Materials Science
Using superpixels for interpretable feature reduction in large 2D diffraction datasets
Andreas Werbrouck, Nikhila C. Paranamana, Andrew C. Meng et al. (+2 more)
Large 2D diffraction
datasets, consisting of hundreds or thousands of measurements, are commonly acquired with 4D-STEM electron diffraction or at synchrotron X-ray beamlines. Machine learning and artificial intelligence offer great promise for analyzing these
datasets. However, the sheer volume of data presents a significant data processing bottleneck. Cropping the detector and pixel binning are standard ways to reduce data size. Here we propose grouping and averaging pixels into superpixels of variable area. High-information regions are sampled densely, while low-information areas are collected into larger superpixels. In the process,
symmetries in the data are captured and exploited, making this approach suitable for preprocessing 2D diffraction data. We compare two variance-minimizing methods: K-means clustering (top-down) and agglomerative clustering (bottom-up) and demonstrate superior scaling and interpretability for the bottom-up method. As these methods are distance-based, we demonstrate that the construction of superpixels can be accelerated using Gaussian random projection. Finally we show over 100-fold acceleration for phase mapping with Non-negative
matrix factorization on a 4D-STEM
dataset when superpixels are used as a preprocessing step.
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All authors Andreas Werbrouck, Nikhila C. Paranamana, Andrew C. Meng, Xiaoqing He, Matthias J. Young
Quantum Physics
Universal Quantum Gate Set for Multi-Mode Schrödinger Cat States Stabilized by Non-Local Dissipation Engineering
Jesper Lind-Olsen, Jonas Lidal, Tron Omland et al. (+1 more)
Schrödinger cat states provide a hardware-efficient platform for bosonic
quantum error correction by encoding logical information in protected
manifolds of harmonic oscillators. While previous work has demonstrated the dissipative stabilization of multi-mode Schrödinger cat states as robust
quantum memories, a framework for universal
quantum computation has remained unavailable. Here we work towards this by introducing a universal gate set for dissipatively stabilized multi-mode cat
qubits as a necessary resource for computation. Using a chain of Kerr non-linear oscillators coupled through engineered non-local dissipation and an effective low-dimensional description, we show how single-
qubit control can be achieved through arbitrary rotation around the $X$-axis and $\pi/2$-rotation around the $Z$-axis. We further show how coupling two such stabilized arrays through just one oscillator on each respective array enables coherent entangling operations through implementation of the $XX_{\pi/2}$ gate. Numerical simulations demonstrate high-fidelity gate dynamics and
entanglement generation under realistic parameters. Finally, we analyze the effects of induced and intrinsic
photon loss, disorder, and the validity regime of the effective low-dimensional theory. Our results establish dissipatively stabilized multi-mode Schrödinger cat states as a potential architecture for universal bosonic
quantum computation.
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All authors Jesper Lind-Olsen, Jonas Lidal, Tron Omland, Joakim Bergli
Computational Physics
Contact-resolved deployment of the Contour Neurovascular System in patient-specific intracranial aneurysms
Ratnadeep Pramanik, Fina Gießler, Martin Frank et al. (+5 more)
While intrasaccular flow disruptors are increasingly used to treat wide-necked intracranial aneurysms (IAs), many patient-specific computational workflows prescribe a pre-seated device geometry and omit deployment mechanics. This simplification is particularly restrictive for the Contour Neurovascular System (CNS), for which neck coverage, wall apposition, and post-contact motion depend on the deployment process. To address this, we present a contact-resolved finite-element framework that models CNS deployment within patient-specific IAs. We represent the device as a dual-layer interwoven Nitinol braid using geometrically exact beam models, and the aneurysm wall as a deformable hyperelastic shell. Frictional contact governs wire-wire and wire-wall interactions during staged release. The framework is demonstrated across three patient-specific anatomies. In the reference anatomy, the seated configuration is sensitive to the assumed device-wall tangential friction and to release depth relative to the aneurysm neck plane. Frictionless wall contact permits pronounced post-contact sliding, whereas finite tangential friction strongly suppresses residual pole motion. Release depth alters both the onset of wall engagement and the subsequent deployment path.
Geometric placement approaches that prescribe the implanted configuration cannot recover this contact history or the associated wall-supported state. Our framework provides a mechanics-based route to deployed geometries for downstream hemodynamic, fluid-structure interaction, and mechanobiological analyses.
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All authors Ratnadeep Pramanik, Fina Gießler, Martin Frank, Ivo Steinbrecher, Matthias Mayr, Naomi Larsen, Sylvia Saalfeld, Alexander Popp
Cosmology and Nongalactic Astrophysics
A Universal Relation Between Primordial Density-Potential Cross-correlation Coefficient and Spin Factor Distribution
Jun-Sung Moon, Jounghun Lee and Juhan Kim
Recent studies have revealed that the key properties of visible
galaxies like their optical sizes,
stellar ages,
star formation rates and morphologies are closely linked with the angular momenta of their host dark matter
halos. According to the linear
tidal torque theory, the
halo angular momentum, as a conserved quantity, is directly proportional to the
primordial spin factor, $\tau$, defined as the degree of misalignment between the principal axes of the initial density and potential Hessian
matrices, which were found by numerical experiments to follow a Gamma distribution, fully characterized by its mean and variance. In this study, we heuristically develop an analytic expression for the mean and variance of $\tau$ in terms of the initial density-potential cross-correlation coefficient, $q$. Analyzing a
dataset from the Multiverse simulations performed for both of the flat $\Lambda$CDM and $w$CDM cosmologies, we prove that this analytic expression is universally valid in describing how the mean and variance of $\tau$ change with $q$, regardless of the smoothing scales for both of the cosmologies. Given the prior finding that the $\tau$-distribution can be reconstructed from the observable
galaxy size distribution, this universal analytic expression may allow us to determine $q$ from the same observable via the mean and variance of $\tau$. We discuss a possibility of constraining the early universe physics from the reconstructed $q$ via our heuristic model, without suffering from cosmological degeneracies.
