Cosmology and Nongalactic Astrophysics
Non-linear Structure Formation in Planck+DESI Favoured Interacting Dark Energy Cosmologies
Yuejia Zhai, Carsten van de Bruck, Eleonora Di Valentino et al. (+2 more)
Following our previous work constraining interacting dark energy (IDE) models, which showed their potential to alleviate the Hubble tension, in this work we investigate the non-linear effects of the IDE scenario favoured by CMB and DESI observations. The implications of IDE for the $S_8$ tension remain unclear, since current weak-
lensing and large-scale-structure analyses either exclude highly non-linear scales or model the non-linear regime using prescriptions calibrated within $\Lambda$CDM. We address this issue by implementing a fully self-consistent IDE pipeline. We perform N-body simulations of the IDE model with a transfer rate $Q=\xi {\cal H}\rho_x$ using a modified implementation of RAMSES. Since the dark matter Euler equation remains unchanged with respect to $\Lambda$CDM, the interaction can be incorporated through the modified background
evolution and an effective time-dependent dark matter particle mass. We find scale-dependent deviations in the quasi-linear and non-linear regimes of the matter power spectrum, together with modifications to the density-field morphology and
halo abundance. Our results show that the impact of IDE on quasi-linear and non-linear structure formation cannot be captured by standard $\Lambda$CDM-calibrated prescriptions, highlighting the importance of model-consistent non-linear modelling for future weak-
lensing and large-scale-structure constraints on interacting dark energy cosmologies.
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All authors Yuejia Zhai, Carsten van de Bruck, Eleonora Di Valentino, Baojiu Li, Rafael C. Nunes
Instrumentation and Methods for Astrophysics
Studying hot evolved stars with ultraviolet spectroscopy
Stephan Geier, Nicole Reindl, Matti Dorsch et al. (+7 more)
Hot evolved
stars are key objects to reconstruct the various evolutionary pathways of Sun-like
stars, to probe binary interactions and the physics of
supernovae. They serve as powerful observational constraints to test
diffusion, mixing, and mass loss in hot
stellar atmospheres. Furthermore, hot
stars serve as laboratories to test and derive atomic data for highly ionised trans-iron group elements and to investigate different nucleosynthesis models. Hot evolved
stars emit most of their flux in the ultraviolet (UV) and a lot of progress has been made in characterizing their UV-spectra both on the observational and on the modelling side. The unique capabilities of HST to obtain high- and medium-resolution UV-spectra played a crucial role and are needed to further advance this field also in preparation for HWO.
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All authors Stephan Geier, Nicole Reindl, Matti Dorsch, Vikrant Jadhav, Helge Todt, Klaus Werner, Ulrich Heber, Marcelo M. Miller Bertolami, Tiara Battich, Semih Filiz
Other Condensed Matter · Cross-listed from cs.IT
Color-Rule-Function Encoding for Combinatorial Memory
Alexander Khitun
Combinatorial
memory is a class of
memory in which information is encoded in the set of paths through a structured mesh. In this work, we introduce a systematic encoding framework, referred to as the Color-Rule-Function (CRF) approach, for representing information in combinatorial
memory. The method consists of four key steps: selecting a sequence of paths in the mesh, assigning values (e.g., colors) to each
cell, defining a set of rules based on the values encountered along each path, and constructing a Boolean function that determines the state of each path. . The coding procedure is illustrated by several examples. The design space scales of the CRF scale fundamentally faster compared to conventional
memory. This apparent advantage arises from the use of rule-based and functional representations but is accompanied by increased hardware complexity. A possible hardware realization of the CRF framework is discussed. Importantly, the hardware overhead can be substantially reduced through the use of customized modules. The examples of the customized design are described in the text. The combination of CRF coding with customized module design may lead to a practical advantage in data storage density. According to the estimates, the data storage density may exceed Exabit per centimeter squared. A key problem that requires further investigation is related to the minimum Hamming distance between an arbitrary target bit sequence and the closest sequence realizable within the CRF framework under fixed hardware constraints.
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Mesoscale and Nanoscale Physics
Chiral anomaly and planar Hall conductance in pseudospin-$1$ Fermions
Azaz Ahmad
Positive longitudinal magnetoconductance (LMC) and planar
Hall conductance (PHC) are hallmark transport signatures of the
chiral anomaly in Weyl semimetals. Recent theoretical developments have extended Weyl
fermions to multifold Fermionic systems with higher-pseudospin quasiparticle excitations, motivating the study of their magnetotransport properties. Here, we employ semiclassical Boltzmann transport theory within the relaxation-time approximation to investigate magnetotransport in pseudospin-1 Weyl semimetals, incorporating momentum-dependent scattering, orbital
magnetic moment corrections, and charge-conservation constraints. To obtain a finite PHC, we break azimuthal
symmetry through either a generic tilt of the quasiparticle dispersion or a finite misalignment between the electric and
magnetic fields. In the untilted case, the PHC is positive and scales quadratically with
magnetic field strength. Increasing the scattering strength induces a sign reversal of the PHC, producing a transition from positive to negative values. The PHC further exhibits the characteristic angular dependence $\sin 2\gamma$, where $\gamma$ is the angle between the
magnetic field and the $x$-axis. Tilt qualitatively alters this behavior: tilt along the $x$- and $z$-directions changes the angular response to $\sin\gamma$ and $\cos\gamma$, respectively, generating strong anisotropy in the planar
Hall signal. Moreover, the PHC shows a nonmonotonic dependence on tilt magnitude, revealing the interplay between tilt-induced
symmetry breaking and
chiral-anomaly-driven transport. Our results provide experimentally accessible signatures of multifold
fermions and a framework for interpreting magnetotransport measurements in candidate materials of space groups 199, 214, and 220.
