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2605.00151 2026-05-04 math.DG math.MG math.SP

Lipschitz rigidity for scalar curvature on singular manifolds in odd dimensions

Lukas Schoenlinner

Comments 40 pages

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The main result of this article is a Llarull-type rigidity statement for scalar curvature on Riemannian spin manifolds with cone-like singularities in odd dimensions. The even dimensional analog was proven in an earlier work together with Simone Cecchini, Bernhard Hanke and Thomas Schick using index theory and the analysis of abstract cone operators, which applies to Dirac operators associated with generalized cone metrics. We will extend the analysis of abstract cone operators, apply it to twisted Dirac operators on singular manifolds and combine it with a spectral flow argument to prove the main result.

2605.00150 2026-05-04 math.SP math-ph math.MP

Negative spectrum of non-local operators with periodic potential

S. Pirogov, E. Zhizhina

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The paper deals with spectral analysis of non-local operators arising in population dynamics models. We consider negative periodic perturbations of non-local operators of the convolution type. Such operators describe evolutions of the first correlation function in the stochastic birth and death dynamcis in the presence of suppression forces that increase mortality. We consider the case when the birth kernel can be non-symmetric and spatially heterogeneous. It has been proven that any negative periodic perturbation of the equilibrium dynamics generator shifts the spectrum to the left half-plane and, consequently, such a perturbation of mortality leads to the population extinction in any dimension.

2605.00149 2026-05-04 physics.chem-ph

Nuclear Spin Isomers and the Pauli Principle in Polaritonic Chemistry

Csaba Fábri, Gábor J. Halász, Lorenz S. Cederbaum, Ágnes Vibók

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The Pauli principle has far-reaching consequences in quantum physics. Here, we investigate, for the first time, its implications, together with nuclear spin isomerism, in polaritonic chemistry. We first present an accurate numerical description in a realistic situation of two $^{14}$NH$_3$ molecules, existing as ortho and para spin isomers, in an infrared cavity. Then, we generalize these results using an analytical model for molecular ensembles. Our findings undoubtedly demonstrate that the Pauli principle and nuclear spin isomerism significantly reshape collective light-matter coupling.

2605.00148 2026-05-04 math.PR math-ph math.MP

Persistence in perturbed contact models in continuum

S. Pirogov, E Zhizhina

Comments arXiv admin note: substantial text overlap with arXiv:2304.14237

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Can a local disaster lead to extinction? We answer this question in this work. In the paper \cite{PZ-PPI} we considered contact processes on locally compact metric spaces with state dependent birth and death rates and formulated sufficient conditions on the rates that ensure the existence of invariant measures. One of the crucial conditions in \cite{PZ-PPI} was the critical regime condition, which meant the existence of a balance between birth and death rates in average. In the present work, we reject the criticality condition and suppose that the balance condition is violated. This implies that the evolution of the correlation functions of the contact model under consideration is determined by a nonlocal convolution type operator perturbed by a (negative) potential. We show that local peaks in mortality do not typically lead to extinction. We prove that a family of invariant measures exists even without the criticality condition and these measures can be described using the Feynman-Kac formula.

2605.00145 2026-05-04 nlin.CD

Critical parameters of an oval billiard with an elliptical component

Anne Kétri P. da Fonseca, Joelson D. V. Hermes, Edson D. Leonel

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We explore the critical parameters responsible for the transition from integrability to chaos in a family of billiards combining elliptical and oval deformations. Unlike standard oval billiards, where a known critical parameter governs the destruction of the last invariant curve, the introduction of an integrable elliptic component yields a second deformation axis. We derive an analytical expression for the critical parameter in this combined system and validate it numerically using Slater's theorem, showing that increasing the elliptical component lowers the critical threshold for global chaos. Moreover, we uncover a previously unexplored regime: when the two deformation components are in phase, the elliptic contribution progressively suppresses chaos, leading to the restoration of invariant curves and periodic orbits. A first-order analytical approximation confirms this behavior, supported by numerical validation. Our results reveal how the interplay between distinct boundary deformations enriches phase-space organization and offers enhanced controllability of chaotic dynamics in billiard systems.