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Biological Physics
Confinement effects on protein stability in a freezing water environment
Yanis R. Espinosa, H. Ariel Alvarez and C. Manuel Carlevaro
Understanding how
proteins behave at low temperatures remains a central challenge in biophysics, with direct implications for cold denaturation and cryopreservation. While cold denaturation of
proteins in the supercooled
liquid regime has been studied extensively, the behavior of a
protein embedded in a growing ice
lattice remains largely inaccessible to experiments. Here we use molecular dynamics simulations that explicitly capture ice Ih formation to characterize the conformational dynamics of yeast frataxin (Yfh1) as its aqueous environment crystallizes. Using four independent ice-seeded replicas and
liquid-water controls at three temperatures, we first validate the
liquid-solid transition through convergent changes in solvent density, potential energy, and local bond-order parameters (W4, W6). Principal component analysis (PCA), dihedral PCA (dPCA), and free-energy landscapes then reveal that crystallization of the solvent markedly reshapes the accessible conformational space, shifting it from a continuous, highly connected regime in
liquid water toward a discretized landscape dominated by confined states. Complementary analyses of solvent-accessible surface area (SASA), radius of gyration, and hydrogen bonding indicate a solvent-driven reorganization of
protein-water interactions: although first-shell water remains
liquid-like, its surface density increases under freezing, while conformational sampling contracts. Together, these results indicate that
protein behavior at low temperatures is governed not by temperature alone but by the structural organization of the surrounding water. By imposing geometrical constraints on the solvent, ice formation restricts conformational sampling while preserving – and even densifying – the interfacial hydration layer, highlighting the role of water structure as a determinant of
protein stability under freezing conditions.
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Instrumentation and Detectors
Kaleidoscopic-ray-tracing-based model of the scintillation flash energy deposition in the photomultipliers attached to a strip scintillator
I. V. Vovchenko, T. M. Khamitov and L. V. Inzhechik
Strip scintillator detectors are used nowadays in many fields of applied physics, particularly in medicine, civil engineering, mapping of underground resources, and security. In this work we provide an analytical description of light transport in a cuboid-shaped strip scintillator detector from the scintillation location to the detecting surface. We use kaleidoscopic-ray-tracing approach to reproduce the average time profile of the energy deposition (light collection) in the detecting surface. We demonstrate the applicability of the model on the case of PWO
crystal of $1.5\times 1.5 \times 30$ cm$^3$ size. We show that the results achieved in the model are in good agreement with Monte Carlo (MC) simulation. Notably, the developed model requires dozens of milliseconds to be implemented, thus, it is applicable for real-time calibration of the detector, while the MC simulation takes hours. Also, we highlight that the kaleidoscopic-ray-tracing itself being used in MC simulations can highly speed them up in the case of specular reflectors.
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High Energy Physics (Phenomenology)
$V/H$+Jet Production with the Cambridge/Aachen Algorithm
K. Khelifa-Kerfa
We present fixed-order perturbative calculations up to four-loop order for a generic non-global QCD observable in
hadron-
hadron collisions. Specifically, we study the invariant-mass distribution of the highest-$p_t$ jet produced in association with a vector
boson or a
Higgs boson, where jets are defined using the Cambridge/Aachen sequential recombination
algorithm. This work is part of a series of papers~\cite{Khelifa-Kerfa:2015mma, Khelifa-Kerfa:2024hwx, Khelifa-Kerfa:2024dut, Khelifa-Kerfa:2025cdn, Khelifa-Kerfa:2024udm, Khelifa-Kerfa:2025jev} examining the impact of various jet
algorithms on the perturbative structure of non-global observables across different collision environments. We find that at fixed order the Cambridge/Aachen
algorithm suppresses the large non-global logarithms more effectively than the anti-$k_t$ and $k_t$
algorithms, while at all orders it performs comparably to the $k_t$
algorithm. Furthermore, comparisons of all-orders resummed form factors reveal that finite-$N_c$ corrections remain at the percent level, consistent with previous findings.
