Geophysics
Anomalous-diffusion synthesis of non-Gaussian reservoir anomalies for time-lapse seismic inversion
Anderson Mateus de Sousa Nogueira, Paulo Vitor Ferreira, Katerine Rincon Perez et al. (+5 more)
We develop a physics-informed framework for learned time-lapse (4D) seismic inversion that estimates production-induced velocity changes associated with subsurface fluid migration. Existing learned inversion methods are commonly trained on seismic data generated from Gaussian
diffusion models, which fail to capture the anomalous transport characteristic of heterogeneous subsurface reservoirs. To overcome this limitation, we introduce a data generator based on space-time fractional
diffusion, in which the temporal and spatial fractional orders independently control
memory effects and nonlocal transport, while elliptical anisotropy represents preferential flow. By sampling this parameter space, we generate a broad ensemble of physically consistent velocity perturbations spanning normal, subdiffusive, superdiffusive, and intermediate transport regimes. We then train a convolutional neural network to map time-lapse seismic residuals directly to velocity updates. Through extensive Monte Carlo validation, we show that the network accurately reconstructs production-induced anomalies across all transport regimes, with reconstruction errors governed primarily by anomaly amplitude and interface sharpness rather than by the
diffusion regime itself. Our results demonstrate that
embedding anomalous-transport physics into the training distribution substantially extends the applicability of amortized 4D seismic inversion, enabling robust recovery of heavy-tailed and anisotropic reservoir signatures beyond the Gaussian assumptions underlying existing approaches.
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All authors Anderson Mateus de Sousa Nogueira, Paulo Vitor Ferreira, Katerine Rincon Perez, João M. de Araújo, Tiago Barros, Samuel Xavier-de-Souza, Sérgio Luiz da Silva, Gilberto Corso
High Energy Astrophysical Phenomena
A GRMHD-Calibrated Semi-Analytical Model for Hot Sub-Keplerian Accretion Flows in Kerr Spacetime
Nabin Bhushal, Manil Khatiwada, Yogesh Maharjan et al. (+2 more)
We develop a simple, semi-analytical, kinematic model for hot, thick
accretion flows, constructed by interpolating between Keplerian and free-fall geodesic solutions in the Kerr metric. Unlike self-consistent general relativistic magnetohydrodynamics (GRMHD) frameworks, our model contains no explicit
magnetic fields or stress terms; instead, it uses a smooth, radially varying transition function T(r) to connect the velocity components from near-Keplerian rotation at large distances to a free-fall state near the event horizon. While the coefficients $\alpha$ and $\beta$ remain constant, the transition function is a true function of radius, allowing the flow properties to vary smoothly with radius. We calibrate and validate this model against time- and azimuthally averaged profiles from long-duration magnetically arrested disk (MAD) simulations spanning a wide range of black hole
spins ($a=-0.9$ to $+0.9$). The model successfully captures the properties of
accretion flow parameters across both prograde and retrograde configurations. Quantitatively, the predicted radial velocity, angular velocity, and density profiles match the simulation data to within an average factor of approximately 1.8, 1.6, and 1.6, respectively, while the specific angular momentum exhibits the closest agreement, remaining within a factor of approximately 1.2. This fast semi-analytical prescription gives significantly lower errors than previous constant-coefficient models and it is a computationally affordable tool for various applications such as ray tracing,
accretion parameter exploration, and spectral modelling.
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All authors Nabin Bhushal, Manil Khatiwada, Yogesh Maharjan, David Garofalo, Chandra B. Singh
Materials Science
Property-Guided Diffusion for Inverse Design of Crystalline Materials
Sourav Mal, Subhankar Mishra and Prasenjit Sen
Diffusion-based generative models with property guidance have emerged as a promising paradigm for inverse materials design by enabling the generation of crystalline materials with user-specified target properties. However, despite recent advances, the effectiveness of property guidance, its influence on crystallographic
symmetry, and the physical viability of generated materials remain poorly understood. To address these questions, we develop a property-guided framework based on the lightweight
diffusion model DiffCrysGen using parameter-efficient adapter fine-tuning and classifier-free guidance (CFG). The resulting framework enables efficient multi-property
crystal generation while preserving the knowledge learned during unconditional pre-training. Using formation energy together with saturation magnetization and Vickers hardness as representative inverse-design tasks, we systematically investigate the influence of CFG across a broad range of guidance strengths. Increasing the guidance scale progressively steers the generated property distributions toward the prescribed targets while reducing the fraction of lowest-
symmetry ($P1$) structures and increasing the proportion of higher-
symmetry structures. To evaluate physical viability, generated structures are geometrically prescreened and subsequently validated using a machine-learning interatomic potential (MLIP)-based workflow comprising structural relaxation and thermodynamic, dynamical, and property-specific analyses. The framework identifies thermodynamically and dynamically stable
magnetic and mechanically hard materials with overall success rates of 12.3% and 3.9%, respectively. These results establish property-guided DiffCrysGen as an efficient framework for inverse materials design while providing new insights into the role of classifier-free guidance in
crystal generation.