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Fluid Dynamics
Linear stability analysis of particle-laden Couette-Poiseuille flows: effect of porous walls
Ananthapadmanabhan Ramesh, Abbas Moradi Bilondi, Mohammadreza Mahmoudian et al. (+1 more)
The current study presents a three-dimensional linear stability analysis of particle-laden Couette-Poiseuille flow suspended in a Newtonian fluid between two parallel plates, with the lower plate coated by a porous medium. The influence of suspended particles is examined using a two-domain formulation in which particles are confined to the fluid layer and do not penetrate the porous substrate. The particle-laden suspension is modeled using the dusty-gas framework, while the flow within the porous layer is described by the volume-averaged Navier-Stokes (VANS) equations. In particle-laden flows over impermeable walls, particle inertia may either stabilize or destabilize the flow depending on the governing parameters. In contrast, the presence of a porous layer introduces an additional permeability-dependent destabilizing mechanism that fundamentally modifies these classical trends. Consequently, particle loading can reduce the critical Reynolds number at sufficiently high permeability, even in parameter regimes where particles stabilize the corresponding rigid-wall flow. The coupled formulation also introduces additional disturbance branches associated with fluid-particle coupling near the permeable interface. Although these modes remain stable across the parameter space investigated, they modify the eigenspectrum and influence the dominant instability by altering coupling pathways. Furthermore, unlike impermeable-wall Couette-Poiseuille flow, where increasing the Couette component generally stabilizes the flow, the porous-wall configuration exhibits a monotonic decrease in the critical Reynolds number over the range examined. These results demonstrate that porous boundaries can fundamentally alter established stability behavior in particle-laden shear flows through permeability-dependent coupling between the suspension and the porous substrate.
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All authors Ananthapadmanabhan Ramesh, Abbas Moradi Bilondi, Mohammadreza Mahmoudian, Parisa Mirbod
Astrophysics of Galaxies
Imprints of the Neutral Interstellar Medium on Polarized Synchrotron Emission and Faraday Rotation
Minjie Lei, S. E. Clark, Mehrnoosh Tahani et al. (+5 more)
The interstellar medium (ISM) is a complex, multiphase medium, where disentangling the distribution of gas and
magnetic field structure across different phases remains a considerable challenge. Recently, Faraday
tomography enabled by broadband polarized
radio observations has emerged as a promising probe of 3D ISM gas and
magnetic field structures. However, the interpretation of these observations is obscured by our limited understanding of the different ISM components probed by the distinct Faraday depth features. In this work, we present a comprehensive multi-frequency ($\sim$300 MHz - 23 GHz) analysis comparing features in the Faraday-rotated, polarized synchrotron emission and HI structures over the full high-latitude (|b|>30 degrees) diffuse sky. Using measures of HI structure complexity along the line of sight (LOS), we observe enhanced depolarization across synchrotron
radio frequencies in regions with high HI complexity characterized by multiple HI velocity components. We also find that the first and second moments of the Faraday depth spectra are linked to the underlying neutral gas structure. These results indicate that regions of the ISM that are dominated by neutral gas could directly contribute a significant portion of the diffuse synchrotron emission and Faraday rotation. These findings establish new observational constraints for
Galactic magnetic field models that synthesize multiphase tracers into a single coherent picture.
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All authors Minjie Lei, S. E. Clark, Mehrnoosh Tahani, A. Bracco, Yik Ki Ma, Amit Seta, Jennifer West, E. Carretti
High Energy Physics (Phenomenology)
Correlated Matter Induced Biases in Long-Baseline Neutrino Oscillation Measurements
Tia Pandit and Bipin Singh Koranga
We demonstrate that treating Earth matter effects via a constant-density approximation introduces a fundamental systematic error in long-baseline
neutrino oscillation analyses. Using exact numerical propagation through realistic PREM profiles, we show that matter-profile mismodeling does not merely affect the $\nu_{\mu}\rightarrow\nu_{e}$ appearance probability, but generates correlated biases across the $\nu_{\mu}\rightarrow\nu_{\tau}$ and $\nu_{\mu}\rightarrow\nu_{\mu}$ channels as dictated by PMNS unitarity. Our
stochastic analysis reveals that the $\nu_{\mu}\rightarrow\nu_{\tau}$ channel is the most volatile carrier of the geophysical systematic. Across varying correlation lengths at baselines like $5000$ km and $7000$ km, the $\tau$-appearance channel consistently carries a larger mean bias and variance than the standard $\nu_{\mu}\rightarrow\nu_{e}$ appearance channel. These findings demonstrate that spatially resolved density treatments are a mathematical necessity for the analysis frameworks of future precision
neutrino facilities.
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Atmospheric and Oceanic Physics
An Ocean Model Ported by a Large Language Model: Experience and Lessons from FESOM2 (Fortran to C to C++/Kokkos)
Nikolay V. Koldunov, Suvarchal K. Cheedela, Sergey Danilov et al. (+3 more)
Large
language models (LLMs) can translate and modify source code, and have been shown to do so for codes of different complexity. Whether they can port a complete, production geophysical model to a different
language without degrading its physics has not been established. We demonstrate that LLM-assisted code translation can preserve the physics of a complete production ocean model while moving it into a modern performance-portable form. We report our experience using an agentic LLM coding assistant, directed by domain experts, to port the FESOM2 unstructured mesh ocean–sea-ice model (about 74000 lines of core Fortran) first to C and then to C++/Kokkos for performance portability across CPUs and GPUs. We describe the practices that proved necessary, what worked and what did not, and the failure modes that we encountered. Three practices mattered most: translating in two stages that separate reproducing the numerics (Fortran to a clean C reference) from introducing parallelism (C to Kokkos); requiring a strictly literal translation in which the assistant was not permitted to “improve” the source; and validating each stage against an acceptance criterion suited to it. The C port reproduces the original Fortran at the level of long-term simulation statistics over five years. The Kokkos port is bit-for-bit identical to the C reference on CPU and statistically close on GPU over multi-year runs. On eddy-rich meshes up to 7.4 million surface vertices a single A100 GPU node runs 1.6–3.7 times faster than a CPU node, reaching the 1-2 simulated-years-per-day required for production integrations. The result is more than a single GPU port: by following a clear validation procedure, an LLM moved a full Fortran ocean model into another
language and onto accelerators while preserving its physics in a matter of weeks.
