactions. After explaining how the method works in computations of the scattering amplitudes, we describe its application to the bound-state
eigenvalue problems. We focus on the results it leads to already in the second-order weak-coupling expansion for effective
Hamiltonians of heavy
quarks. They include the concept of confinement in an effective theory with the
gluon mass parameter sent to zero and a heuristic scenario concerning extension of the
Hamiltonian approach to the dynamics of light
quarks.
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Quantum Physics
Stabilizer entropy is trustworthy for mixed states
Gianluca Esposito, Michele Viscardi and Alioscia Hamma
Quantifying non-stabilizerness in mixed states is provably intractable, as any strict monotone requires superexponential time. We propose a linear Stabilizer
Entropy that acts as a proper non-stabilizerness monotone with overwhelming probability when restricted to non-adaptive Clifford channels acting on flat mixed stabilizer states. Analytical and numerical results for Haar-random states, Clifford orbits, and random
matrix product states show that monotonicity violation probabilities decay as $\exp-\eta N$. We also prove the validity of Stabilizer
Entropy in specific many-body systems undergoing partial measurements, where the amount of resource never increases for each measurement outcome as well as when averaged over outcome probabilities. Given the hardness of strict alternatives, Stabilizer
Entropy emerges as a practical and theoretically justified resource measure.
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Solar and Stellar Astrophysics
Evidence of Supernova Between Formation of Stellar Populations in a Globular Cluster
Evan N. Kirby, Roman Gerasimov, Alice Cai et al. (+3 more)
Globular clusters do not undergo conventional chemical
evolution driven by
supernova enrichment. Instead, they exhibit unique abundance patterns of the light elements, which cannot be fully explained by any of the proposed enrichment mechanisms. "Normal"
stars of low sodium abundances comprise the first population of cluster
stars, and "enriched"
stars of high sodium abundances, which are found only in globular clusters, comprise the second population. Here we show from a differential line-by-line analysis of
stars that span a small range of effective temperature that the globular cluster M92 has higher Fe abundances in second-population (sodium-enhanced)
stars than first-population
stars. The two populations are well separated in Na, Al, and Fe abundances. The rise in Fe abundance between the first and second
stellar populations suggests that M92 was able to retain at least some
supernova ejecta, all of which exploded after the first population finished forming. This result provides a lower limit for the time delay between populations.
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All authors Evan N. Kirby, Roman Gerasimov, Alice Cai, Benjamin Coco, Pranav Nalamwar, Lauren Henderson
Quantum Physics
Steady-state Bell nonlocality in an autonomous quantum thermal machine
Bradley Longstaff
A
quantum thermal machine is presented that is able to autonomously generate steady-state Bell nonlocality. A Lindblad equation is derived for two
qubits that are incoherently coupled to a pair of thermal baths and the resulting Liouvillian is found to have a strong
symmetry. This out-of-
equilibrium system can generate Bell-nonlocal steady states across a range of parameters and at arbitrarily high temperatures for certain initial conditions. To analyse how the machine operates in a more realistic setting, experimental imperfections are then included via a
stochastic perturbation to the system
Hamiltonian. This breaks the strong
symmetry and results in collective and local dephasing noise. It is found that if the sole source of noise is local noise, then the steady state is Bell local. The co-presence of collective noise is then shown to be advantageous, with the ability to increase the degree of Bell-inequality violation and transform a steady state from Bell local to Bell nonlocal.
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Quantum Physics
Squeezing-enhanced Pairwise Fusion of Photonic Qudits
Pradip Laha and Peter van Loock
Pairwise fusion gates are linear-optical measurements that herald Bell projections onto two-rail subspaces of two \(d\)-rail single-
photon qudits. Without ancillary input
photons, these passive measurements succeed with probability \(1-d^{-1}\), with all failures confined to the diagonal logical subspace. We show that identical single-mode squeezers applied to the \(2d\) interferometer outputs before
photon-number-resolving detection recover part of this structured failure sector.
Photon-number parity preserves the successful off-diagonal fusion signatures, while selected all-even patterns yield POVM elements proportional to definite pairwise Bell projectors. We derive the exact logical-space POVM and prove that a diagonal pattern is accepted if and only if its
photon-number-imbalance vector has exactly two nonzero components of equal magnitude. The resulting closed
elliptic-integral expression increases the ideal success probability, for instance, from \(75\%\) to \(79.62\%\) for \(d=4\), and from \(83.33\%\) to \(87.15\%\) for \(d=6\). With a representative finite detector saturation threshold, \(n_{\rm sat}=7\), the respective certified values remain \(78.84\%\) and \(86.71\%\). These results establish active Gaussian processing as a method for recycling structured measurement failures without ancillary input
photons, at the cost of \(2d\) squeezing operations and a larger
photon-number range at detection.
