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Physics

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Friday 21 August

Strongly Correlated Electrons

Berry-Curvature Effect in Anomalous Transport

V.P.Mineev

A theory of the Berry-phase effect in anomalous transport in ferromagnets driven by statistical forces such as the gradient of temperature or chemical potential has been developed by Di Xiao et al in Phys. Rev. Lett. 97, 026603 (2006) based on a field-dependent density of states generating an additional contribution to the current density. We present an alternative derivation of the Berry- phase effect in anomalous transport in altermagnets and noncentrosymmertric metals based on quasiclassic matrix kinetic equation. Along with anomalous Hall effect an anomalous heat flow and anomalous thermalelectric currents are derived.
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High Energy Astrophysical Phenomena

CtaAgnVar : a Pipeline for Variability Studies with the Cherenkov Telescope Array Observatory

G. Grolleron, J.-P. Lenain, J. Biteau et al. (+2 more)

Blazars are active galactic nuclei whose relativistic jet points toward the observer, accelerating particles that radiate across the electromagnetic spectrum. Characterizing their flux and spectral variability constrains the physics of the central black hole and its jet, making blazars a key science case for the Cherenkov Telescope Array Observatory (CTAO). The CTAO, with two sites and a sensitivity five to ten times better than current Imaging Atmospheric Cherenkov Telescopes, should reconstruct AGN variability at very high energies with unprecedented precision. To quantify these capabilities for blazars and transients, we developed CtaAgnVar, a pipeline based on Gammapy, the open-source Python package for gamma-ray analysis selected as core library of the CTAO Science Analysis Tools. It covers the full chain from a time-dependent spectral energy distribution to the simulation of a realistic observation sequence, accounting for source visibility, and to the reconstruction of spectra and light curves. It provides variability estimators, including a new statistical estimator quantifying the detection of hysteresis patterns in hardness-ratio diagrams. Released as open source, it lets the instrument enter only through the response functions and array location, so its use is not restricted to the CTAO. We simulated over 15 years of CTAO observations of PG 1553+113, whose high-energy emission shows a periodicity in Fermi-LAT data. Assuming the very-high-energy emission follows the high-energy one, the CTAO would recover this periodicity above 5 sigma with 15 years of 30 min observations on a weekly cadence, the period determination being then limited by the light-curve sampling rather than by photon statistics.
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All authors G. Grolleron, J.-P. Lenain, J. Biteau, C. Boisson, M. Cerruti

Quantum Physics

Entangling Power Dynamics: Ergodicity and Mixing

Rahul V, Ranjan Modak, Shaon Sahoo et al. (+1 more)

We study quantum dynamics through the lens of entanglement generation and characterize the underlying unitary evolution by the distinct signatures it imprints on the time-dependent entangling power. For a unitary operator, we characterize ergodicity by the equality between its long-time-averaged entangling power and the Haar-averaged linear entropy. We define mixing more stringently as the convergence of the time-dependent entangling power itself to the Haar value at long times. Within this framework, we establish the ergodic hierarchy of dynamical behavior, showing in particular that mixing implies ergodicity, whereas ergodicity does not necessarily imply mixing. As an application, we find that two-qubit unitary gates are neither ergodic nor mixing: their long-time-averaged entangling power can take only four discrete values, none of which coincides with the Haar average. We then investigate many-body dynamics using the kicked Ising chain and find that the long-time-averaged entangling power converges to the Haar value in both integrable and nonintegrable cases, indicating ergodicity. Remarkably, however, the nonintegrable chain exhibits mixing, whereas the integrable chain, despite being ergodic, is demonstrably nonmixing. We also introduce a Lyapunov-like exponent to characterize the rate at which the time-dependent entangling power approaches its saturation value. We find that this exponent increases systematically with the degree of integrability breaking in the many-body system. Our results establish entanglement generation as a useful framework for characterizing dynamical systems and reveal qualitatively different signatures of integrability beyond conventional diagnostics.
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All authors Rahul V, Ranjan Modak, Shaon Sahoo, S Aravinda

Materials Science

Symmetry-engineering ferroelectricity in silicon dioxides

Yin Dai and Menghao Wu

It is a long-established rule for classical ferroelectricity that any ferroelectric crystal must adopt one of the 10 specific polar point groups. Here we predict a unique type of ferroelectricity that can be generated in some crystals belonging to nonpolar noncentrosymmetric groups. This principle can be applicable to many systems including silicon dioxides, the most widely used dielectric materials. Most of their crystalline phases do not belong the polar groups, while the nonlinear Si-O-Si configurations lead to multiple identical states. We show first-principles evidence that the crystal symmetry forbidding the formation of polarizations, can be broken by either parallel surfaces in thin-films or applying a uniaxial strain. As a result, the multiple identical states are endowed with polarizations of different directions, and low-barrier ferroelectric switching can be realized via transition between them, which can be room-temperature robust down to the thickness of 1 nm. Our findings may not only enable low-cost and large-scale manufacture of ferroelectrics directly integrated in silicon chips, but also open a new avenue for exploring ferroelectricity in prevalent nonpolar materials.
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High Energy Physics (Phenomenology)

Unraveling QCD dynamics with heavy quark energy correlators

Ivan Vitev

Heavy-flavor jets and their substructure provide a unique window into the role of quark mass on QCD radiation and its modification in nuclear matter. In this work, we investigate heavy-quark energy-energy correlators (EECs) that are explicitly sensitive to mass effects, focusing on angular distributions, energy flow, and the dead-cone effect. We demonstrate how the finite mass of charm and bottom quarks reshapes the intra-jet radiation pattern, leading to characteristic suppression at small angles and measurable deviations from massless jet expectations. Using effective field theory analysis, we extend the calculation of these observables to reactions with nuclei to show that medium-induced radiation competes with vacuum mass suppression, resulting in a nontrivial modification of jet substructure. Specifically, we identify regimes where EECs are dominated by the heavy quark mass, leading to qualitatively and quantitatively different behavior of this observable in QCD matter. We discuss the charm and bottom jet energy-energy correlators modification in reactions with nuclei, and further demonstrate how the formalism can be tested in small collision system at current facilities.
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Astrophysics of Galaxies