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All authors Nikolay V. Koldunov, Suvarchal K. Cheedela, Sergey Danilov, Dmitry Sidorenko, Sebastian Beyer, Thomas Jung
Atomic and Molecular Clusters
Nonadiabatic Dynamics and Rotational Coupling in $\mathrm{HeH^+}$ Dissociative Recombination and Resonant Ion-Pair Formation
Sifiso Musa Nkambule, Malibongwe Tsabedze, Oscar N. Mabuza et al. (+1 more)
We present a time-dependent wave-packet study of dissociative recombination (DR) and resonant ion-pair (RIP) formation in $\mathrm{HeH^+}$ isotopologues.
Nuclear dynamics are treated on a
manifold of 23 coupled electronic states of $^2\Sigma$, $^2\Pi$, and $^2\Delta$
symmetries, including rotational couplings between different
symmetries. The results reveal that inclusion of a large
manifold of resonant states and rotational couplings significantly enhances the DR cross section relative to earlier theoretical studies. In the diabatic representation, $^2\Sigma$ states dominate the recombination dynamics, while in the adiabatic representation, $^2\Pi$ and $^2\Delta$ states contribute significantly at low collision energies. For RIP formation, two different diabatization schemes yield systematically larger cross sections than previous models, highlighting the sensitivity of ion-pair production to electronic coupling structure. Isotopic effects are examined, showing a clear inverse dependence of cross section magnitude on reduced mass. Thermal rate coefficients are computed over $10^{2}$ to $2\times 10^4$ K thermal electron temperatures. Isotopic effects are examined, showing a clear inverse dependence of cross section magnitude on reduced mass. The results are compared with rotational-state-resolved experimental and theoretical results. The present results highlight the importance of multistate coupling and rotational interactions in electron-driven fragmentation processes relevant to
primordial and astrophysical
plasmas.
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All authors Sifiso Musa Nkambule, Malibongwe Tsabedze, Oscar N. Mabuza, Mbuso K. Matfunjwa
High Energy Physics (Phenomenology)
Radiative Neutrino Mass in a Nonholomorphic $T'$ Modular Invariant Model
Mohamed Amin Loualidi, Mohamed Miskaoui and Salah Nasri
The T4-2-i
topology provides a one-loop realization of Majorana
neutrino mass and may be viewed as a radiative extension of the type-II seesaw, with a scalar triplet, two inert scalar doublets, and singlet
fermions propagating in the loop. A central difficulty in realizing this
topology lies in the simultaneous presence of tree-level type-I and type-II seesaw contributions arising from the same particle content. In addition, the stability of the dark matter candidate typically requires the introduction of an ad hoc discrete
symmetry. In this work, we revisit the T4-2-i
topology within a nonholomorphic modular invariant framework based on the double cover group $T'$. The presence of both even and odd weight polyharmonic Maaß forms considerably enlarges the space of allowed modular structures. An exact $Z_2$ parity inherited from the $T'$ modular
symmetry stabilizes the lightest odd state for arbitrary values of $\tau$, whereas the vicinity of $\tau=i$ determines the
flavor textures. The modular assignments exclude the tree-level type-I operator and determine the
flavor structure, while
lepton number conservation in the Yukawa sector excludes the tree-level type-II coupling. The modular invariant Majorana mass
matrix provides the soft $\Delta L = 2$ breaking required by the radiative mechanism. We confront the model with
neutrino oscillation data, charged
lepton flavor violating bounds, electroweak precision observables, the
Higgs diphoton signal strength, the observed dark matter relic abundance, the cosmological bound on the sum of
neutrino masses, and direct detection limits. Focusing on the fermionic dark matter candidate, in which the lightest odd state is the Majorana
fermion $N_1$, we find that both normal and inverted
neutrino mass orderings remain viable.
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Astrophysics of Galaxies
JADES: the mass-metallicity relation at $z=1-10$. New calibrations, extremely metal-poor galaxies, and chemical diversity
Yuki Isobe, Mirko Curti, Roberto Maiolino et al. (+28 more)
We present gas-phase
metallicities of
star-forming
galaxies at $z=1$-10 with deep JWST/NIRSpec spectra from the JADES full data release, Dark Horse, and OASIS programmes. We stack $\sim$1500 medium-resolution spectra, yielding detections of the [OIII]$\lambda$4363 auroral line down to $12+\log(\mathrm{O/H})=7.0$ to derive stack-based strong-line calibrations over the
metallicity range $12+\log(\mathrm{O/H})=7.0$-8.7. At a fixed
metallicity, our stacks exhibit [OIII]$\lambda$5007/H$\beta$ and [OIII]$\lambda$5007/[OII]$\lambda\lambda$3726,3729 values generally lower than calibrations based on high-$z$ individual auroral-line emitters, suggesting an observational bias towards higher excitation introduced when requiring auroral line detections in individual spectra. Based on our new calibrations, we obtain canonical mass-
metallicity relations (MZRs) at z$=$1-10, identifying a decrease in
metallicities from $z\sim0$ to z$\sim$4-10, without significant change in slope. Moreover, we identify 50 promising candidates of extremely metal-poor
galaxies (EMPGs) with $12+\log(\mathrm{O/H})=6.7$-7.3 (1-4%
solar metallicity) at $z=1.2$-9.1. The MZRs of EMPGs are characterised by a large scatter, with those having lower
metallicities generally exhibiting lower sSFRs, opposite of what expected from the local Fundamental
Metallicity Relation. These results support a
stochastic star-formation history involving gas consumption/ejection and metal-poor inflow, strongly affecting
metallicities of low-mass
galaxies. Furthermore, we identify two Little Red Dots in our EMPG candidates, both exhibiting broad H$\alpha$ and prominent Ly$\alpha$, offering insights into the early black-hole growth in extremely metal-poor environments.