2605.00144 2026-05-04 physics.med-ph physics.bio-ph

Model-aided quantification of patient-specific benefit in mitigating radiation induced lymphopenia by particle therapy of cancer

Vladislav Sandul, Marco Durante, Thomas Friedrich

Comments 27 pages, 4 figures

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Treatment-related lymphopenia is a frequent and clinically significant consequence of cancer therapy that can compromise immune-mediated tumor control and worsen patient outcomes. Despite its importance, no mechanistic framework exists to accurately predict the severity of lymphopenia from patient-specific data. Here, we present a biokinetic model that quantitatively describes lymphocyte depletion and recovery during and after radiotherapy, integrating radiation dose-volume distributions, blood circulation dynamics, and distinct kinetics of fast- and slow-recovering lymphocyte populations. The model was calibrated and validated using 56 independent clinical datasets encompassing various tumor sites and treatment modalities. It reproduces observed lymphocyte counts and enables prediction of individual severity of lymphopenia from baseline or early-treatment counts. Applying this framework, we demonstrate that particle therapy reduces lymphocyte depletion by ~30% compared with photon therapy, providing a quantitative explanation for its observed immune-sparing benefit. By linking radiation physics, immune kinetics, and clinical outcomes, our model establishes a mechanistically grounded predictive approach for anticipating systemic immune toxicity. Beyond radiotherapy, this framework offers a generalizable strategy for integrating early biological markers into treatment optimization, advancing personalized and immune-preserving cancer therapy.

2605.00142 2026-05-04 physics.acc-ph

Achromatic Telescopic Squeezing for Dynamic Aperture Optimization in the Electron Storage Ring of the EIC

Jonathan Unger, Georg Hoffstaetter

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We investigate the application of the Achromatic Telescopic Squeezing (ATS) scheme to the Electron Storage Ring (ESR) of the Electron-Ion Collider (EIC) as a method to improve dynamic aperture and momentum acceptance. A comparative study is performed between conventional sextupole correction schemes and ATS-based optics using both a simplified test lattice and the full ESR lattice. We show that ATS optics can reduce the required sextupole strengths and mitigate higher-order nonlinear effects, leading to improved momentum aperture. With the ATS principle one could reduce the number of sextupoles in an arcs by a factor of two while maintaining similar momentum aperture. We additionally show a scheme utilizing all sextupoles which provides an advantage in momentum aperture. While the resulting ATS optics provides a measurable increase in momentum acceptance ($\sim$0.1\% under the test conditions), it also induces emittance growth due to increased $β$-functions in the arcs. This trade-off limits its applicability for the ESR but suggests potential advantages for storage rings where moderate emittance growth is acceptable.

2605.00141 2026-05-04 math.RA

Combinatorics on finite words and the length of a finite-dimensional associative algebra

M. A. Khrystik

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Let $f_W(n)$ be the number of different factors of length $n$ appearing in $W$. A classical result of Morse and Hedlund, stated in 1938, asserts that an infinite word $W$ is ultimately periodic if and only if $f_W(n)\leq n$ for some $n\in \mathbb N$. In this paper, we describe the form of finite words that satisfy the condition $f_W(n)\leq n$. We study relations between power avoidance and subword complexity of a finite word. We apply our combinatorial results to study the interrelations between various numerical invariants of finite-dimensional associative algebras.

2605.00139 2026-05-04 math.RA

Identities in differential perm algebras

F. A. Mashurov, B. K. Sartayev

Comments 25 p

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Let $(P,\cdot,d)$ be a differential perm algebra over a field of characteristic $0$, i.e. an associative algebra satisfying $(ab)c=(ba)c$ equipped with a derivation $d$. We investigate polynomial identities in the algebras obtained from $d$ by the derived operations \[ a\prec b=ab',\quad a\succ b=a'b,\quad a\blacklozenge b=ab'+ba',\quad a\bullet b=a'b+ab',\quad a\Diamond b=ab'-ba',\quad a\circ b=a'b-ab', \] where $a'=d(a)$. Our first result shows that any nontrivial differential polynomial identity (not supported by the right annihilator forced by the perm law) implies a purely differential consequence of the form $a_1'a_2'\cdots a_m'=0$ for some positive integer $m$. We then study the subalgebras of the free differential perm algebra generated by $X$ under $\blacklozenge$ and under $\bullet$, giving explicit generating sets and computing the multilinear dimensions of their homogeneous components. Finally, we construct perm-Witt type Lie and Leibniz algebras arising naturally from differential perm algebras.