Angular momentum in isolated disc galaxies: Insights from TNG100

A. Sorgho, L. Verdes-Montenegro, M. Baes et al. (+5 more)

Angular momentum is a fundamental property that shapes the evolution of disc galaxies, strongly influencing the internal mechanisms that regulate star formation. Its content within disc galaxies is predicted to change over time, mainly as a result of external processes that regulate galaxy evolution. While several numerical studies paint a complex picture of angular momentum variation with environmental mechanisms, a recent observational finding suggests that galaxies are subject to angular momentum loss when they undergo interactions. By studying the stellar angular momentum of simulated disc galaxies selected at various degrees of isolation, we aim to investigate whether isolation affects the stellar angular momentum content of disc galaxies and assess whether the environmental trends previously reported for baryonic angular momentum may also be reflected exclusively in the stellar component. We selected star-forming disc galaxies in the IllustrisTNG simulation suite, for which we computed an isolation parameter based on local density. Using a density threshold, we identified isolated discs from non-isolated galaxies and performed a comparative study of their angular momentum content against other evolutionary parameters. We find that isolation alone does not define the angular momentum content of a galaxy. Rather, whether a disc is gas-rich or gas-poor is directly linked to the specific angular momentum content, $j_*$, of its stellar disc.
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All authors A. Sorgho, L. Verdes-Montenegro, M. Baes, R. Ianjamasimanana, M. Korsaga, B. Namumba, S. Sanchez-Expósito, J. Garrido

Astrophysics of Galaxies

The curious case of HCO$^+$: Extreme abundances under extreme conditions

Katarzyna M. Dutkowska, Bin Jia, Serena Viti et al. (+2 more)

Context. HCO$^+$ is widely observed in both Galactic and extragalactic environments and typically exhibits abundances of $10^{-9}-10^{-8}$. However, recent modeling studies suggest that in environments exposed to elevated cosmic-ray ionization rates and strong thermal or mechanical processing its abundance may increase by several orders of magnitude. Aims. To interpret these predictions, we need to understand the physical conditions that produce extreme HCO$^+$ abundances and the chemical pathways that drive these enhancements. Methods. We used UCLCHEM, a gas-grain chemical code, to model the chemistry of HCO$^+$ in dense molecular, protostellar, and shocked gas under elevated cosmic-ray ionization rates ($\zeta \ge 10^{-15}\,\mathrm{s^{-1}}$). Results. Extreme HCO$^+$ enhancements leading to $X$(HCO$^+$) $\gtrsim 10^{-4}$ occur only under specific combinations of temperature, density, and cosmic-ray ionization rate, primarily in protostellar and shocked gas. Increasing density generally suppresses the peak HCO$^+$ abundance, requiring higher ionization rates to produce comparable enhancements. More importantly, the extreme enhancements seem to be very dependent on the chemical network used (in our case UMIST12 versus UMIST22, with the latter leading to extreme abundances). These differences among networks arise from the removal of the destruction pathway of HCO$^+$: C + HCO$^+$ $\rightarrow$ CO + CH$^+$, and propagate to several other species including N$_2$H$^+$, H$_2$O, and H$_3$O$^{+}$.
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All authors Katarzyna M. Dutkowska, Bin Jia, Serena Viti, Tobias M. Dijkhuis, Gijs Vermariën

Earth and Planetary Astrophysics

Transit Searches for Habitable-Zone Exoplanets with Artificial Intelligence

Qingtian Liu

Searching for Earth-sized planets in stellar habitable zones ultimately means finding a small number of very shallow, widely separated transits in noisy light curves. Around Sun-like stars, habitable-zone planets generally have long orbital periods, so a finite observing baseline may record only a few transits. At the same time, intrinsic stellar variability, instrumental systematics, and data gaps can obscure these weak events or produce transit-like brightness changes. This review examines recent progress in AI-assisted light-curve preprocessing, weak-signal searches, candidate vetting, and parameter inference, and considers the potential roles of pretraining and multimodal models. Taken together, the studies reviewed here show that AI has practical value in making large-scale light-curve analysis more efficient, recovering more signals at low signal-to-noise ratios in some injection tests, and reducing the number of targets requiring manual review. This review concludes that combining AI with physical modeling, statistical inference, and follow-up observations provides a practical route to improve both the discovery efficiency and the reliability of habitable-zone candidate studies.
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High Energy Physics (Theory)

BMPV black holes in higher-derivative supergravity

Yide Cai, Sabarenath Jayaprakash, James T. Liu et al. (+2 more)

There are five independent four-derivative superinvariants for the five-dimensional STU model, of which two are vector invariants that do not involve curvature tensors. We construct the corrected BMPV black hole directly in five dimensions with this set of general four-derivative couplings, a computation made possible with the help of AI. We find that the vector invariants do not correct the solution or the entropy, while the entropy associated with the heterotic corrections agrees with recent results.
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All authors Yide Cai, Sabarenath Jayaprakash, James T. Liu, Yi Pang, Robert J. Saskowski

Optics

Neuromorphic Infrared Fibre-Optic Event-Based Sensing with Fast and Efficient Photonic-Electronic Spiking Neurons

Dylan Black, Giovanni Donati, Joshua Robertson et al. (+5 more)

Current photonic technologies for remote sensing require the capture of large amounts of data, suffering as a result from high energy consumption, excessive data redundancy and storage, and costly data processing requirements, limiting their ability for direct and efficient edge-processing for rapid decision making and alarm triggering. In contrast, biological sensing systems, given their event-driven nature and in-sensor processing capabilities offer energy-efficient and practical alternatives. In this work, we draw direct inspiration from the neural spiking in biological sensory systems, to propose a novel neuromorphic event-based photonic technology permitting the remote sensing of environmental events-of-interest efficiently, at high speeds and across a wide dynamic frequency range. Our approach combines widely-deployed fibre-optic telecommunication links and photo-detecting resonant tunnelling diodes (pRTD) acting as light-triggered spiking neurons. We demonstrate that this new neuromorphic photonic sensing approach allows the remote detection of different types of environmental events, including temperature variations, strain-induced motion, audio and air turbulence, with high temporal resolution (encoding them with fast nanosecond-rate neural-like spikes). These results pave the way for novel light-enabled neuromorphic remote infrared fibre-optic sensing networks that are fast, efficient, event-driven, scalable, permit direct processing at-the-edge, and offer practical alternatives to current data-intensive approaches for photonic remote sensing.
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All authors Dylan Black, Giovanni Donati, Joshua Robertson, Qusay Raghib Ali Al-Taai, José Figueiredo, Edward Wasige, Bruno Romeira, Antonio Hurtado

Quantum Physics

Semidefinite optimization as many-body thermodynamics: Boltzmann, Fermi-Dirac, and Bose-Einstein frameworks

Michele Minervini, Nana Liu, Dhrumil Patel et al. (+1 more)