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Solar and Stellar Astrophysics
Magnetically guided accretion and extremely slow rotation in a metal-enriched white dwarf
S. Bagnulo, M.A. Stroet, C.P. Folsom et al. (+3 more)
White
dwarfs that show atmospheric metal enrichment offer a direct window into the bulk composition of exoplanetary material and provide some of the most direct constraints on the building blocks of rocky exoplanetary systems. Recent work has suggested that
magnetic fields may influence how this material is accreted, potentially channelling debris along field lines and retaining it near
magnetic poles rather than allowing it to be redistributed uniformly across the
stellar surface. Here we report the discovery of photometric, spectroscopic, and spectropolarimetric variability in the
magnetic DZ white
dwarf WD1532+129, revealing a rotation period of about 289 days, by far the longest yet directly measured for any degenerate
star. The observed period may result from the combined effect of angular-momentum loss during the
evolution leading to the white
dwarf stage and an unusually slowly rotating progenitor, perhaps a
magnetic Ap
star. The white
dwarf exhibits surface abundance inhomogeneities, with metals concentrated near both
magnetic poles, and the observed modulation is consistent with localised metal-rich regions aligned with the
magnetic geometry. WD1532+129 is the third of the four known
magnetic DZ white
dwarfs within 20 pc to show evidence for polar metal enhancement, indicating that magnetically guided inhomogeneities are a common property of
magnetic metal-enriched white
dwarfs.
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All authors S. Bagnulo, M.A. Stroet, C.P. Folsom, M.A. Hollands, J.D. Landstreet, G. Ramsay
Solar and Stellar Astrophysics
Rate of caustic crossing microlensing events in stellar binary lenses with significant orbital motion
Arjun Murlidhar, B. Scott Gaudi and Todd. A. Thompson
Binary lens microlensing events in which the source crosses a caustic produce sharp, distinctive magnification peaks and can therefore be readily identified. In this paper, we explore the importance of binary orbital motion for the binary lens caustic crossing cross section. If the orbital timescale of the binary system is smaller than the Einstein ring crossing timescale, the caustics sweep out a larger area in the source plane, generally enhancing the cross section. We find that face-on binaries in circular orbits exhibit a substantial increase (up to 4$\times$) in the cross section for caustic crossings. However, highly inclined orbits produce a net decrease relative to a static face-on binary with the same semi-major axis. Using a sample of ~$2800$ synthetic binary microlensing events drawn from a realistic Milky Way population-synthesis model, we calculate the average change in the caustic crossing cross section for individual systems with and without orbital motion. Although orbital motion can significantly alter the cross section for specific geometries, we find that, when averaged over the full population, it produces only a small, negligible increase of ~$0.1\%$ in the average cross section. We also compute the overall rate of caustic crossing binary events in the simulated sample and find that, with sufficiently dense photometric sampling, $6.3 \pm 0.2\%$ of microlensing events with impact parameter $u_0 < 1$ should exhibit caustic crossings. This rate depends on the distributions of binary separation, mass ratio, and multiplicity of
stars and compact objects, and can therefore be used to test our understanding of these underlying properties.
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Astrophysics of Galaxies
A Multiwavelength Inventory for the Local Group L-band Survey I: Atlas and Radial Profiles of Local Group Galaxies
Cosima Eibensteiner, Adam K. Leroy, Jiayi Sun et al. (+21 more)
Resolving atomic gas at $\lesssim100$ pc physical resolution is currently feasible only for the very nearest
galaxies. We combine 120 pc resolution HI data using the Karl G. Jansky Very Large Array (VLA) from the first data release of the Local Group L-Band Survey (LGLBS) with uniformly processed infrared, ultraviolet, H$\alpha$, and CO maps. We analyze the radial profiles of gas,
stars, and recent
star formation for six local
galaxies: M31, M33, IC 10, IC 1613, NGC 6822, and WLM. Across the sample, atomic-gas disks are the most extended component, reaching $r_{\rm HI}=2.8$-$5.8$ kpc in the
dwarfs and $13$-$26$ kpc in M33 and M31. Azimuthally averaged $\Sigma_{\rm HI}$ profiles are often flat or only slowly declining compared to the steeper decline of $\Sigma_{\star}$ and $\Sigma_\mathrm{SFR}$, with outer HI scale lengths of $l_{\rm HI}^{\rm outer}\approx1.0$-$8.5$ kpc. The mass-weighted HI surface densities on 120 pc scale generally exceed the azimuthally averaged values by 10-70%, showing that localized high-column-density atomic structures persist even where azimuthally averaged profiles appear smooth. Atomic-gas depletion times rise from $\tau_{\rm dep}^{\rm atom}\approx0.8$-17 Gyr within the
stellar half-mass radius to 10s-100 Gyr in the outer disks. Molecular depletion times are shorter. We provide a public release of these multi-wavelength data, which provide a valuable reference for the LGLBS targets and also form the basis for a companion paper that relates
star formation, gas phases, and midplane pressure on 120 pc scales.
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All authors Cosima Eibensteiner, Adam K. Leroy, Jiayi Sun, Erik Roslowsky, Eric W. Koch, Nickolas Pingel, Chang-Goo Kim, Laura B. Chomiuk, Ryan Chown, Alberto D. Bolatto, Michael P. Busch, Julianne J. Dalcanton, Amanda A. Kepley, Christina W. Lindberg, Eve C. Ostriker, Jürgen Ott, Sumit K. Sarbadhicary, Adam Smercina, Snežana Stanimirović, Elizabeth Tarantino, Vicente Villanueva, Tobin M. Wainer, Fabian Walter, Thomas G. Williams
General Relativity and Quantum Cosmology
Soliton-Black Hole Phase Transitions in the Presence of String Clouds
Ziqing Chen and Robert B. Mann
We study
soliton-black hole phase transitions in asymptotically AdS planar spacetimes sourced by a cloud of strings. In the planar background, the string cloud exhibits a brush-like configuration, where the strings are aligned parallel to each other and extend along the radial direction. This leads to a stress tensor with nonvanishing components only along the temporal and radial directions. By comparing the Euclidean on-shell actions of the planar black hole and the corresponding AdS
soliton under the same boundary conditions, we obtain the free energy difference between the two phases. Our results show that the string cloud parameter significantly modifies the competition between the black hole phase and the
soliton phase. In particular, positive and negative values of the string cloud parameter affect the phase structure in different ways, changing the dominance relation between the black hole and
soliton configurations.