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Solar and Stellar Astrophysics
Distribution of energy release events due to magnetic braiding
David I. Pontin, Klaus Galsgaard and James A. Klimchuk
Energy conversion by reconnection-powered nanoflare heating is one of the leading explanations for the heating of the
solar chromosphere and corona. The aim of this paper is to shed light on this mechanism by exploring the
magnetic Reynolds number dependence of the energy conversion process. To do this we employ boundary-driven, magnetohydrodynamic, flux-braiding simulations at different
magnetic Reynolds numbers ($R_m$), and explore in detail the properties of the individual
magnetic energy release events. The properties of the reconnecting current sheets that mediate the energy release are shown to depend on $R_m$. For increasing $R_m$, the current sheets become thinner, more intense, and more numerous. For sufficiently large $R_m$, the current sheets fragment along their length, leading to a sharp cutoff in the current sheet length distribution. The cutoff is consistent with the threshold for non-linear tearing/plasmoid instability. For increasing $R_m$ the
magnetic field lines become increasingly tangled, the mean and peak values of the
magnetic field strength increase, and the Poynting flux into the domain increases, implying that the heating rate also increases. The global reconnection rate is essentially independent of $R_m$. These results support the braiding mechanism as a viable way to effectively heat the internal portions of coherent flux tubes in the corona.
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Biological Physics
Entropic Time, Psychophysics, and Deformed Neural Dynamics: A Unified Physical Theory for Human Time Perception
José Weberszpil and Oscar Sotolongo-Costa
We present a unified physical theory demonstrating that human subjective time perception does not track
geometric coordinate time $t$, but instead emerges from a local metric mutation driven by macroscopic physical
entropy production. By establishing the Nonextensive Troika – a closed, mutually dependent algebraic triplet linking the phase-space fractal dimension $D$, the conformable derivative order $\alpha$, and the Tsallis nonextensive parameter $q$ – we eliminate independent phenomenological fitting constants. We prove that the local time metric inherently scales as $t^{\alpha}$, deriving the conformable operator as a necessary kinetic consequence. Furthermore, we derive the $q$-index from the equiprobable monofractal Tsallis
entropy $S_q$. This structural closure unifies anomalous neural dissipative transport within a deformed leaky integrate-and-fire framework and analytically predicts macroscopic psychophysical response transitions, providing a clear thermodynamic basis for time dilation in psychedelic states (the REBUS model) and temporal compression during cognitive aging.
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Mathematical Physics · Cross-listed from math.PR
Random homomorphisms and Lipschitz functions on trees
Alon Heller and Yinon Spinka
A graph homomorphism is an integer-valued function on the vertex set of a graph that assigns values differing by exactly one to adjacent vertices. We consider uniformly random homomorphisms on general finite trees, conditioned to take the value zero at all leaves, and study the distribution of the value at the root. Our main result is a
stochastic comparison, both from above and below, between the absolute values of the homomorphism value at the root and certain discrete Gaussian-like random variables. In particular, we obtain a subgaussian tail bound valid for all deviations, a matching lower bound that holds up to a certain threshold, and upper and lower variance bounds that differ by a constant factor. These bounds depend solely on the effective resistance between the root and the leaves in the associated electrical network. As a consequence, in the setting of infinite locally finite trees, we obtain that the homomorphism model is localized on transient trees and delocalized on recurrent trees. Analogous results are obtained for random integer-valued Lipschitz functions. Our results extend previous results of Benjamini–Häggström–Mossel on homomorphisms on regular trees, of Peled–Samotij–Yehudayoff on Lipschitz functions on regular trees, and of Lammers–Toninelli on homomorphisms on trees of minimum degree at least three.
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Medical Physics
Pawel Moskal, Deepak Kumar, Sushil Sharma et al. (+37 more)
Annihilation
photons are
quantum-entangled in polarization, a phenomenon that has not been exploited in medical diagnostics so far. We present the first in vivo imaging of the degree of
quantum entanglement of
photons originating from positron-electron annihilation within a human subject. This study utilized the Jagiellonian Positron Emission
Tomography (J-PET) scanner, constructed from plastic scintillators. In plastics, annihilation
photons interact primarily via the Compton effect, which provides simultaneous information regarding the
photon interaction position and time, as well as the
photon polarization plane. The patient was injected with a DOTA-TATE radiopharmaceutical labeled with the $^{68}$Ga radionuclide. Using the J-PET scanner, we determined the image of the radiopharmaceutical uptake and, simultaneously, the image of the degree of
quantum entanglement. The latter was determined from the relative angle between the polarization planes of the annihilation
photons. The values of the degree of
quantum entanglement extracted for the liver and the spleen are smaller than those predicted for maximally entangled two-
photon states, yet larger than expected for separable
photons. This demonstration opens new perspectives for the application of
quantum entanglement in clinical diagnostics.