2605.00138 2026-05-04 math.AG

Cylinders and the zero locus of the plinth ideal

Kirill Shakhmatov

Comments 8 pages

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Given a $\mathbb{G}_\mathrm{a}$-action on an affine variety $X$, we show that the complement of the union of all principal invariant cylinders in $X$ is equal to the zero locus of the plinth ideal of the corresponding locally nilpotent derivation.

2605.00137 2026-05-04 cond-mat.supr-con cond-mat.quant-gas

Demonstration of a fermion Quadrupling Condensate via Quantum Monte Carlo Simulation

Alexandru Golic, Egor Babaev, Johan Carlström

Comments 9 pages, 4 figures

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Fermionic condensation typically occurs via pairing. In recent decades, however, a fundamental question has emerged: whether alternative forms of order exist, such as condensates of fermion quadruplets. These states--including ``charge-4e" superconductors and ``charge-0" counterflow condensates--lie beyond the standard Bardeen-Cooper-Schrieffer framework, and require strong fluctuations and correlation effects that invalidate the BCS mean-field description. This makes the problem notoriously difficult to study numerically at a microscopic level, as it involves both strong interactions and the fermionic sign problem. Here, we present a microscopic fermionic model featuring correlated hopping that significantly mitigates the sign problem, enabling rigorous Monte-Carlo-based analysis. Using large-scale simulations, we demonstrate the existence of a fermion-quadrupling condensate with a transition temperature comparable to the hopping energy scale. These results provide direct numerical evidence for quartic fermionic order in a microscopic system and suggest that these exotic states are also experimentally accessible in ultracold atomic gases.

2605.00135 2026-05-04 cond-mat.stat-mech math.PR

Graph theoretic derivation of mutual linearity for transient probabilities and hitting time distributions in Markov networks

Julian B. Voits, Ulrich S. Schwarz

Comments Revtex, 14 pages

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For irreducible, time-homogeneous Markov networks, mutual linearity has recently been established for both occupation probabilities and network currents in the stationary regime as well as in the non-stationary regime in Laplace space. The derivation of this property for the stationary distribution utilized the Markov-chain tree theorem, which also allows for an explicit combinatorial expression of the response ratios under variation of a single transition rate. The extension of this result was proven at the trajectory level by employing the Doob-Meyer decomposition. By employing the all-minors matrix-tree theorem, we show that this property also follows from a graph theoretic formulation and derive explicit combinatorial expressions for the non-stationary response ratios. The stationary result follows as the long-time limit and we also show that the small-time asymptotics are entirely determined by minimal path distances in the underlying graph. Finally we use the graph theoretic approach to prove that mutual linearity also extends to hitting time densities.

2605.00134 2026-05-04 cs.GT

Compatible $k$-Relaxations of Fairness and Non-Wastefulness Under Hereditary Constraints

Tenma Wakasugi, Zhaohong Sun, Kei Kimura, Makoto Yokoo

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We study two-sided matching markets under hereditary constraints, which extend beyond simple capacity limits and arise in applications such as diversity requirements and refugee resettlement. In these settings, fairness and non-wastefulness are often incompatible, and existing approaches typically address this tension by prioritizing one property at the expense of the other. We take a different approach by relaxing both properties simultaneously in a controlled and symmetric manner. We introduce two notions indexed by an integer $k$: envy-received up to $k$ peers (ER-$k$) and non-wastefulness up to $k$ objections (NW-$k$). Our main theoretical result shows that ER-$k$ and NW-$k$ are always compatible under hereditary constraints for any fixed $k$. We provide two equivalent polynomial-time algorithms to compute such matchings: a $k$-admissible cutoff algorithm and a $k$-admissible college-proposing deferred acceptance mechanism. Finally, experimental results demonstrate that even small relaxations achieve a favorable balance between fairness and non-wastefulness.

2605.00132 2026-05-04 quant-ph cs.IT math.IT

Entanglement Enabled Data Transmission over an Arbitrarily Varying Channel

Janis Nötzel, Florian Seitz

Comments 6 pages, one figure, accepted for presentation at ISIT 2026

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Shared randomness is the central ingredient for stabilizing symmetrizable communication systems against arbitrarily varying jammers. Given the presence of the jammer, however, the question arises how this precious resource could have been distributed. Several works discuss the use of external sources for this task. In this work, we show, based on the most standard optical communication model, how the sender and receiver can employ entangled two-mode squeezed states to counter the jamming attack of an energy-limited jammer during the distribution phase when both the sender and jammer are allowed to use binary phase shift keying and two-mode squeezed vacuum states.