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Astrophysics of Galaxies
Even central galaxies feel their environment: cosmic siphoning of cool gas accretion
Ke Xu and Tao Wang
Identifying the key processes regulating cool gas
accretion in
galaxies is essential for understanding the
baryon cycle within
galactic ecosystems. Recent studies indicate that the most fundamental internal process is likely the competition between
halos and central black holes. This is revealed through a universal relation between increasing black hole masses and decreasing cool gas fraction ($\mu_{\rm HI} \equiv M_{\rm HI}/M_{\star} \propto M_{\rm BH}^{-0.6}$). Here we further explore the primary external effects on cool gas
accretion in central
galaxies. We find that
galaxies deviating significantly from the $\mu_{\rm HI}-M_{\rm BH}$ relation are overwhelmingly isolated central
galaxies without substantial satellites. These isolated, gas-poor centrals exhibit systematically higher black-hole-to-
stellar-mass ratios and more prominent bulges. At larger scales, they are preferentially located near massive neighboring
halos. We suggest that this may reflect a “
cosmic siphoning" scenario, replenished by their satellites and by gas flowing along the
cosmic web. This model naturally explains the prevalence of gas-poor isolated central
galaxies near massive
halos. It complements internal regulation by supermassive black holes and suggests a
cosmic 'rich get richer' scenario.
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High Energy Physics (Phenomenology)
Comment on 'Primary Dimensions'
G. Buchalla, O. Catà, A. Celis et al. (+1 more)
We show that the concept of primary dimensions, first introduced in [1] as an organizing principle for
chiral Lagrangians, is inconsistent. Although this had been pointed out already in [2], the notion of primary dimensions has re-appeared in recent literature. We briefly comment on the proper power counting for such effective field theories, including the electroweak
chiral Lagrangian with a light
Higgs, which is based on
chiral dimensions, equivalent to the counting of loop orders.
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All authors G. Buchalla, O. Catà, A. Celis, C. Krause
Optics
Temporal Fourier Optics Reveals Hidden Hybridized Light-Matter States
Juan-Feng Zhu, Wenjie Zhou, Shihao Feng et al. (+5 more)
Spectral measurements provide fundamental insights into wave systems by revealing resonances, mode hybridization, and light-matter interactions. However, intrinsic dissipation and measurement-related spectral broadening often obscure the spectral signatures of the underlying hybridized light-matter states. Here, we establish a temporal
Fourier optics framework based on a space-time
Fourier correspondence, which interprets spectral broadening as the
Fourier counterpart of temporal attenuation. This perspective introduces a temporal point-spread function (TPSF) that enables direct, synthesis-free reconstruction of the underlying spectral response from experimentally measured spectra by compensating for effective temporal decay before transformation back to the frequency domain. We experimentally validate the framework using deterministic single-molecule Au nanosphere dimers and open Au@Ag nanorod- and nanotriangle-based plasmonic nanocavities coupled to J-aggregate
excitons. Across these distinct platforms, TPSF consistently resolves hidden upper and lower polaritonic branches, revealing hybridized light-matter states and strong coupling that remain inaccessible in conventional scattering spectra. The reconstructed spectra agree closely with the recently developed complex-frequency formalism while providing a substantially simpler and experimentally accessible implementation. More broadly, temporal
Fourier optics establishes a general framework for recovering dissipation-obscured spectral information, opening new opportunities for spectroscopy, imaging, sensing, and inverse wave measurements across photonics and wave physics.
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All authors Juan-Feng Zhu, Wenjie Zhou, Shihao Feng, Zicheng Song, Ruicong Zhang, Cheng-Wei Qiu, Rengming Liu, Lin Wu
Fluid Dynamics
Metamorphosis of transition between states of limit cycle oscillations in aeroacoustic system
Siddharth Kancharlapalli, Beeraiah Thonti, Sivakumar Sudarshanan et al. (+2 more)
Dynamical systems undergoing transition to oscillatory state exhibit change in the nature of the transition from supercritical to subcritical
Hopf bifurcation or vice versa upon variation of a secondary parameter. This phenomenon is referred to as change of criticality. Many real-world systems undergo transition to oscillatory state that do not fit in the framework of
Hopf bifurcation, and hence the change of criticality. We perform experiments on a ducted turbulent aeroacoustic flow constrained by two orifices separated at a distance apart. We vary the Reynolds number (Re), a bifurcation parameter causing a transition between various limit cycles. We change the distance between the orifices as the secondary parameter. We discover that turbulent aeroacoustic flows exhibit a metamorphosis of the transition from continuous to abrupt through a canard explosion, a bifurcation unique for its continuous yet rapid nature. We observe two distinct abrupt bifurcations, differing in their dynamical states associated with the transition. Understanding this metamorphosis from continuous to abrupt aids in developing low-cost control and preventive strategies for systems undergoing a route to oscillatory instabilities.
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All authors Siddharth Kancharlapalli, Beeraiah Thonti, Sivakumar Sudarshanan, Ramesh S. Bhavi, R. I. Sujith
Optics
ZPAN: An Organic Nonlinear Optical Crystal for High Intensity THz Generation
Matthew J. Lutz, Sin-Hang Ho, Zachary B. Zaccardi et al. (+5 more)
We report an optimized synthesis and
crystal growth protocol as well as structural, optical, and terahertz (THz) generation characteristics of the organic nonlinear optical
crystal ZPAN ((Z)-1-(((4-Phenylamino)phenylamino)methylene)naphthalen-2(1H)-one). Noncentrosymmetric packing of ZPAN is most reliably achieved by slow evaporation from an acetone-based solvent system, producing long rectangular prisms (7 cm \times 1 cm \times 0.2 cm) with (010) as the main face and [001] as both the polar axis and the direction of elongated
crystal growth. [001] is thus the most effective pump polarization direction for generating THz light via optical rectification. The THz generation characteristics of the developed ZPAN
crystals are determined at different near-infrared irradiation wavelengths,
crystal thicknesses, and pump powers, revealing that ZPAN can generate a peak-to-peak electric field of near 1 MV/cm with a smooth spectrum from 0.5-3.4 THz. Calculated second order nonlinear optical coefficients indicate that both the (100) and (010) faces are theoretically capable of THz generation, though (010) is consistently the dominant growth face. The large size of this face (7 cm \times 1 cm) makes it possible to scale
laser power with aperture size, for use in extremely high-power
laser systems.