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Quantum Physics
SSP-QST: Spectral Subspace Purification for Photonic Quantum State Tomography
Anuvab Sen and Saibal Mukhopadhyay
Photonic
quantum sensing often uses low-rank entangled probes such as Greenberger-Horne-Zeilinger (GHZ), Bell, and NOON states. Although these probes are ideally rank-1, practical
quantum state
tomography (QST) can produce density-
matrix estimates with many small finite-shot and noise-induced eigenmodes. This
eigenvalue contamination can increase the estimated
entropy of the reconstruction and reduce the
quantum Fisher information (QFI) available for downstream sensing, while fixed rank-1 purification can discard valid signal modes when real probes acquire additional signal modes. We introduce Spectral Subspace Purification for
Quantum State
Tomography (SSP-QST), a rank-adaptive post-processing layer for least-squares
quantum state
tomography (LS-QST). SSP-QST eigendecomposes the least-squares estimate, computes a Weyl-motivated noise floor from the measured spectrum and shot count, removes eigenmodes below this floor, and renormalises the retained subspace. It requires no rank prior, no iterative optimisation, and only one eigendecomposition. In Qiskit Aer simulations, SSP-QST achieves the highest fidelity among the tested non-iterative baselines across the evaluated probe ranks, with a maximum fidelity gain of $+0.584$. It also improves shot efficiency by at least $8\times$ within the tested range. These results show that SSP-QST can make photonic QST more reliable under finite-shot noise while providing a lightweight reconstruction primitive for feedback-oriented
quantum sensing pipelines.
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Cosmology and Nongalactic Astrophysics
The diffraction-lensing interpretation of GW231123 with astrophysical priors
Mark Ho-Yeuk Cheung, Digvijay Wadekar, Matias Zaldarriaga et al. (+3 more)
GW231123, if unlensed, is a rare binary black hole merger with high masses and high
spins for both progenitors. We show that the signal is better fitted by a lower-mass, lower-
spin merger that is diffraction-lensed by an isolated object of redshifted mass $\sim 1000\,\rm M_\odot$, modeled either as a point mass or as a spherically symmetric compact
halo. Because diffraction-lensed events are also rare, hypothesis testing should quote the posterior odds ratio rather than the Bayes factor, which requires quantifying our prior belief in the two hypotheses. We adopt the GWTC-5 population distribution as our source parameter prior, and quantify the prior on the lens hypothesis through the
lensing optical depth. For a point-mass lens, observational constraints on the abundance of black holes in the Universe yield an upper bound on the optical depth, and hence on the posterior odds, which do not rule out
lensing. However, using a predicted mass function of intermediate-mass black holes formed in
star clusters gives a low optical depth that strongly disfavors
lensing. For a dark matter
halo lens, standard collisionless cold dark matter does not form
halos compact enough to give the required optical depth, but self-interacting dark matter with a large cross section at low velocities can trigger gravothermal collapse and form them, in which case the posterior odds are inconclusive. In either case, from a frequentist perspective, we show that detecting a lensed event with properties like GW231123 is unlikely. These conclusions apply to isolated lenses, while a lens embedded in an external gravitational potential could change the picture.
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All authors Mark Ho-Yeuk Cheung, Digvijay Wadekar, Matias Zaldarriaga, Tejaswi Venumadhav, Javier Roulet, Ajit Kumar Mehta
Accelerator Physics
Energy-resolved measurement of individual GeV muon tracks generated by electrons from a compact Laser-Plasma Accelerator
Davide Terzani, Luc Le Pottier, Stanimir Kisyov et al. (+17 more)
Recently, the possibility of LPA-produced
muon beams has gained significant interest within the accelerator application community. Directional, multi-GeV
muons can be produced via Bethe-Heitler interactions when multi-GeV electrons hit solid targets. They are highly penetrating and, thanks to the compactness of the LPA, offer a path toward a deployable, active
muon source. At the BELLA Center of the Lawrence Berkeley National Laboratory, we previously unambiguously detected
muons generated during the interaction of multi-GeV electron beams with a 4 meter-thick electron beam dump. A new campaign has now extended our diagnostic capabilities to single-
muon trajectory reconstruction and energy measurements. The setup allowed us to individually reconstruct each
muon trajectory, defined by us as a
muon passing through three detectors used for the reconstruction. For a subset of events, we extracted the
muon energy from the
magnetic-field bending angle, demonstrating production of GeV-scale
muons. This work provides a key demonstration of track-based active-source muography, which enables non-invasive 3D density mapping of concealed or inaccessible samples, and it will accelerate the development of active LPA-based
muon sources where compactness, controlled directionality, low divergence, and deep penetration are required.