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All authors Pawel Moskal, Deepak Kumar, Sushil Sharma, Ermias Y. Beyene, Neha Chug, Catalina Curceanu, Eryk Czerwiński, Atharva Dalvi, Manish Das, Alicja Hubalewska-Dydejczyk, Sharareh Jalali, Krzysztof Kacprzak, Tevfik Kaplanoglu, Łukasz Kapłon, Kamila Kasperska, Aleksander Khreptak, Grzegorz Korcyl, Tomasz Kozik, Sumit Kumar Kundu, Anoop Kunimmal Venadan, Bartosz Leszczyński, Edward Lisowski, Filip Lisowski, Justyna Mędrala-Sowa, Simbarashe Moyo, Wiktor Mryka, Szymon Niedźwiecki, Marta Opalińska, Anand Pandey, Piyush Pandey, Alessio Porcelli, Bartłomiej Rachwał, Magdalena Skurzok, Anna Sowa-Staszczak, Tomasz Szumlak, Satyam Tiwari, Pooja Tanty, Keyvan Tayefi Ardebili, Kavya Valsan Eliyan, Ewa Ł. Stepień
General Relativity and Quantum Cosmology
Gravitational lensing by extremal rotating black holes in the strong deflection limit
Fabiano Feleppa, Valerio Bozza and Welmoed Marit de Graaf
In the strong deflection regime, light rays passing close to an astrophysical black hole may remain trapped near unstable
photon orbits for a long time before escaping to infinity. The traditional strong-deflection limit, which accurately describes the logarithmic divergence of the deflection angle for spherically symmetric and slowly rotating black holes, breaks down when the relevant prograde critical
photon orbit coincides with the degenerate horizon of an extremal rotating black hole. We present a new strong deflection limit expansion for this horizon critical orbit, covering a general class of extremal rotating black holes. We show that the deflection angle exhibits a stronger power-law divergence in addition to the logarithmic divergence. For an adequate description of higher-order images, additional terms in the expansion must be retained. We first study prograde gravitational
lensing in the equatorial plane and then extend the analysis to quasi-equatorial motion, which allows us to calculate the magnification of the higher-order images and the position of the caustic points. We finally apply the general framework to explicit examples, including the Kerr, Kerr-Newman, and Kerr-Sen metrics.
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High Energy Physics (Phenomenology)
Exploring $K\Xi^*$ and $K^*\Xi$ molecular states and the triangle singularity in the $K^- p \to K \Xi(1530)$ reaction
Ke Wang, Fei Huang and Bing-Song Zou
We investigate the $K^- p \to K \Xi(1530)$ reaction within an effective Lagrangian approach, exploring possible $K \Xi^*$ and $K^* \Xi$ hadronic molecular states and the role of the triangle singularity (TS). The $\Lambda(2050)3/2^-$ is interpreted as a $K \Xi^*$ molecule, whereas a $K^* \Xi$ molecule with $I(J^P)=0(3/2^-)$ and mass about 2150~MeV denoted as $\Lambda(2150)$ can generate a TS through triangle-loop diagrams with intermediate $K^*$, $\Xi$, and $\pi$. The peak structure observed in the cross section near $\sqrt{s}=2.25$ GeV is analyzed in terms of both the $\Sigma(2250)$ resonance production and the TS mechanism associated with $\Lambda(2150)$. We find that the TS induces pronounced
spin effects in the final state $\Xi^*$, which can be probed through measurements of its
spin density
matrix elements. In particular, significant variations of the
spin observables in the $\sqrt{s}=2.2$–$2.3$ GeV region serve as a distinct TS signature absent in a pure resonance scenario. Furthermore, for the three-body reaction $K^- p \to K^+ \pi^- \Xi^0$, we demonstrate that $\Xi^*$
spin observables can be reliably extracted from the $\pi$ angular distribution in the $\Xi \pi$ rest frame by applying an appropriate kinematic cut on the $\Xi\pi$ invariant mass to suppress background contributions. These predictions can be tested in future high-precision measurements at J-PARC, providing crucial insights into the nature of the TS and the possible existence of the $K^* \Xi$ molecular state.
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Instrumentation and Detectors
All-directional gamma-ray imaging using a NaI(Tl) scintillator with double-sided SiPM readout
Anzori Sh. Georgadze
Gamma-ray imaging systems capable of determining the direction of incident radiation are essential for homeland security,
nuclear non-proliferation, environmental monitoring, and radiological emergency response. This work presents a compact, high-efficiency omnidirectional gamma-ray imaging concept based on a monolithic cylindrical 2 x 2 inch NaI(Tl) scintillation
crystal coupled to dual-ended 16 x 16 Silicon Photomultiplier (SiPM)
matrices. The system exploits scintillation light distributions collected from both
crystal faces to reconstruct three-dimensional interaction positions. GEANT4 Monte Carlo simulations incorporating full optical
photon transport were performed for 662 keV gamma rays from a ^137Cs source. The simulated energy resolution is 6.69% +- 0.31% FWHM at the photopeak. A hybrid directional reconstruction framework is implemented, combining volumetric self-attenuation (active masking) for robust low-energy localization with intra-
crystal Compton imaging for higher energies. With approximately 40,000 accumulated photopeak counts, the active-masking
algorithm achieves angular resolutions of FWHM_rm elev 5.7^degrees and FWHM_rm az 3.7^degrees. The system fully complies with the EN IEC 62327 standard for handheld radionuclide identification devices. Under the required 120-second acquisition window, it suppresses terrestrial background (NORM) from the lower hemisphere by a factor of ~320, improving to ~980 with 300-second integration. These results demonstrate that a monolithic dual-ended NaI(Tl) detector can transform a conventional scalar spectrometer into a sensitive, real-time directional imaging instrument suitable for portable field use and automated cargo inspection.
