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Physics

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Tuesday 30 June

High Energy Physics (Theory)

The geometric bookkeeping guide for $\varepsilon$-factorised differential equations

Antonela Matijašić

Precision predictions for high-energy experiments rely on accurately evaluating multi-loop, multi-scale Feynman integrals in dimensional regularisation. The method of differential equations is by now the standard tool for this task, but its full power is only realised when the system can be brought into an $\varepsilon$-factorised form. In this talk, we present an algorithmic framework that systematically constructs $\varepsilon$-factorised differential equations for arbitrary integral families, independent of their underlying geometry. We work in the setting of twisted cohomology and study the space of differential forms associated with a given family of Feynman integrals in the Baikov representation. Our approach consists of two steps. First, we introduce a particular ordering for the Laporta algorithm that orders Feynman integrals within a sector according to their geometric properties. We observe that this order relation yields a basis whose differential equation is in a Laurent polynomial form in the dimensional regulator $\varepsilon$. In the second step, we systematically construct transformation matrices such that the resulting system is in the $\varepsilon$-factorised form.
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Instrumentation and Methods for Astrophysics · Cross-listed from math.NA

GQL-Based Physical-Constraint-Preserving High-Order Finite Difference Schemes for Special Relativistic Hydrodynamics in Arbitrary Dimensions

Linfeng Xu, Shengrong Ding and Kailiang Wu

High-order accurate simulations of special relativistic hydrodynamics (RHD) are prone to numerical breakdown if intrinsic physical constraints (positive rest-mass density/pressure and subluminal velocity) are violated near strong discontinuities. In this work, we develop a robust and efficient physical-constraint-preserving (PCP) flux-limiting framework for high-order schemes, using finite-difference WENO as a representative example. By leveraging the geometric quasilinearization (GQL) representation, which equivalently reformulates the nonlinear RHD constraints into a family of linear inequalities, we integrate a Zalesak-type Flux-Corrected Transport (FCT) update into a scalar-style limiter that acts directly on conservative variables. A critical innovation is the explicit, non-iterative determination of limiting parameters via a rational stereographic parameterization of the GQL normal vector. This technique transforms the required worst-case minimization over auxiliary variables into a generalized Rayleigh-quotient formulation, allowing the optimal parameters to be obtained by solving small symmetric eigenvalue problems ($2\times2$ in 1D; $(d+1)\times(d+1)$ in $d$ dimensions). Relaxed variants are further introduced to reduce computational costs in multidimensions while retaining the PCP guarantee. Extensive numerical benchmarks ranging from 1D to 3D, including ultra-relativistic Riemann problems and astrophysical jets, demonstrate that the proposed method robustly enforces physical admissibility, sharply resolves discontinuities, and maintains design-order accuracy for smooth solutions.
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Statistical Mechanics

Exploring the entropic asymmetry on logical stochastic resonance with energetically equivalent intrinsic outputs

Vipul Rai and Moupriya Das

Small-scale systems are inherently subject to environmental noise that can be harnessed constructively to realize reliable logic operations – a phenomenon known as logical stochastic resonance (LSR), where a bistable system produces correct logical outputs within an optimal window of noise intensity. The Brownian dynamics governed by appropriate inputs inside a double-well potential, modeling the bistable system, mimic the logic operations. The two wells of this potential represent two distinct logical output states 0 and 1. Asymmetry in this potential is known to be essential for improving logical reliability. However, prior studies have focused on energetic asymmetry, characterized by unequal depths of the two wells of the potential. This left the role of the width asymmetry in the potential, unexplored. This latter class of asymmetry emerges due to the dissimilar widths of the two wells of the potential. It can be classified as the entropic asymmetry between the two logical output states. Here, we systematically investigate the effect of width or the entropic asymmetry in the system on the logical response for OR and AND gate operations. Unlike energetic asymmetry, width asymmetry preserves the energetic equivalence of the two intrinsic logical output states, making it a geometric effect. We find that increasing width asymmetry consistently improves the optimal P(logic), the quantifier measuring the successful logical outcome. Moreover, when it is combined with an energetic bias, it produces reliable logic gate operation at a significantly reduced energetic cost compared to the symmetric case. The requirement of this energy bias also diminishes gradually with the increasing degree of width asymmetry in the potential.
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Cosmology and Nongalactic Astrophysics

Joint inference of weak lensing convergence map and cosmology with diffusion models

Benjamin Remy, Chihway Chang and Rebecca Willett

We present a method for joint inference of cosmological parameters and convergence maps from weak lensing observations, targeting the full posterior conditioned on the observed shear field. Our approach uses implicit inference with diffusion models, learning the joint distribution from simulations, without the need to have an explicit and differentiable forward model for gradient-based MCMC sampling. We introduce a transformer-based architecture that operates in pixel space and treats cosmological parameters as additional tokens in a unified sequence, enabling efficient multimodal processing within a single network. At inference time, the trained model generates posterior samples of joint convergence maps and cosmological parameters conditioned on observed noisy shear fields. We demonstrate the method on simulated weak lensing data generated from log-normal fields in a wcdm cosmology. The model accurately reconstructs convergence maps and recovers cosmological posteriors that agree with traditional MCMC, while remaining well calibrated across the prior, with a MIRA calibration score of $0.635 \pm 0.017$ on the joint posterior (where $0.667$ is optimal). The inferred fields reproduce the correct two-point statistics as well as non-Gaussian statistics such as the one-point distribution. This work establishes diffusion-based implicit inference as a viable route toward full field-level cosmological analyses, paving the way for applications to more realistic, non-differentiable simulators.
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High Energy Physics (Theory)