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All authors Davide Terzani, Luc Le Pottier, Stanimir Kisyov, Pranav Manoj, Ryan Heller, Maria Mironova, Alex Picksley, Joshua Stackhouse, Hai-En Tsai, Raymond Li, Timon Heim, Maurice Garcia-Sciveres, Carlo Benedetti, John Valentine, Kei Nakamura, Anthony J. Gonsalves, Jeroen van Tilborg, Carl B. Schroeder, Eric Esarey, Cameron G. R. Geddes
Computational Physics
Learning Lattice Parameters from Powder X-Ray Diffraction Data Using Invariants
Elyssa Hofgard, Kyucheol Min, Nofit Segal et al. (+8 more)
We present a machine learning (ML) method to determine unit
cell parameters from powder X-Ray diffraction (XRD) data using a novel invariant
lattice representation. In ML, the data representation used can have a substantial impact on the prediction quality. Previous approaches have directly predicted
lattice parameters ($a,b,c,\alpha,\beta,\gamma$) from XRD inputs. However, these parameters depend strongly on the unit
cell reduction or convention used. In this work, we construct an invariant representation of the reciprocal
lattice that is independent of primitive
cell convention, based on the bispectrum–a descriptor built from spherical harmonic projections of
lattice points. The calculation of the
lattice bispectrum is differentiable, and we demonstrate how to invert it using gradient-based optimization initialized from a nearest-neighbor lookup. We show that with a fixed ML model architecture, using the
lattice bispectrum as the ML target rather than the unit
cell parameters leads to more accurate
lattice parameter predictions. For example, using the MP-20
dataset, the bispectrum reduces length mean absolute percentage error (MAPE) from 11.08% to 2.43% and angle MAPE from 12.15% to 2.45% compared to direct prediction with the same model architecture. We additionally
benchmark our approach against pre-existing XRD to
crystal structure models such as Crystalyze and assess its performance on experimental data. Beyond unit
cell representation, we anticipate this invariant
lattice representation could serve more broadly as a geometry-aware target for other crystallographic machine learning tasks such as structure generation.
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All authors Elyssa Hofgard, Kyucheol Min, Nofit Segal, David W. Mittan-Moreau, Aria Mansouri Tehrani, Vanessa Oklejas, Rafael Gómez-Bombarelli, Jigyasa Nigam, Daniel W. Paley, Aaron S. Brewster, Tess Smidt
Strongly Correlated Electrons
Hydrodynamic Memory and Long-Time Tails in Clean Frustrated Magnets
Yufei Pei, Claudio Castelnovo and Roderich Moessner
In a simple, clean but constrained magnet, we identify a self-interacting random walk with
memory. For the motion of a single monopole – a fractionalized quasiparticle in
spin ice – this produces a subtle and unusually slow relaxation toward diffusive motion. This is manifested as an algebraic long-time tail in the velocity autocorrelation function, decaying as $t^{-3/2}$. At finite monopole density, the interactions between the trails of different monopoles introduce an additional timescale, corresponding to the disruption of a monopole's
memory by other monopoles, and leading to an exponential cutoff of the long-time tail. Our results identify clean frustrated magnets as microscopic platforms for studying self-interacting
stochastic processes, hydrodynamic
memory, and the emergence of non-Markovian quasiparticle transport from local Markovian dynamics.
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Astrophysics of Galaxies
From relics to stripped systems: the environmental origin of compact galaxies
Guangwen Chen, J. Alfonso L. Aguerri, Carlos del Burgo et al. (+1 more)
Compact
galaxies represent a key population for understanding
galaxy evolution, but the relative role of internal structure and environment in shaping their origin remains unclear. We aim to investigate how the abundance and quenching of compact
galaxies depend on environment, and to determine whether their formation is governed by a single evolutionary pathway or multiple channels. We analyse a large sample of
galaxies in the nearby Universe ($z<0.05$) with
stellar masses in the range $8.2<\log(M_\star/M_\odot)<10.5$, comparing compact and control populations as a function of local overdensity. We find that the environmental dependence of compact
galaxies is non-monotonic, with two characteristic overdensities, the transition overdensity ($\delta_t$) and the critical overdensity ($\delta_c$), defining three distinct regimes. Below $\delta_t$, compact
galaxies are relatively more abundant than the control population, while between $\delta_t$ and $\delta_c$ their relative abundance decreases significantly. Above $\delta_c$, compact
galaxies become increasingly overabundant again. The environmental trends show a strong
stellar-mass dependence, with low-mass
galaxies exhibiting the strongest deficit at intermediate overdensities and high-mass
galaxies dominating the excess population above $\delta_c$. In addition, the red
galaxy fraction increases with local overdensity and is systematically higher in compact
galaxies. Our results support a unified evolutionary framework in which compact
galaxies do not arise from a single evolutionary channel, but instead reflect multiple pathways whose relative importance depends strongly on
stellar mass and environment. Low-mass compact
galaxies are closely linked to environmentally driven transformation, whereas high-mass compact
galaxies occur across all environments and become increasingly overabundant in the densest regions.
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All authors Guangwen Chen, J. Alfonso L. Aguerri, Carlos del Burgo, Stefano Zarattini
Astrophysics of Galaxies
Emissivity line ratios for [Mn III] and spectral diagnostics of H II regions
Zher Samak, Sultana N. Nahar and Anil K. Pradhan
We present the first theoretical emission-line study of Mn III as potential determinant of physical conditions and manganese abundance. We compute atomic data for a set of Mn III lines and line emissivity ratios as temperature-density diagnostics. Accurate relativistic Breit-Pauli R-
matrix calculations have been carried out for electron impact excitation of Mn III transitions that have not been previously studied. Selected forbidden lines are shown to be sensitive to temperature and density under nebular conditions in H II regions such as SNRs. The coupled channel R-
matrix calculations include a wavefunction expansion that includes 38 levels of Mn III dominated by the ground and first excited electronic configurations $3d^5$ and $3d^44s$. Collision strengths for all 703 forbidden transitions among those levels, and Maxwellian averaged rate coefficients are obtained. A collisional-radiative model yields emissivity line ratios using calculated collision strengths and radiative decay A-values. Based on the present analysis, certain [Mn III] lines are predicted to be sensitive to density and/or in the typical nebular range. The detection of those lines could also yield
cosmic Mn abundance relative to other elements.