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Biological Physics
Flow-polarity decoupling and universal mobility enhancement in dense bacterial active fluids
Yuhao Wang, Premkumar Leishangthem, Yiming Ding et al. (+2 more)
Active fluids consisting of living
cells or synthetic microswimmers display rich emergent behavior and nonequilibrium mechanical properties, which not only shed light on various biological processes but also inform the engineering of autonomous fluidics and self-driven materials. The individual behavior of microswimmers and their interaction with self-generated mesoscale solvent flows underlie the emergent properties of active fluids. Here we studied the microscopic dynamics in dense 3D bacterial active fluids by simultaneous imaging of
cell body, flagella, and flow field. A surprising finding is that the polarity of
cells was randomly distributed in mesoscale flow regimes, and yet the system displays mesoscale order in the self-generated solvent flows. Despite the apparent flow-polarity decoupling, the motion of
cells relative to local solvent flows predominantly navigated upstream, with the self-advection speed overall enhanced by a flow-controlled constant. Numerical modeling with full hydrodynamic interactions reveals that the observed flow-polarity decoupling arises from the breakdown of the commonly held force-dipole assumption for anisotropic microswimmers: in the presence of flow gradient and near-field hydrodynamic interactions, the direction of total active forcing exerted by a swimming bacterium to the surrounding fluid no longer aligns with its polarity. The simulations suggest that near-field interactions serve as a new type of emergent, configuration-dependent active forcing, which profoundly impact self-organization and transport in dense bacterial suspensions. Taken together, our work establishes fundamental knowledge for faithfully understanding the collective behavior of dense polar active fluids.
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All authors Yuhao Wang, Premkumar Leishangthem, Yiming Ding, Xinliang Xu, Yilin Wu
High Energy Physics (Theory)
New Beta Integral from Supersymmetric Gauge Theory on Projective Space
Ilmar Gahramanov, Tuğba H{\i}rl{\i}, R. Semih Kanber et al. (+1 more)
We derive a new beta-type basic hypergeometric integral identity from the equality of supersymmetric partition functions on $\mathbb{RP}^{2}\times\mathbb{S}^{1}$. Unlike previously known identities obtained from lens-space partition functions, this integral does not appear to arise as a degeneration of the lens
elliptic beta integral. Our result enriches the collection of basic hypergeometric beta integrals arising from supersymmetric dualities and has applications to supersymmetric gauge theories, integrable models, and the theory of special functions.
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All authors Ilmar Gahramanov, Tuğba H{\i}rl{\i}, R. Semih Kanber, Hjalmar Rosengren
Mathematical Physics
A Multi-Body Dobrushin-Sokal Criterion – Part II
Jan Philipp Neumann
We prove a sufficient condition for the absolute convergence of Mayer cluster expansions of log-partition and correlation functions applicable to
lattice gases with possibly complex-valued multi-body interactions. Not only are several classical results subsumed but a partition scheme for spanning hypergraphs also makes our methods well-suited for treating stronger multi-body interactions, including higher-order hard-core repulsion in the context of hypergraph independence
polynomials. Furthermore, our approach is easily combined with the Gruber–Kunz condition to produce extended convergence results for the
polymer expansion of
lattice gases, rivalling those obtained not too long ago by Nguyen and Fernández (2024).
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General Relativity and Quantum Cosmology
Self-force on a static scalar charge in traversable wormholes
Jerome P. Mecca and Ian Vega
The self-force acting on a charged particle is sensitive to the global structure of curved spacetime and can serve as a probe of geometry beyond local
curvature. We compute the static scalar self-force on a point charge in the two-parameter family of spherically symmetric wormholes introduced by Konoplya and Zhidenko, members of the broader Morris-Thorne class of traversable wormholes. Using mode-sum regularization, we analyze its dependence on the shape exponent $q$, which controls the throat geometry, and the
redshift parameter $p$, which determines the
redshift function and
tidal strength. We find that the self-force is generally not unidirectional: it can change sign with radial distance from the throat, with up to two distinct zero crossings depending on $(p,q)$. We provide a systematic characterization of how both the direction and large-distance falloff depend on the wormhole parameters. For sufficiently large $p$, the force can decay at a slower rate than the canonical $\sim r^{-3}$ behavior typical of isolated-body spacetimes, with stronger flaring (more negative $q$) leading to more rapid decay. In the combined limit $p \to \infty$ and $q \to -\infty$, the asymptotic falloff approaches that of the static scalar self-force in the Ellis wormhole.