BMPV black hole at first order in $\alpha'$

Alejandro Ruipérez

We consider the low-energy effective action of the heterotic string and derive an analytic solution describing the first-order $\alpha'$ corrections to the supersymmetric and extremal BMPV black hole with three unequal charges. The solution interpolates between an asymptotically-flat region and the near-horizon geometry. We compute the corrected black hole entropy using a generalization of Wald formula available in the literature, which correctly accounts for the Lorentz Chern-Simons term. The resulting expression agrees with recent results in the literature, which are based on the evaluation of an appropriate supersymmetric index.
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Statistical Mechanics

Non-Maxwellian Velocity Statistics in Supercooled Liquids and Their Possible Relation to Super-Arrhenius Viscosity

Giorgi Tsereteli and Zohar Nussinov

For particles of fixed mass, classical equilibrium statistical mechanics dictates a Maxwellian velocity distribution determined solely by the temperature, regardless of the interactions, density, or structure. Supercooled glass forming liquids realize long lived metastable states that evade equilibrium crystallization and may thus violate assumptions underlying Maxwellian statistics. We numerically demonstrate that supercooled liquids can exhibit persistent non-Maxwellian velocity distributions with deviations connected to their exceptionally slow super-Arrhenius relaxation. Our work is motivated by a general result establishing that long lived metastable states may exhibit finite width distributions of intensive variables. A distribution of temperatures implies non-Maxwellian velocity statistics. We test this prediction by introducing stochastic thermostats that generate stationary states while, unlike conventional thermostats, not imposing Maxwellian velocity distributions. Simulations with these thermostats yield long lived states that have, by comparison to Maxwellian velocity distributions, an excess kurtosis $0<\kappa\lesssim0.3$. Crystallization is strongly impeded with increasing $\kappa$. In a minimal description, temperature fluctuations are characterized by a dimensionless width $\overline{A}$ with $\kappa\simeq3\overline{A}^{2}$. The nearly constant $\overline{A}$ (of an average value $0.08$ and standard deviation $0.03$) found in viscosity data collapse across $45$ glass formers and in specific heat signatures is consistent with kurtosis found in our simulations. Long time non-Maxwellian velocity statistics may thus link slow relaxation, transport, and thermodynamic measurements. Independent of the tested theory, the stochastic thermostats that we introduce offer a molecular dynamics route to non-Maxwellian velocity statistics.
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Astrophysics of Galaxies

COSMOS-Web: does halo mass alone shape the clustering of star-forming and quiescent galaxies?

Louise Paquereau, Clotilde Laigle, Henry Joy McCracken et al. (+29 more)

While stellar mass correlates strongly with halo mass, it remains unclear whether halo mass alone governs galaxy star-formation activity, or whether secondary halo properties and environment also play a role. We investigate these effects beyond halo mass by measuring the auto- and cross-correlations of star-forming and quiescent galaxies in the COSMOS-Web survey from $z = 5$ to the present day. To isolate environmental contributions, we introduce a method that matches the halo mass distributions of both populations using the UniverseMachine model. We find that quiescent galaxies remain more strongly clustered than star-forming systems by at least $0.5-1$ dex at all redshifts, even after controlling for halo mass. At $z \le 2$, this excess clustering increases towards lower stellar masses, with the most clustered objects being $\log(M_\star/{\rm M}_\odot) \le 9.5$ quiescent galaxies. This points to environmental quenching significantly affecting low-mass galaxies at $z \le 2$, likely driven by ram-pressure stripping or the suppression of cold gas accretion, as these objects show disky morphologies. Cross-correlations further reveal one-halo conformity up to $z \simeq 2$: low-mass (or satellite) quiescent galaxies are more strongly clustered around massive (or central) quiescent galaxies than around star-forming centrals of the same halo mass. This signal may arise from quenching mechanisms affecting both centrals and satellites, correlated assembly histories prior to infall, or dependencies on secondary halo properties. Both environmental quenching and conformity appear to vanish between $z \simeq 5$ and $2$. Together, these results challenge the common assumption that clustering and star-formation activity depend solely on halo mass.
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All authors Louise Paquereau, Clotilde Laigle, Henry Joy McCracken, Olivier Ilbert, Hollis B. Akins, Rafael C. Arango-Togo, Nguyen Binh, Caitlin M. Casey, Yohan Dubois, Maximilien Franco, Ghassem Gozaliasl, Santosh Harish, Michaela Hirschmann, Baptiste Jego, Aidan Kaminsky, Jeyhan S. Kartaltepe, Anton Koekemoer, Damien Le Borgne, Joseph S. W. Lewis, Daizhong Liu, Georgios Magdis, Jed McKinney, Wilfried Mercier, Lauro Moscardini, Thibaud Moutard, Jason D. Rhodes, Brant E. Robertson, Sogol Sanjaripour, Marko Shuntov, Greta Toni, Maxime Trebitsch, Laurence Tresse

Cosmology and Nongalactic Astrophysics

Constraining dark energy with complementary probes of large-scale structure

Neel Shah, Kazuya Koyama, Johannes Noller et al. (+1 more)