2605.00131 2026-05-04 math.OC econ.GN q-fin.EC

An Adaptive Variable Neighborhood Search for a Family of Set Covering Routing Problems with an Application in Disaster Relief Operations

Andreas Hagn, Jan Krause, Moritz Stargalla, Lorenza Moreno

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This paper studies a variant of the Set Covering Routing Problem (SCRP) motivated by post-disaster humanitarian logistics. We consider a hybrid distribution concept in which the majority of transportation is performed by helicopters, while ground transport is limited to the last mile, addressing severe accessibility constraints in disaster-affected regions. The resulting problem integrates landing site location, routing, and covering decisions, incorporating features of the Multi-Vehicle Covering Tour Problem (m-CTP) and the Vehicle Routing with Demand Allocation Problem (VRDAP) in a facility-capacitated, multi-depot setting. Due to the computational complexity of the problem, we develop an Adaptive Variable Neighborhood Search (AVNS) that combines established routing operators with novel mechanisms for covering decisions. The performance of the proposed approach is evaluated on benchmark instances for the related m-CTP and VRDAP problems, demonstrating competitive solution quality compared to problem-specific state-of-the-art approaches. Furthermore, we apply our AVNS to a real-world case study based on the 2024 flash floods in Afghanistan. The results highlight the practical relevance of the proposed framework and provide managerial insights into effective distribution strategies for disaster response operations.

2605.00129 2026-05-04 quant-ph hep-ph

Comment on "Quantum teleportation, entanglement, LQU and LQFI in $e^{+} e^{-} \rightarrow \mathrm{Y} \overline{\mathrm{Y}}$ processes at BESIII through noisy channels''

Saeed Haddadi

Comments Comment on arXiv: 2510.13402 and/or DOI: https://doi.org/10.1016/j.nuclphysb.2025.117255

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We provide a critical assessment of a recent study applying quantum information concepts, including noisy channels and teleportation fidelity, to hyperon-antihyperon pairs produced in $e^{+}e^{-} \to Y\bar Y$ reactions at BESIII. While the spin density matrix reconstructed from experimental data provides a physically meaningful description of production correlations, we argue that its subsequent interpretation in terms of standard decoherence models-such as amplitude damping, phase damping, and phase flip-lacks a clear physical correspondence for these systems. The produced particles emerge from a single scattering event and propagate as free, unstable relativistic states, without a well-defined system-environment interaction acting on their spin degrees of freedom. As a result, the variation of quantum correlations with an abstract noise parameter does not describe a genuine physical evolution. We further contend that the reported teleportation fidelity should not be interpreted as evidence for operational quantum communication, since hyperon states cannot be prepared, controlled, or measured in a way that would enable a realizable teleportation protocol. More generally, quantities such as logarithmic negativity, local quantum uncertainty, and local quantum Fisher information primarily characterize static production correlations rather than directly usable quantum resources. Our analysis highlights the importance of distinguishing between formal quantum-information measures and their physical interpretation in high-energy particle systems.

2605.00127 2026-05-04 quant-ph hep-ph

Comment on "Controlling the dynamical evolution of quantum coherence and quantum correlations in $e^{+} e^{-} \rightarrow Λ\barΛ$ processes at BESIII''

Saeed Haddadi

Comments Comment on arXiv: 2510.25615 and/or DOI: https://doi.org/10.1103/kxw9-wdth

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We critically examine recent claims [Phys. Rev. D 113, 016024 (2026)] regarding quantum coherence, steering, and non-Markovian dynamics in the hyperon-antihyperon system produced in the process $e^{+} e^{-} \rightarrow Λ\barΛ$. We argue that the theoretical framework employed in the analyzed work suffers from fundamental physical inconsistencies. In particular, the treatment of the $Λ\barΛ$ pair as a bipartite system evolving under correlated quantum channels is not physically justified, since the produced hyperons are free, unstable particles that do not interact with a common environment after production. Consequently, the application of open quantum system techniques, including Markovian and non-Markovian quantum channels, lacks a clear physical basis. Moreover, we show that the computation and interpretation of quantum steering for this system is operationally and conceptually meaningless, as no well-defined measurement-induced state update or controllable local measurement scenario exists for unstable relativistic particles. These issues call into question the physical relevance of the reported quantum correlations, their hierarchy, and their dynamical behavior. Our analysis highlights the necessity of carefully distinguishing between formal mathematical quantifiers of quantumness and physically realizable quantum information protocols in high-energy particle systems.