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Cosmology and Nongalactic Astrophysics
Probing the Baryon Distribution with Fast Radio Bursts
Manisha Caleb, Jéferson A. S. Fortunato, Steffen Hagstotz et al. (+12 more)
Baryonic feedback redistributes matter on small to mid cosmological scales, ultimately limiting inferences from Stage IV
galaxy surveys. Direct
baryon tracers are crucial for recovering cosmological signals masked by astrophysical effects, and vice versa:
galaxy formation and other astrophysical processes must be interpreted cosmologically. Fast
radio bursts (FRBs) serve as such tracers: their dispersion measure (DM) records the line-of-sight integrated ionised electron density. The Square Kilometre Array (SKA) will be the only
radio telescope capable of detecting many FRBs in the southern hemisphere, significantly enhancing synergy with surveys such as Rubin Observatory. This chapter completes the FRB trilogy by
forecasting the SKA's potential to constrain the
baryon distribution from cosmological to
galactic scales and across
cosmic time. We tackle this question by investigating the DM scatter as a function of
redshift. We also study the statistical properties of the DM field and its cross-correlation with Stage IV
galaxy surveys. Our focus is on
cosmic shear and
galaxy clustering. This shows that the SKA can play a crucial role in pinpointing baryonic feedback models, thereby greatly enhancing the cosmological constraining power of Stage IV
galaxy surveys. Furthermore, we show that the SKA will be able to measure the properties of the circumgalactic medium using the scattering timescale of FRBs. Lastly, the large
redshift range of FRB detections with the SKA can improve our understanding of the epoch of reionisation. It may also clarify the mechanism behind FRBs.
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All authors Manisha Caleb, Jéferson A. S. Fortunato, Steffen Hagstotz, Clancy W. James, Joscha N. Jahns-Schindler, Dylan L. Jow, Evan F. Keane, Koustav Konar, Yin-Zhe Ma, Daniele Michilli, Robert Reischke, Amit Seta, Priyanka Singh, Laura G. Spitler, Yidan Wang
Optics
Coupling Efficiency and Laser-Induced Damage Threshold Characterization of an End-Capped Optical Fiber with a Sub-Nanosecond Pulsed Laser
George Stavrakakis, Kostas G Mavrakis, Mikis Mylonakis et al. (+1 more)
This report presents experimental measurements of coupling efficiency and
laser-induced damage thresholds for a polarization-maintaining (PM) fiber patchcord with integrated end caps, evaluated at 532 nm using a compact actively Q-switched DPSS
laser with sub-nanosecond pulses. It also describes the development of a custom free-space coupling array through which the problem of low coupling efficiency was identified and successfully addressed. No instantaneous damage was observed at peak power densities exceeding 10 GW/cm$^2$. Sustained operation at 30 kHz was maintained over extended durations (>5 h) at peak power densities of ~13 GW/cm$^2$, while prolonged 1 kHz operation led to gradual degradation at peak power densities of ~24 GW/cm$^2$. The broader context of this work is the investigation of stimulated Raman scattering (SRS) in optical fibers for nonlinear frequency conversion. This process requires the efficient delivery of high-peak-power pulses into the fiber, which serves as the nonlinear medium. In the course of these experiments, a substantial
dataset was accumulated on fiber coupling performance and damage thresholds under repeated high-intensity illumination at 532 nm. These characterization data offer practical insight into the operational limits of end-capped PM fibers in demanding pulsed
laser applications.
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All authors George Stavrakakis, Kostas G Mavrakis, Mikis Mylonakis, Giannis Zacharakis
High Energy Astrophysical Phenomena
Search for Diffuse Supernova Neutrino Background in the Full KamLAND Dataset with Neural-Network-Based Event Classification
D. Chernyak, T. Eda, M. Eizuka et al. (+63 more)
We report a search for the diffuse
supernova neutrino background (DSNB) with the KamLAND detector, targeting electron antineutrinos via inverse beta decay in the
neutrino energy range of 8.3 to 30.8 MeV. Using
liquid-scintillator exposures of 9.02 kton-year for 8.3 to 9.3 MeV and 9.42 kton-year for 9.3 to 30.8 MeV, we observe seven candidate events after applying a new deep-neural-network-based event classification technique. This result is consistent with the background-only expectation of 16.2 plus or minus 9.4 events, including systematic uncertainties associated with the neural-network selection. A spectral analysis of the energy and radial distributions finds no significant excess attributable to the DSNB. We therefore set 90 percent confidence-level upper limits on the DSNB flux of 38 to 43 per square centimeter per second, depending on the assumed DSNB model. We also derive model-independent 90 percent confidence-level upper limits on the electron-antineutrino flux, obtaining some of the most stringent constraints below 13.3 MeV. Beyond the DSNB search itself, this work demonstrates neural-network-based event classification as a promising approach for suppressing
neutron-associated backgrounds in
liquid-scintillator
neutrino detectors.