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General Relativity and Quantum Cosmology
Unit Killing Initial Data
Igor Khavkine and Salvador Mengual Sendra
We find a system of differential equations on an initial data surface whose solutions are in bijection with unit vector fields on the Einstein $\Lambda$-
vacuum development that are proportional to a Killing vector. We refer to these conditions as the unit Killing initial data (uKID) equations, analogous to the classical Killing initial data (KID) equations. The uKID equations can be useful in a setting where only the unit-normalized part of the Killing vector is geometrically distinguished. We eliminate the scaling degree of freedom of a general Killing vector to obtain the space-time equations characterizing unit normalized Killing vector fields and also the uKID equations. These equations are also prolonged to canonical connection form, showing their finite type character. Finally, we obtain an independent derivation of the uKID equations by revisiting the propagation identity method, which has previously been used to characterize the initial data of other
geometric equations.
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Soft Condensed Matter · Cross-listed from math.DS
The two momenta of an elastic rod: a Hamiltonian picture on framed Lie groups
Thomas Lessinnes
The
equilibrium equations of elastic rods can be obtained by balancing forces and moments, or by rendering a potential energy stationary. For complex filaments the energy route asks less of one's mechanical intuition. However, in the classical
Hamiltonian picture, the components of the generalized momenta are postulated a priori and their physical meaning changes at the whim of the coordinate chart. Here, we draw on two ideas from mathematical physics. First, the extended tangent bundle of the configuration Lie group is framed by left-invariant vector fields. Second, we follow a one-dimensional reading of the Cartan–Lepage–Krupka theory of variational forms: in this setting the momenta are not postulated but forced. The Legendre transform becomes a linear change of frame, and a Poisson structure on the extended tangent bundle follows. For an isolated Cosserat rod, the momenta coincide, in every encoding of the rotation group, with the material force and moment familiar from rod theories. In the presence of interactions, two cases arise: interactions that depend only on the configuration, such as
gravity, leave this identification intact; interactions that depend on the strains destroy it — the conjugate momenta and the internal stresses part company. Because energies add, the momenta decompose into the internal stresses and an interaction contribution. Expressing the two factors of the Poisson bivector in different frames — one adapted to the internal stresses, the other to the conjugate momenta — then exposes the
Hamiltonian flow directly in the internal variables. Applied to a tendon-actuated rod, where the standard passage to the
Hamiltonian picture demands a nonlinear inversion, the construction delivers explicit
equilibrium equations, the required inversion collapsing to a rank-one correction.
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Instrumentation and Methods for Astrophysics
Determination of Earth's Orbital Parameters Using Doppler Measurements
Gary Atkins, Marcus Leech, Daniel Marlow et al. (+1 more)
Precision determinations of the parameters of Earth's orbit around the Sun using methods based on the Doppler shift of 21-cm emissions from the
galaxy and the repetition rate of
pulsar J0332+5434 are reported. The observed values and statistical errors for the orbital parameters for the 21-cm observations are semi-major axis $a = 1.00020 \pm 0.00015~{\rm au}$ and eccentricity $e= 0.017077 \pm 0.000077$. For the
pulsar observations, the observed values are $a = 1.000034 \pm 0.000034~{\rm au}$ and $e=0.016667 \pm 0.000017$. The observations are based on a year-long campaign of daily drift-scan observations using a 12.8-m
parabolic antenna and a receiver chain tuned to the 21-cm frequency band. The data used in the analysis are available for use in educational exercises in the supplementary material
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All authors Gary Atkins, Marcus Leech, Daniel Marlow, Doug Yuill
Quantum Physics
Efficient Unclonable Encryption from Pauli Eigenstates
Seyoon Ragavan
We give, to our knowledge, the first plain-model, one-time information-theoretically secure, efficient unclonable encryption scheme for one classical bit. Previous work by Bhattacharyya and Culf (Nature Physics, 2026) and Bhattacharyya, Broadbent, and Culf either only showed $1/\mathsf{poly}(\lambda)$ security loss or required inefficient encryption/decryption operations. We avoid both of these caveats; in doing so, we obtain (to our knowledge) the first plain-model construction of many-time secure $1 \to 2$ unclonable encryption for arbitrary
polynomial-length messages, assuming the existence of pseudorandom function-like states (Bartusek and Goldin). The key is a uniformly random non-identity phase-free Pauli on $n$
qubits, and bit $a$ is encrypted as a random $(-1)^a$ eigenstate of that Pauli. The scheme is exponentially secure; we prove that the probability that both receivers recover the bit is at most $\frac{1}{2}+\frac{1}{2}\sqrt{{2^n}/({4^n-1})} = \frac{1}{2} + O\left(2^{-n/2}\right).$ By a lower bound due to Broadbent, Culf, and Rochette, this is the best probability bound achievable with $n$-
qubit ciphertexts (up to the constant hidden in the $O(\cdot)$). The main conceptual idea is to leverage, in a precise spectral sense, the balanced commutation-anticommutation structure of the Pauli group. The proof is intricate but completely elementary and makes use of standard spectral bound techniques. The main technical workhorse is a standalone linear-algebraic lemma that informally relates the positivity of two different operators, each capturing the intuition that if the two receivers can individually decrypt unusually often then they must also disagree often. GPT-5.6 Sol Ultra found this proof in an extended conversation with the author and drafted a preliminary version of this paper. The author is fully accountable for the correctness of this paper.