2605.00122 2026-05-04 astro-ph.CO astro-ph.GA

Towards a measurement of the primordial helium isotope ratio

Ryan J. Cooke, James W. Johnson, Pasquier Noterdaeme, Max Pettini, Louise Welsh, Aldric Wong, Celine Peroux

Comments 21 pages, 5 figures, Accepted for publication in the Astrophysical Journal

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We report the discovery of two metastable neutral helium (He I*) absorbers in the Milky Way, and use the upgraded CRyogenic InfraRed Echelle Spectrograph on the Very Large Telescope to determine the helium isotope ratio, $^{3}$He/$^{4}$He, along these sightlines. We have also obtained deeper observations of a third sightline to report a $\lesssim4\%$ precision measure of $^{3}$He/$^{4}$He in the Orion Nebula. These data have allowed us to place a $2σ$ limit on the time-variability of He I* absorption in the Orion nebula, ${\rm d}\log_{10} [N({\rm He\,I}^{*})/{\rm cm}^{-2}]/{\rm d}t\leq7.2\times10^{-4}~{\rm dex~yr}^{-1}$ ($<0.17\%~{\rm yr}^{-1}$), suggesting that these absorbers are in radiative equilibrium. We compute new galactic chemical evolution models of the Milky Way, and use our observations to infer the primordial helium isotope ratio and a scaling factor for the yields reported by nucleosynthesis calculations. Based on the data and models that we report here, we infer a best-fit value ($^{3}$He/$^{4}$He)$_{\rm P}=(1.15^{+0.24}_{-0.21})\times10^{-4}$, which agrees with Big Bang nucleosynthesis calculations that assume the Standard Model of particle physics in combination with the baryon density inferred from the cosmic microwave background temperature fluctuations. We infer the stellar yield scale relative to the solar metallicity, $y/Z_{\odot}=2.12^{+0.31}_{-0.29}$, which is somewhat higher than previously found. Finally, we note that the forthcoming extremely large telescopes are poised to determine $^{3}$He/$^{4}$He in more metal-poor environments, to secure a model-independent determination of the primordial value.

2605.00118 2026-05-04 quant-ph

Toward Secure Multitenant Quantum Computing: Circuit Affinity, Crosstalk Patterns, and Grouping Strategies

Andrew Woods, Chi-Ren Shyu

Comments 11 Pages, 8 Figures. This work was submitted to an IEEE conference for possible publication

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Multitenancy increases throughput and reduces costs in cloud-based quantum computing, but concurrent job execution introduces security risks through inter-circuit crosstalk. We characterize the structural predictability of these interference patterns across seven IBM superconducting processors, spanning Heron (r1-r3) and Nighthawk (r1) architectures and five different circuit types. We evaluate pairwise interactions, by applying the Structural Similarity Index (SSIM) and a structural $t$-statistic to the concurrent execution of five foundational quantum circuits (QAOA, Grover's, QPE, QFT, and ZZFeatureMap), we quantify behavioral consistency across disparate hardware. Our results identify three types of circuits: universally aggressive, universally sensitive, and cotenant-dependent circuits. Aggressive circuits, such as Grover's Algorithm, exhibit a statistically significant interference pattern, yielding a $t$-statistic range of $[1.37,2.61]$ relative to the standalone baselines across all tested pairings. Conversely, sensitive circuits, such as the Quantum Fourier Transform, demonstrate a disproportionate susceptibility to multitenant execution, showing high deviations from single-tenant computational behavior. We demonstrate that crosstalk signatures are highly consistent within architectural revisions--with intra-revision similarity reaching $0.77$ (Hr3) and $0.68$ (Hr2)--while inter-revision similarity drops to $0.43$. Furthermore, we identify a ``topological decoupling" between Heavy-Hex and square lattice systems, where structural similarity falls to $0.01$ between Heron r1 and Nighthawk r1. These findings provide an empirical foundation for hardware-aware schedulers to strategically pair jobs, maximizing system utilization while preserving computational integrity.