We study the semidefinite programs (SDPs) of quantum information whose variables are density operators, measurement operators, or unbounded positive semidefinite operators, together with their thermodynamic regularizations by the von Neumann, Fermi-Dirac, and Bose-Einstein entropies, which have been associated with Boltzmann, Fermi-Dirac, and Bose-Einstein statistics, respectively. We find that this correspondence is exact: the Fermi-Dirac and Bose-Einstein regularized SDPs coincide with the constrained free-energy minimization of an ideal Fermi or Bose gas whose Hamiltonian and non-commuting charges are the second quantizations of the SDP data and whose one-body density matrix is the SDP variable, while the Boltzmann framework corresponds to the single-particle case. We show that the three frameworks can be unified under one framework, in which each entropy-regularized dual is, up to a term linear in the chemical potentials, the grand potential of the corresponding system; the duals are unconstrained and concave in the chemical-potential vector, with gradient and Hessian given by thermal expectation values that hybrid quantum-classical algorithms can estimate. We further identify the Fermi-Dirac and Bose-Einstein relative entropies with the Umegaki relative entropy between quasi-free states, which yields their monotonicity under gauge-covariant Gaussian channels. The result places a wide class of SDPs and their solvers within the thermodynamics of ideal quantum gases and points to extensions to interacting gases.
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All authors Michele Minervini, Nana Liu, Dhrumil Patel, Mark M. Wilde

High Energy Physics (Theory)

Target-space fusion of classical topological defects

Saskia Demulder and Chuying Wang

Classical fusion of sigma-model defects is commonly approached by combining their worldsheet actions and eliminating the intermediate fields. This procedure, however, does not systematically identify the resulting target-space defect or its possible branches. We address this problem by formulating fusion as a reduction of the target-space defect data. Local descent of the intrinsic two-form and global descent of the connection determine the admissible branches. For symmetry-preserving bi-branes in the $SU(2)$ WZW model and Hopf-fibre T-duality defects, the prescription reproduces the known biconjugacy-class branches and the finite family of fibre-shift defects. The appearance of several branches provides a classical manifestation of non-invertible fusion. We further use the framework to construct TsT and T-dual biconjugacy defects, including their global consistency conditions. It therefore provides a systematic method for computing classical fusion and constructing new defects from known ones.
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High Energy Physics (Experiment)

New Limits on $n \rightarrow n'$ Transformation from HFIR Cold Neutron Beam

James M. Rogers, Leah J. Broussard, Christopher B. Crawford et al. (+16 more)

Hypothetical neutron $n$ to sterile neutron $n'$ transformations would violate baryon number $\mathcal{B}$ and point to the nature of Dark Matter. We performed a new search for $n \rightarrow n'$ using an intense cold neutron beam from the High Flux Isotope Reactor at Oak Ridge National Laboratory. We used a theoretical model that describes the transformation $n \rightarrow n'$ with two parameters: a small mass difference $\Delta{m}$ between the interaction states $n$ and $n'$ and a mixing vacuum angle $\theta_0$. A thin absorbing cadmium wafer was used in the center of the superconducting 6.6 T magnet which provided a large gradient for the non-adiabatic $n \rightarrow n'$ transition. No signal was observed above background in the $^{3}\text{He}$ neutron detector 20 meters downstream of the magnet. This result gives an order of magnitude improvement in the lower limit for the probability $2\theta_0^2$ of the $n \rightarrow n'$ transformation in vacuum in the range of $\Delta{m}$ between $0.1$ neV and $1000$ neV.
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All authors James M. Rogers, Leah J. Broussard, Christopher B. Crawford, Lisa DeBeer-Schmitt, Matthew J. Frost, Francisco M. Gonzalez, Carolyn O. Haviland, Lawrence Heilbronn, Erik B. Iverson, Yuri Kamyshkov, Mubasshir Khan, Andrew Mullins, David Milstead, Linus B. Persson, Cary Rock, Valentina Santoro, Alexander Saunders, Shaun Vavra, Nathan D. Whittington

Physics and Society

From Timbuktu to SKA: Who owns the Astronomy knowledge Africa produces?

Rhea Koch and Amare Abebe

Africa has deep and diverse traditions of astronomical knowledge, ranging from archaeological astronomy, pharaonic stellar timekeeping, and manuscript astronomy in Timbuktu and the Sahel, to ecological seasonal astronomy in southern Africa and calendrical computation in the Ethiopian tradition. These multiple epistemic traditions form part of a long intellectual history that precedes and intersects with contemporary astronomy on the continent. In the context of this long-standing intellectual heritage, an important question arises regarding the contemporary circulation of African astronomical knowledge within the global scientific system. This study therefore examines where African astronomical knowledge is produced, validated, and circulated in modern scholarly communication. Using bibliometric data from the Web of Science Core Collection, our analysis investigates publication and citation patterns in the research area Astronomy and Astrophysics between 2000 and 2025, with particular attention to the publication venues of African scholars. The findings highlight a critical paradox: while African researchers are active contributors to global astronomical discovery, the intellectual capital generated through this work is largely stored, validated, and circulated through publication systems located outside the continent. This pattern reflects broader asymmetries within global scholarly communication, where dominant publishing infrastructures shape visibility, citation impact, and authority. By applying a decolonial lens to metrics such as citation impact and ownership, the paper calls for a critical reassessment of the academic practices that sustain epistemic coloniality. It concludes that achieving scientific equity requires a strategic shift in publication choices to build and fortify a sovereign African knowledge archive.
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General Relativity and Quantum Cosmology

Mannheim–Kazanas Black Holes: Horizons, Temperatures and Thermodynamics

Bekir Can Lütfüoğlu

Static black holes in conformal Weyl gravity differ from their Einstein counterparts in a simple but important way: the Mannheim–Kazanas geometry is encoded in a Bach-flat lapse function whose radial dependence is richer than that of Schwarzschild–de Sitter. We study the de Sitter branch of this solution in the Schwarzschild gauge, keeping the characteristic linear term together with the quadratic de Sitter term. In the branch continuously connected to the positive-mass Schwarzschild–de Sitter spacetime, a regular static region between a black-hole horizon and a cosmological horizon exists precisely when \[ -\frac{1}{3}<\beta\gamma<\frac{2}{3}, \qquad 0<\kappa<\frac{1+3\beta\gamma}{27\beta^{2}}. \] In this window the singularity at the origin is hidden, the two positive horizons obey $0<r_b<3\beta<r_c$, and the limiting endpoint is the Nariai geometry. The thermodynamic interpretation is subtler than the root structure: the two horizons generally have different temperatures, and the static patch has no asymptotic region that would select a unique normalization of time. We therefore compare the Killing, Bousso–Hawking normalized, Tolman local, and effective two-horizon temperature conventions, and we compute the corresponding Wald entropy for the pure Weyl-squared action. The result is a local horizon thermodynamic description that keeps the geometric facts separate from the ensemble-dependent choices needed for any global first law.
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High Energy Physics (Theory)