To observationally pin down the nature of dark energy, it is essential to consistently model cosmological perturbations in the presence of dark energy alongside the background expansion and constrain this joint theory space with a large array of complementary probes. Here, we achieve this by constraining a model in the Effective Field Theory of Dark Energy (EFTofDE) framework by supplementing probes of the expansion history with several probes of large-scale structure: redshift space distortions (RSD) from DESI DR1, $3\times2$pt measurements from DES Y3, and the Integrated Sachs-Wolfe effect from cross-correlating CMB temperature anisotropies with galaxy number counts or CMB lensing. We demonstrate the complementarity of different probes which leads to strong improvements on constraints on DE perturbations. For our most constraining dataset combination that supplements CMB+BAO+SNe probes with DESI DR1 RSD, DES Y3 $3\times2$pt and ISW cross-correlations between CMB temperature and galaxy counts, we find an improvement in the Figure of Merit (FoM) for the DE perturbation parameters $\{c_B, c_M\}$ by a factor of 2.69. We show the phenomenological implications of these constraints by mapping them to the present-day values of the phenomenological functions $\{\mu(z), \Sigma(z)\}$, where we see an FoM improvement by a factor of 3.37. We find a significant interdependence between the posteriors of $\{w_0, w_a\}$ and $\{c_B, c_M\}$, caused by the theoretical prior imposed by the gradient stability condition within the EFTofDE framework. Finally, we compute the significance of deviation from $\Lambda$CM for the EFTofDE model when constrained with CMB+BAO+SNe datasets, finding it to be at 2.9$\sigma$. This significance is nontrivially similar to the significance for the $w_0w_a$CDM model for the same dataset combination which we find to be 3.1$\sigma$.
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All authors Neel Shah, Kazuya Koyama, Johannes Noller, Lanyang Yi

High Energy Physics (Phenomenology)

Reheating in No-Scale Models of Inflation

Ignatios Antoniadis, John Ellis, Dimitri V. Nanopoulos et al. (+2 more)

Analogously to the suppression of inflaton decays into conformally-coupled scalar fields in the original Starobinsky $R + R^2$ model of inflation, inflaton decays to Standard Model fields are also suppressed in minimal no-scale models of inflation with field space curvature $\mathcal{R} = 2/3$. We study how this suppression can be avoided in generalized no-scale inflationary models. These include models in which the field space curvature $\mathcal{R} = 2/(3\alpha)$ with $\alpha \ne 1$ as exemplified by models derived from string theory, as well as models with non-minimal gauge kinetic terms and anomaly-induced couplings. We analyze direct and anomaly-induced inflaton couplings to gauge bosons and gauginos and demonstrate the Kähler-frame invariance of the physical gauge coupling. We determine the resulting reheating temperatures and the corresponding predictions in the $(n_s,r)$ plane. Finally, we consider an $R^3$ deformation of Starobinsky supergravity, which modifies the inflaton and stabilizer sectors but does not, by itself, generate new tree-level inflaton couplings to visible matter fields.
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All authors Ignatios Antoniadis, John Ellis, Dimitri V. Nanopoulos, Keith A. Olive, Sarunas Verner

Pattern Formation and Solitons

Dissipative surface solitons in two-dimensional truncated lattices with linear gain and loss

Changming Huang, Yan Wang, Pengcheng Liu et al. (+2 more)

Dissipative solitons constitute a robust class of self-localized nonlinear states sustained by the dynamic balance between nonlinearity and gain-loss, possessing an intrinsic stability that stems from their fundamental attractor nature. When combined with lattice truncation, this balance gives rise to dissipative surface solitons (DSSs), whose existence and stability are jointly dictated by boundary-induced confinement and non-Hermitian dynamics. In two-dimensional truncated lattices with linear gain and loss, surface localization emerges within gap regimes, where families of DSSs bifurcate from linear surface localized gain modes as the nonlinearity increases. Increasing the number of waveguide rows at the interface enriches the diversity of supported surface modes in both linear and nonlinear regimes. Although multiple DSS families with distinct phase configurations may coexist within the same gap, their dynamical stability is strongly phase selective. These insights establish linear gain-loss engineering as a powerful mechanism for controlling nonlinear surface localization and provide practical guidelines for realizing robust nonlinear surface states in gain-loss-tailored photonic platforms.
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All authors Changming Huang, Yan Wang, Pengcheng Liu, Qidong Fu, Liangwei Dong

Quantum Physics

The contact temperature of arbitrary quantum states

Alain Joye and Marco Merkli

An intuitive scheme to assign a temperature to an arbitrary state of a quantum system is to investigate the heat flow resulting from the coupling to a thermometer. We introduce a simple model of a universal thermometer with the following property. When it is prepared in a Gibbs equilibrium state at inverse temperature $\beta\in\mathbb R$ and brought into thermal contact with a system in any state, the heat flow between the system and thermometer vanishes for a unique value of $\beta$. We call this value the contact temperature $\beta_{\rm op}\in\mathbb R$ of the system state. The thermometer is universal in that it yields a unique contact temperature for arbitrary states of finite dimensional quantum systems.
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Astrophysics of Galaxies

Caught in the act: interaction-driven evolution in the nearby compact galaxy group Roberts Quartet (SCG0018-4854)

Saili Keshri, Sudhanshu Barway, Mousumi Das et al. (+1 more)

We present a spatially resolved multiwavelength study of the compact galaxy group Roberts Quartet (RQ, SCG0018-4854), aimed at understanding interaction-driven galaxy evolution in a dense environment. RQ comprises of four galaxies (NGC 87, NGC 88, NGC 89, and NGC 92) that span a range of masses and evolutionary states. Using UV-to-IR data from GALEX, DECaLS, MUSE/VLT (IFU), VISTA/VIRCAM, 2MASS, and WISE, we investigate the interplay between kinematics, star formation, and stellar populations across the group. The spatially resolved analysis reveals disturbed stellar and gas kinematics, enhanced turbulence, and asymmetric structures in all members, consistent with repeated gravitational interactions. The most massive galaxy, NGC 92, exhibits prominent tidal features, a bar, and ring-like star-forming structures, indicative of interaction-driven gas inflows. Another massive member, NGC 89, shows suppressed star formation and signatures of AGN-driven feedback, while the lower-mass galaxies NGC 88 and the dwarf galaxy NGC 87 display enhanced star formation and kinematic decoupling between stellar and gas component consistent with recent gas accretion. Combining UV age estimates with non-parametric star formation histories, we constrain the recent interaction timescale of the group to <= 500 Myr, whereas the crossing timescale is 424 Myr. These results indicate that RQ is a dynamically young system undergoing ongoing assembly, where interactions, gas exchange, and feedback processes are actively shaping galaxy evolution. The dynamical complexity of the group further suggests that its present configuration may involve more than four progenitor components. In this context, RQ provides a nearby analogue of compact, rapidly evolving groups observed at high redshift by recent JWST observations, offering a resolved view of the physical processes governing galaxy assembly in the early Universe.
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All authors Saili Keshri, Sudhanshu Barway, Mousumi Das, Abhishek Paswan