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All authors Matthew J. Lutz, Sin-Hang Ho, Zachary B. Zaccardi, Paige Petersen, Elisha Jones, Stacey J. Smith, David J. Michaelis, Jeremy A. Johnson
Mathematical Physics
Log-Sobolev inequalities for boundary-driven anharmonic chains
Jianfeng Lu
We study the non-
equilibrium steady state of a weakly anharmonic chain of $N$ oscillators driven at its boundary by Langevin thermostats at unequal temperatures. Under a perturbative weak-anharmonicity condition, we prove a full-gradient logarithmic Sobolev inequality whose constant is independent of the chain length $N$. For homogeneous pinned chains, an additional quantitative regularity assumption yields a boundary space-time logarithmic Sobolev inequality and relative-
entropy decay on the same $O(N^3)$ relaxation time scale as the harmonic chain. The proof extracts a finite-dimensional Gaussian component from the boundary noise and compares conditional terminal-state laws by a change of variables. The estimates are uniform over bounded positive temperatures and require no near-
equilibrium assumption on their difference.
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Nuclear Experiment
High-precision measurement of the kaonic hydrogen 1s level shift and width with SIDDHARTA-2
M. Bazzi, F. Clozza, C. Guaraldo et al. (+37 more)
Kaonic atoms provide a unique experimental probe of strong interaction in the low-energy regime. In particular, the strong-interaction-induced shift ($\varepsilon_{1\text{s}}$) and width ($\Gamma_{1\text{s}}$) of kaonic hydrogen directly constrain the low-energy antikaon-nucleon ($\bar{K}N$) interaction at threshold and the theoretical description of the $\Lambda$(1405) resonance. We report a new high-precision measurement of kaonic hydrogen X-ray transitions performed by the SIDDHARTA-2 experiment at the DA$\Phi$NE
collider (INFN-LNF), based on an integrated luminosity of 237 pb$^{-1}$. The extracted values, $\varepsilon_{1\text{s}}\,=\,-303.0\,\pm\,17.0\,(stat.)\,\pm\,2.5\,(syst.)$ eV and $\Gamma_{1\text{s}}\,=\,607\,\pm\,62\,(stat.)\,\pm\,6\,(syst.)$ eV, represent the most precise determination to date, improving the precision by approximately a factor-of-two with respect to the previous SIDDHARTA measurement. These results significantly tighten the experimental constraints on theoretical description of the low-energy $\bar{K}N$ interaction.
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All authors M. Bazzi, F. Clozza, C. Guaraldo, M. A. Iliescu, A. Scordo, F. Sgaramella, D. Sirghi, F. Sirghi, J. Zmeskal, L. Abbene, C. Amsler, F. Artibani, G. Borghi, D. Bosnar, M. Bragadireanu, A. Buttacavoli, M. Carminati, A. Clozza, L. De Paolis, R. Del Grande, K. Dulski, C. Fiorini, I. Friščić, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, C. Milardi, P. Moskal, F. Napolitano, H. Ohnishi, K. Piscicchia, F. Principato, M. Silarski, M. Skurzok, A. Spallone, K. Toho, M. Tüchler, O. Vazquez Doce, C. Curceanu
Materials Science
Dolomite Mineral-Inspired Equilateral Triangular-Lattice Magnets for Quantum Magnetism
Yang Zhao, Zhaoyi Li, Zhibin Qiu et al. (+3 more)
Equilateral triangular
lattice magnets provide a versatile materials platform for exploring exotic
quantum spin phenomena, while their field-tunable
magnetic entropy offers opportunities for low-temperature adiabatic demagnetization refrigeration. Inspired by the natural mineral, we proposed a chemical strategy to achieve equilateral TL magnets, leveraging the high
crystal symmetry of a large family of dolomite-type materials. As typical examples, the dolomite-type materials SnM(BO3)2 (M = Co, Mn) were synthesized, and structural analysis reveals that Co2+ and Mn2+ ions form equilateral triangular
lattices with an A-B-C stacking fashion. The
magnetic susceptibilities and specific heat measurements reveal dominant
antiferromagnetic interactions, with Neel temperatures of 0.49K for SnCo(BO3)2 and 0.96K for SnMn(BO3)2, respectively. Our results establish the dolomite-type M'M(X)2 (M'and M sites allow various valence states, e.g., +4/+2 or +3/+3; X = CO32- or BO33-) system as a chemically flexible and structurally perfect material platform for exploring frustrated magnetism and low-temperature magnetocaloric applications.