Canonical representation of the Snyder-de Sitter algebra with correct flat and commutative limits

V.G. Kupriyanov and E.L.F. de Lima

The Snyder–de Sitter algebra provides a Lorentz-covariant deformation of phase-space geometry characterized by a curvature parameter $\alpha$ and a noncommutativity parameter $\beta$. We construct an explicit canonical (Darboux) representation of this algebra that is regular in both parameters. Starting from the symplectic structure associated with the Snyder–de Sitter Poisson brackets, we derive the canonical transformation between the physical phase-space variables and Darboux coordinates and obtain its inverse in closed form to all orders in $\alpha$ and $\beta$. The resulting representation has well-defined flat ($\alpha\to0$) and commutative ($\beta\to0$) limits, reducing respectively to the Snyder and de Sitter phase-space algebras, while the simultaneous limit $(\alpha,\beta)\to(0,0)$ yields the standard canonical phase-space coordinates. We then apply this representation to the construction of Poisson gauge transformations on Snyder–de Sitter phase space. In particular, we derive the corresponding gauge transformation matrix and Poisson field strength, both of which are regular in $\alpha$ and $\beta$. Our construction provides a convenient framework for investigating gauge theories and other physical systems formulated on Snyder–de Sitter phase space.
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Astrophysics of Galaxies

The GASKAP-HI Survey towards the Magellanic Clouds: Cold Atomic Gas Survival and Evolution in the Large Magellanic Cloud

Hongxing Chen, Snezana Stanimirovic, James Dempsey et al. (+18 more)

We use atomic hydrogen (HI) absorption detections from the GASKAP-HI survey to investigate the properties of cold atomic gas in the Large Magellanic Cloud (LMC). Using the radiative transfer method, we decompose 155 sightlines into 330 cold neutral medium (CNM), 2 thermally unstable neutral medium (UNM), and 310 warm neutral medium (WNM) components. We find that the CNM in the LMC exhibits higher optical depths (median 0.46), lower spin temperatures (median $\sim$37 K), broader linewidths (median $\sim$4.9 km s$^{-1}$), and slightly lower CNM fractions (median $\sim$23%) than in the Milky Way. We examine the connection between the CNM, molecular gas, and star formation, finding that CNM correlates more closely with molecular gas than WNM, while molecular gas shows a tighter relation with star formation. Molecular hydrogen (H$_2$) formation begins near $N{_\mathrm{HI,CNM}}\sim10^{20}~\mathrm{cm^{-2}}$, and nearly all sightlines with $N_{\mathrm{HI,CNM}}>10^{21}~\mathrm{cm^{-2}}$ contain molecular gas. The CNM fraction increases with visual extinction ($A_V$), and the LMC maintains CNM fractions comparable to those in the Milky Way at substantially lower $A_V$, likely due to higher local densities and a longer line-of-sight depth. Sightlines near expanding shells tend to show higher CNM fractions, although this is partly driven by higher total HI column densities. Finally, the CNM kinematics generally follow the HI disk rotation, with about 7% of components showing velocity offsets greater than $25~\mathrm{km~s^{-1}}$, likely tracing inflows or outflows driven by stellar feedback or large-scale interactions within the Magellanic System.
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All authors Hongxing Chen, Snezana Stanimirovic, James Dempsey, Jacco Th. van Loon, Yik Ki Ma, Hiep Nguyen, Nickolas M. Pingel, John M. Dickey, Min-Young Lee, N. M. McClure-Griffiths, Claire E. Murray, Lister Staveley-Smith, Denis Leahy, Callum Lynn, Antoine Marchal, Daniel R. Rybarczyk, Helga Dénes, Steven Gibson, Katherine Jameson, Ian Kemp, Ioana A. Stelea

Mesoscale and Nanoscale Physics

An autonomous feedback protocol: responding to temperature and potential changes in energy converters

Elsa Danielsson, Krishna Lyn Delima, Bruno Bertin-Johannet et al. (+1 more)

Nanoscale thermoelectric devices convert tiny amounts of heat into power. But what happens if the external conditions and resulting temperature differences are not a priori known? We propose a feedback mechanism that optimizes the performance of a quantum-point-contact-based heat engine (QPC). A quantum-dot detector measures the external conditions and gives autonomous feedback on the QPC's properties. We expect this feedback mechanism to be experimentally relevant for steady-state engines with unknown external conditions and for adapting dynamic charging processes to the potential buildup.
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All authors Elsa Danielsson, Krishna Lyn Delima, Bruno Bertin-Johannet, Janine Splettstoesser

Quantum Gases

Pair size versus coherence length and quantum geometry in the spin-orbit coupled BCS-BEC crossover

R. N. Kalkan and M. Iskin

We investigate the interplay between pairing correlations and quantum geometry in the spin-orbit-coupled BCS-BEC crossover. Working in the helicity basis, we derive the exact pair-size tensor for the two-body bound states and show that it separates into intraband and quantum-geometric interband contributions, with the latter determined by the quantum metric. We extend this decomposition to two distinct many-body length scales at zero temperature: the Cooper-pair size, obtained from mean-field BCS theory, and the coherence length, obtained from the Gaussian fluctuation theory. Although these quantities almost coincide in the BCS regime, they describe distinct physical properties away from it, with the pair size characterizing the internal extent of a pair and the coherence length characterizing the long-wavelength response of the order parameter. We evaluate both quantities for three-dimensional Rashba, three-dimensional Weyl, and two-dimensional Rashba spin-orbit coupling models. We find that the pair size decreases monotonically with increasing spin-orbit coupling as the pair localizes, whereas the coherence length develops a pronounced minimum in the crossover regime before growing again in the BEC regime as the composite bosons become weakly interacting. This minimum is tied to the collapse of the noninteracting Fermi surface onto the ring or sphere of helicity-band minima. The quantum-geometric contributions reach up to nearly one third of the pair size and about 40% of the coherence length, tracking these same changes in the underlying helicity Fermi-surface topology.
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Mathematical Physics

Axiomatization of the Levin–Wen Wave Function

Zhengwei Liu and Zishuo Zhao

The Levin–Wen model provides a lattice realization of topological orders associated with a given unitary fusion category. A longstanding open problem is to characterize Levin–Wen ground-state wave functions intrinsically, without assuming a priori categorical symmetry data or a Hamiltonian. We address this by proposing six axioms on a family of wave functions defined on lattices at multiple scales. These axioms allow us to reconstruct the underlying unitary fusion category and prove that the resulting wave functions map to nonzero Levin–Wen ground-state vectors of the emergent category.
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Atmospheric and Oceanic Physics