Atmospheric and Oceanic Physics · Cross-listed from stat.AP

Locally stationary Argo ocean heat content estimates: Modeling, validation and uncertainty quantification

Thea Sukianto, Mikael Kuusela, Donata Giglio et al. (+3 more)

Argo profiling floats measure seawater temperature and salinity in the upper 2000 meters of the ocean. These floats are uniquely capable of measuring the global Ocean Heat Content (OHC), a quantity that is of central importance for understanding Earth Energy Imbalance. Yet, producing Argo-based OHC estimates with reliable uncertainties is statistically challenging due to the complex structure and large size of the Argo dataset. Here we present an end-to-end mapping and uncertainty quantification framework for Argo-based OHC estimation using state-of-the-art methods from spatio-temporal statistics. The framework is based on modeling vertically integrated Argo temperature profiles as a locally stationary Gaussian process defined over space and time. This enables us to produce computationally tractable OHC anomaly maps based on data-driven decorrelation scales estimated from the Argo observations. Our modeling choices are validated using statistical cross-validation, which demonstrates the importance of including a climatological time trend in the mean field and accounting for time in the covariance function. We quantify the uncertainty of these maps using local conditional simulation ensembles, a novel approach that leads to principled spatially and temporally correlated uncertainty quantification. A new paired cross-validation technique is presented to validate these uncertainties. The mapping framework is implemented in an open-source codebase that is designed to be modular, reproducible and extensible. To demonstrate the mapping and uncertainty quantification capabilities of this approach, we present new Argo OHC maps with uncertainties for 2004-2022 and report on various downstream climatological estimates and their uncertainties.
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All authors Thea Sukianto, Mikael Kuusela, Donata Giglio, Anirban Mondal, Pulong Ma, Douglas W. Nychka

High Energy Physics (Theory)

Convergence of Nekrasov instanton sum for unitary quivers

Bruno Le Floch

The convergence radius of Nekrasov partition functions (as a function of instanton counting parameters) is shown to be positive for 4d $\mathcal{N}=2$ quiver gauge theories with unitary gauge groups in an open dense subset of parameters. For $U(N)$ SQCD this is established if the ratio of equivariant parameters $b^2=\epsilon_1/\epsilon_2$ belongs to $\mathbb{C}\setminus[0,+\infty)$ and Coulomb parameters or masses are away from a lattice of hyperplanes. For general quivers it is only established for $b^2\in\mathbb{C}\setminus\mathbb{R}$. When gauge multiplets are asymptotically free, the radius is infinite, whereas in the (mass-deformed) conformal case the radius admits a positive lower bound that only depends on $b^2$. The proof relies on the expression of the partition function as a sum over tuples of partitions, and a proof of absolute convergence based on combinatorial inequalities on products of (co)hook lengths. Through the AGT correspondence this implies that large classes of Virasoro and W-algebra conformal blocks on the sphere or torus have positive convergence radius, for generic dimensions and complex central charges.
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Quantum Physics

An efficient Pauli decomposition algorithm for structured matrices

Daniel J. Spencer, Kishor Bharti and Alexey V. Gorshkov

Decomposing classical matrices into linear combinations of Pauli strings is a major bottleneck for end-to-end implementations of near-term quantum algorithms. In this work, we consider a promise version of this Pauli decomposition problem in which the matrix is guaranteed to have support on only $k = \mathsf{poly}(n)$ Pauli strings and is given through classical sparse query access. Existing Pauli decomposition algorithms are designed for the generic, dense problem and do not inherently take advantage of this promised sparsity, so these approaches take time that is exponential in $n$. We present a randomized classical algorithm that does take advantage of this sparsity and recovers the exact Pauli decomposition with success probability at least $1 - \delta$, for any $\delta$. Under the stated access model, the algorithm executes with query and runtime complexity that is polynomial in $n$, $k$, and $\log(1/\delta)$. These results show that, even though finding the Pauli decomposition is exponentially hard for general matrices, it becomes efficiently solvable for matrices that are known to be sparse in the Pauli basis, a regime that is relevant to near-term quantum algorithms operating on structured classical input.
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Instrumentation and Methods for Astrophysics

An overview of stray light findings and interpretation during on-sky commissioning of LSSTCam

Gabriele Rodeghiero, Alex Drlica-Wagner, Alessio Taranto et al. (+78 more)