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All authors D. Chernyak, T. Eda, M. Eizuka, R. Endo, A. Gando, Y. Gando, T. Hachiya, F. Haneishi, K. Hata, T. Hirai, K. Hosokawa, K. Ichimura, H. Ikeda, K. Inoue, K. Ishidoshiro, Y. Kamei, N. Kawada, Y. Kishimoto, M. Koga, K. Mikami, H. Miyake, K. Mizukoshi, D. Morita, K. Nakamura, R. Nakamura, J. Nakane, Y. Nakano, N. Obata, Y. Ota, K. Saito, I. Sakaki, I. Shimizu, J. Shirai, A. Suzuki, K. Tachibana, A. Takeuchi, K. Tamae, H. Watanabe, Z. Xu, S. Yoshida, S. Umehara, K. Fushimi, K. Kotera, Y. Urano, S. Kurosawa, H. Ozaki, B. E. Berger, B. K. Fujikawa, J. G. Learned, J. Maricic, Z. Li, L. A. Winslow, Y. Efremenko, H. J. Karwowski, D. M. Markoff, W. Tornow, S. Dell'Oro, T. O'Donnell, J. A. Detwiler, S. Enomoto, M. P. Decowski, K. M. Weerman, C. Grant, O. Penek, H. Song, A. Li
High Energy Physics (Phenomenology)
$\lambda$, $\rho$, and $\sigma$ Regge trajectories for the hexaquark ${(\bar{u}(cc))(b(\bar{b}\bar{b}))}$ in the triquark-antitriquark picture
Xin-Ru Liu, Qi Liu and Jiao-Kai Chen
We propose Regge trajectory relations for the hexaquark ${(\bar{u}(cc))(b(\bar{b}\bar{b}))}$ by using the Regge trajectory relations for diquarks and triquarks. With these newly derived relations, we investigate five series of hexaquark Regge trajectories: the $\lambda$-, $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories. We demonstrate that, apart from the simplest $\lambda_1$-trajectories, the $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories cannot be constructed by merely mimicking the
meson Regge trajectories, since
mesons possess no internal substructures. To derive these trajectories, one must account for the structure and internal substructure of hexaquark. Without this structural information, the $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories could only be obtained through direct fits to available theoretical predictions or future experimental data. We demonstrate that the $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories for the hexaquark do not correspond respectively to the Regge trajectories for the triquark, antitriquark, diquark, and antidiquark. Nevertheless, their behaviors match those of the Regge trajectories for the triquark $(\bar{u}(cc))$, the antitriquark $(b(\bar{b}\bar{b}))$, the diquark $(cc)$, and the antidiquark $(\bar{b}\bar{b})$, in that respective order. Furthermore, we present rough mass estimates for the excited states corresponding to the $\lambda$-, $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories.
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Quantum Gases
Breathing mode of quantum droplets in dipolar quantum gases: A sum-rule analysis
Xinran Zhang, Junli Liu, Huiyun Xiao et al. (+2 more)
We investigate theoretically the ground-state properties and breathing-mode collective excitations of three-dimensional dipolar Bose gases in anisotropic harmonic traps incorporating
quantum fluctuations. Combining a Gaussian variational ansatz with a sum-rule analysis, we derive explicit analytical expressions for both axial and radial breathing-mode frequencies, which are validated by numerical solutions of the time-dependent extended Gross-Pitaevskii equation. Our theoretical predictions show great agreement with existing experimental data for $^{166}$Er and $^{162}$Dy gases. By constructing comprehensive phase diagrams across the parameter space of the $s$-wave scattering length, atom number, and trap aspect ratio, we reveal both discontinuous first-order phase transitions and smooth crossovers between the dilute Bose-Einstein condensate and dense
quantum droplet phases. We confirm that the enhanced incompressibility induced by
quantum fluctuations significantly elevates the breathing-mode frequencies in the droplet phase compared with conventional weakly interacting Bose gases. Furthermore, the system undergoes a phase transition and a crossover over the scattering length under the elongated and flattened confinements, characterized by discontinuous jumps and continuous crossovers in peak density and atomic cloud sizes, respectively. Our work offers a useful analytical framework to characterize collective excitations in dipolar
quantum gases, providing quantitative insights for forthcoming ultracold atom experiments in lanthanide atoms and polar molecules.
