Earth and Planetary Astrophysics
Finding Habitable Exoplanets with Binary Relative Astrometry: Planet Detection and Characterization with the Microarcsecond Astrometric Retrieval Algorithm (MARA)
William Roberson, Eric L. Nielsen, Jessie L. Christiansen et al. (+8 more)
Binary relative astrometry is a technique to search for rocky
planets in the habitable zone of nearby binary
stars using 1D relative astrometry at the microarcsecond level. This unprecedented precision would allow a custom-designed space
telescope to directly measure the occurrence rate of these
planets. The success of such a mission depends on our ability to recover and characterize
planets from the unique format of extreme precision binary relative astrometry data. We present MARA, the Microarcsecond Astrometric
Retrieval Algorithm, specifically designed for these data. We describe the design and format of the MARA pipeline, and demonstrate its accuracy and performance with a series of validation tests on simulated data, using the SHERA SMEx mission concept as an example. Our injection/recovery tests show that with these data, MARA is able to detect and characterize rocky
planets in the habitable zone of alpha Cen A, down to a coplanar mass of about 1 Earth mass in 1 year orbits. Expanding to a range of input
planet masses and periods for the same example mission, we find that the results from these injection/recovery tests generally agree with the analytic predictions of binary relative astrometry sensitivity. We use MARA to map out the expected completeness as a function of
planet mass and period, which in this case reaches down to about 0.5 M Earth masses at 3 year orbits around alpha Cen A. These depth-of-search calculations will be a vital ingredient in demographics calculations from the final data from a binary relative astrometry mission.
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All authors William Roberson, Eric L. Nielsen, Jessie L. Christiansen, Gautam Vasisht, Eduardo Bendek, Alex Davis, Eric E. Mamajek, Catherine A. Clark, Kaitlin M. Kratter, Juliette Becker, Michael R. Meyer
Optics
Measurement and Optimal Targeting of a Hidden Scatterer in a Complex Environment Utilizing Fisher Information
Nadav Shaibe, Jared Erb and Steven M. Anlage
A complex, non-Hermitian scattering system with a high degree of multiple scattering and interference is often treated as a black box, described simply by the relationship between a set of incoming and outgoing waves of a given frequency or energy. The scattering
matrix S that describes the system is a non-unique, generally sub-
unitary matrix that reveals very little about the microscopic processes that are responsible for the observed scattering. We form the Fisher information operator $F_x$, a Hermitian
matrix, utilizing a derivative of S with respect to the value of some varying parameter x of the system, associated with a localized perturbation, and experimentally demonstrate that the principal eigenvector of Fx can be used to quantitatively measure changes in the value of parameter x using only information from the scattering
matrix. We propose a "discrete feedback loop" protocol enabled by the knowledge we gain from the Fisher information operator, that repeatedly determines the counter perturbation necessary to return a varying parameter to some fixed
benchmark value. A further application of the Fisher information operator for energy focusing that utilizes the principal eigenvector excitation is demonstrated through compelling indirect evidence of targeting within a complex system. These methods are experimentally demonstrated to work even in the presence of time-reversal
symmetry breaking due to absorption and/or loss of scattering reciprocity.
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Physics and Society
Second-Order Continuum Model for Disordered Traffic
Shashank Rajput, Venkatesan Kanagaraj, Martin Treiber et al. (+2 more)
In this study, a two-dimensional second-order macroscopic traffic flow model is proposed to capture the complex dynamics of disordered traffic by explicitly incorporating coupled longitudinal and lateral interactions. The framework extends the classical continuity equation to two spatial dimensions and introduces acceleration equations consisting of self-driven, interaction-induced, and road-boundary-related components. The macroscopic longitudinal acceleration is formulated based on the Full Velocity Difference Model (FVDM), while lateral dynamics are governed by interaction principles consistent with the Optimal Velocity Model (OVM). The explicit inclusion of road-boundary effects enables the representation of vehicle confinement and space-sharing behavior that are essential in lane-free and weakly lane-disciplined traffic systems. The model is examined through a series of numerical experiments in which longitudinal and lateral dynamics are analysed individually as well as simultaneously within a coupled two-dimensional setting under a range of initial conditions, including transitions between free-flow, medium congestion, and heavy congestion, and different lateral density configurations. The simulations demonstrate the model's ability to reproduce key traffic features such as shockwave propagation, lateral dispersion, vehicle rearrangement, and stable density
evolution across the road width. The numerical scheme, based on upwind and Lax-Friedrichs discretisations, ensures stable solutions of the coupled partial differential equations. Overall, the proposed framework provides a robust macroscopic description of disordered traffic and offers a consistent basis for analysing two-dimensional vehicular flow dynamics.