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All authors Yuki Isobe, Mirko Curti, Roberto Maiolino, Qiao Duan, William McClymont, Dávid Puskás, Francesco D'Eugenio, Pierluigi Rinaldi, James A. A. Trussler, Jan Scholtz, Tobias J. Looser, Erica Nelson, Xihan Ji, Danial Langeroodi, Sandro Tacchella, Gareth C. Jones, Ignas Juodžbalis, Robert G. Pascalau, Tiger Yu-Yang Hsiao, Hannah Übler, William M. Baker, Andrew J. Bunker, Stefano Carniani, Stéphane Charlot, Emma Curtis-Lake, Sophia Geris, Maria Koller, Jianwei Lyu, Brant Robertson, Christina C. Williams, Zihao Wu
Earth and Planetary Astrophysics
Planet formation at the inner edge of the dead zone II. Outbursts, rings, vortices, and suppression of planetesimal formation
Alexandros Ziampras and Tilman Birnstiel
Accretion outbursts have been observed in a variety of young
stellar objects, but models of their dynamical
evolution have been largely limited to axisymmetric models due to their computational cost. We investigate the azimuthal stability of
accretion outbursts and the formation of planetesimals during these events. We performed high-resolution 2D, vertically integrated multifluid radiation-hydrodynamical simulations of the inner 10 au of protoplanetary disks with a dynamically growing
dust population, including radiation transport and a realistic
dust opacity model.
Accretion outbursts are highly unstable to the Rossby-wave instability, with the burst front quickly diffusing into a large number of small-scale
vortices that coalesce over time into a single, compact
vortex and inducing azimuthal asymmetries.
Vortices act as a source of vigorous turbulent
diffusion, strongly suppressing planetesimal formation. Our results suggest that azimuthal asymmetries associated with
accretion outbursts should be both common and detrimental to
planet formation. Nevertheless, planetesimal formation will resume post-burst, as the burst-induced
vortices eventually decay and the disk returns to a quiescent state featuring a pressure bump at ~1 au.
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Quantum Physics
Fisher geometry reshapes the effect of incompatibility in multiparameter quantum estimation
Jiayu He and Matteo G. A. Paris
Multiparameter
quantum estimation faces two fundamental obstacles: sloppiness, i.e., anisotropy of the
quantum Fisher information
matrix (QFIM) that renders some parameter directions insensitive, and incompatibility, the non-commutativity of optimal measurements for different parameters. The trade-off bound $C_T$ captures their joint impact on precision, but it has remained unclear how the distribution of incompatibility across parameter planes affects its overall cost. Here we separate the total amount of incompatibility from its location. We introduce a dimensionless quantity $G_n^{(F)}$ that measures the
alignment between the incompatibility distribution and the
eigenvalues of the QFIM, and show how the Frobenius scale of the incompatibility contribution factorizes. We obtain a bound and prove the incompatibility cost lies between this bound and a rank-dependent multiple thereof. We also prove that at fixed sloppiness, or equivalently fixed Fisher volume, concentrating incompatibility into a single parameter plane reduces the optimized trade-off cost because the Fisher geometry can then be reshaped to allocate more Fisher area to that plane. A qutrit $SU(2)$ encoding numerically confirms that states with larger incompatibility strength can nevertheless incur a smaller cost if the matching factor $G$ is sufficiently small. Our results establish that the distribution of incompatibility relative to the Fisher eigenbasis is a central diagnostic for multiparameter estimation, beyond the total incompatibility strength.
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Quantum Physics
Q-DICE: Quantum Distributed Interconnect Compiler and Emulator
Michael Silver, Zachary Vernec and Hans-Arno Jacobsen
As distributed
quantum computing (DQC) offers a leading path towards scalable
quantum computation, the ability to
benchmark distributed
algorithms under realistic conditions becomes critical for system co-design. However, without access to physical systems, researchers lack tools to evaluate distribution protocols. We introduce Q-DICE (
Quantum Distributed Interconnect Compiler and Emulator), a hardware-aware emulation environment for benchmarking distributed
quantum circuits on classical simulators and on NISQ-era monolithic hardware. This work provides three core contributions: (1) a programmatic scheme to construct distributed QPU backends, utilizing two novel techniques - QPU slicing and stitching - to facilitate distributed
circuit mapping, (2) a methodology for modeling nonlocal link noise using physically motivated Kraus operators and
stochastic error channels, and (3) a boundary-aware
circuit mapping
algorithm enforcing distributed QPU
topology constraints during transpilation. Together, these components constitute a distribution-aware compiler and noise-modeling engine that faithfully enforces the physical limitations of distributed
quantum hardware within existing execution environments. We validate Q-DICE against a multitude of experimentally demonstrated
quantum circuits, including a distributed Grover's search on optically linked trapped-ion hardware, achieving a worst-case fidelity deviation of 4% between simulated and experimental results. These findings demonstrate Q-DICE's capacity to accurately reproduce real distributed
quantum system behavior across platforms, streamlining experimentation with distributed
quantum algorithms and architectures.
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Quantum Gases
Universal critical behavior in ideal Bose-Einstein condensation
Arturo Camacho-Guardian, Leon Kleebank, Frank Vewinger et al. (+4 more)
Ideal Bose-Einstein condensation (BEC) remains a paradigmatic example of a continuous phase transition and a cornerstone for understanding
quantum degenerate bosonic matter. We demonstrate that critical behavior of the ideal Bose gas near the BEC phase transition falls into three distinct classes, determined exclusively by the low-energy scaling of the density of states. Depending on its scaling exponent, which is controlled by dimensionality and confinement, the transition displays either the usual algebraic divergences of thermodynamic susceptibilities, divergent behavior with marginal logarithmic corrections, or a more subtle form of criticality, where only the correlation length diverges. Our work provides a unified framework for criticality in noninteracting bosonic systems. This classification applies broadly to atomic, photonic, polaritonic, and magnonic condensates, where dimensionality, confinement, and spectral engineering can strongly reshape the density of states.