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All authors Yang Zhao, Zhaoyi Li, Zhibin Qiu, Jianqiao Wang, Bo Wen, Shu Guo
Optics
Polariton Topological Insulators with Disclinations
Khalil Sabour and Yaroslav V. Kartashov
We introduce polariton topological
insulator on aperiodic array of microcavity pillars with disclination. This unique dissipative and nonlinear topological system can have discrete rotational
symmetry not achievable in structures constructed on periodic arrays that qualitatively affects the structure of topological modes. In such system resonant optical pump can be used for selective excitation of topological states forming on the disclination core in the center, while imposing vorticity on the pump profile allows to excite not only the simplest disclination states, but also
vortex-carrying disclination states. Strong repulsive nonlinearity of polaritonic system leads to increasing with pump amplitude tilt of the resonance curves and bistability, with rich possibilities for control of shapes of nonlinear disclination states within topological gap by pump frequency detuning. Stability analysis predicts remarkable robustness of both
vortex-free and
vortex-carrying nonlinear disclination states in this system. We show that when topological charge of the pump exceeds maximal allowed charge in the disclination array with a given discrete rotational
symmetry, the stationary states form that contain
vortex clusters in their phase distributions. Our results extend the concept of topo-logical
insulators with disclinations to the realm of nonlinear resonantly driven systems and show that rich bistability effects in them can be observed even for excited
vortex-carrying topological states with different topological charges allowed by discrete rotational
symmetry of the system.
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High Energy Physics (Theory)
Hodge numbers for orbifolds of Calabi-Yau threefolds Fermat type and the Roan pairs
Sergey Aleshin, Alexander Belavin and Gleb Koshevoy
First, for orbifolds of Calabi-Yau threefolds of Fermat type, we define Roan's Hodge numbers. We prove,
Theorem \ref{main} , that for all orbifols of Calabi-Yau threefolds Fermat type, Roan's Hodge numbers correctly count the stringy Euler numbers due to Vafa formula. Second, for Calabi-Yau threefolds Fermat type, we apply Roan's Hodge numbers to get a relation between the Borcea-Voisin construction \cite{Borcea, Voisin} and Berglund-Hübsch-Krawits mirror
symmetry (BHK mirror
symmetry). Third, for orbifolds of K3 surfaces Fermat type, we establish relations twisted and untwisted parts of the second mixed
cohomology to deformations and the Roan pairs. This allow us to confirm the BHK mirror
symmetry for such orbifolds, since the Euler numbers computed by the Vafa formula are equal $24$ for all of them.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.CV
PlumeQuant: Uncertainty-aware consistency assessment of methane plume masks and emission-rate estimates
Parisa Masnadi Khiabani, Wolfgang Jentner, Alireza Rangrazjeddi et al. (+4 more)
Imaging spectrometers increasingly distribute source-resolved methane plume products in which the plume mask, integrated mass enhancement (IME), plume length, emission rate, and uncertainty are physically and algorithmically linked. Using 63 EMIT-derived Carbon Mapper plume records from 27 scenes, we show that these published scalar quantities do not uniquely constrain the plume boundary: substantially different yet plausible masks reproduce the same IME, plume length, and emission rate. Genetic-
algorithm (GA) ensembles conditioned on the published IME and plume length make this equifinality explicit: the high-confidence core selected by nearly all target-consistent masks covers a median of 13% of the plausible footprint envelope, and ambiguity is largest for weak, low-overlap plumes. The diagnostics come from PlumeQuant, which recomputes IME, plume length, emission rate, and five-term uncertainty from distributed product components under stated conventions and evaluates four mask representations: the distributed reference mask, a transparent Carbon Mapper-informed analogue (CM-like), the GA ensemble, and optional expert edits. The CM-like mask is generated per plume without access to the reference mask or published quantities, with settings fixed once on a scene-disjoint 44-plume development split. It reproduced published IME with +0.72% median difference and emission rate with +0.16% (6.98% mean absolute), reached 0.843 median intersection-over-union against the reference masks, and matched the published uncertainty scale (median ratio 1.01). Holdout mean absolute errors were 7.6% (IME), 9.5% (length), and 6.1% (rate). These are product-level consistency diagnostics, not independent validation. They flag weak, offset, or ambiguous plumes for expert review.