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All authors Xinran Zhang, Junli Liu, Huiyun Xiao, Xiao-Long Chen, Yunbo Zhang
Instrumentation and Methods for Astrophysics
PIE-ADA: Physics-Informed Ensemble with Adaptive Data Augmentation for Photometric Transient Classification
Deba Priyo Guha and Fariya Tabassum
The upcoming Large Synoptic Survey
Telescope (LSST) is expected to observe approximately 10 million astronomical transient events per night, creating an urgent need for automated classification systems. A key challenge is the extreme class imbalance in transient
datasets, where rare event types represent less than 1% of all observations. This paper presents PIE-ADA (Physics-Informed Ensemble with Adaptive Data Augmentation), a framework that generates physically realistic synthetic light curves for underrepresented classes using astrophysically motivated transformations. PIE-ADA applies four augmentation operations, namely correlated noise injection, cosmological time dilation, wavelength-dependent
dust extinction, and observation phase shifting, while enforcing physical constraints to prevent unrealistic samples. We extract 271 multi-scale features from six photometric passbands covering statistical, temporal, peak, color, and frequency-domain properties. Evaluated on the PLAsTiCC
dataset (7,848 original objects augmented to 8,148 across 14 classes), five classifiers were compared using stratified 5-fold cross-validation. LightGBM achieved the best performance with a weighted log loss of 0.5763 ($\pm$0.0083) and 80.33% accuracy, improving over Random Forest, Extra Trees, and Neural Network baselines by 24-49% in log loss. The framework is computationally efficient, completing the full pipeline in under 37 minutes and classifying individual objects in less than 0.05 seconds, making it suitable for real-time LSST alert processing.
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High Energy Astrophysical Phenomena
SKA-VLBI Probes of High-energy Emission Processes in Relativistic Jets
M. Kadler, E.K. Bempong-Manful, P. G. Edwards et al. (+10 more)
Relativistic jets in the
nuclei of active
galaxies are ubiquitous sources of high-energy emission. In particular, blazars represent the most luminous persistent X-ray and gamma-ray sources, whose defining characteristics are small jet inclination angles to the line of sight. Blazars can be detected in many cases up to TeV energies and the largest class of TeV emitting extragalactic AGN is represented by high-synchrotron peaked (HSP) BL Lac objects, which are generally comparably faint
radio sources. Moreover, evidence has also been accumulated that high-energy
cosmic neutrinos detected by IceCube can be associated with blazars. There is an increasing number of suggested blazar-
neutrino associations, along with many cases of coincident flaring
radio emission, but in a majority of cases, faint blazars on the level of millijanskies or below have to be considered. These high-energy
photon and
neutrino emission processes hold many unanswered questions including the unknown source of seed-
photons for photo-pion production and the infamous Doppler crisis of TeV-emitting BL Lac objects. SKA-VLBI offers the opportunity to achieve superior sensitivity at milliarcsecond resolutions, provided by the combination of the phased SKA-Mid and global VLBI arrays. This opens the possibility to perform high-sensitivity and high-angular resolution imaging and polarimetric probes of faint blazars. The resulting high-fidelity spatially resolved parameterizations of structured jets in bright sources will yield key insights to constrain physical models of high-energy
photon and particle emission in AGN jets.
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All authors M. Kadler, E.K. Bempong-Manful, P. G. Edwards, F. Eppel, C. M. Fromm, M. Giroletti, J. Heßdörfer, T. Hovatta, Y. Y. Kovalev, K. Mannheim, R. Ojha, F. Rösch, E. Ros
Superconductivity
Self-resonance effects for intrinsic Josephson junctions in Nd(2-x)CexCuO4 films
T. B. Charikova, V. N. Neverov, M. R. Popov et al. (+2 more)
To detect Josephson self-resonances, we used an original method, namely, studying the voltage Uy at the
Hall contacts in the Nd2-xCexCuO4/SrTiO3 film, where the CuO2 planes are aligned along the longest side of the sample, perpendicular to the substrate. It is argued that the observed Uy(j) oscillations are a set of Fiske steps in a layered
superconductor system, indicating the manifestation of the ac-Josephson effect in a multilayer
superconductor Nd2-xCexCuO4 with a significant number of intrinsic Josephson junctions.
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All authors T. B. Charikova, V. N. Neverov, M. R. Popov, S. D. Popov, N. G. Shelushinina
Earth and Planetary Astrophysics
Henrik Melin
The
giant planets, Jupiter, Saturn, Uranus, and Neptune, all have vibrant and dynamic atmospheres. The iconic belt–zone structure of Jupiter, together with the Great Red Spot, is instantly recognizable. Saturn, with its dramatic ring system and more muted atmosphere, is a formidable jewel in the
Solar System. In the outer reaches, the pale blue Uranus and Neptune are found, worlds about which ultimately very little is known. The atmospheres of these
planets are dominated by hydrogen and helium, and unlike the Earth, they do not have a solid surface. These differences generate inherently different types of atmospheres, but there are also similarities. For example, the condensation of water, which forms the familiar clouds on Earth, also occurs on the
giant planets. Broadly speaking, the atmosphere can be divided into different regimes defined by their temperature gradients. In the troposphere, where weather occurs, the temperatures decrease as a function of increasing altitude as convection moves internal heat upward; the rising material expands and cools. Above this region lies the stratosphere, defined by a positive temperature gradient, where hydrocarbons are heated by ultraviolet radiation from the Sun (analogous to ozone heating in the terrestrial stratosphere), which also drives substantial photochemistry. This is followed by a mesosphere that cools as a function of altitude, a region that is ill-defined at the
giant planets. Finally, the upper atmosphere connects to the space environment and is heated by both
solar extreme ultraviolet light and auroral processes. The
giant planets are energized both by internal heat and by
solar heating. These energy inputs, along with the fast rotation rates of these
planets, drive dynamics by establishing global circulation patterns and generating both waves and instabilities. [...]