2605.00117 2026-05-04 quant-ph math-ph math.MP

Topological Charge of Causality at a PT-Symmetric Exceptional Point

Kejun Liu

Comments 4 pages, 4 figures. Supplemental Material included (2 pages)

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Causality in linear response is conventionally treated as a binary property: a response function is either analytic in the upper half-plane or it is not. We show that in a PT-symmetric open dimer it instead carries a topological charge. As the gain-loss parameter crosses the exceptional point, a single pole of the reflection coefficient migrates into the upper half-plane, the Blaschke winding number jumps from 0 to 1, and standard Kramers-Kronig (KK) reconstruction acquires a Lorentzian residual fixed by the pole residue. The transition is sharp, protected by the codimension-one structure of the exceptional point, and directly measurable in a one-port reflection experiment. Most strikingly, the violation magnitude scales as Delta_KK ~ |gamma - gamma_c|^nu with nu ~ -1.08 in the single-port geometry: the breakdown of standard KK is strongest at threshold and weakens deeper in the broken phase. We derive the exact reflection coefficient, verify the residue-corrected dispersion relation, and propose a THz time-domain spectroscopy protocol that detects the topological charge through the residual itself.

2605.00115 2026-05-04 hep-ph

Crossing into the $m_a > f_a$ Region for Leptophilic ALPs

Marta F. Zamoro, Álvaro Lozano-Onrubia, Luca Merlo, Samuel Rosende Herrero

Comments Mathematica ancillary file, 34 pages

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Axion-like particles (ALPs) are typically identified as pseudoscalars whose couplings are shift-symmetry invariant with the exception of their couplings to gauge bosons and their mass term. Additionally, the ALP mass $m_a$ is usually assumed to be (much) smaller than the ALP decay constant $f_a$. The latter condition is conservative, at best, and excludes part of the ALP parameter space that is presently viable. We revisit the interpretation of the $m_a\ll f_a$ and perform an analysis focussing on leptophilic ALPs. In particular, we explore regions of the parameter space still uninvestigated, where $m_a>f_a$, thus providing a phenomenological study of the ALP-lepton couplings complementary to the existing literature. We point out that a leptophilic ALP may explain the $-3.8σ$ tension in the anomalous magnetic dipole moment of the electron for the Caesium determination in a large region of the $m_a\times f_a$ parameter space, testable in the near future through studies on $μ\to e$ conversion in nuclei.

2605.00114 2026-05-04 gr-qc

The formalism of energy conservation during particle decay in the Kerr spacetime

Shurui Zhang, Remo Ruffini

Comments comments are welcome!

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We derive a compact, covariant expression for the relative Lorentz factor of two particles in curved spacetime and apply it to particle decay in Kerr spacetime. This allows us to show that energy conservation in the local center-of-mass frame requires the rest-mass loss of the parent particle to be converted into kinetic energy of the decay products. We verify this relation analytically and confirm it with high-precision reconstructions of three representative Penrose-process examples, for which both equivalent conservation formulas are satisfied to machine precision. These results clarify the local kinematics underlying energy extraction from rotating black holes and show that mass loss is not optional but is required for the decay products to separate.

2605.00112 2026-05-04 physics.optics quant-ph

Cryogenic Graphene-Based Phase Modulators for Quantum Information Processing

Leonard Barboza Navarro, Maria Carolina Volpato, Alisson Ronieri Cadore, Pierre-Louis de Assis

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Electro-optic modulators are key components for photonic quantum computing, particularly in fully cryovenic integrated platforms where low loss and compactness are critical. We present a systematic theoretical investigation of compact dual-layer graphene (DSLG) electro-optic phase modulators integrated on silicon nitride waveguides, with emphasis on cryogenic operation. By combining electromagnetic simulations with a physically consistent description of graphene conductivity based on the Kybo formalism, we analyze the interplay between electrostatic tuning, optical mode confinement, and material-dependent losses. We show that cryogenic operation enhances device performance by sharpening the Fermi-Dirac distribution, enabling access to the Pauli-blocking regime at lower Fermi levels and reducing the required modulation length. Through optimization of the waveguide geometry, dielectric spacer thickness and permittivity, and graphene quality, we identify regimes that simultaneously minimize insertion loss and device footprint under realistic voltage constraints. The optimized designs achieve near-pure phase modulation with insertion losses below 0.3 dB and modulation lengths below 50 um at 10 K, while maintaining GHz-scale bandwidths. These results provide quantitative design guidelines for low-loss, compact, cryogenic graphene phase modulators for scalable integrated quantum photonics.