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All authors Arturo Camacho-Guardian, Leon Kleebank, Frank Vewinger, Martin Weitz, Julian Schmitt, Rosario Paredes, Victor Romero-Rochín
Mathematical Physics · Cross-listed from math.QA
The many faces of higher Hilbert spaces
Giovanni Ferrer, Lukas Müller, David Penneys et al. (+1 more)
Finite-dimensional operator
algebras can be viewed as $\mathrm{C}^*$, $\mathrm{W}^*$, or $\mathrm{H}^*$-
algebras, leading to different notions for their categories of modules and correspondence 2-categories. In this article, we show how these differences can be understood systematically using the notion of $G$-dagger category from arXiv:2403.01651 for different subgroups $G\leq O(2)$. To do so, we first introduce $G$-Hermitian $2$-vector spaces using fixed points of a certain $O(2)$-action on $2\mathsf{Vect}$. We then propose criteria for when such pairings are `positive', generalizing the passage from Hermitian vector spaces to
Hilbert spaces. Finally, we outline an inductive approach to defining higher
Hilbert spaces in arbitrary dimension, suggesting an extension of these ideas beyond the 2-categorical setting.
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All authors Giovanni Ferrer, Lukas Müller, David Penneys, Luuk Stehouwer
Quantum Physics
Observable signatures of exceptional points from left-right eigenstate distinction
Leela Ganesh Chandra Lakkaraju, Soumik Bandyopadhyay, Sudipto Singha Roy et al. (+1 more)
Non-Hermitian
quantum systems exhibit qualitatively distinct physical behavior compared to Hermitian systems, a
prime example being spectral singularities known as exceptional points. Their relevance in, e.g.,
quantum sensing, unidirectional transport, and robust lasing makes it important to be able to identify exceptional points through observable features of a many-body system. Here, using as an example a one-dimensional complex XY
spin chain realizing both rotation-time RT- and parity-time PT-symmetric regimes, we develop a framework for detecting exceptional points based on the distinction between left and right eigenvectors of the
Hamiltonian, which in a non-Hermitian system are no longer the adjoint of each other. We first show that a global measure constructed from the difference between the
Hamiltonian and its adjoint locates exceptional points via distinct non-analytic behavior. At the level of observables, differences in local
spin correlations evaluated on the right and left eigenstates provide a reliable static detection scheme. In contrast, static bipartite
entanglement measures fail to capture this distinction, urging us to study the
quantum dynamics of the model. Following a sudden quench, we demonstrate that the time-averaged right-left
entanglement entropy difference directly encodes signatures of the exceptional point. In the RT-symmetric regime, it exhibits a pronounced peak at the exceptional point, whereas in the PT-symmetric regime it behaves as an order-parameter-like quantity, remaining finite in one phase and vanishing at the transition. Our results establish a direct link between the structure of non-Hermitian eigenstates and observable signatures of exceptional points, providing a practical route to identify them in existing
quantum simulators.
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All authors Leela Ganesh Chandra Lakkaraju, Soumik Bandyopadhyay, Sudipto Singha Roy, Philipp Hauke
Optics
Phase and coherence retrieval from near- and far-field intensities
Eran Bernstein, Amit Pando, Asher A. Friesem et al. (+1 more)
Quantifying the coherence properties of complex optical fields is essential for applications ranging from high power
laser arrays to
quantum coherent systems. Here, we present a new paradigm for coherence
retrieval inspired by the Gerchberg Saxton framework, enabling reconstruction of the first order spatial coherence function (mutual intensity) of partially coherent light from intensity measurements in the near and far fields. We introduce two complementary approaches: a four dimensional Tensor GS
algorithm that directly reconstructs the mutual intensity with high accuracy, and a Monte Carlo GS variant that significantly reduces computational cost at the expense of controlled approximation. We validated both methods by reconstructing partially coherent fields in simulated linear and ring arrays of up to 600 beams with prescribed Gaussian decaying coherence. Experimentally, we applied the Tensor GS method to a triangular array of 130 coupled
lasers with inhomogeneous spatial coherence, achieving good agreement with theory and a root mean square phase error as low as 2pi over 250.
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All authors Eran Bernstein, Amit Pando, Asher A. Friesem, Nir Davidson
Earth and Planetary Astrophysics
Do Super-Puffs Defy Core Accretion? Population-Wide Interior Structure Constraints
Nicholas T. Marston, Juliette Becker and Alex R. Howe
Sub-Saturn mass
planets with extremely low bulk densities $(\rho\lesssim0.3)\mathrm{g/cm^3}$, or “super-puffs”, are one of the most interesting and least understood populations of
exoplanets. While many short-period super-puffs can be attributed to the effects of high irradiation and
star-
planet interactions, cold super-puffs appear to challenge the expectations of core
accretion theory. We constrain the possible properties of 34 cold super-puffs by computing hydrostatic interior structures using PlanetSolver. We find that 28
planets in our sample can be reproduced by models consistent with core
accretion based on their observed masses and radii and adjusting for
planet age. We identify HIP 41378 f, Kepler-30 d, Kepler-51 d, Kepler-177 c, TOI-1420 b, and WASP-107 b as
planets inconsistent with core
accretion theory which necessitate a non-standard explanation (e.g. exo-rings). With the exception of TOI-1420 b, core
accretion-compatible solutions are possible for these
planets if an additional heat source is present. We modify planetary
evolution models to determine whether enhanced radiogenic heating or late impacts with sub-planetary mass objects can plausibly inflate sub-Neptunes enough to achieve super-puff densities. We find that the effects of radiogenic heating are insufficient to produce super-puff densities, but that impacts can in many cases produce the necessary inflation for upwards of 1Gyr. We also compile and present here an index of all currently known super-puffs.