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All authors Shashank Rajput, Venkatesan Kanagaraj, Martin Treiber, Gowri Asaithambi, Ostap Okhrin
Astrophysics of Galaxies
Tracing Lyman alpha escape in the CRISTAL-02 galaxy at z~5.3
Arshi Ali, Lucia Guaita, Manuel Aravena et al. (+20 more)
We investigate the mechanisms regulating Lyman-alpha (Ly$\alpha$) escape in the
star-forming
galaxy CRISTAL-02 at z~5.3. The
galaxy has clumpy morphology, suggestive that it may be interacting with other system(s). Two clumps (A and B, hereafter) are suggested as a site for intense
star-formation or potential AGN candidates. We investigate how the local gas,
dust, and feedback shape the escape of Ly$\alpha$
photons around these clumps. Using VLT/MUSE and JWST/NIRSpec IFU observations, complemented by NIRCam UV imaging, we constructed spatially matched emission-line maps. We derived flux, line-ratio, and extinction maps, together with spatially resolved Ly$\alpha$ escape fractions and ionizing
photon production efficiencies. We find that Ly$\alpha$ is significantly more extended than H$\alpha$ and UV, reaching ~33 kpc and preferentially extending along the cold molecular gas
outflow traced by [C II] emission. Clumps A and B show contrasting Ly$\alpha$ properties: Clump A has lower
dust attenuation and enhanced Ly$\alpha$/H$\alpha$ ratios and escape fraction, whereas Clump B is brighter in H$\alpha$ and UV but has suppressed Ly-$\alpha$ despite a higher ionizing
photon production efficiency. These results indicate that Ly$\alpha$ escape is strongly influenced by the local H I geometry,
dust, and
outflows and cannot be explained by ionizing
photon production alone. The observed Ly$\alpha$ morphology and zELDA radiative transfer modeling favor an
outflow-driven escape scenario, while the available data cannot uniquely distinguish between AGN and
star formation-driven feedback.
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All authors Arshi Ali, Lucia Guaita, Manuel Aravena, Rebecca L. Davies, Jorge Gonzalez, Vicente Villanueva, Diego Oyarzun, Rodrigo Herrera-Camus, Ambra Nanni, Andreas Faisst, Anton M. Koekemoer, Deanne B. Fisher, Hanae Inami, Juan Molina, Justin Spilker, Lun-Jun Liu, Manuel Solimano, Michele Ginolfi, Michael Romano, Negin Nezhad, Poulomi Dam, Wuji Wang, Yuan Li
Solar and Stellar Astrophysics
Correlations with Magnetic Activity in the Solar Near-Surface Shear Layer. I. Rotation
M. Cristina Rabello Soares, Sarbani Basu and Richard S. Bogart
We used data from the Helioseismic and
Magnetic Imager to determine the rotation rate of the near-surface shear layer and its time variation. We applied the ring-diagram analysis technique allowing us to probe the layer between the depths of 1 Mm and 17 Mm. We find that the rotation rate increases inwards; it reaches values consistent with those inferred from global helioseismic analyses in the deeper layers, however, there are differences in the rotation rate of the northern and southern hemispheres. We show that the time variation of the rotation rate can be determined even without subtracting the time-averaged rotation rate from each epoch; however, such a subtraction is needed to get the canonical “torsional oscillation” signal. We find that even at depths as shallow as 1 Mm, the rotation rate shows the typical torsional oscillation pattern. The cumulative zonal displacement inferred from the residual flows exhibits a pronounced high-latitude hemispheric asymmetry and varies on
solar-cycle timescales; at $75^\circ$ it shows an apparent temporal association with the polar
magnetic field. We find significant correlations between the cumulative displacement and
magnetic activity at a subset of latitudes, with multi-year lags: the displacement leads activity by ~5 years near $15^\circ$, whereas at higher latitudes activity leads by ~4 years. At mid to high latitudes, the inferred lags show a hemispheric dependence, with activity tending to lead in the north and lag in the south, suggesting possible hemispheric differences in the timing of cycle
evolution and motivating longer time series to test cycle-to-cycle variation.
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Cosmology and Nongalactic Astrophysics
Does Early Dark Energy Absorb the DESI Late-Time Dynamics Signal? A Combined Analysis
Mohammad Malekjani and Saeed Pourojaghi
While the recent
Baryon Acoustic Oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) collaboration are largely consistent with a flat $\Lambda$CDM cosmology, the preferred parameters are in mild tension with those determined from the
cosmic microwave background (CMB). A late-time dynamical dark energy (DDE) solution has been proposed by the DESI collaboration to address this tension. In this work, we investigate whether the statistical preference for DDE is a genuine late-time phenomenon or an artifact of unresolved early-universe physics. To do so, we simultaneously allow for both early- and late-time modifications to the expansion history by combining the Early Dark Energy (EDE) framework with the Chevallier-Polarski-Linder (CPL) parametrization. Excluding the DESI BAO measurements, our joint analysis of the CMB+Pantheon+
datasets demonstrates that within an EDE-extended framework, the CPL parameters remain statistically consistent with the standard $\Lambda$CDM model. This supports the hypothesis that a DDE signal at low
redshifts can be effectively accounted for by an EDE component within the $\Lambda$CDM background. However, upon the inclusion of the DESI BAO measurements in the joint analysis, a statistically significant deviation from a cosmological constant emerges. Within this combined framework, the best-fit CPL parameters robustly indicate a departure from the standard $\Lambda$CDM model, favoring a phantom-to-quintessence transition in the DE equation of state. This demonstrates that the DESI preference for the late-time DDE is a robust signature that cannot be absorbed by modifying the physics of the early Universe.
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Astrophysics of Galaxies
Reconstructing orbits of galaxies in extreme regions (roger v2.0): an extension to intermediate mass systems
Martín de los Rios, Héctor J. Martínez, Andrés N. Ruiz et al. (+3 more)
In this paper, we present an updated version of the roger code, called roger v2.0, developed to perform the orbital classification of
galaxies residing in and around
galaxy groups and clusters. In addition to the projected phase-space coordinates, the new version incorporates the host
halo mass as an additional input parameter. Although the inclusion of the
halo mass leads to only modest changes in the classification, it contributes to improving the overall robustness of the method. We also extend the range of host
halo masses over which roger can be applied, enabling the analysis of systems with masses down to $10^{13.5} h^{-1} M_{\odot}$. We further provide a Python implementation of the new code, which will be made publicly available. This implementation enables users to efficiently and robustly classify arbitrary
galaxy samples using either version of the method. Moreover, it allows users to train a customized classifier on an alternative training set, providing the flexibility to adapt the method to different
datasets and scientific applications.