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High Energy Physics (Phenomenology)
Searching for the $G(3900)$ via the $K^- p \to D_s^- \Lambda_c^+ G(3900)^0$ reaction
Qing Lu, Cai Cheng and Yin Huang
The nature of the $G(3900)$ structure, observed in $e^{+}e^{-}\to D\bar{D}$, remains unclear and may stem either from a genuine resonance or from charmonium interference and threshold effects. We therefore propose searching for the $G(3900)$ signal in the reaction $K^- p \to D_s^- \Lambda_c^+ G(3900)^0$, where the interference effects present in $e^{+}e^{-}\to \bar{D}^{*}D$ are absent. We employ an effective Lagrangian approach, where the reaction proceeds via a central production mechanism dominated by $t$-channel $D^{0}$ and $D^{*0}$ exchanges, based on the possible interpretation of $G(3900)$ as a $P$-wave $\bar{D}^{*}D$ molecular state, whose coupling to the $\bar{D}^{*}D$ channel is fixed from our previous fit to the $e^{+}e^{-}\to \bar{D}^{*}D$ data. The $\bar{K}N$ initial-state interaction, mediated by Pomeron and Reggeon exchanges, is also included and leads to a significant enhancement of the production cross section. If measured in future experiments, the predicted total cross sections and angular distributions can provide a promising probe of the nature of the $G(3900)$, and in particular of its possible genuine resonance nature.
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Mathematical Physics
PDE-constrained optimization for virtual sensing in structural dynamics: Full-field displacement and force recovery from sparse sensors
Minjae Kim, Jaehwan Jeong, Seulki Lee et al. (+1 more)
Virtual sensing – recovering full-field structural response from sparse sensor measurements – is a fundamental challenge in structural health monitoring (SHM). Fracture assessment, fatigue evaluation and remaining useful life (RUL) prognosis all take the applied load as their input, and that load frequently acts on surfaces that cannot be instrumented. An improved load estimate is therefore of direct practical value for SHM and for prognostics and health management (PHM). The mode-based approach reconstructs the displacement field accurately from a small number of sensors and has been applied successfully for that purpose. The load inferred from this reconstructed displacement is far less reliable, because the residual displacement error is amplified when it is mapped back through the dynamic stiffness. This study therefore formulates virtual sensing as a PDE-constrained optimization (PDE-CO) problem in which the elastodynamic equation is an equality constraint and the applied load is the optimization variable, so that displacement and load are estimated together rather than in sequence. To manage the computational cost, the framework separates offline finite element model preparation from online reconstruction. The assembled
matrices are reused during online optimization, and the forward and gradient evaluations can use GPU-based parallel computation. The numerical comparisons support improved noise robustness of PDE-CO displacement reconstruction relative to the mode-based approach within the tested settings. These results provide a theoretical and computational foundation for the development of virtual sensing for SHM and PHM.
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All authors Minjae Kim, Jaehwan Jeong, Seulki Lee, Jaemin Kim
High Energy Physics (Theory)
Bounded Chaos in a Ghost-Coupled Hamiltonian System
Zahra Molaee and Soleyman Fatholahzadeh
We study the dynamics of a
Hamiltonian system with a ghost degree of freedom, characterized by a negative kinetic-energy contribution and the possibility of runaway behavior due to an indefinite energy functional. We present numerical evidence that a nonlinear interaction term, together with a saturating exponential potential $V_c$, can suppress phase-space escape over the parameter ranges explored in this work. Using direct numerical integration of the
Hamiltonian equations of motion, Poincaré surfaces of section, and trajectory projections, we find that the ghost sector and nonlinear couplings generate a mixed phase-space structure with both regular islands and chaotic regions. The maximal Lyapunov exponent supports bounded chaotic motion: nearby trajectories separate exponentially while remaining confined to a finite region of phase space for the investigated initial conditions and parameters $(\varepsilon,\alpha)$. These results suggest that nonlinear confinement can significantly alter the stability properties of negative-energy sectors at the classical level. They provide numerical evidence for a bounded-chaos regime in which ghost-induced divergences are avoided within the explored domain.
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