Remote sensing of the temporal and spatial variability of atmospheric refractivity using ADS-B interferometry (ADSBi)

Ollie Lewis, Chris Brunt, Malcolm Kitchen et al. (+2 more)

The extreme variability of humidity in the lower atmosphere over short spatial and temporal scales presents an enormous challenge for existing observing systems. Variations in humidity can be detected due to changes in the refractive properties of the atmosphere, which influence the propagation of electromagnetic radiation. We demonstrate the ability to retrieve high-resolution refractivity gradient measurements using an interferometer to measure the refraction of the Automatic Dependent Surveillance-Broadcast (ADS-B) radio transmission routinely broadcast by commercial aircraft. The ADS-B interferometry (ADSBi) technique is sensitive to small-scale spatial and temporal variability in the refractivity gradient due to changes in humidity. We demonstrate how the retrieval of refractivity profiles is possible exploiting the differences in the observed refraction of radio transmissions broadcast by aircraft at different distances and altitudes.
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All authors Ollie Lewis, Chris Brunt, Malcolm Kitchen, Neill E. Bowler, Edmund K. Stone

Quantum Physics

Quantifying Entangling Power of Controlled Unitary Gates

Ankur Haldar, Pankaj Agrawal and Prasenjit Deb

Applying controlled unitary gates to generate entanglement between qubits is a routine task in both quantum communication and computation. The existing tools for predicting how much entanglement a given gate can generate require either simulation of the entangling circuit or averaging over a distribution of inputs for a given controlled unitary gate. Here, we introduce a computable quantity $\zeta$ that not only determines whether a controlled unitary gate generates entanglement, but also quantifies the entanglement for any specific input without requiring the construction of the output state. For two-qubit controlled unitary gates, we establish the physical conditions corresponding to the extremum values of the proposed quantity. Extending the dimension of control and target registers to arbitrary size through a generalized controlled unitary architecture, we derive a universal upper bound on $\zeta$ and identify the conditions for its saturation. Later we establish functional relation between the quantity and other known quantities, such as purity, normalized linear entropy, and von Neumann entropy. Finally, we compare our results with previous research work and show that the quantity proposed in this work achieves the previously known optimal values of entangling power of controlled unitary gates for some specific dimensions of target and control registers.
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Quantum Physics

Symmetry Constrained Quantum Error Mitigation for the Schwinger Model

Alexander Tomlinson, Graham Van Goffrier, Bipasha Chakraborty et al. (+1 more)

Quantum error mitigation (QEM) is at the very heart of near-term quantum simulations and lattice gauge theories are no exceptions, rather their physical symmetries provide natural consistency checks on noise quantum states. In this work, we exploit the parity and fermion-number symmetries of a gauge theory, the (1+1)-dimensional Schwinger model, under depolarising noise and investigate symmetry verification under digital quantum simulation. We investigate two set-ups - symmetry- sector post-selection in adiabatic state preparation followed by real-time measurements of the chiral condensate and symmetry verification within a variational quantum eigensolver (VQE). In the first case, post-selection reduces the bias in the chiral condensate consistently removing up to 60% of the quantum noise induced error in our system. Motivated by the observed regularity of the residual bias (in the low-noise regime), we further introduce a global-noise calibration obtained from classically accessible smaller lattices and implemented on larger lattices recovering noiseless chiral condensate values within statistical uncertainty. However, in VQE, symmetry verification does not seem to generally improve the optimised parameters or the fidelity of the prepared states, although it reduces the bias in the estimated ground-state energy. This demonstates that improving a noisy cost-function estimator in variational algorithms does not necessarily improve the outcome of the algorithm. Our results show the strength of symmetry verification in different approaches while establishing that its usefulness critically depends on where it is applied in the computational workflow, and provide practical guidance for symmetry-assisted quantum error mitigation in quantum simulations of lattice gauge theories.
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All authors Alexander Tomlinson, Graham Van Goffrier, Bipasha Chakraborty, Zhenyu Cai

Pattern Formation and Solitons

Saturable nonlinear Schrödinger equation with space- and time-dependent variable coefficients

Maurilho R. da Rocha, Mateus C. P. dos Santos and Wesley B. Cardoso

In this paper we study the dynamics and stability of localized solutions in a saturable nonlinear Schrödinger equation with space- and time-dependent variable coefficients. Using a variational approach and numerical simulations, we analyze the effects of different external potential configurations. Our results reveal that the stability of the solutions is highly sensitive to the modulation parameters, leading to the emergence of alternating stable and unstable regions as a function of the modulation frequency. These findings provide valuable insights into the control of localized structures in nonlinear wave systems, with potential implications for optical waveguides, Bose-Einstein condensates, and other nonlinear media.
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High Energy Physics (Experiment)

Angular analysis of the decay ${\it \Lambda}_{\it b}^{0} \to {\it \Lambda}(1520){\it \mu^{+}\mu^{-}}$

LHCb collaboration: R. Aaij, M. Abdelfatah, A.S.W. Abdelmotteleb et al. (+1188 more)