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All authors Martín de los Rios, Héctor J. Martínez, Andrés N. Ruiz, Selene Levis, Valeria Coenda, Hernán Muriel
High Energy Physics (Theory)
Holographic Bit Threads from String-Diagrammatic Quantum Information Flow
Yi-Yu Lin and Song Cheng
Bit threads, arising as the convex dual of the minimal-surface formula for
holographic entanglement entropy, are line-like structures with nontrivial bulk trajectories. Their physical picture has long been associated with Bell-pair interpretations, yet the meaning of their detailed trajectories, particularly their nonuniqueness, remains unclear. We propose to apply Coecke's notion of
quantum information flow (QIF) in protocol-network geometry, developed within categorical
quantum mechanics, to a
holographic setup, and show that its trajectories within the discrete
holographic bulk—the tensor network—obey the divergence-free and density-bound conditions of bit threads. From this process-centered perspective, bit-thread nonuniqueness becomes natural: for a given resource state, different protocols realizing the same
distillation task can give rise to different QIF trajectories. We further analyze stabilizer-type
holographic tensor networks using ZX string diagrams and show that QIF trajectories can probe finer
entanglement structure beyond the level captured by
entanglement entropy.
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Quantum Physics
Compressibility of genuine multipartite entanglement under the Hadamard map
Klára Baksová and Lisa T. Weinbrenner
One of the most counterintuitive effects in the examination of
quantum states is the phenomenon of superactivation, which describes the fact that a
quantum state, which is useless for a specific task, may become useful when one considers multiple copies of it. This effect can be observed in the case of genuine multipartite
entanglement, where local projections from multiple copies to the single-copy
Hilbert space could significantly simplify the practical accessibility of its superactivation. We investigate how such projections behave in the limit of many copies, using the Hadamard map as an example, and studying different state families. We show that, in this scheme, for a fixed map, an optimal number of copies exists, beyond which the obtained
entanglement decreases, highlighting the differences between
entanglement distillation and local projection schemes.
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Strongly Correlated Electrons
Tunable inter-bilayer magnetic correlations and candidate multipolar physics in the van der Waals oxyhalides DyOCl, DyOBr, and DyOI
F. C. Brooks, X. Bai, J. Bacsa et al. (+5 more)
Rare-earth van der Waals magnets provide a route to combining strong
spin-orbit coupling, large
magnetic moments, and reduced dimensionality in bulk
crystals. We report a comparative study of the dysprosium oxyhalides DyOX (X = Cl, Br, I), which realize square-
bilayer networks of Dy3+ moments separated by a tunable van der Waals gap. Structural refinements show that increasing the halide ionic radius strongly expands the inter-
bilayer spacing while leaving the local
bilayer geometry nearly unchanged. Magnetization and heat-capacity measurements reveal two low-temperature anomalies in all three compounds:
antiferromagnetic order at TN ~ 7-10 K and a broader anomaly near TQ ~ 27-30 K. Single-
crystal magnetization on DyOCl and DyOBr establishes a strong hard-c-axis anisotropy, consistent with
crystal-field analysis of DyOCl, which yields an XY-like ground-state g tensor.
Neutron diffraction shows long-range
antiferromagnetic order in DyOCl, whereas DyOBr and DyOI exhibit sharp
magnetic scattering coexisting with Warren-like diffuse features, consistent with robust in-plane correlations and imperfect inter-
bilayer registry. Inelastic
neutron scattering on DyOCl identifies
crystal-field excitations near 25-30 meV and an additional
magnetic mode near 10 meV whose temperature dependence is tied to the high-temperature anomaly. Taken together, these results establish DyOX as a tunable family of quasi-two-dimensional rare-earth magnets and point to candidate multipolar physics associated with low-lying
crystal-field states. Direct probes of quadrupolar order, such as resonant x-ray scattering or elastic-constant measurements, will be required to determine the order parameter at TQ.
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All authors F. C. Brooks, X. Bai, J. Bacsa, V. O. Garlea, S. Calder, N. Butch, M. B. Stone, M. Mourigal
Solar and Stellar Astrophysics
Responses of the X-ray spectrometer/imager STIX onboard Solar Orbiter
Hualin Xiao, Olivier Limousin, Ewan Dickson et al. (+1 more)
Solar flares are explosive events that release X-rays from hot
plasma and accelerated electrons. The STIX instrument on the
Solar Orbiter provides imaging spectroscopy of
solar X-ray emissions from 4 to 150 keV. To interpret the STIX data accurately, understanding the instrument's response is crucial. Given the complexity of interactions of X-rays with the instrument, we developed a detailed Monte Carlo model for STIX based on Geant4. The model accurately depicts the instrument's components, such as grids, detectors, X-ray windows, and collimators, with their responses. We studied various effects, including grid shadowing, fluorescent X-rays emitted by materials in STIX, and grid transmission, to assess their impacts on STIX's scientific goals. Model validation was performed using Crab Nebula observations, a standard calibration source that provides reliable ground truth for X-ray instruments. Our simulations align with the Crab Nebula observations within the uncertainties, thereby validating the accuracy of the Geant4 model and showcasing its potential for interpreting STIX data. With the help of the generated response
matrices, which are indispensable for
solar spectroscopy, we discuss the applications and limitations of the model for future STIX data analysis.