2605.00110 2026-05-04 math.AP

Formation and Behavior of Dirac Singularities in the Parabolic-Elliptic Keller-Segel System in Dimensions $n\geq 3$

Gregor Flüchter

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We consider nonnegative radially symmetric solutions of the parabolic-elliptic Keller-Segel system \begin{align*} \left\lbrace \begin{array}{r@{}l@{\quad}l} &u_t=Δu-\nabla \cdot \big(u\nabla v\big),\\ &0=Δv -μ+ u , \\ \end{array}\right. \end{align*} where $μ$ is the spatial average of $u$, under homogeneous Neumann boundary conditions in a ball in $\mathbb R^n$ for $n\geq 3$. In two dimensions, it is well established that solutions blowing up in finite time converge to a Dirac profile in the vague topology. In contrast, for $n\geq 3$, blow-up solutions with finite existence time do not appear to exhibit such concentration behavior. By generalizing to measure-valued solutions corresponding to accumulated densities of $u$, we extend the analysis beyond the blow-up time. Within this framework, we establish the existence of a minimal solution \[ u(t)=θ(t)δ_0 + ρ(\cdot,t) dx, \qquad t \geq 0, \] where $ρ$ is integrable and $θ$ is increasing and right-continuous. We further construct a class of initial data for which $θ(t_0)>0$ for some $t_0>0$, thereby establishing the formation of a Dirac mass at the origin. Unlike in the case $n=2$, the singular mass does not jump to a positive level instantaneously; instead, $θ$ becomes positive continuously. Moreover, $θ$ is strictly increasing on $[t_0,\infty)$, and the entire mass is asymptotically absorbed at the origin.

2605.00109 2026-05-04 cs.HC

What is (H)CI: Why Does the "Human'' Matter?

Sejal Agarwal, Delara Forghani, Brandon Lit, Thomas Driscoll, Anthony Maocheia-Ricci

Comments Accepted Workshop Proposal for Graphics Interface 2026

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Human-Computer Interaction (HCI) is a diverse field bringing together theories and methods from fields such as computer science, psychology, and human factors. Historically, HCI has focused on the human through ``user'' or ``human'' centered design, where the focus was either on information processing or understanding people and their concerns with respect to technology. However, amid the increasing adoption of generative AI tools, this workshop explores two critical questions in regards to HCI: What is HCI? and Why does the ``human'' matter? We aim to bring together researchers from diverse disciplines to reflect on these questions. Through guided discussions, group brainstorming, and reflection, we explore what HCI means, what the field may look like in the future, and why it is important to remember the ``human'' aspect of the field.

2605.00108 2026-05-04 physics.soc-ph econ.GN q-fin.EC stat.AP

Urban Science Beyond Samples: Up-to-Date Street Network Models and Indicators for Every Urban Area in the World

Geoff Boeing

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Journal ref
Environment and Planning B: Urban Analytics and City Science, 2026
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Urban planners need up-to-date, global, and consistent street network models and indicators to measure resilience and performance, model accessibility, and target local quality-of-life interventions. This article presents up-to-date street network models and indicators for every urban area in the world. It uses 2025 urban area boundaries from the Global Human Settlement Layer, allowing users to join these data to hundreds of other urban attributes. Its workflow ingests 180 million OpenStreetMap nodes and 360 million OpenStreetMap edges across 10,351 urban areas in 189 countries. The code, models, and indicators are publicly available for reuse. These resources unlock worldwide urban street network science beyond samples as well as local analyses in under-resourced regions where models and indicators are otherwise less-accessible.

2605.00106 2026-05-04 quant-ph cs.DS cs.LO

From Tensor Networks to Tractable Circuits, and back

Arend-Jan Quist, Marc Farreras Bartra, Alexis de Colnet, John van de Wetering, Alfons Laarman

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Tensor networks and circuits are widely used data structures to represent pseudo-Boolean functions. These two formalisms have been studied primarily in separate communities, and this paper aims to establish equivalences between them. We show that some classes of tensor networks that are appealing in practice correspond to classes of circuits with specific properties that have been studied in knowledge compilation as \emph{tractable circuits}. In particular, we prove that matrix product states (tensor trains) coincide with nondeterministic edge-valued decision diagrams and that tree tensor networks exactly correspond to structured-decomposable circuits. These correspondences enable direct transfer of structural and algorithmic results; for example, canonicity and tractability guarantees known for circuits yield analogous guarantees for the associated tensor networks, and vice versa.