The first angular analysis of ${\it \Lambda}_{\it b}^{0} \to {\it \Lambda}(1520){\it \mu^{+}\mu^{-}}$ decays is presented, using proton-proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb$^{-1}$. The leptonic forward-backward asymmetry, $A_\text{FB, 3/2}^\ell$, and the $CP$-averaged angular observable, $S_{1cc}$, are determined by fitting projections of the angular distributions in four intervals of the square of the dimuon invariant mass between 0.1 and 12.5 GeV$^2/c^4$. The results are in good agreement with predictions based on the Standard Model of particle physics.
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All authors LHCb collaboration: R. Aaij, M. Abdelfatah, A.S.W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A.A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C.A. Aidala, S. Akar, K. Akiba, H. Al Saleh, P. Albicocco, J. Albrecht, R. Aleksiejunas, F. Alessio, P. Alvarez Cartelle, A.A. Alves Jr, S. Amato, J.L. Amey, Y. Amhis, Z. Amos, L. An, L. Anderlini, P. Andreola, M. Andreotti, S. Andres Estrada, A. Anelli, D. Ao, C. Arata, F. Archilli, Z. Areg, M. Argenton, S. Arguedas Cuendis, L. Arnone, M. Artuso, E. Aslanides, R. Ataíde Da Silva, M. Atzeni, B. Audurier, J.A. Authier, D. Bacher, I. Bachiller Perea, S. Bachmann, M. Bachmayer, J.J. Back, M. Bai, Z.B. Bai, V. Balagura, A. Balboni, W. Baldini, Z. Baldwin, L. Balzani, H. Bao, J. Baptista de Souza Leite, C. Barbero Pretel, I.R. Barbosa, W. Barker, R.J. Barlow, M. Barnyakov, S. Baron, S. Barsuk, W. Barter, J. Bartz, S. Bashir, B. Batsukh, P.B. Battista, A. Bavarchee, A. Bay, A. Beck, M. Becker, F. Bedeschi, I.B. Bediaga, N.A. Behling, S. Belin, A. Bellavista, I. Belyaev, G. Bencivenni, E. Ben-Haim, J.L.M. Berkey, R. Bernet, A. Bertolin, L. Bertsch, F. Betti, J. Bex, O. Bezshyyko, S. Bhattacharya, M.S. Bieker, N.V. Biesuz, A. Biolchini, M. Birch, F.C.R. Bishop, A. Bitadze, A. Bizzeti, T. Blake, F. Blanc, J.E. Blank, S. Blusk, J.A. Boelhauve, O. Boente Garcia, T. Boettcher, A. Bohare, C. Bolognani, R.B. Bonacci, A. Bordelius, F. Borgato, S. Borghi, M. Borsato, J.T. Borsuk, E. Bottalico, S.A. Bouchiba, M. Bovill, T.J.V. Bowcock, A. Boyer, C. Bozzi, J.D. Brandenburg, A. Brea Rodriguez, N. Breer, C. Breitfeld, J. Brodzicka, J. Brown, E. Buchanan, M. Burgos Marcos, C. Burr, E. Butera, C. Buti, J.S. Butter, W. Byczynski, S. Cadeddu, H. Cai, Y. Cai, Y. Cai, A. Caillet, R. Calabrese, L. Calefice, M. Calvi, M. Calvo Gomez, P. Camargo Magalhaes, J.I. Cambon Bouzas, P. Campana, A. Campomagnani, A.C. Campos, A.F. Campoverde Quezada, Y. Cao, S. Capelli, M. Caporale, L. Capriotti, R. Caravaca-Mora, A. Carbone, L. Carcedo Salgado, R. Cardinale, A. Cardini, P. Carniti, L. Carus, R. Caspary, G. Casse, M. Cattaneo, G. Cavallero, V. Cavallini, S. Celani, I. Celestino, S. Cesare, A.J. Chadwick, M. Charles, Ph. Charpentier, E. Chatzianagnostou, R. Cheaib, M. Chefdeville, C. Chen, J. Chen, S. Chen, Z. Chen, A. Chen Hu, M. Cherif, S. Chernyshenko, X. Chiotopoulos, G. Chizhik, V. Chobanova, A. Christakakis, M. Chrzaszcz, Y. Chu, V. Chulikov, P. Ciambrone, X. Cid Vidal, P. Cifra, P.E.L. Clarke, M. Clemencic, H.V. Cliff, J. Closier, C. Cocha Toapaxi, V. Coco, A. Codovini, C. Codovini, J. Cogan, E. Cogneras, L. Cojocariu, S. Collaviti, P. Collins, T. Colombo, M. Colonna, A. Comerma-Montells, L. Congedo, J. Connaughton, A. Contu, N. Cooke, A. Corallo, G. Cordova, C. Coronel, I. Corredoira, A. Correia, G. Corti, G.C. Costantino, C. Cotirlan, J. Cottee Meldrum, B. Couturier, D.C. Craik, N. Crepet, M. Cruz Torres, M. Cubero Campos, E. Curras Rivera, R. Currie, C.L. Da Silva, X. Dai, J. Dalseno, C. D'Ambrosio, G. Darze, A. Davidson, O. De Aguiar Francisco, C. De Angelis, F. De Benedetti, J. de Boer, K. De Bruyn, S. De Capua, M. De Cian, U. De Freitas Carneiro Da Graca, F. De Gregorio, E. De Lucia, J.M. De Miranda, L. De Paula, A. De Robertis, E. De Santis, M. De Serio, P. De Simone, F. De Vellis, J.A. de Vries, F. Debernardis, D. Decamp, S. Dekkers, L. Del Buono, B. Demaire-Lepape, J. Deng, O. Deschamps, F. Dettori, B. Dey, P. Di Nezza, S. Ding, Y. Ding, L. Dittmann, J.F. Diverchy, A.D. Docheva, A. Doheny, C. Dong, F. Dordei, J. Dorta Moreno, A.C. dos Reis, J. Dos Santos Oliveira, A.D. Dowling, L. Dreyfus, W. Duan, P. Duda, L. Dufour, V. Duk, P. Durante, M.M. Duras, J.M. Durham, K. Duwe, A. Dziurda, S. Easo, E. Eckstein, U. Egede, S. Eisenhardt, E. Ejopu, L. Eklund, M. Elashri, D. Elizondo Blanco, J. Ellbracht, S. Ely, A. Ene, T. Evans, F. Fabiano, S. Faghih, L.N. Falcao, B. Fang, R. Fantechi, L. Fantini, M. Faria, K. Farmer, F. Fassin, D. Fazzini, L. Felkowski, C. Feng, M. Feng, A. Fernandez