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Astrophysics of Galaxies
CRIRES+ reveals the chemistry of the stellar sub-populations in the bulge fossil fragment Liller 1
L. Chiappino, L. Origlia, C. Fanelli et al. (+10 more)
In this paper we present the chemical screening of the complex
stellar population discovered in the Bulge Fossil Fragment Liller 1. This study is part of the Bulge Cluster Origin (BulCO) survey based on a Large Program at the ESO-VLT with the high resolution spectrograph CRIRES+. The survey is aimed at performing an unprecedented chemical screening of 17
stellar systems orbiting the Milky Way bulge, with the ultimate goal of unveiling their origin and true nature. We measured precise chemical abundances of iron, CNO, iron-peak, $\alpha$- other light-elements, and
neutron-capture elements for a sample of 30 red
giant branch
stars, kinematic members of Liller 1. The presented analysis provides the high-resolution spectroscopic proof of the complex chemistry of this massive
stellar system, with multi-
metallicity sub-populations of different ages that nicely fits into a self-enrichment scenario. We find no evidence for the Na-O anticorrelation associated with genuine globular clusters; rather the overall abundance trends are similar to those seen in the bulge field and in Terzan 5, providing definitive evidence of an in-situ formation of Liller 1 within the
Galactic bulge.
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All authors L. Chiappino, L. Origlia, C. Fanelli, A. Bartolomei, F.R.Ferraro, B. Lanzoni, C. Pallanca, M. Cadelano, D. Romano, E. Dalessandro, D. Massari, E. Valenti, R.M. Rich
Astrophysics of Galaxies
Morphology, sizes, and scatter in a large sample of distant quiescent galaxies
G. Scarpe, F. Valentino, K. Ito et al. (+3 more)
After quenching
galaxies keep growing in size across time, as established in the literature up to
cosmic noon. In this work, we assemble one of the largest and most comprehensive multi-wavelength photometric sample of massive quenched
galaxies at z>3, counting 137 quiescent candidates within 825 sq. arcmin and
redshift 3<z<7 across the well-studied extragalactic JWST fields. We model their surface brightness distribution across 5 bands mapping their UV-to-NIR rest-frame wavelength with Sersic profiles, and derive their sizes, concentrations, and ellipticities. The size-mass relation is consistent with previous studies. Size decreases with increasing
redshift, in agreement with previous studies and extending them up to z_spec=4.9. The intrinsic scatter of the mass-size relation has no relevant dependence on the
redshift and the filter used. Our multi-wavelength modeling reveals that size decreases with increasing observed wavelength, and the wavelength gradient decreases with increasing
stellar mass. This result proves that in the NIR-bands massive elliptical
galaxies appear more compact. The Sersic index does not show significant dependence on wavelength, independently of the
stellar mass. Following a forward/backward
Bayesian fit analysis to assess the significance of several parameters in predicting the size of our sample, we do not identify any significant secondary dependence of the size on axis ratio q, Sersic index n, UVJ-colors, and environment. The combination of
stellar mass and
redshift is sufficient to predict the size of quiescent
galaxies at z>3, albeit with a large scatter. This suggests that the commonly used parameters of a Sersic distribution cannot explain the large intrinsic scatter around the
stellar mass-size relation, suggesting that other physical quantities need to be taken into account to break the degeneracy between
evolution paths across the
galaxy population.
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All authors G. Scarpe, F. Valentino, K. Ito, M. W. Baker, A. Pensabene, P. Zhu
Astrophysics of Galaxies
Phase-dependent magnetic coherence in the turbulent interstellar medium
Iryna S. Butsky, Caleb Redshaw, Minjie Lei et al. (+2 more)
Magnetic fields permeate the multiphase interstellar medium (ISM), yet their phase-dependent structure remains poorly constrained by observations.
Dust polarization and \ion{H}{1} emission together offer complementary probes of the plane-of-sky
magnetic field and cold neutral medium (CNM) gas structure, respectively. Recent observational work has shown that in the diffuse ISM, the
dust polarization fraction correlates positively with the CNM mass fraction ($f_{\rm CNM}$) but not with total \ion{H}{1} column density, suggesting a phase-dependent
magnetic field geometry. Here, we use extremely high-resolution ($2048^3$) simulations of the turbulent, magnetized, multiphase ISM to investigate the physical origin of this trend. By constructing synthetic \ion{H}{1} and
dust polarization maps, we directly compare our simulations to the observational results of \citet{Lei:2024}. We recover a positive $f_{\rm CNM}$-polarization correlation most clearly for sightlines intersecting fewer than $\sim$20 discrete CNM clouds, while the trend becomes weak or intermittent for larger cloud counts, consistent with the expectation that high-
Galactic-latitude sightlines contain relatively few independent cold structures. We show that this correlation reflects genuine phase-dependent
magnetic structure: CNM clouds tend to be elongated along the local
magnetic field and, when normalized by column density, exhibit lower
magnetic disorder than the warm neutral medium (WNM). We further demonstrate that apparent discrepancies between simulation- and observation-based measures of
magnetic disorder arise from whether disorder is quantified per unit path length or per unit mass. Our results support a picture in which CNM structures host relatively ordered
magnetic fields, producing higher polarization fractions along CNM-dominated sightlines in the diffuse ISM.