Wide-field telescopes are intrinsically difficult to shield from unwanted stray and scattered light, while the search to identify sources of contaminating light is frequently a challenging task. The Vera C.~Rubin Observatory, which achieved its first photon with the LSST Camera (LSSTCam) on April 15, 2025, will initiate a revolutionary era for the study of dark matter, dark energy, the transient sky, the Solar System, and the Milky Way. LSSTCam will provide near seeing-limited images of the sky in six bands ($u,g,r,i,z,y$) over a $3.^\circ 5$-diameter field of view, and over the course of a decade, it will execute the Legacy Survey of Space and Time (LSST). This work provides an overview of the dedicated stray and scattered light test campaign that has been undertaken since the start of Rubin commissioning. In particular, we highlight the processes used to characterize, model, and mitigate stray light present in LSSTCam images. The Rubin commissioning team created a series of testing and analysis tools to track stray light artifacts from their initial discovery through reproduction with timely observations, simulation using ray tracing to identify opto-mechanical origins, and finally devising corrective actions. The complex stray light features encountered by Rubin provide a wealth of experience for the future wide-field and extremely wide-field observatories. This work covers the many stages of a long journey that started with conceiving an innovative and challenging optical design, followed by the engineering and system engineering efforts to build it, to finally delivering an optimized and revolutionary cutting-edge facility.
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All authors Gabriele Rodeghiero, Alex Drlica-Wagner, Alessio Taranto, Luca Rosignoli, Hannah Pollek, Aashay Pai, Lynne Jones, Erin Howard, Sean MacBride, John Andrew, Douglas Neill, Travis Lange, Andrew Rasmussen, Aaron Roodman, Brian Johnson, Elana Urbach, Parker Fragelius, Eli Rykoff, Tomislav Vucina, Christopher Stubbs, Robert Lupton, Charles Claver, Joshua Meyers, Anastasia Alexov, Keith Bechtol, Lee Kelvin, Brian Stalder, Pierre Antilogus, Alexandre Boucaud, Aurelien Marini, Alexander Broughton, Leanne Guy, Tiago Ribeiro, Erik Dennihy, Bruno Quint, Aaron Watkins, Alysha Shugart, Lukas Eisert, Kevin Fanning, Marina Pavlovich, Yijung Kang, Hye Park, Paulo Lago, Kristopher Mortensen, Paulina Venegas Salas, Minhee Hyun, Karla Peña Ramírez, David Sanmartim, Shuang Liang, Gonzalo Aravena, Kshitija Kelkar, Kate Napier, Jacqueline Seron Navarrete, Carlos Morales Marín, Danica Žilková, Narayan Khadka, Eric Christensen, Yousuke Utsumi, Merlin Fisher-Levine, Yusra Alsayyad, Colin Slater, Fritz Müller, William O'Mullane, Enrico Giro, Rodolfo Canestrari, Guillem Homar Megias, Sandrine Thomas, Kevin Reil, Roberto Tighe, Mario Rivera, Juan Lopez, Claudio Araya Cortes, David Jiménez Mejías, Hernán Herrera, Freddy Muñoz Arancibia, Dimitri Buffat, Johan Bregeon, Jacques Sebag, Holger Drass, Pablo Zorzi, Massimo Brescia

Disordered Systems and Neural Networks · Cross-listed from q-bio.NC

Stationary covariance spectra of discrete-time non-normal random recurrent dynamics

Jacob A. Zavatone-Veth

Principal component analysis is widely used to characterize structure in the dynamics of recurrent neural networks. For stationary noise-driven dynamics, the distribution of variance among the principal components is determined by the spectrum of the stationary covariance matrix. While the spectral properties of this matrix are well-understood for linear networks with normal synaptic weight matrices, our understanding of the stationary covariance spectrum for random non-normal dynamics remains incomplete. In this note, we use a free-probability approach to formally derive a closed functional equation for the moment generating series of the limiting stationary covariance spectrum of discrete-time dynamics with random non-normal Gaussian weights. This characterization allows us to analyze the behavior of tail eigenvalues in the critical regime: they decay with the inverse-square of their rank. In contrast, applying the same approach to the analogous continuous-time dynamics leads to an infinite hierarchy of Schwinger-Dyson equations, rather than a closed scalar equation. We conclude with some comments regarding the relevance of these results to comparisons of models of non-normal dynamics to neural data.
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Statistical Mechanics · Cross-listed from q-bio.PE

Invasion with size-dependent dispersion range

Ulysse Marquis

The coalescing colony model provides a minimal framework for biological invasions with long-range dispersion. In its standard formulation, the dispersion range is assumed independent of the size of the invading population. Here, we relax this assumption and consider size-dependent dispersal: a main colony of linear size $r$ emits secondary colonies at distance $r^\mu$, with $0 \leq \mu \leq 1$. We derive the generalized dynamical equations for this extended model and map out the growth phase diagram for the leading order contribution. Depending on $\mu$, the main colony exhibits distinct regimes: linear expansion, power-law growth, exponential regime and finite-time blow-up. We confront these theoretical predictions with a spatially explicit physical model. While the coalescing colony approach correctly captures the scaling of the perimeter, it fails to predict the scaling of the volume. We trace this discrepancy to an effective breakdown of circular symmetry in the morphology of the main colony. Finally, we quantify temporal evolution of the population fraction residing outside of the main colony. The coalescing colony model predicts its decay to~$0$ like a power-law when~$\mu<1$, and a macroscopic amount of the population remains in the secondary colonies at~$\mu=1$. Simulations of the physical model reveal a persistent satellite population not captured by the theory at~$\mu>\mu^*\approx 0.7$. Broadly, our findings highlight how coupling dispersal range to population size fundamentally alters invasion dynamics, with implications for biological invasions, metastatic growth, and urban expansion.
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Instrumentation and Methods for Astrophysics

Investigation and Mitigation of a Prominent Off-Axis Stray Light Path in Rubin Observatory Commissioning

Alex Drlica-Wagner, Alessio Taranto, Gabriele Rodeghiero et al. (+12 more)