Casani, M. Fernandez Gomez, B. Fernandez Rodino, J. Fernandez-John, A.D. Fernez, F. Ferrari, F. Ferreira Rodrigues, R.A. Fini, R. Fiorenza, M. Fiorini, M. Firlej, D.S. Fitzgerald, C. Fitzpatrick, T. Fiutowski, F. Fleuret, A. Fomin, M. Fontana, M. Fontes Vaz, L.A. Foreman, R. Forty, D. Foulds-Holt, V. Franco Lima, M. Franco Sevilla, M. Frank, E. Franzoso, G. Frau, C. Frei, D.A. Friday, J. Fu, Y. Fu, Q. Führing, T. Fulghesu, M. Fulghieri, G. Galati, M.D. Galati, A. Gallas Torreira, D. Galli, S. Gambetta, M. Gandelman, P. Gandini, B. Ganie, H. Gao, R. Gao, T.Q. Gao, Y. Gao, Y. Gao, Y. Gao, L.M. Garcia Martin, P. Garcia Moreno, J. García Pardiñas, P. Gardner, L. Garrido, C. Gaspar, A. Gavrikov, J. George, E. Gersabeck, M. Gersabeck, T. Gershon, S. Ghizzo, Z. Ghorbanimoghaddam, F.I. Giasemis, V. Gibson, H.K. Giemza, A.L. Gilman, M. Giovannetti, A. Gioventù, L. Girardey, M.A. Giza, F.C. Glaser, V.V. Gligorov, A. Glioti, C. Göbel, L. Golinka-Bezshyyko, E. Golobardes, A. Golutvin, S. Gomez Fernandez, A.G. Gomez Mongui, W. Gomulka, F. Goncalves Abrantes, I. Gonçales Vaz, M. Goncerz, G. Gong, S. Gong, J.A. Gooding, C. Gotti, E. Govorkova, J.P. Grabowski, L.A. Granado Cardoso, R. Grande Quartieri, E. Graugés, E. Graverini, L. Grazette, G. Graziani, A.T. Grecu, N.A. Grieser, L. Grillo, C. Gu, M. Guarise, L. Guerry, M. Guittiere, A.-K. Guseinov, Y. Guz, T. Gys, K. Habermann, T. Hadavizadeh, C. Hadjivasiliou, G. Haefeli, C. Haen, S. Haken, G. Hallett, P.M. Hamilton, Q. Han, S. Han, X. Han, S. Hansmann-Menzemer, N. Harnew, T.J. Harris, L. Hartman, M. Hartmann, S. Hashmi, J. He, N. Heatley, A. Hedes, F. Hemmer, C. Henderson, R. Henderson, R.D.L. Henderson, A.M. Hennequin, K. Hennessy, A. Henrot, J. Herd, P. Herrero Gascon, J. Heuel, A. Heyn, A. Hicheur, G. Hijano Mendizabal, J. Horswill, R. Hou, Y. Hou, D.C. Houston, N. Howarth, W. Hu, X. Hu, W. Hulsbergen, R.J. Hunter, D. Hutchcroft, M. Idzik, P. Ilten, A. Iohner, S. Jacevicius, H. Jage, S.J. Jaimes Elles, S. Jakobsen, T. Jakoubek, E. Jans, A. Jawahery, C. Jayaweera, A. Jelavic, V. Jevtic, Z. Jia, E. Jiang, X. Jiang, Y. Jiang, Y.J. Jiang, E. Jimenez Moya, N. Jindal, M. John, A. John Rubesh Rajan, D. Johnson, C.R. Jones, S. Joshi, B. Jost, J. Juan Castella, N. Jurik, I. Juszczak, K. Kalecinska, D. Kaminaris, S. Kandybei, M. Kane, Y. Kang, C. Kar, A. Kauniskangas, J.W. Kautz, M.K. Kazanecki, F. Keizer, M. Kenzie, T. Ketel, B. Khanji, S. Kholodenko, V. Kholoimov, G. Khreich, F. Kiraz, T. Kirn, V.S. Kirsebom, N. Kleijne, A. Kleimenova, D. Klekots, K. Klimaszewski, M.R. Kmiec, T. Knospe, R. Kolb, S. Koliiev, L. Kolk, A. Konoplyannikov, P. Kopciewicz, P. Koppenburg, A. Korchin, I. Kostiuk, O. Kot, S. Kotriakhova, E. Kowalczyk, O. Kravcov, M. Kreps, W. Krupa, W. Krzemien, O. Kshyvanskyi, S. Kubis, M. Kucharczyk, A. Kupsc, A. Kurzina, V. Kushnir, B. Kutsenko, J. Kvapil, I. Kyryllin, D. Lacarrere, P. Laguarta Gonzalez, A. Lai, A. Lampis, D. Lancierini, C. Landesa Gomez, G. Lanfranchi, C. Langenbruch, T. Latham, F. Lazzari, C. Lazzeroni, R. Le Gac, H. Lee, R. Lefèvre, M. Lehuraux, C. Lemettais, E. Lemos Cid, O. Leroy, T. Lesiak, E.D. Lesser, B. Leverington, A. Li, C. Li, C. Li, H. Li, J. Li, K. Li, L. Li, L. Li, P. Li, P.-R. Li, Q. Li, T. Li, T. Li, W. Li, Y. Li, Y. Li, Y. Li, Z. Li, Z. Lian, Q. Liang, X. Liang, Z. Liang, S. Libralon, A. Lightbody, J. Lin, S. Lin, T. Lin, R. Lindner, H. Linton, R. Litvinov, D. Liu, F.L. Liu, G. Liu, K. Liu, S. Liu, W. Liu, X. Liu, Y. Liu, Y. Liu, Y.L. Liu, G. Loachamin Ordonez, I. Lobo, A. Lobo Salvia, A. Loi, T. Long, F.C.L. Lopes, J.H. Lopes, A. Lopez Huertas, C. Lopez Iribarnegaray, Q. Lu, C. Lucarelli, D. Lucchesi, M. Lucio Martinez, Y. Luo, A. Lupato, M. Lupberger, E. Luppi, K. Lynch, J. Lyu, S. Lyu, X.-R. Lyu, H. Ma, S. Maccolini, F. Machefert, F. Maciuc, B. Mack, I. Mackay, L.M. Mackey, L.R. Madhan Mohan, M.J. Madurai, D. Magdalinski, J.J. Malczewski, S. Malde, L. Malentacca, G. Manca, C. Mancuso, R. Manera Escalero, A. Mangalasseri, F.M. Manganella, R. Mangrulkar, D. Manuzzi, S. Mao, D. Marangotto, J.F. Marchand, R. Marchevski, U. Marconi, L. Mareso, E. Mariani, S. Mariani, C. Marin Benito, J. Marks, A.M. Marshall, L. Martel, G. Martelli, G. Martellotti, L. Martinazzoli, M. Martinelli, C. Martinez, A. Martinez Armas, D. Martinez Gomez, D. Martinez Santos, F. Martinez Vidal, A. Martorell i Granollers, A. Massafferri, R. Matev, A. Mathad, C. Matteuzzi, K.R. Mattioli, L. Matzner, A. Mauri, E. Maurice, J. Mauricio, P. Mayencourt, J. Mazorra de Cos, M. Mazurek, D. Mazzanti Tarancon, M. McCann, N.T. McHugh, A. McNab, R. McNulty, B. Meadows, S.E.R. Medaer, D. Melnychuk, D. Mendoza