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All authors Parisa Masnadi Khiabani, Wolfgang Jentner, Alireza Rangrazjeddi, Michael C. Wimberly, Binbin Weng, David Ebert, Charles Nicholson
Astrophysics of Galaxies
The dynamical environment of the high-mass star-forming region G28.288$-$0.364
Jyotirmoy Dey, Devendra K. Ojha and Jagadheep D. Pandian
Massive
stars form within deeply embedded
dust cores, and the development of hypercompact and ultracompact H II regions characterizes their early
evolution. Identifying and analyzing such regions is essential for understanding the physical processes that govern massive
star formation and the transitions between early evolutionary stages. In this article, we investigate the physical and kinematic properties of the massive
star-forming region G28.288$-$0.364 to constrain the evolutionary stages of embedded H II regions and the surrounding cores. We analyze multiwavelength observations, including uGMRT
radio continuum data; archival continuum and
radio recombination line data from the GLOSTAR-D survey; high-angular-resolution ALMA Band 3
radio recombination line and 1.36-mm
dust continuum data from the ALMAGAL survey; and complementary molecular line tracers. We derive spectral indices, measure linewidths and velocities of the
radio recombination line emission, identify compact
dust cores using dendrogram analysis, and estimate their physical properties. The
radio continuum emission exhibits a positive spectral index, consistent with partially optically thick free-free emission. High-resolution observations resolve the ionized gas into two distinct components with physical sizes of $\sim$ 0.06 pc, and their RRL linewidths ($\sim$ 37 and 32 km s$^{-1}$, respectively) indicate that one component is in a transitional stage between hypercompact and ultracompact H II regions, while the other is more evolved. The 1.36-mm
dust continuum data reveal five
dust cores with surface densities consistent with the theoretical threshold for massive
star formation. In summary, these results highlight the complex and sequential nature of massive
star formation in clustered environments and demonstrate the importance of high angular resolution observations for resolving the early
evolution of massive
stars.
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Quantum Physics
Quantum observables for probabilistic classical particles
Christof Wetterich
The classical observables of position and momentum are not well adapted to particles in a microphysical situation where typical probability distributions are characterized by a substantial dispersion. We propose the use of more robust
quantum observables for probabilistic classical particles. The
quantum observables are statistical observables which do not take fixed values for a given classical position and momentum. Solutions of the Liouville equation are discussed in the
quantum formalism for classical statistics. Statistical observables are represented by non-commuting operators. No classical correlation function is defined for these observables and Bell's inequalities do not apply. We demonstrate for a general potential how a
quantum system emerges from classical statistics. For the particular cases of a harmonic potential and a Coulomb potential we investigate subsystems which describe all features of a
quantum particle. This covers the discrete energy spectrum of the hydrogen atom and
quantum harmonic oscillator. We discuss the interference for the double-slit experiment. Conserved statistical observables may also be relevant for the probabilistic dynamics of
dust or
planets.
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Medical Physics · Cross-listed from cs.CV
A novel unsupervised machine learning strategy to handle multimodal cardiac PET/MRI data
Brunnhilde Ponsi, Thomas Carlier, Lara Marteau et al. (+5 more)
Arrhythmogenic left ventricular cardiomyopathy is a genetic myocardial disease difficult to diagnose due to the lack of gold standard criteria. Simultaneous PET/MR imaging, combined with multiparametric quantitative analysis, could facilitate the identification of different profiles related to the phenotype and progression of cardiomyopathy. This preliminary study focuses on a methodological strategy for dealing with PET/MRI data, including inter-patient data linkage and regional analysis. Two-step clustering was applied to T1 and T2 maps, LGE, and 18F-FDG-PET images of 99 patients genetically diagnosed with arrhythmogenic left ventricular cardiomyopathy. Each patient's images were independently z-scored and summed into a single volume, which was clustered into supervoxels. Thirty-two inter-patient groups of supervoxels were obtained by spectral clustering. An "abnormality" score was assigned to each cluster and modality, and used to visualise abnormal regions likely associated with disease. They enabled the generation of automated textual and bullseye health reports for each patient, which were compared with cardiac imager assessments using balanced accuracy in repeated nested cross-validation. This approach was further validated on a larger cohort of 167 numerical phantoms. The reports generated by clustering accurately identified most of the cardiac physicians' observations (BA = 0.76 $\pm$ 0.04 in repeated nested cross-validation on patients, and BA $\ge$ 0.8 on phantoms). Furthermore, the identified abnormal clusters closely matched their visual observations, facilitating the identification of varying degrees of fibrosis or inflammation on the images. This approach enables a more systematic handling of
multimodal PET/MRI data to characterise myocardial heterogeneity in arrhythmogenic left ventricular cardiomyopathy patients.
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All authors Brunnhilde Ponsi, Thomas Carlier, Lara Marteau, Aurélien Monnet, Thomas Eugène, Jean-Michel Serfaty, Nicolas Piriou, Hatem Necib
Strongly Correlated Electrons
Lecture Notes: The two-dimensional electron Wigner crystal – What's old and what's new?
Brian Skinner
These are lecture notes created for a short lecture series at the 2026 CTEQ Summer School at Penn State. They are written in a conversational and informal style. The goal of these notes is to introduce and review a smattering of old and new ideas about the Wigner
crystal (the solid phase of the two-dimensional electron system) in the context of recent experiments. Particular emphasis is given to the semiclassical description of the Wigner
crystal, its
quantum melting transition, its
spin order, and the ways in which the Wigner
crystal can be modified by Berry
curvature.