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All authors Iryna S. Butsky, Caleb Redshaw, Minjie Lei, Susan E. Clark, Drummond B. Fielding
High Energy Astrophysical Phenomena
Ring Position Angles and Spin in M87* and Sgr A*
Nicholas S. Conroy, Michi Bauböck, Vadim Bernshteyn et al. (+4 more)
Event Horizon
Telescope (EHT) images of black holes appear as rings with a brightness asymmetry. Here, we expand on our previous study of the asymmetry magnitude $a_1$ to study the position angle of the peak brightness asymmetry $\mathrm{PA}_1$ in general relativistic magnetohydrodynamic (GRMHD) models. For larger
spin magnitudes ($a_{*}>0$ and $a_{*}\lesssim-0.5$), the mean $\mathrm{PA}_1$ falls within $1\sigma$ of the approaching limb of the black hole, regardless of viewing inclination, disk magnetization, or source. By comparing the $(a_1, \mathrm{PA}_1)$ distribution in M87* observations with models, we demonstrate that we can mildly disfavor low-magnitude
spins and strongly disfavor all
spin vectors that point toward Earth. The
alignment of $\mathrm{PA}_1$ relative to the large-scale jet axis may suggest that M87*'s disk does not have a large tilt. By combining $\mathrm{PA}_1$ with the pattern speed measured in optimistic 2026 M87*
video conditions, the EHT can constrain whether M87* is prograde or retrograde with $\sim 84\%$ accuracy. In Sgr A*, we show that a detection of $(a_1, \mathrm{PA}_1)$ could constrain the magnitude and direction of the
galactic center
spin vector. Finally, if future EHT expansions increase the sample of horizon-scale sources, a simple set of observables (ring diameter, asymmetry magnitude, and asymmetry angle) could enable robust constraints on black hole mass,
spin, and inclination.
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All authors Nicholas S. Conroy, Michi Bauböck, Vadim Bernshteyn, Paul Tiede, Abhishek V. Joshi, Cora Prather, Charles F. Gammie
Disordered Systems and Neural Networks · Cross-listed from cs.LG
Neural networks become centroid classifiers when trained on heavily corrupted inputs
Justin Tahmassebpur, Asadullah Bhuiyan, Hyejin Kim et al. (+1 more)
Learning from imperfect data is a central theme in machine learning, connecting practical questions of robustness to fundamental questions of learnability. Here we examine attribute noise: learning from corrupted inputs while keeping the labels intact, a setting that has received considerably less analytical
attention than its label-noise counterpart. We consider two types of corruption models: additive noise and replacement noise. Through experiments with multi-layer perceptrons (MLPs) on corrupted classification
datasets, we find that neural networks remain robust, maintaining well-above-chance accuracy even when inputs are >90% corrupted – far beyond human recognition. To understand this robustness, we analyze infinite-width networks in the heavy-corruption regime using a mean-field-inspired approach and derive a leading-order decision rule for the classification outcome: the network implements a prototype rule, the nearest-class-mean, assigning each test point to the class whose training-set average it most closely resembles. This leading-order decision rule is universal across a broad range of MLP architectures, holding for any depth, as well as a wide class of activation functions and noise distributions. The same centroid mechanism closely matches finite-width network behavior in our experiments and provides an interpretable and analytically tractable account of why learning can succeed even when individual training examples carry almost no signal.
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All authors Justin Tahmassebpur, Asadullah Bhuiyan, Hyejin Kim, Omri Lesser
High Energy Physics (Theory)
Lectures on Semiclassical Methods for Composite Operators
Francesco Sannino
These lecture notes are intended as a coherent introduction to conformal field theory in general, and composite operators in particular, through a semiclassical framework for computing scaling dimensions, with emphasis on operators of the form $\phi^n$. In doing so, they aim to fill a gap in the literature and to help decode some of the relevant concepts. The physical idea is that at large $n$ an (heavy) operator creates a highly occupied state. Through the state-operator correspondence, this state lives on the cylinder $\mathbb{R}\times S^{d-1}$, and its scaling dimension is the corresponding energy of the theory on the cylinder. The notes are organized as a self-contained route from conformal
symmetry to semiclassical dynamics. Part I reviews the conformal group, primary operators, radial quantization, the state-operator correspondence, and operator mixing. Part II builds the semiclassical framework, first in the free scalar theory, where the dimension of $\phi^n$ is recovered in three independent ways, and then through the double-scaling limit, the action variable, and Bohr-Sommerfeld quantization. Part III develops the general machinery of periodic saddles, Floquet theory, fluctuation determinants, the Gel'fand-Yaglom method, and the Gutzwiller trace formula. Part IV applies the framework to the $O(N)$ $\phi^4$ theory in $d=4-\epsilon$ at the Wilson-Fisher fixed point, deriving the classical
elliptic solution, the Lamé fluctuation spectrum, the zero modes, and the one-loop contribution to the large-$n$ scaling dimensions. Beyond the explicit computation, the notes emphasize the role of composite operators as probes of collective sectors of
quantum field theory, with extensions to gauge theories, conformal windows, and asymptotically safe field theories.
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Astrophysics of Galaxies
Spiral arms across cosmic time: JWST measurements of the pitch angles of spiral galaxies at $z<3.5$
Vicki Kuhn, Yicheng Guo, Sophie Rentschler et al. (+4 more)
The properties of spiral
galaxies in the early universe remain poorly studied and, as such, little is known about their nature and
evolution. We use JWST data to measure the pitch angles of spiral
galaxies across
cosmic time. Our sample consists of 593 spiral
galaxies with
stellar masses ($M_*$) greater than $10^{10} M_\odot$ up to $z \sim 3.5$, drawn from the CEERS and JADES surveys. Spiral
galaxies are identified by fine-tuning a Zoobot deep-learning model. We use SpArcFiRe to identify spiral arms and measure their pitch angles. We find no significant
redshift evolution in the average pitch angle across the full sample. However, in the most massive systems (log$(M_*/M_\odot)=11-12$), spiral arms slightly wind up with time. We show that at $z>1.25$, pitch angle does not correlate with some key internal
galaxy properties (
stellar mass, bulge mass, disk mass, specific
star formation rate [sSFR]). In contrast, at $z<1.25$, pitch angle shows a weak but statistically significant negative correlation with
stellar mass, bulge mass, and disk mass, and a positive correlation with sSFR at $z<0.75$. We also find no dependence of pitch angle on the
tidal strength applied by nearby companions. These results indicate a transition epoch at $z\sim1$: above this
redshift, spiral structures appear to be primarily locally driven and not correlated with global
galaxy properties; and below this
redshift, spiral arms are regulated by global gravitational potential, consistent with the predictions of the density wave theory.