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All authors Hualin Xiao, Olivier Limousin, Ewan Dickson, Säm Krucker
Instrumentation and Methods for Astrophysics
Microlensify: a Transformer Based Machine Learning Classifier for Microlensing Events Trained on TESS Light Curves
Atousa Kalantari, Somayeh Khakpash, Sedighe Sajadian et al. (+3 more)
Microlensing can reveal populations of faint compact objects that are otherwise difficult to detect. Depending on their design, all-sky surveys have the potential to search for these objects across the sky. The Transiting
Exoplanet Survey Satellite (TESS), primarily designed to detect transiting
exoplanets, also provides near all-sky coverage with high cadence. In this work, we use TESS data to search for microlensing candidates using both traditional and machine-learning methods and to identify associated false positives in high-cadence surveys. Microlensify is a physics-informed,
transformer-based variational autoencoder trained on simulated single-lens microlensing light curves and real TESS Sector 12 data. The model classifies events, reconstructs light curves, and estimates microlensing event durations. Applied to $\sim 5.6$ million TESS light curves, it identified between $0.036\%$ and $1.89\%$ as microlensing candidates across different TESS pipelines. After applying microlensing detection metrics and cross-matching with SIMBAD, we obtained a final list of candidates and identified false positives including long-period variables, Mira variables, cataclysmic variables, red
giants, and transients. We also found Gaussian-like peaks caused by asteroid crossings, a potential source of false positives in high-cadence microlensing surveys. The model also predicts event duration with an accuracy of $R^2 = 0.97$. The model was further tested on published events from different ground-based microlensing surveys, confirming 92.7% as microlensing, demonstrating its applicability across surveys with different cadences.
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All authors Atousa Kalantari, Somayeh Khakpash, Sedighe Sajadian, Hosein Haghi, Willow Fox Fortino, Rosanne Di Stefano
High Energy Physics (Theory)
BCFW recursion for light-like Wilson loop correlators
James Drummond, Matthew Rochford and Rowan Wright
We apply the idea of holomorphic linking (arXiv:1101.1329) to correlators of multiple light-like loop operators in $\mathcal{N}=4$ super Yang-Mills theory. This allows us to extend the BCFW recursion relations for planar scattering amplitude integrands or single Wilson loops in the planar theory to correlators of multiple loop operators. We discover a novel term which feeds the recursion for single loops into the relation for multiple loop operators. We illustrate the recursion relations with several examples and highlight its applicability in combination with the $\bar{Q}$-equation for multiple loop operators. Finally, we again employ holomorphic linking to derive a recursion relation for colour-exact Wilson loop correlators.
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Fluid Dynamics
Stability and nonlinear dynamics of three-layer viscous films inside a vertical cylindrical tube
David Halpern and Awa Traore
We investigate the dynamics and stability of three immiscible viscous
liquid layers coating the interior of a vertical cylindrical tube, a configuration relevant to stratified core–annular transport processes. A long-wave asymptotic analysis yields a coupled system of nonlinear
evolution equations governing the motion of the three interfaces. Linear stability analysis predicts a persistent long-wave instability, the capillary (Rayleigh–Plateau) instability of the air–core interface, together with secondary finite-wavenumber instability bands that emerge from interfacial coupling in certain parameter regimes. These stability characteristics depend sensitively on the layer thicknesses, viscosity ratios, and surface tension parameters, and include mode-switching associated with competing maxima in the dispersion relation. Nonlinear simulations reveal three distinct dynamical outcomes: saturation to finite-amplitude travelling waves, air-core closure through plug formation, and rupture of the intermediate
liquid layer while the air core remains open. The intermediate-layer rupture mechanism is unique to the three-layer configuration which has no analogue in one- or two-interface cylindrical film flows. Numerical continuation is used to compute branches of travelling-wave solutions and their associated limit points. Comparison with time-dependent simulations shows that travelling-wave branches successfully predict the transition from saturated waves to plug formation, but do not capture the distinct rupture mechanism associated with collapse of the intermediate layer.
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Instrumentation and Methods for Astrophysics
ADORA: a differentiable optical modeling and astrometric retrieval framework for SHERA
Dylan McKeithen, Stuart Shaklan, Gautam Vasisht et al. (+4 more)
Searching for Habitable
Exoplanets with Relative Astrometry (SHERA) is a proposed Small Explorer mission concept designed to measure the separation of nearby binary
stars at microarcsecond-class precision. Recovering this signal requires separating astrophysical motion from coupled changes in pointing, plate scale, wavefront error, spectral response, and detector calibration. We present the Astrometric Differentiable Optics and
Retrieval Algorithm (ADORA), an image-domain framework that combines a three-plane differentiable physical-optics model with a layered astrometric inference
algorithm. The forward model includes a diffractive pupil, mirror-specific wavefront error and beamwalk, polychromatic source and throughput models, and configurable detector effects. Per-frame registration states are treated locally and eliminated through Schur reduction before the slower astrometric and instrument state is updated in a prior-whitened Fisher eigenbasis. Five-minute matched-model simulations show no detected separation bias at the current Monte Carlo depth and approximately 11 uas realization-to-realization scatter. A SHERA target sweep reveals a more-than-fivefold variation in astrometric information between Alpha Centauri and 61 Cygni, motivating future target-dependent accumulation and update cadence. High-order-wavefront knowledge error can drive the
retrieval toward a strongly biased astrometric solution while leaving the local posterior sigma nearly unchanged, demonstrating that statistical
curvature alone does not capture unmodeled bias. Pixel-position errors across the tested range remain near the matched-model recovery scale indicating robustness to certain detector calibration errors. ADORA provides a flexible framework for studying astrometric extraction, calibration-bias diagnosis, and future SHERA requirements.