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Instrumentation and Detectors
Radiation effects on surface and bulk properties of ATLAS18 silicon sensors under low- and high-dose gamma irradiation and annealing
Marcela Mikestikova, Vitaliy Fadeyev, Pavla Federicova et al. (+10 more)
Silicon strip detectors for the ATLAS Inner Tracker (ITk) at the HL-LHC must withstand harsh radiation conditions, including fluences of up to 1.6E15 1 MeV n$_{eq}$/cm$^{2}$ and total ionizing doses (TID) of up to 66 Mrad. These requirements are met using radiation-hard n+-in-p technology implemented in the ATLAS18 silicon strip sensors currently under production. This work presents a combined study of gamma-irradiation effects in ATLAS18 silicon sensors, including both segmented miniature strip sensors (minis) and unsegmented MD8 diodes fabricated on ATLAS18 production wafers. The samples were irradiated with a $^{60}$Co gamma source to multiple low TIDs between 0.5 and 100 krad, corresponding to the dose range relevant for the early operational phase of the ITk tracker. Additional measurements extending up to a few Mrad were performed to investigate the saturation of surface related damage effects. Post-irradiation characterization included measurements of total, bulk, and surface leakage currents, as well as capacitance-voltage measurements used to extract the full depletion voltage. The thermal stability of radiation-induced defects was studied using isochronal annealing between 80{\deg}C and 300{\deg}C and isothermal annealing at 60{\deg}C and 160{\deg}C. In addition, complementary studies of MD8 diodes irradiated to ultra-high doses of several hundred Mrad, well beyond the ATLAS ITk requirements, are included to investigate possible bulk-related effects induced by pure gamma irradiation and their annealing behavior. The combined analysis of low- and ultra-high-dose irradiation provides a comprehensive picture of surface- and bulk-related gamma-induced effects in ATLAS18 silicon sensors and their thermal
evolution.
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All authors Marcela Mikestikova, Vitaliy Fadeyev, Pavla Federicova, Petr Gallus, Jana Kozakova, Jiri Kroll, Magdalena Kutova, Jiri Kvasnicka, Igor Mandic, Pavel Tuma, Miguel Ullan, Yoshinobu Unno, Iveta Zatocilova
Nuclear Theory
NNStar: An end-to-end AI agent for nuclear matter and neutron star physics
Yao Ma, Yong-Liang Ma and Jia-Ying Xiong
Constraining the equation of state of dense matter requires confronting effective models with massive data that spans many orders of magnitude in scale, from sub-saturation
nuclear matter properties to the masses, radii, and
tidal deformabilities of
neutron stars. Exploring the high-dimensional coupling space of such a model and fine tuning it against all of these constraints is a labor- and time-intensive task. We present NNStar, an end-to-end artificial-intelligence
agent that automates this workflow. Rather than a bespoke application, NNStar is delivered as a portable skill for an open large-
language-model (LLM)
agent platform – a self-describing module that pairs worked usage conventions with symbolic and numerical physics engines that (i) build a relativistic mean-field model directly from a Lagrangian, (ii) solve the mean-field equations of motion and evaluate the saturation properties, (iii) construct the $\beta$-
equilibrium equation of state, splice it to a crust, and integrate the Tolman–Oppenheimer–Volkoff equations, and (iv) score the resulting predictions through a
Bayesian joint analysis against
nuclear matter and astrophysical observations. The
agent can read a model, fit its parameters, and report the full set of
nuclear matter and
neutron star observables without human intervention. NNStar therefore provides a new, AI-driven framework for analyzing
nuclear matter and
neutron-
star observations.
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Strongly Correlated Electrons
Angular momentum splitter effect of $d$-wave axial phonons in orbital altermagnets
Dimos Chatzichrysafis and Alexander Mook
We theoretically demonstrate that axial
phonons,
lattice vibration quanta carrying finite angular momentum, can host a $d$-wave angular momentum texture in orbital altermagnets in the absence of
spin-orbit coupling. We consider a minimal electronic tight-binding model with $d$-wave loop-current order that breaks time-reversal
symmetry. Within the Born-Oppenheimer approximation, we incorporate electron-
phonon coupling via the molecular Berry
curvature and show that the underlying $d$-wave orbital
magnetic moment texture of the electronic state is transferred to the
phonons without requiring the relativistic
spin-orbit coupling. Our results expand the range of platforms available for engineering axial
phonons and point to functionality unique to $d$-wave textures, including angular-momentum Seebeck and splitter effects, corresponding to longitudinal and transverse angular-momentum currents driven by a temperature gradient.
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Statistical Mechanics
Modified Family-Vicsek Scaling and Probability Distributions for Brownian Castle Interfaces
Noah Sublett, Charles Sutton, Benjamin Long et al. (+1 more)
The Brownian Castle is a new interface growth model that is a variation on the well-known ballistic deposition model that results in an entirely new universality class. We present numerical verification that the interface width for BC interfaces displays modified Family-Vicsek scaling properties up to finite size corrections. Specifically, we find a growth exponent of $\beta=0.470 \pm 0.012$ and a roughness exponent of $\alpha=1.01 \pm 0.018$. The scaling is modified at short times with a size scaling exponent that described the early time dependence of interface width on length. The probability distribution of heights for the BC interface shows significant deviations from simple Gaussian behavior and the probability distribution of height changes shows a Cauchy-Lorentz form consistent with expectations for a process involving relatively large jumps.