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Soft Condensed Matter
Quantifying reticulocyte biomechanics in health and disease
Zhaojie Chai, Jianlu Zheng, He Li et al. (+2 more)
Red blood
cell (RBC) populations are mechanically and morphologically heterogeneous, yet how this heterogeneity governs transport, splenic retention and blood rheology in confinement remains unclear. We combine microchannel experiments with dissipative particle dynamics (DPD) simulations to determine how the morphology, deformability and hydrodynamic interaction of immature RBCs (reticulocytes) shape microconfined flow in acute and chronic mountain sickness. Reticulocyte-rich samples present the three shapes that the maturation literature assigns to successive reticulocyte stages – multilobular, cup-shaped and near-discocytic – which we model as R1-R3, each with a membrane shear modulus within the range reported for reticulocytes. A 5-um microchannel resolves these models only weakly, R1 taking at most ~18% longer than control discocytes to cross it, whereas a 1.5-um splenic slit, driven at its own loading, delays R1 by ~30%; both geometries order the models by shear modulus. In
cell pairs, a leading
cell never lets a follower pass below its own single-
cell threshold, ruling out the order-of-magnitude reduction that a wake-"unjamming" picture would suggest; instead the follower queues behind the leader, and a stiffer leader, which clears the slit more slowly, delays it more. The controlling variable is the single-
cell critical pressure gradient Delta P_c, which rises monotonically from control discocytes through the reticulocyte subtypes to sickled
cells. Set against published rheograms, an analytical estimate attributes chronic-mountain-sickness hyperviscosity mainly to hematocrit-driven crowding rather than single-
cell rheology. These results place benign acclimatization, chronic-mountain-sickness hyperviscosity and sickle-
cell-trait splenic syndrome on a single mechanical axis defined by Delta P_c.
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All authors Zhaojie Chai, Jianlu Zheng, He Li, Ming Dao, George Em Karniadakis
Mesoscale and Nanoscale Physics
Observation of room temperature intrinsic nonlinear thermoelectric effects in low-dimensional semimetals
Kurea Nakagawa, Krishnaraajan Sundararajan, Cédric A. Cordero-Silis et al. (+2 more)
Nonreciprocal control of thermoelectric responses offers a promising strategy for next-generation thermal-management and energy-conversion. While nonlinear electrical transport has recently emerged as an intrinsic property of low-
symmetry quantum materials, their thermoelectric counterparts have not been demonstrated. Here, exploiting harmonic detection with gradient-reversal techniques, we report intrinsic nonlinear thermoelectric responses up to room temperature in the low-
symmetry type-II Weyl semimetals $T_\mathrm{d}$-WTe$_2$ and TaIrTe$_4$ in the absence of
magnetic fields or
magnetic materials. We resolve all
symmetry-allowed components of the second-order thermoelectric tensor, including the nonlinear Seebeck, nonlinear Nernst, and nonlinear mixed-directional thermoelectric effects and demonstrate that both Berry-
curvature-related and scattering-induced contributions govern the different nonlinear thermoelectric responses. Our results show that nonlinear thermoelectricity arises intrinsically from reduced
crystal symmetry and that engineering effects related to scattering in these materials provides a versatile platform for exploring higher-order heat-to-charge current conversion beyond the linear response.
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All authors Kurea Nakagawa, Krishnaraajan Sundararajan, Cédric A. Cordero-Silis, Bart J. van Wees, Marcos H.D. Guimarães
Strongly Correlated Electrons
Intrinsic single crystals of MnTe altermagnet
Kim-Khuong Huynh, Michael Anthony Quintero, Martin Klanjšek et al. (+8 more)
We report the synthesis methodology, structure, and intrinsic properties of ultra-high quality single
crystals of MnTe, an archetypal altermagnet. The
crystals, obtained from self-flux method, are nearly free from
crystal imperfections and disproportionate chemical compositions as seen by various investigation methods. In measurements under quasi free-standing configuration minimizing stress induced effects, the
crystals exhibit complex and anisotropic domain kinetics in both superheating and supercooling regimes around the altermagnetic transition at $T_{\mathrm{N}} = 310\,\mathrm{K}$. An Anderson insulating state is observed below $T_{\mathrm{MI}}\approx 150\,\mathrm{K}$ with a carrier density of about $1.6\times 10^{17}\,\mathrm{cm}^{-3}$, being sharply contrast to metallic states usually seen in Te-deficit samples. Nevertheless, hallmarks of altermagnetism, anomalous
Hall effect and X-ray
magnetic circular dichroism signal, are robust in this intrinsic limit, however with significantly reduced magnitudes.
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All authors Kim-Khuong Huynh, Michael Anthony Quintero, Martin Klanjšek, Tilen Knaflič, Yuta Ishii, Norimasa Sasabe, Nhu-Quynh T. Phan, Frej Søren Rattenborg, Yuichi Yamasaki, Denis Arčon, Bo Brummerstedt Iversen
Superconductivity
Thermal phase slips in superconducting films near the critical current at arbitrary temperatures
Ivan M. Artemov and Mikhail A. Skvortsov
We develop a theory of thermal phase slips in disordered superconducting films biased near the critical current $I_c(T)$. Generalizing recent results obtained close to $T_c$, we show that the optimal fluctuation governing the phase-slip barrier in two dimensions satisfies the exactly integrable Boussinesq equation for arbitrary temperatures $T<T_c$. Since both the transverse and longitudinal sizes of the optimal
nucleus diverge as $I\to I_c(T)$, the Usadel equation for quasiparticles in the presence of a slowly varying order parameter can be solved perturbatively using a gradient expansion. The resulting field theory for a complex order parameter is further reduced to the Boussinesq free energy for a single real field, with the coefficients expressed as Matsubara sums over the solutions of the uniform Usadel equation at $I_c(T)$. The activation barrier near $I_c$ has the asymptotic form $\Delta F(T,I\to I_c) = E(T) (1-I/I_c)^\alpha$. We calculate $E(T)$ over the full temperature range for both two-dimensional films ($\alpha=3/4$) and one-dimensional wires ($\alpha=5/4$). For films, the theory is valid within a narrow $10\%$ window below $I_c(T)$, where the saddle-point configuration remains
vortex-free. For wires, $\Delta F(T,I\to I_c)$ provides a good approximation to the activation barrier for all temperatures and currents.