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All authors Dylan McKeithen, Stuart Shaklan, Gautam Vasisht, Joe Green, Rhonda Morgan, Louis Desdoigts, Peter Tuthill
High Energy Physics (Phenomenology)
Bayesian Forecasts on Cosmic Superstring Searches with LISA
Satyabrata Datta and Rome Samanta
Cosmic superstrings are well-motivated early-Universe sources of
stochastic gravitational waves, with phenomenology controlled by the string tension $G\mu$ and the intercommutation probability $P$. We study whether LISA can reconstruct these parameters and distinguish different superstring signal models in the presence of instrumental noise and astrophysical foregrounds. We consider two phenomenological models. In Model I, reduced intercommutation acts only as an amplitude enhancement of a cusp-dominated spectrum, $\Omega_{\rm SS}^{\rm I}=P^{-\beta}\Omega_{\rm cusp}$. In Model II, the signal is a cusp–kink mixture, $\Omega_{\rm SS}^{\rm II} =P^{-\beta}[p_c\Omega_{\rm cusp}+(1-p_c)\Omega_{\rm kink}]$, so that $P$ controls both amplitude and spectral shape. Using simulated LISA data, we perform
Bayesian inference with noise uncertainties, unresolved extragalactic compact-binary backgrounds, and a flexible
Galactic double-white-
dwarf foreground. We compare the models using
Bayesian evidences and map the $(G\mu,P)$ posterior geometry with marginalized widths, correlations, covariance anisotropy, principal
eigenvalues, posterior area, and bias. We find that reduced intercommutation generically produces strong $G\mu$–$P$ correlations, because the data often constrain an amplitude-like combination. However, when the cusp–kink spectral difference lies in the LISA band and the signal is sufficiently loud, Model II can be favored and the posterior can retain genuine shape information. As an optimistic foreground scenario, we also compute the Bayes factor using a reduced tanh
Galactic foreground template, finding improved model discrimination when the foreground shape is constrained.
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Classical Physics
Scalar-Longitudinal Radiation in Extended Electrodynamics with Multipole Theory and a Compensated Source Model
Natan Rentzber
Extended electrodynamics (EED) leaves the Lorenz gauge condition unimposed and treats the scalar combination $C=\nabla\cdot\mathbf{A}+c^{-2}\partial\Phi/\partial t$ as a dynamical field. For a conserved source with no scalar initial field, $C=0$ and the theory reduces to classical electrodynamics. A source with a nonzero local continuity anomaly has no Maxwell solution, but EED remains well posed and can support a scalar-longitudinal sector. For each radiating frequency of a localized source, the far field separates into the usual transverse Maxwell channel and a scalar-longitudinal channel with a longitudinal electric field, no
magnetic field of its own, and a co-propagating $C$ field. Under the field-only energy balance used here, the time-averaged fluxes add without interference. The scalar channel depends only on $\Lambda=\partial\rho/\partial t+\nabla\cdot\mathbf{J}$ and radiates when its moments at $k=\omega/c$ are nonzero. An all-orders multipole formula is derived for this flux. Bound polarization and magnetization sources conserve charge identically and cannot excite the scalar channel. A compensated polarized carrier with a globally neutral anomalous surface layer isolates the channel and gives its dipole flux in closed form. The connection between the adopted flux and a physical stress-energy tensor remains unresolved. These results are conditional predictions of EED and do not imply a failure of charge conservation in classical electrodynamics.
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Materials Science
Dynamic Ensembles of Phosphine-Stabilized Gold Nanoclusters
Caitlin A. McCandler, Disha Sanwal and Jutta Rogal
Atomically precise phosphine-stabilized gold nanoclusters are commonly characterized by single-
crystal X-ray diffraction, yet the extent to which these static structures represent finite-temperature behavior remains unclear. To explore the free-energy landscapes,
equilibrium populations, and isomerization kinetics of these nanoclusters in the gas phase, we establish a general framework that combines molecular dynamics simulations based on a machine-learned interatomic potential with Markov state models (MSMs). Analysis of the MSMs indicates that experimentally reported
crystal structures frequently correspond to minor metastable states or transient configurations rather than the dominant finite-temperature structures. Increasing ligand coverage systematically alters both the thermodynamics and kinetics of structural rearrangements, driving the transition from planar to three-dimensional gold cores while accelerating isomerization dynamics. Moreover, catalytically accessible geometries are often only minor members of the
equilibrium ensemble, highlighting a trade-off between structural stability and surface accessibility. These results emphasize that ligand-protected nanoclusters need to be viewed as dynamic ensembles and their finite-temperature behavior cannot be fully captured by their corresponding crystallographic structures alone.