The "scratched tape" stray light feature is the most prominent and prevalent stray light artifact identified during the commissioning of the Vera C. Rubin Observatory. The scratched tape feature originates when light from large off-axis angles (~20 deg) passes between the mid-level and center-section light baffles, reflects off the primary mirror, and illuminates the LSST Camera focal plane. This scenario represented an unobstructed stray light path to the sky during Rubin commissioning due to delays in the integration of the dome slit light-wind screen. This document describes the identification, modeling, characterization, and mitigation of the scratched tape stray light artifact.
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All authors Alex Drlica-Wagner, Alessio Taranto, Gabriele Rodeghiero, Joshua E. Meyers, John Andrew, Douglas R. Neill, Christian Aguilar, Brian Stalder, Robert H. Lupton, Aashay Pai, Lee S. Kelvin, Aaron E. Watkins, Luca Rosignoli, Hannah M. M. Pollek, Anastasia Alexov

High Energy Physics (Phenomenology)

PBHs and GWs from Scaling Monopoles

Daiki Aburatani, Wakutaka Nakano and Wen Yin

Monopoles with sufficiently weak gauge couplings, or from global symmetries, can form scaling networks in the early Universe whose average energy density tracks the cosmological background. In this work, we find, by performing classical lattice simulations to estimate the overdensities, that primordial black holes (PBHs) with a broad mass spectrum can be produced during this evolution if the Higgs expectation value $v$ satisfies $v\gtrsim 0.1 M_{\rm pl}$. The formation is driven by the stochastic realization of the monopole number in Hubble patches causing the overdensities. We also show that gravitational waves (GWs) generated by the scaling dynamics are produced at the same epoch, with spectra correlated with the PBH spectra and with amplitudes testable in future observations. Interestingly, if the scaling regime is terminated by the gauge boson mass for the gauged monopole, a non-negligible fraction of the PBHs can carry magnetic charge, and the resulting magnetic Coulomb force between such charged PBHs is predicted to be comparable to the gravitational force. Together with the PBH and GW signals, this provides a smoking-gun signature of the scenario. We also point out simple cosmological scenarios, which may also apply to PBH formation from scaling cosmic strings, that allow PBHs to constitute dominant dark matter.
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Mesoscale and Nanoscale Physics

Untangling 3D atomic reconstruction in twisted bilayer 2D crystals via dark field transmission electron microscopy

Pankaj Kumar, Michel Bosman, Nikolai Lavrentev et al. (+4 more)

Reconstruction of the atomic crystal structure in twisted 2D materials has been demonstrated to be responsible for multiple exciting phenomena in van der Waals heterostructures, from the appearance of flat bands in twisted bilayer graphene to Wigner crystallization in transition metal dichalcogenides (TMDs). However, there are still no experimental methods for accessing the 3D atomic distributions nor models that describe the exact atomic shifts in such reconstructed structures, which significantly impedes the development of the field. Dark field (DF) transmission electron microscopy (TEM) has been conventionally employed to visualize the local in-plane atomic displacements. Here we expand this method to obtain a full description of the reconstructed atomic systems and demonstrate the quantitative relations between the local stacking and the intensity in the DF image. We show how local 3D atomic displacements and the interlayer distance can be extracted from a DF image.
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All authors Pankaj Kumar, Michel Bosman, Nikolai Lavrentev, He Zheng, Ding Peng, Kostya S. Novoselov, Tatiana Latychevskaia

Chemical Physics

Resonant and collective modification of London dispersion interactions under vibrational strong coupling

Marit R. Fiechter and Jeremy O. Richardson

Experiments have shown that, by tuning a microcavity to resonance with a vibrational mode of the molecules contained within it, one can modify chemical properties, such as reaction rates. This gives rise to the exciting prospect of steering chemical reactivity, just by placing a pair of carefully spaced mirrors around the reaction mixture. However, a decade after the first demonstration, the mechanism behind this effect remains ill-understood. Here, we show how vibrational strong coupling can lead to resonant modification of vibrationally-resolved London dispersion interactions. Employing a mixed quantum-classical dynamics scheme, we then show how this in turn can give rise to resonant rate enhancement in the case of two molecules strongly coupled to the cavity mode, for all regimes of solvent friction. The resonant changes of the London dispersion interaction seem to persist when increasing the number of molecules. Whether this also leads to altered reaction rates in the experimentally relevant collective limit remains an open question, as this regime falls outside the range of applicability of our mixed quantum-classical dynamics approach. Nevertheless, the framework presented here offers an exciting new avenue to explore, and hopefully bring us a step closer towards explaining the mechanism behind vibropolaritonic chemistry.
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Computational Physics

Conditional Normalizing Flow for Gas-Surface Scattering from Thermal to Hypersonic Velocities

Miklas Schütte, Stephen Hocker, Hansjörg Lipp et al. (+3 more)

Accurate aerodynamic modeling of satellites in very low Earth orbit (VLEO) requires gas-surface interaction (GSI) models that capture the full velocity spectrum from thermal to orbital speeds. Atmospheric particles initially strike spacecraft surfaces at hypersonic velocities of 6 000 - 10 000 m/s. Due to surface roughness and complex geometries, especially within air-breathing electric propulsion (ABEP) intake systems, multiple collisions occur, progressively reducing the particle velocities. A recent machine learning framework for deriving scattering kernels from molecular dynamics (MD) simulations has shown promise, but remains limited to high-velocity single impacts and possibly violates fundamental equilibrium principles such as detailed balance. This work extends this machine learning based scattering kernel to cover the complete velocity range using conditional normalizing flows trained with physics-informed constraints, enabling accurate modeling of multi-bounce scenarios in realistic VLEO applications. We train a conditional Real-valued Non-Volume Preserving (cRealNVP) model on expanded molecular dynamics simulations covering velocities from thermal to hypersonic speeds, incorporating a detailed balance loss term. The resulting model demonstrates improved accuracy compared to previous approaches even in the original high-velocity regime, while successfully capturing thermal-velocity scattering. Quantitative assessment shows that thermalization is approximated within acceptable tolerances. This framework provides essential capabilities for accurate ABEP intake optimization and VLEO mission planning while offering a general methodology applicable to broader rarefied gas dynamics problems requiring thermodynamic consistency.
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All authors Miklas Schütte, Stephen Hocker, Hansjörg Lipp, Johannes Roth, Stefanos Fasoulas, Marcel Pfeiffer