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All authors Noah Sublett, Charles Sutton, Benjamin Long, Daniel B. Dougherty
Data Analysis and Statistics · Cross-listed from q-fin.TR
Detecting unusual trading patterns on cryptocurrency exchanges by means of complexity measures
Jakub Zwydak, Marcin Wątorek, Jarosław Kwapień et al. (+1 more)
Artificial transaction generation remains an important source of potential
market manipulation on cryptocurrency exchanges, as it may distort reported liquidity and reduce
market transparency. This study proposes a diagnostic framework for detecting unusual trading patterns based on complexity and statistical-structure measures derived from high-frequency trade-level data. The analysis considers log-returns, trading volume, and transaction counts, using tail distributions, autocorrelation functions, multifractal characteristics, approximate
entropy, and detrended cross-correlations. The methodology is applied to BTC, ETH, and XRP traded on Binance, Bitget, KuCoin, and Kraken over the period from April 1 to June 30, 2025. The results reveal a pronounced anomaly on Bitget for BTC and ETH after mid-May 2025. The number of transactions increases sharply, but there is no proportional increase in traded volume or return fluctuations. This regime is characterised by numerous low-volume trades, weaker autocorrelations, reduced multifractal organisation, higher short-pattern irregularity, and weaker cross-correlations involving the transaction-count series. These features are consistent with a noise-like component in trading activity and may indicate artificially increased transaction counts, although they do not provide direct proof of wash trading. The findings show that complexity-based indicators can be useful for detecting exchange-specific trading anomalies that remain hidden in price-based measures.
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All authors Jakub Zwydak, Marcin Wątorek, Jarosław Kwapień, Stanisław Drożdż
Solar and Stellar Astrophysics
Long-Baseline VLF Observations of Solar Flares from Antarctica
Kamen Kozarev, Peter Petkov, Ivaylo Nachev et al. (+4 more)
We present long-baseline Very Low Frequency (VLF) observations of
solar flare-induced ionospheric disturbances obtained at the Bulgarian Polar Astronomical Observatory (St. Kliment Ohridski Base) on Livingston island, Antarctica. Using continuous VLF transmissions at 21.4 kHz (NPM, Hawaii) and 24.0 kHz (NAA, Maine), propagating over trans-hemispheric paths exceeding 11 000 km, we analyze observations of
solar flares during the period 24 January-8 February 2025. After removing the strong diurnal signal via superposed epoch analysis, we analyse the
flare-related perturbations in VLF amplitude and their correlation with GOES soft X-ray flux for 250
flares of C and M class. The long propagation paths provide enhanced sensitivity to
flare-driven changes in D-region ionization. The observations reveal clear, frequency-dependent responses and measurable time delays between X-ray peaks and VLF extrema. These delays, including cases of near-zero or negative correlation lag for stronger events, are consistent with a possible role for
flare spectral characteristics and D-region recombination processes, although alternative explanations related to waveguide propagation and signal-profile differences cannot presently be excluded. Our results demonstrate the scientific value of long-baseline Antarctic VLF observations for detecting and timing GOES-class
flares, while also highlighting key limitations, such as background variability and path-dependent propagation effects, which must be quantified for reliable VLF-based
flare monitoring.
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All authors Kamen Kozarev, Peter Petkov, Ivaylo Nachev, Veselka Radeva, Momchil Dechev, Galin Borisov, Anton Atanasov
Cosmology and Nongalactic Astrophysics
Testing string theory with combined cosmological probes: a case study for dark matter gravitons
Alkistis Pourtsidou
The string theory Swampland programme has resulted in distinct scenarios for the particle nature of dark matter. In this research note, I use combined cosmological probes to constrain the Dark Dimension scenario, which predicts that dark matter consists of decaying massive gravitons characterised by a time-dependent kick velocity. I first provide updated constraints using a combination of CMB and BAO data. I then produce forecasts for a Stage-IV tomographic survey, and outline strategies for predicting the model's behaviour on nonlinear scales. The results demonstrate the potential of surveys like Euclid and LSST to confirm or rule out string theory models of the dark sector.
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Solar and Stellar Astrophysics
A Homogeneous Spectroscopic and Evolutionary Study of cool HgMn and hot Metallic A Stars
F. Kahraman Aliçavuş, E. Çelik and E. Niemczura
We present a homogeneous spectroscopic and evolutionary analysis of chemically peculiar
stars, focusing on HgMn and metallic A (Am) subclasses. Particular emphasis was placed on the coolest HgMn
stars and the hottest Am
stars, motivated by the long-standing hypothesis that these objects may represent consecutive evolutionary stages of a similar
stellar population. High-resolution spectra of 13 HgMn and 14 Am targets were analyzed to derive atmospheric parameters and detailed chemical abundances. While all HgMn
stars were confirmed to retain their chemically peculiar nature, only six of the fourteen candidate Am
stars exhibit abundance patterns consistent with genuine Am characteristics, highlighting the importance of homogeneous spectroscopic classification. We investigate the temperature dependence of elemental abundances, finding a positive correlation between Mn abundance and $T_{\rm eff}$ and a negative correlation for Ni, supporting the operation of atomic
diffusion.
Stellar evolutionary models were computed with the MESA code using atmospheric parameters derived from the spectroscopic analysis. The locations of the confirmed HgMn and Am
stars in the Hertzsprung–Russell diagram support the possibility that the cool HgMn
stars and the hot Am
stars may occupy overlapping evolutionary sequences. Although only a limited number of candidate pairs were identified, further analyses using evolutionary models that include atomic
diffusion are needed to test the possible connection between the two subclasses.
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