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Quantum Physics
Rescaled Mandelstam Tamm characterization of discrete time crystal response in a disordered Floquet Ising chain
Abrar Ahmed Naqash, Salman Sajad Wani and Saif Al-Kuwari
For pure state
unitary dynamics, the Mandelstam Tamm (MT) lower-bound functional compares the endpoint Fubini Study return angle with path averaged energy dispersion. Their distinct size and temporal dependences obscure the origin of period two MT structure in discrete time
crystal (DTC) like dynamics and its relation to the
spin response. For binary Floquet drives, we derive an exact segment resolved MT expression without assuming commuting segment
Hamiltonians and apply it to a disordered Floquet Ising chain. Absolute and uniform summability of connected covariances of local energy terms implies an $O(\sqrt{L})$ upper bound on the path-averaged energy dispersion. Endpoint data for four system sizes are consistent with this leading behavior and support the corresponding rescaling of the MT functional. At a representative point in the finite-size region with a locked
spin response, odd and even rescaled MT branches remain separated throughout the $10^2$ period observation window. The return angle alternates strongly, whereas the size-normalized path-averaged energy dispersion shows little discernible parity dependence, indicating that endpoint geometry is the main source of the branch splitting. Across the interacting parameter grid, the period-two MT component has a strong partial Spearman rank correlation with the locked
spin response after controlling for pulse error and interaction strength. The rescaled MT functional characterizes the global return geometry of finite-size period-two dynamics and quantifies its association with the locked
spin response.
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High Energy Astrophysical Phenomena
Modeling Relativistic Tidal Disruptions of MESA Stars
Liam M. Wang, Giovanni Maria Tomaselli and Zihan Zhou
Tidal disruption events (TDEs) occur when a
star passes so close to a black hole that its self-
gravity is overcome by the external
tidal field. As the
star passes, it initially deforms, then is ripped apart, and some of its material eventually falls back on bound orbits, forming an
accretion disk around the black hole. A Newtonian model of TDEs, based on
stellar perturbation theory of MESA
stars, was recently introduced as an alternative to computationally intensive hydrodynamical simulations. In this work, we add relativistic corrections to the model, incorporating equatorial Kerr geodesics, relativistic
tidal fields, and relativistic fallback times. Compared to the Newtonian case, we find that
stars are disrupted earlier in their orbit, which gives them less time to accumulate physical deformations. Additionally, we find that the increased distance from the black hole at the time of disruption makes the fallback time longer. However, the black hole
spin has a negligible impact on fallback time, except for orbits with exceptionally close pericenter. Our results allow for a more accurate calculation of fallback rates than the Newtonian model, while also remaining computationally cheap. The code is available on GitHub.
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High Energy Physics (Theory)
Lorentzian Kähler-Dirac fermions
Simon Catterall and Jay Hubisz
We examine the formulation of Kähler
fermions on spacetimes with Lorentz signature. In practice we focus on Minkowski spacetime since most of the difficulties that are encountered are visible even when the spacetime is flat. We show that the theory, when interpreted as a Lorentz invariant theory of forms or antisymmetric tensor fields, is non-
unitary. We show that unitarity can be restored provided one adopts a modified inner product on the
Hilbert space. This modified inner product requires the insertion of an operator J that anti-commutes with certain modes of the Kähler field in such a way as to guarantee all states have positive norm. We give an explicit (and local) form for J and show that while it commutes with the
Hamiltonian, it is incompatible with the Lorentz transformation properties of the tensor fields. In flat space, the unitarized formulation is equivalent to 4 Dirac
fermions.
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General Relativity and Quantum Cosmology
Action-level characterization of gravitational-wave propagation in dynamical Barbero–Immirzi gravity
Zhi-Fu Gao, Hui Wang, Luiz Carlos Garcia de Andrade et al. (+3 more)
We investigate which operators in first-order dynamical Barbero–Immirzi (BI)
gravity control cosmological tensor propagation at the action level. Within a bosonic, two-derivative,
curvature-linear Einstein–Cartan class, eliminating the algebraic Lorentz connection reveals a separation between the scalar sector and the tensor kinetic normalization. In particular, the Holst-to-Palatini ratio determines the scalar kinetic structure, whereas the transverse-traceless tensor mode is normalized by the parity-even
Hilbert–Palatini coefficient. As a consequence, a minimal dynamical Holst sector with fixed parity-even normalization remains exactly on the general-relativistic tensor-propagation surface and does not generate anomalous gravitational-wave friction. We then construct a regular nonminimal parity-even realization in which the tensor normalization evolves cosmologically, derive the corresponding standard-siren observable, and apply current GWTC-3, GWTC-4.0, and GWTC-5.0 information as an observational test of this action-level tensor sector. The resulting constraints should therefore be interpreted as limits on the
evolution of the tensor kinetic normalization rather than direct constraints on minimal BI torsion dynamics.
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All authors Zhi-Fu Gao, Hui Wang, Luiz Carlos Garcia de Andrade, Na Wang, Guo-Qiang Jin, Zhou-Jian Cao
Statistical Mechanics
State convertibility and fluctuation theorems from a dynamical reference: majorization meets martingales
Davide Cugini and Giacomo Guarnieri
State convertibility represents a fundamental concept used to determine whether a transformation is possible given a specific set of resources. Within the field of Thermodynamics, where physical process are required to preserve a reference state typically in microcanonical or canonical form, this translates into the notions of majorization and thermo-majorization —criteria that require constructing and comparing state-dependent Lorenz curves. In this work, we firstly unify and extend these notions to an arbitrary and possibly time-dependent reference distribution $g(t)$, introducing the concept of $g(t)$-majorization; we then introduce a dual picture whereby state convertibility is turned into a one-dimensional convex-order problem, which allows us to demonstrate that a transition is admissible if and only if the associated real-valued distributions of relative populations $ k_j(t)/g_j(t)$ are connected by a martingale. Building on it, we then derive an exact fluctuation
theorem for a reference-relative
entropy production whose average violation certifies, through a $\chi^{2}$-divergence bound, the mismatch between an assumed and the true reference
evolution—a model-independent diagnostic that requires no independent characterization of the latter and turns an observed breakdown of the fluctuation relation into a certified lower bound on the reference error.