High Energy Astrophysical Phenomena

A Suppressed Volumetric Rate of High-Luminosity Mid-Infrared Selected Tidal Disruption Events

Prajna Nair, Christos Panagiotou, Megan Masterson et al. (+4 more)

Tidal Disruption Events (TDEs) serve as direct probes of the population of supermassive black holes in the center of galaxies and are nowadays regularly detected in optical wide-field time-domain sky surveys. Recent studies have demonstrated that a large fraction of TDEs can be uniquely identified in the infrared (IR) waveband, but these studies have to date been limited to relatively nearby events. In this work, we searched for highly luminous IR-bright TDEs that are rare and thus missed by searches in the local universe. We performed a systematic search of the NEOWISE archive and developed a new selection criterion based on the evolution of the W1-W2 color to select TDE candidates. We identified 10 IR bright TDEs with peak luminosities above $L_{\rm peak\, W2} \simeq 3 \times 10^{43}$ erg s$^{-1}$ and estimated an event rate of $1.2^{+0.5}_{-0.4}\times10^{-10}$ Mpc$^{-3}$year$^{-1}$ for the luminosity range of our sample. Compared to the existing local luminosity function of lower luminosity events, we detect a suppressed rate for these highly luminous events. This turn-over in the luminosity function can be naturally explained by the suppressed amount of TDEs taking place in systems with larger black hole masses, thereby confirming the TDE nature of our sources.
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All authors Prajna Nair, Christos Panagiotou, Megan Masterson, Kishalay De, Erin Kara, Eleanor Winkler, M. Subhi Abo Rdan

High Energy Physics (Theory)

Fate of "Space-like singularities" in $c=1$ Matrix Model

Sumit R. Das, Shaun D. Hampton, Sinong Liu et al. (+1 more)

A class of time dependent backgrounds in two dimensional String Theory leads to superluminal Liouville walls on the worldsheet. In the dual double scaled $c=1$ matrix model these backgrounds involve eigenvalues leaking out to infinity, and the collective field fluctuations become strongly coupled along space-like regions, resembling singularities. We realize these backgrounds as results of quantum quenches in the matrix model, retaining non-linear terms in the matrix potential, thus departing from a double scaling limit. Working in the fermion picture in a Thomas-Fermi approximation, we show that while the early time behavior of the phase space density near the maximum of the potential agrees with that obtained in the double scaled theory, at times of the order $(\log N)$ the effect of the IR wall becomes significant. At later times, with a characteristic winding time of order $(\log N)^2$, folds on the fermi surface proliferate and eventually cover the allowed region in phase space densely. Using action-angle variables, we show that the phase space density oscillates around a time independent and angle independent value rapidly at late times. A coarse-grained density in the angle space relaxes to a time independent equilibrium value as a power law with an exponent largely independent of the details of the initial state. Thus, the appearance of a space-like singularity is an artifact of the strict double scaling limit. We comment on the interpretation of the final state in String Theory.
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All authors Sumit R. Das, Shaun D. Hampton, Sinong Liu, Gautam Mandal

Materials Science

What enables GaOx as hole transport layer for a 16 percent 1.0 eV CuInSe2 Bottom Cells with VOC above 550 mV?

Francesco Lodola, Zhuangyi Zhou, Boaz Koren et al. (+10 more)

Among the highly efficient photovoltaic technologies, that do not rely on epitaxy, only chalcopyrites have a bandgap tunable down to 1.00 eV, the ideal for tandem applications. This is obtained with a pure CuInSe2 absorber without Ga. GaOx has been shown to be an efficient hole transport layer that prevents recombination at the metallic back contact. On the other hand, GaOx has proven detrimental, when it forms on In containing transparent back contacts in bifacial solar cells. Here, we investigate the conditions that make the GaOx layer conductive. We employ a GaOx hole transport layer that is formed through ion exchange during co-evaporation of the low band gap absorber layer. We find that no additional Cu is needed, and that Na is not necessary for a conductive GaOx. Nor did we find a systematic influence of oxygen flow during the sputtering process of the oxide layer. The GaOx layer is partly crystalline. The optimized passivating hole transport layer enables a CuInSe2 bottom solar cell, without any addition of Ag or heavy alkalis, with an active area efficiency above 16% and a record-certified open-circuit voltage VOC of 552meV
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All authors Francesco Lodola, Zhuangyi Zhou, Boaz Koren, Saeed Bayat, Alessandro Magon, Yucheng Hu, Adrian-Marie Philippe, Michele Melchiorre, Hasan Arif Yetkin, Gunnar Kusch, Nathalie Valle, Rachel A. Oliver, Susanne Siebentritt

Astrophysics of Galaxies

Unveiling the Cosmic Dawn with SHARP: Probing extended Lyman-$\alpha$ nebulae in a Universe less than 600 Myr old

Susanna Bisogni, Giustina Vietri, Enrico Piconcelli et al. (+5 more)