2605.00105 2026-05-04 astro-ph.CO

Deep Learning galaxy cluster's structural parameters from Weak Lensing observations

M. Fogliardi, M. Meneghetti, C. Giocoli, L. Moscardini, P. Rosati, L. Leuzzi, G. Angora, L. Bazzanini, C. Spinelli

Comments 18 pages, 9 figures. Submitted to A&A

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英文摘要

Galaxy clusters are the most massive gravitationally bound structures in the Universe and key probes of cosmic evolution. The large data volume expected from upcoming surveys requires efficient automated analysis methods for tens of thousands of clusters. We present a study using Convolutional Neural Networks (CNNs) to infer cluster structural parameters from weak gravitational lensing observations. Three architectures (VGG-Net, Inception-v4, Inception-ResNet-v2) were implemented in PyTorch and trained on 75,000 synthetic reduced shear maps generated with MOKA, simulating galaxy clusters at $z = 0.25$. The networks simultaneously predict five parameters: virial mass, NFW concentrations, substructure count, and substructure mass fraction. Tests on 5000 clusters show high accuracy for primary properties. With realistic noise ($n_{\rm gal}=30$, $σ_ε=0.3$), mass predictions remain robust (RMS $\sim 1.02 \times 10^{14}$ M$_\odot$/h, $\sim20$\% deviation). Concentration estimates are stable, with VGG-22 achieving the lowest RMS. Substructure properties are more challenging, with systematic underestimation across models. Comparison with traditional shear profile fitting shows improved CNN performance. VGG-22 achieves near-unbiased mass estimates and significantly better concentration recovery, reducing systematic errors. These results demonstrate that CNNs provide an effective and scalable alternative to traditional methods, particularly suited for large survey datasets.[Abridged]

2605.00104 2026-05-04 cond-mat.str-el cond-mat.stat-mech hep-th quant-ph

Criticality on Rényi defects at (2+1)$d$ O(3) quantum critical points

Yanzhang Zhu, Zhe Wang, Meng Cheng, Zheng Yan

Comments 7+4 pages; 4+6 figures

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英文摘要

At a quantum critical point, the universal scaling behavior of Rényi entanglement entropy is controlled by the universality class of the codimension-two Rényi (or conical) defects in the infrared theory. In this work we perform a systematic study of critical correlations along Rényi defect lines in (2+1)d quantum spin models realizing quantum phase transitions described by the O(3) Wilson-Fisher universality class, using large-scale quantum Monte Carlo simulations. We present numerical evidence that, for a fixed Rényi index $n$, there exist multiple Rényi defect universality classes, with distinct critical exponents for the O(3) order parameter on the defect. These universality classes are realized by choosing microscopically different entanglement cuts in lattice models, which we classify as ordinary, special and extraordinary according to their relation to surface criticality. For the extraordinary entanglement cut, we further find evidence for a phase transition on the defect as a function of the Rényi index. Our results highlight the key role of defect universality classes in determining the universal scaling of Rényi entropy, and provide a framework for understanding the previously observed dependence of Rényi entropy scaling on microscopic lattice details.

2605.00103 2026-05-04 hep-ph astro-ph.CO hep-th

Pre-inflationary QCD axion stars after moduli domination

Edward Hardy, Noelia Sánchez González, Henry Stubbs, Lorenzo Tranchedone

Comments 5 pages + appendices

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英文摘要

The growth of adiabatic density perturbations during an era of early matter domination induces $\mathcal{O}(1)$ fluctuations in pre-inflationary QCD axion dark matter across a broad, string-theory-motivated parameter space. Remarkably, at $Λ$CDM matter-radiation equality the scale of these perturbations coincides with the quantum Jeans scale, so they collapse to solitonic ``axion stars''. These axion stars have densities up to $10^4\,\mathrm{eV}^4$, and, including their surrounding halos, they contain as much as $50\%$ of dark matter. Direct searches for a smooth axion background can be suppressed, but transient enhancements or indirect astrophysical signals at axion masses $m_a\lesssim 10^{-5}\,{\rm eV}$ would point to a non-standard cosmological history.