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Plasma Physics
Informing spectral models for dense plasmas with K-edge absorption measurements of warm dense copper
T. Cordova, E. V. Marley, D. A. Chin et al. (+14 more)
Warm dense matter remains a challenging regime to characterize experimentally and to model with predictive accuracy. Recent experimental platforms have been developed to generate, characterize, and diagnose uniform warm dense matter, enabling detailed comparisons with models. Here, we present experiments conducted at the OMEGA
laser facility that compress and heat a buried layer target to warm dense matter conditions, where the targets are heated to temperatures of approximately 20 eV and compressed to densities of 25 g/cm^3. We probe the warm dense
plasma using x-ray absorption spectroscopy, using the K-edge and bound-bound absorption features to constrain the temperature and charge state distribution of the
plasma. We compare these measurements with two types of models: collisional-radiative models with detailed electronic structure and ad-hoc density effects, and a multi-ion model based on density functional theory in combination with excited-state projector augmented-wave potentials. Neither approach fully reproduces the observed data, We show that the broad structure and position of the K-edge region can be modeled using density functional theory in combination with excited-state projector augmented-wave potentials. The density functional theory results are contrasted with a collisional-radiative model approach that incorporates ad-hoc density effects, which show incomplete agreement with the experimental observations, highlighting a need for improved density-dependent atomic modeling in warm dense
plasmas.
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All authors T. Cordova, E. V. Marley, D. A. Chin, R. A. London, S. B. Hansen, S. M. Vinko, J. E. Pask, H. A. Scott, H. P. Le, D. Aberg, M. K. G. Kruse, T. Döppner, F. N. Beg, J. Emig, P. M. Nilson, P. Sterne, M. J. MacDonald
High Energy Physics (Theory)
Stochastic Schwinger Effect: de Sitter and beyond
Lucas Vicente García-Consuegra and Azadeh Maleknejad
We develop a
stochastic formulation of the Schwinger effect in de Sitter spacetime using the Schwinger–Keldysh (in-in) formalism, tailored to particle production by non-stationary gauge backgrounds in the early Universe. Treating the gauge field as a prescribed classical
stochastic ensemble, we integrate out massless charged matter and derive the corresponding influence functional and particle-production kernel to leading non-trivial order in the gauge coupling. Conformal invariance allows the result to be extended directly from de Sitter to generic spatially flat FLRW spacetimes, without relying on asymptotic out states. We establish the infrared safety and classicality conditions of the
stochastic description and clarify its relation to the conventional static Schwinger effect. We further extend the framework to massless conformally coupled scalars and to weakly coupled non-Abelian gauge sectors, including Standard Model and hidden-sector examples, in regimes where thermal corrections are negligible. Our results provide a general framework for matter creation by
stochastic gauge fields in inflation, preheating, and non-thermal BSM sectors, connecting
quantum field theory in curved spacetime with early-Universe and high-energy phenomenology.
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High Energy Physics (Theory)
Krylov complexity and the growth of the black hole interior in 3D gravity
Arpan Bhattacharyya, Sounak Pal and Juan F. Pedraza
We investigate the growth of the black hole interior in three-dimensional
gravity from the boundary theory. For the two-sided BTZ black hole, we propose a boundary reconstruction of the time dependence of a codimension-one surface in terms of correlation functions of smeared operators in the thermofield double state, reproducing the characteristic late-time linear growth predicted by the complexity-volume proposal. Using the Chern–Simons formulation of three-dimensional
gravity, these nonlocal correlators are represented by bulk Wilson lines with smeared endpoints, extending the familiar connection between Wilson lines and codimension-two observables underlying
holographic entanglement entropy to codimension-one observables. We then ask whether the same
geometric growth is captured by Krylov complexity. For the smeared operators, we extract the Lanczos data from their correlation functions and find that operator Krylov complexity reproduces the late-time linear growth of the black hole interior, extending previous connections between operator growth and bulk geometry to AdS$_3$. By contrast, the Krylov spread complexity of the thermofield double state, obtained from the semiclassical gravitational partition function, does not exhibit the linear growth of the bulk volume within the regime accessible to our analysis. Our results therefore point to a distinguished role for operator Krylov complexity in encoding black hole interior growth beyond two-dimensional
gravity, while highlighting a qualitative distinction between operator and state notions of Krylov complexity.
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Instrumentation and Methods for Astrophysics
Shaping SHAPE - A spectro-polarimeter onboard Chandrayaan-3 to observe Earth as an Exoplanet
Anuj Nandi, Swapnil Singh, Bhavesh Jaiswal et al. (+33 more)
Spectro-polarimetry of HAbitable
Planet Earth (SHAPE) is an experimental instrument onboard the Propulsion Module (Orbiter) of the Chandrayaan-3 mission, designed to perform disc-integrated spectro-polarimetric observations of Earth from lunar and highly elliptical Earth orbits. SHAPE is a compact, lightweight spectro-polarimeter comprising three subsystems: the Electro-Optical Detector System (EODS)-Optics, EODS-Electronics, and
Radio Frequency Source (RFS). An Acousto-Optic Tunable Filter (AOTF), driven by an in-house-developed 80$-$135 MHz RF source, provides spectral filtering in the near-infrared (NIR) wavelength range of 1.0$-$1.7 $\mu$m and produces two narrow-band beams with mutually perpendicular linear polarization states. The instrument optics, with a field of view of approximately 2.6{\deg}, focus the two beams onto InGaAs detectors. A spectral resolution of 2$-$4 nm is achieved using in-house-designed low-noise front-end electronics. The instrument also incorporates processing and power electronics for signal processing, detector biasing, and subsystem control. We present the overall instrument design, results from pre-launch ground-based testing, and in-orbit operational performance. The current configuration enables SHAPE to measure disc-integrated signatures of Earth over a range of phase angles, providing a test bed for characterizing Earth-like
exoplanets and benchmarking future
exoplanet observations.