The existence of luminous quasars just a few hundred million years after the Big Bang challenges our understanding of both black hole growth and galaxy formation and evolution. These objects harbour supermassive black holes exceeding a billion solar masses (M$_{BH} > 10^{9} M_{\odot}$) by redshift $z\sim 6.5$-$7.5$, powered by extreme gas accretion. At the same time, their host galaxies are also undergoing intense star formation, consuming gas at the rate of hundreds of solar masses per year. Characterising the circumgalactic medium (CGM) and intergalactic medium (IGM) surrounding high-redshift quasars becomes an essential tool to understand the conditions that enable the rapid formation and evolution of these extreme sources. While in the last decades spatially resolved observations in the optical band have targeted CGM through Ly$\alpha$ nebulae surrounding $z \sim 2-6$ quasars, current instrumental limitations hamper observations of high-z ($z>8$) quasars that will be discovered by Euclid/Roman/LSST surveys. Despite the large fraction of neutral hydrogen at the epoch of reionisation, in the last decade several surprising Ly$\alpha$ detections have been obtained from sources deep in the epoch of reionisation. The unprecedented collecting area of ELT, coupled with the resolution and wavelength coverage of SHARP, specifically VESPER, will enable us to map for the first time $z>9$ Ly$\alpha$ emission down to the structures of size $\sim$150 pc, while simultaneously capturing their large-scale structure up to 100 kpc for the first time at this redshift. This will allow a major and long-awaited step forward in the exploration of quasars and galaxies formation and evolution deep in the epoch of reionisation.
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All authors Susanna Bisogni, Giustina Vietri, Enrico Piconcelli, Federica Ricci, Andrea Travascio, Paolo Franzetti, Adriana Gargiulo, Chiara Mancini

Soft Condensed Matter

Drift-diffusion interplay in active Brownian particles under orienting field

Andrey A. Kuznetsov, Vittoria Sposini, Sofia S. Kantorovich et al. (+1 more)

Magnetic active particles offer a versatile route to externally controlled microscale transport by combining self-propulsion with field-tunable orientation, as realized in both synthetic and living magnetic microswimmers. Here, we develop a theoretical framework for three-dimensional active Brownian motion in a uniform magnetic field, incorporating coupled translational and rotational dynamics and providing analytical approximations for low-order displacement moments. At long times, the system dynamics reduces to a combination of enhanced diffusion and permanent drift absent in regular active Brownian particles. The field acts as an external controller, channeling activity toward one of these two types of motion. At intermediate time scales, the interplay between rotational noise, self-propulsion, and magnetic alignment results in pronounced non-Gaussian displacement statistics. First-passage properties exhibit strong field sensitivity, highlighting the potential of magnetic guidance to optimize search processes and targeted delivery in active matter systems. Theoretical predictions are validated by numerical simulations.
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All authors Andrey A. Kuznetsov, Vittoria Sposini, Sofia S. Kantorovich, Aleksei V. Chechkin

Quantum Physics

Certifying quantum states without independence assumptions

Mariana Navarro and Leonardo Zambrano

Standard quantum verification and certification protocols often assume that experimental sources emit independent and identically distributed (i.i.d.) states. In realistic scenarios, however, temporal drift, memory effects, feedback, and correlated noise can violate this assumption, causing standard analyses to underestimate uncertainty and overestimate device performance. Here, we introduce a general framework for quantum verification and certification in which the state produced in each round may depend arbitrarily on the preceding experimental history. Our method provides rigorous confidence intervals for observable expectation values averaged over the experimental trajectory. The framework covers both full verification, in which every state is measured, and spot-checking certification, in which a randomly selected subset is tested to certify the average observable value of the complementary, remaining systems. We apply the framework to importance-sampled Pauli measurements for direct fidelity estimation, energy estimation, and entanglement witnessing, and to classical shadows, allowing multiple observables to be certified simultaneously from the same test data. We illustrate the framework numerically and demonstrate it experimentally through Bell-state certification on a quantum processor.
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Quantum Physics

Electrons on Helium and Entangled Quantum Sensors for Particle Physics

Maria Elena Perruzza, Niyaz R. Beysengulov, Stian D. Bilek et al. (+12 more)

Quantum sensors that harness quantum coherence and entanglement are emerging as powerful tools in many fields, including particle physics, promising unprecedented sensitivity beyond classical detection methods. At the same time, electrons trapped on the surface of liquid helium have emerged as a promising quantum computing, and possibly sensing, platform owing to a nearly impurity-free environment and large predicted coherence times. In this context, single-electron confinement and control using microfabricated traps on helium has been experimentally demonstrated, highlighting the feasibility of scalable qubit architectures on this platform. In line with the DRD5 initiative at CERN, we propose here a sensor concept that uses an entangled pair of electron qubits on superfluid helium for particle physics experiments. We outline the motivation for such spatially and spin-entangled sensors, develop the theoretical formalism for two electrons and their spins and spatial degrees of freedom in a helium-based double-well trap (analogous to a double quantum dot in semiconductor systems), and discuss the potential advantages for detecting rare high-energy events with quantum-enhanced sensitivity. By exploiting quantum entanglement between the two trapped electrons, this sensor concept can surpass classical sensitivity limits, potentially enabling the detection of signals beyond the reach of classical detectors.
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All authors Maria Elena Perruzza, Niyaz R. Beysengulov, Stian D. Bilek, Antoine Y. M. C. Camper, Jonas B. Flaten, Morten Hjorth-Jensen, Gunnar F. Lange, Oskar Leinonen, Jan Malamant, Francesco P. Massel, Johannes Pollanen, Heidi Sandaker, Zachary J. Stewart, Viktor Svensson, Jared D. Weidman