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Medical Physics
A Dual Path Framework with Hotspot Guided Fusion for Three Dimensional CT to PET Synthesis in Head and Neck Cancer
Mohd Maaz Khan and Oluwaseyi Oderinde
18F-FDG PET/CT plays a central role in staging, treatment planning, and response assessment for head and neck cancer by providing functional information that complements anatomical CT imaging. However, PET acquisition requires radiotracer administration, specialized infrastructure, and additional cost, limiting its availability for repeated imaging. We present a proof of concept deep learning framework for synthesizing PET like images directly from routine CT scans with the goal of providing complementary metabolic information that may support imaging triage and clinical decision support rather than replace diagnostic PET. Forty-four patients from the publicly available QIN-HEADNECK
dataset were retrospectively analyzed using five fold cross-validation. We propose a fully three dimensional dual path architecture consisting of (i) a regression U-Net optimized for voxel-wise quantitative SUV estimation and (ii) a conditional generative
adversarial network optimized for realistic PET texture. Their outputs are integrated using hotspot guided
Laplacian pyramid blending, allowing quantitative information from the regression pathway to be preserved within metabolically active regions while leveraging
adversarial texture synthesis elsewhere. The proposed framework achieved a mean absolute error of 0.00395, PSNR of 39.19 dB, and SSIM of 0.9634 on reconstructed three dimensional PET volumes. Qualitative evaluation demonstrated accurate localization of many FDG-avid lesions while producing anatomically realistic background texture. Consistent with previous CT to PET synthesis studies, the principal limitation was systematic underestimation of SUV within highly metabolically active tumor regions.
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Quantum Physics
Spectral Gap of the Davies Generator for the Mean-Field Heisenberg Model
Joao Basso, Thiago Bergamaschi, Lin Lin et al. (+2 more)
The mean-field Heisenberg ferromagnet is a
quantum spin model on the complete graph with isotropic
spin-1/2 interactions. This non-commuting
Hamiltonian is permutation and $\mathsf{SU}(2)$ invariant, and its Gibbs states undergo an $\mathsf{SU}(2)$
symmetry breaking phase transition at inverse temperature $\beta=2$. We consider the associated Davies generator, a canonical model of open-system thermalization, and prove tight asymptotic estimates for its spectral gap at all noncritical temperatures. For fixed $\beta<2$, the gap as a function of number of
qubits $n$ is $\Theta(1)$, while for fixed $\beta>2$ the gap is $\Theta(n^{-1})$. The matching upper bound of the spectral gap is witnessed by the total magnetization order parameter, suggesting that the low-temperature ($\beta>2$) slowdown is associated with broken continuous
symmetry. Two key ingredients in our approach are a comparison argument, which introduces auxiliary generators to bound dissipation on nontrivial representations of the
symmetry groups $\mathsf{SU}(2)$ and $\mathsf{S}_n$, and a decomposition of the space of observables into spherical tensor operators to reveal a form of monotonicity.
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All authors Joao Basso, Thiago Bergamaschi, Lin Lin, Michael Ragone, Kevin D. Stubbs
Fluid Dynamics
Load-dependent Taylor dispersion in a compliant electroosmotic pump conveying a simplified Phan-Thien-Tanner fluid
Subhajyoti Sahoo and Ameeya Kumar Nayak
We develop a coupled model for electroosmotic pumping and passive-solute dispersion of a solvent-free simplified Phan-Thien-Tanner fluid in a compliant slit microchannel. Pressure, wall deformation, axial field, velocity, and dispersion are evaluated self-consistently along the finite-throughput pump characteristic. Lubrication theory, Debye-Huckel electrostatics, an elastic-foundation wall law, and Taylor-Aris macrotransport yield a closed-form flux relation for combined electroosmotic and pressure-driven forcing. Because the shear rate depends cubically on the total shear stress, the two contributions cannot be superposed. The flux decreases monotonically with pressure gradient, ensuring a unique inversion at prescribed throughput. Current conservation couples the axial field to the deformed gap under constant-current and constant-voltage operation. In pressure-free flow, thinning the electric double layer produces a plug-like profile and the Newtonian Taylor coefficient decays as the inverse square of the Debye parameter. Under hydraulic loading, an adverse pressure gradient drives a sheared core counterflow that persists in the thin-double-layer limit, causing the coefficient to approach a finite plateau. At fixed nonzero throughput, partial cancellation between electroosmotic and pressure-driven shear yields a maximum plate number at finite double-layer thickness. This optimum is conditional: joint optimization over throughput and double-layer thickness shifts the overall optimum toward free-flow, thin-double-layer operation. Viscoelasticity can enhance or suppress loaded dispersion, while compliance shifts the pump characteristic and separation optimum. Brownian dynamics validates the reduced model. The resulting load-resolution relation identifies conditions that balance pressure delivery and separation performance.
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Mathematical Physics · Cross-listed from math.AG
A topological Chern character for matrix factorizations
Mark Shoemaker
For $Y$ a quasi-projective complex variety and $w \colon Y \to \mathbb C$ a regular function, we construct a Chern character from the Grothendieck group of the category of
matrix factorizations of $w$ to the critical
cohomology of $w$, and show that it factors through a certain topological $K$-theory group. We prove a Grothendieck-Riemann-Roch
theorem with respect to this Chern character, and verify several functorial properties.