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All authors Anuj Nandi, Swapnil Singh, Bhavesh Jaiswal, Anand Jain, Smrati Verma, Reenu Palawat, Ravishankar B. T., Brajpal Singh, Priyanka Das, Supratik Bose, Supriya Verma, Waghmare Rahul Gautam, Yogesh Prasad K. R., Bijoy Raha, Bhavesh Mendhekar, Sathyanaryana Raju K., Srinivasa Rao Kondapi V., Sumit Kumar, Mukund Kumar Thakur, Vinti Bhatia, Nidhi Sharma, Govinda Rao Yenni, Neeraj Kumar Satya, Venkata Raghavendra, Vivechana M. S., Evangelin Leeja Justin, Praloy Karmakar, Naga Manjusha J., Motamarri Srikanth, Abhishek Singh, Prabakaran B., Honey Gupta, Priyanka Mishra, Chinmay Kumar Rajhans, Kalpana K., Veeramuthuvel P
Quantum Physics
Steven Rayan
These notes develop four interconnected ways of reading a
quantum circuit. A
circuit for us begins as an operational composition of gates; then, it becomes a diagram whose local equalities may be used as calculations; next, it becomes a protected process once errors, syndromes, and logical degrees of freedom are separated; and finally, it becomes
geometric when its connectivity,
topology, and boundary data are treated as physical design parameters. The development begins at the level of bits and
qubits before appealing to Deutsch's and Grover's
algorithms as basic examples of
quantum circuits. With the basics in hand, we interpret
quantum circuits diagramatically, leading us to compact closed string diagrams and the ZX-calculus. After that, we consider how to correct
quantum circuits by introducing the Knill–Laflamme condition, homological surface codes, and related concepts with a view towards thinking of these as operations on diagrams. The lectures eventually arrive at the properties of
hyperbolic quantum codes and the prospect of physical superconducting
circuits emulating the negatively-curved
lattices needed to support those codes. These mathematical ideas and physical experiments, taken together, represent one way to impart a
geometric layer onto
quantum circuits. By the very end, we bring the ideas nearly full circle by assessing the extent to which these device physics experiments operationalize the basic ZX diagrams encountered much earlier in the story. While the later material reports on original research, and while the discussion becomes increasingly mathematical as the sections progress, no prior knowledge of
quantum information,
quantum computing, or
quantum error correction is actually assumed.
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High Energy Physics (Phenomenology)
TeV-scale leptogenesis in a parity symmetric neutrino mass model
Keisuke Harigaya and Gio Leone
We study leptogenesis via out-of-
equilibrium decays of right-handed
neutrinos in a parity symmetric extension of the Standard Model with gauge group $SU(3)_c \times SU(2)_L \times SU(2)_R \times U(1)_X$, spontaneously broken to the Standard Model gauge group at a scale $v_R$. We focus on the minimal
Higgs realization, in which the strong CP problem is resolved without invoking additional
symmetries. In this framework,
lepton number is violated through Yukawa interactions, while
neutrino masses arise only at higher loop order, a feature that permits the CP-violating
quantum corrections to right-handed
neutrino decays to be parametrically large. For thermal production of right-handed
neutrinos, we find that successful leptogenesis requires $v_R \gtrsim 6\times 10^{12}$ GeV. Non-thermal production, however, relaxes this bound dramatically, requiring only $v_R \gtrsim 10$ TeV, a scale accessible to
collider searches for new particles and searches for rare processes.
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Soft Condensed Matter
Layered matter that maintains spacing but loses stacking order
Osvaldo Trigueiro Neto, Paulo Henrique Michels-Brito, Bruno Ceccato Telli et al. (+5 more)
In layered materials, spacing and stacking-order extent are usually locked. Here we show that in swollen suspensions of stiff, charged nanosheets they decouple, and that this defines a distinct regime, apart from the crystalline- and Wigner-swelling regimes such systems usually occupy. The mean spacing stays sharp and salinity-tunable while scattering-weighted stacking spans only two to three layers. We demonstrate this in a near-perfect model material, so the behaviour is intrinsic, not defect-driven. X-ray and
neutron scattering, sedimentation and a Donnan analysis show the spacing is held by a parameter-free osmotic restoring slope below one pascal per nanometre. Because the slope is so weak, the spacing sits at
equilibrium while faults relax slowly, a quenched metastable registry whose ageing-like relaxation of low-dimensional periodic order has not, to our knowledge, been realised before. The same decoupling is expected across stiff, swollen nanosheets, from clays to
oxide nanosheets and
graphene oxide.
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All authors Osvaldo Trigueiro Neto, Paulo Henrique Michels-Brito, Bruno Ceccato Telli, Natalie Jasmin Eichstaedt, Leide P. Cavalcanti, Tomás S. Plivelic, Josef Breu, Jon Otto Fossum