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All authors Vicki Kuhn, Yicheng Guo, Sophie Rentschler, Maxmillian Castillo, Gourab Nandi, Ellie Dugdale, Tsinat Mitiku
Astrophysics of Galaxies
Comparison and verification methods to trace interaction-driven disturbances in galaxies
Haotian Lyu, Sarah Brough, Aman Khalid et al. (+2 more)
Low surface brightness
tidal debris around
galaxies, such as tails, streams, and shells, together with other interaction-driven morphological disturbances, serve as valuable indicators of past or ongoing
galaxy mergers. With the growing data volume from surveys like the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), automated detection methods are essential. This paper evaluates the performance of two automated methods, a Self-Supervised Learning (SSL) model and the Concentration-Asymmetry-Smoothness (CAS) parameter method, in tracing interaction-driven disturbances and merger signatures, with visual classification used as the
benchmark. Visual classification yields a high-confidence disturbance fraction of 25.1 +/- 1.5% in our sample and serves as the reference standard for assessing the completeness and precision of the automated approaches. Visual classification is affected by
galaxy distance and image resolution, which limit the detectability of faint low surface brightness structures. The SSL model achieves high recall (0.86 +/- 0.04) and low contamination (0.2) by retraining only its linear classifier on a small labelled
dataset, making it suitable for identifying a broad set of disturbed systems, including faint
tidal debris and other interaction-driven morphological disturbances, thereby providing a more complete census of merger-related features. The CAS method, using the traditional threshold A > 0.35, shows higher precision (0.77) but lower recall (0.20), indicating a conservative approach that captures cleaner but less complete samples. Visual classification and the SSL model show a significant positive correlation between
stellar mass and disturbance fraction, while the CAS method exhibits a much weaker trend.
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All authors Haotian Lyu, Sarah Brough, Aman Khalid, Alice Desmons, Elizaveta Sazonova
Cosmology and Nongalactic Astrophysics
CMB Constraints on Pre-Inflationary Axion Dark Matter Isocurvature
Catherine Petretti, Praniti Singh, Matteo Braglia et al. (+3 more)
Although measurements of the
Cosmic Microwave Background (CMB) are consistent with a nearly scale-invariant
primordial spectrum of adiabatic perturbations, in which the energy densities of different components (radiation,
baryons, and dark matter) fluctuate proportionally, there could also exist isocurvature perturbations, in which density fluctuations of the individual components differ from the adiabatic mode. Cold dark matter isocurvature (CDI) perturbations with a variety of spectral tilts generated in pre-inflationary
axion models provide one such example. In this article, we present the most updated constraints on these
axion CDI perturbations using the latest CMB anisotropy measurements from Planck, the Atacama Cosmology
Telescope (ACT), and the South Pole
Telescope (SPT). We study both fixed spectral indices with values ranging from red- to blue-tilted spectra as well as the case with a free index. We find that the constraint on the spectral index gets moderately improved with the combined
datasets compared to Planck alone, while the bounds on the isocurvature amplitudes for the fixed spectral indices we consider do not get tighter. We also discuss the theoretical implications of our constraints, in particular for models giving rise to blue-tilted spectra.
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All authors Catherine Petretti, Praniti Singh, Matteo Braglia, Xingang Chen, JiJi Fan, Lingfeng Li
Quantum Physics
Exact Entanglement Dynamics Beyond Nearest-Neighbor Dual-Unitary Floquet Systems
Tanay Pathak
Exact results using dual-unitarity largely rely on nearest-neighbor structures, while finite-range interactions typically lead to complications. Going beyond the usual nearest-neighbor setting, we introduce an analytically tractable family of finite-range kicked Ising models that admit exact closed-form
entanglement dynamics. The construction is based on a staggered structure in which dual-unitarity is present on sublattices that are then coupled to each other. The central observation is that these inter-sublattice couplings do not obstruct the dual-unitarity of the resulting model. For the minimal interaction range of $r= 2$, we derive exact expressions for all the $n-$Rényi
entanglement entropies at all times and show that the result is the sum of the two coupled sublattice contributions. Our framework extends naturally to larger finite interaction ranges and to systems with heterogeneous local
Hilbert spaces, without additional assumptions. It thus provides a controlled setting for studying exact
entanglement growth beyond strictly nearest-neighbor dual-
unitary models.
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High Energy Physics (Phenomenology)
Direct Detection of Millicharged Particles from Supernovae
Yanou Cui, Fengyi Li, Xiaolin Qi et al. (+2 more)
This work proposes a new terrestrial probe for millicharged particles (mCPs) and demonstrates promising discovery prospects. mCPs can be copiously produced in core-collapse
supernovae (SNe), and a fraction may escape, travel to Earth and yield distinct signals. The mCP mass induces a time-of-flight (ToF) delay relative to the SN
neutrino burst, opening a clean search window after the
neutrino signal has passed. We compute the mCP-induced electron-
recoil signals at XENONnT, JUNO, DUNE, and Hyper-Kamiokande for
benchmark SN scenarios, and find that for $\varepsilon = 10^{-9}$ and sub-MeV to MeV-scale masses, more than 10 events per year can be detected. This search can improve upon existing SN cooling bound on $\varepsilon$ by up to an order of magnitude.
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All authors Yanou Cui, Fengyi Li, Xiaolin Qi, Ian M. Shoemaker, Yu-Dai Tsai