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General Relativity and Quantum Cosmology
Static Black Holes and Iyer-Wald Entropy in $f(\mathcal{R},\mathcal{K})$ Gravity
I. Díaz-Saldaña, J. López-Domínguez, Wilfredo Yupanqui et al. (+2 more)
We investigate static, spherically symmetric black hole solutions in a class of higher-
curvature gravitational theories described by a Lagrangian that depends on the
Ricci and Kretschmann scalars. The modified Einstein equations contain higher-order
curvature terms. We develop a perturbative scheme to look for a black hole solution that deviates parametrically from the Schwarzschild geometry. We obtain first-order corrections to the metric by solving the resulting coupled differential equations. The corresponding Iyer–Wald
entropy is then evaluated consistently to first order in the perturbative coupling. We show that the higher-
curvature contribution gives rise to a power-law correction to the Bekenstein–Hawking
entropy.
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All authors I. Díaz-Saldaña, J. López-Domínguez, Wilfredo Yupanqui, Javier Chagoya, M. Sabido
General Relativity and Quantum Cosmology
Quantum-Corrected Thermodynamics, Dirac Perturbations, Geodesic Structure, and Topological Phases of Black Holes with Non-Minimal Logarithmic Coupling
İzzet Sakall{\i}, Özcan Sert, Erdem Sucu et al. (+1 more)
We study the thermodynamic and dynamical properties of static, spherically symmetric BHs in Einstein-Maxwell theory modified by a non-minimal $\ln(R)F^{2}$ coupling. The Hawking temperature follows from the Hamilton-Jacobi form of the fermionic tunnelling method for
spin-$\tfrac12$ particles, and it carries scale-dependent logarithmic corrections. We then analyze the propagation of massless Dirac fields, compute the quasinormal-mode (QNM) spectrum with the third-order WKB approximation, and read off a quality factor whose balance between oscillation and damping depends on the logarithmic coupling in a mode-dependent way. Moving outward from the horizon, we work out the transmission of the fermionic field and its Hawking emission, and we solve the null and timelike geodesic problems to obtain the
photon sphere, the shadow radius, the innermost stable circular orbit (ISCO), the associated zoom-whirl bound orbits, and the orbital and epicyclic frequencies that set the twin-peak quasiperiodic-oscillation (QPO) ratio. A
photon-sphere reading of the eikonal QNM frequencies ties the geodesic sector back to the field perturbations. On the thermodynamic side, we build the phase space with
quantum-
geometric corrections through the Barrow
entropy, and we characterize the global phase structure with the topological method, where the winding numbers of the off-shell free energy are governed by the interplay of the fractal Barrow deformation, the electric charge, and the logarithmic coupling. We find that the effective pressure vanishes exactly on the topological defect line, which links the pressure sign to the local stability of each branch.
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All authors İzzet Sakall{\i}, Özcan Sert, Erdem Sucu, Yusuf Sucu
Chemical Physics
Graph-Theoretic Neural Network Fragmentation with Covariant Direct Molecular Force Learning: Enabling Coupled-Cluster Accuracy AIMD for Fluxional Systems
Xiao Zhu and Srinivasan S. Iyengar
Accurate ab initio molecular dynamics (AIMD) simulations of complex, fluxional chemical systems are severely limited by the high computational scaling of correlated electronic structure methods. To overcome this bottleneck, we present a robust, graph-theoretic molecular fragmentation framework integrated with machine learning to directly model post-Hartree-Fock
nuclear forces at coupled cluster accuracy. Bypassing the limitations of automatic differentiation on learned energy surfaces that may struggle with link-atom Jacobians, our approach directly predicts
nuclear force vectors. By projecting these vectors onto fragment-fixed principal axes of inertia, we establish co-variant descriptors that naturally preserve rotational, translational, and permutational invariance. The methodology achieves exceptional high parameter efficiency through a vector-valued training protocol that reduces trainable parameters by over an order of magnitude, while an unsupervised mini-batch k-means space tessellation
algorithm constructs highly representative training databases using only 10% to 20% of reference configurations. We rigorously validated this framework on the highly fluxional solvated Zundel cation H_{13}O_6^+ ). Our fully machine-learning-predicted AIMD trajectories successfully reproduced complex dynamical signatures and key structural characteristics, including radial distribution functions and the velocity autocorrelation power spectrum. Ultimately, this scalable, systematically improvable framework bridges the gap between high-level correlated wavefunction theories and long-timescale reactive sampling, laying the foundation for advanced, LLM-inspired transfer learning in modern chemical dynamics simulations.
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Optics
Time diffraction of optical helicity
Alex J. Vernon, Jingyi Wu, Anton Y. Bykov et al. (+4 more)
If in a classic double-slit interference experiment the light that passes though one slit is in an orthogonal polarisation state to that of the second slit, no visible interference fringes emerge. Interference fringes are instead present in a different observable that relates to the difference in energy carried by two orthogonal polarisation components, causing spatially varying polarisation patterns: the optical helicity density in the case of linearly polarised fields. Here, we develop a generalised treatment of interference in space and time, and experimentally demonstrate the helicity patterns produced by interference of orthogonally polarised pulses, which would be produced by two temporal slits in time diffraction observations. The developed approach may be important for understanding and applications of complex polarisation patterns and polarisation effects in time varying media.
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All authors Alex J. Vernon, Jingyi Wu, Anton Y. Bykov, Guy L. Whitworth, Henry Cossey, Francisco J. Rodríguez-Fortuño, Anatoly V. Zayats