Granada, P. Menendez Valdes Perez, F.M. Meng, M. Merk, A. Merli, L. Meyer Garcia, D. Miao, H. Miao, S. Mico, M. Mikhasenko, D.A. Milanes, A. Minotti, E. Minucci, B. Mitreska, D.S. Mitzel, R. Mocanu, A. Modak, L. Moeser, R.D. Moise, E.F. Molina Cardenas, T. Mombächer, M. Monk, T. Monnard, S. Monteil, A. Morcillo Gomez, G. Morello, M.J. Morello, M.P. Morgenthaler, A. Moro, J. Moron, W. Morren, A.B. Morris, A.G. Morris, R. Mountain, Z. Mu, N. Muangkod, E. Muhammad, F. Muheim, M. Mulder, K. Müller, V. Mytrochenko, P. Naik, T. Nakada, R. Nandakumar, G. Napoletano, I. Nasteva, M. Needham, N. Neri, S. Neubert, N. Neufeld, J. Nicolini, D. Nicotra, E.M. Niel, L. Nisi, Q. Niu, B.K. Njoki, P. Nogarolli, P. Nogga, J. Nombela Royo, C. Normand, A. Novo Cal, J. Novoa Fernandez, G. Nowak, H.N. Nur, A. Oblakowska-Mucha, T. Oeser, O. Okhrimenko, R. Oldeman, N. Oldman, F. Oliva, E. Olivart Pino, M. Olocco, R.H. O'Neil, J.S. Ordonez Soto, D. Osthues, J.M. Otalora Goicochea, P. Owen, A. Oyanguren, O. Ozcelik, F. Paciolla, A. Padee, K.O. Padeken, B. Pagare, T. Pajero, A. Palano, L. Palini, L. Palombini, M. Palutan, C. Pan, X. Pan, S. Panebianco, S. Paniskaki, L. Paolucci, A. Papanestis, M. Pappagallo, L.L. Pappalardo, C. Pappenheimer, C. Parkes, D. Parmar, G. Passaleva, D. Passaro, A. Pastore, M. Patel, J. Patoc, C. Patrignani, A. Paul, C.J. Pawley, A. Pellegrino, J. Peng, X. Peng, M. Pepe Altarelli, S. Perazzini, H. Pereira Da Costa, M. Pereira Martinez, C. Perez, A. Perez Casas, P. Perret, A. Perrevoort, A. Perro, M.J. Peters, A. Petkovic, K. Petridis, A. Petrolini, S. Pezzulo, J.P. Pfaller, H. Pham, L. Pica, E. Picatoste Olloqui, M. Piccini, L. Piccolo, F. Piernas Diaz, B. Pietrzyk, R.N. Pilato, D. Pinci, F. Pisani, M. Pizzichemi, V.M. Placinta, M. Plo Casasus, T. Poeschl, F. Polci, M. Poli Lener, A. Poluektov, I. Polyakov, E. Polycarpo, S. Ponce, D. Popov, K. Popp, K. Prasanth, C. Prouve, D. Provenzano, V. Pugatch, A. Puicercus Gomez, G. Punzi, J.R. Pybus, Q. Qian, W. Qian, N. Qin, R. Quagliani, R.I. Rabadan Trejo, B. Rachwal, R. Racz, J.H. Rademacker, M. Rama, M. Ramírez García, V. Ramos De Oliveira, M. Ramos Pernas, G. Ramsey, M.S. Rangel, G. Raven, M. Rebollo De Miguel, F. Redi, J. Reich, F. Reiss, Z. Ren, P.K. Resmi, M. Ribalda Galvez, R. Ribatti, G. Ricart, D. Riccardi, S. Ricciardi, K. Richardson, M. Richardson-Slipper, F. Riehn, K. Rinnert, P. Robbe, G. Robertson, E. Rodrigues, A. Rodriguez Alvarez, E. Rodriguez Fernandez, J.A. Rodriguez Lopez, E. Rodriguez Rodriguez, J. Roensch, A. Rogovskiy, D.L. Rolf, P. Roloff, A. Romano, V. Romanovskiy, A. Romero Vidal, G. Romolini, F. Ronchetti, T. Rong, W. Rose, M. Rotondo, M.S. Rudolph, G. Ruggiero, M. Ruiz Diaz, J. Ruiz Vidal, J. Ruz Armendariz, J.J. Saavedra-Arias, J.J. Saborido Silva, D. Sahoo, N. Sahoo, B. Saitta, M. Salomoni, I. Sanderswood, R. Santacesaria, C. Santamarina Rios, M. Santimaria, L. Santoro, E. Santovetti, A. Saputi, A. Sarnatskiy, G. Sarpis, M. Sarpis, C. Satriano, A. Satta, M. Saur, H. Sazak, F. Sborzacchi, A. Scarabotto, S. Schael, S. Scherl, M. Schiller, H. Schindler, M. Schmelling, B. Schmidt, N. Schmidt, S. Schmitt, H. Schmitz, O. Schneider, A. Schopper, N. Schulte, H. Schumacher, M.H. Schune, G. Schwering, B. Sciascia, A. Sciuccati, G. Scriven, I. Segal, S. Sellam, M. Senghi Soares, A. Sergi, N. Serra, L. Sestini, B. Sevilla Sanjuan, Y. Shang, D.M. Shangase, R.S. Sharma, L. Shchutska, T. Shears, S. Shelton, J. Shen, Z. Shen, S. Sheng, B. Shi, J. Shi, Q. Shi, W.S. Shi, E. Shmanin, R. Silva Coutinho, G. Simi, S. Simone, M. Singha, I. Siral, N. Skidmore, T. Skwarnicki, M.W. Slater, E. Smith, M. Smith, M. Smith, L. Soares Lavra, M.D. Sokoloff, F.J.P. Soler, A. Solomin, K. Solovieva, N.S. Sommerfeld, R. Song, Y. Song, Y. Song, Y.S. Song, F.L. Souza De Almeida, G. Souza De Castro, B. Souza De Paula, K.M. Sowa, E. Spadaro Norella, E. Spedicato, J.G. Speer, P. Spradlin, F. Stagni, M. Stahl, S. Stahl, S. Stanislaus, M. Stefaniak, O. Steinkamp, F. Suljik, J. Sun, L. Sun, M. Sun, D. Sundfeld, P. Svihra, V. Svintozelskyi, J. Swallow, K. Swientek, F. Swystun, A. Szabelski, T. Szumlak, Y. Tan, Y. Tang, Y.T. Tang, M.D. Tat, J.A. Teijeiro Jimenez, F. Terzuoli, F. Teubert, E. Thomas, D.J.D. Thompson, A.R. Thomson-Strong, R. Thornton, H. Tilquin, V. 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Zheng, X.Z. Zheng, Y. Zheng, T. Zhou, X. Zhou, V. Zhovkovska, L.Z. Zhu, X. Zhu, X. Zhu, Y. Zhu, V. Zhukov, J. Zhuo, T. Zies, D. Zuliani, X. Zuo

Accelerator Physics

Flow-based surrogate models for particle tracking

Matthias Remta, Yann Dutheil and Francesco Velotti

Particle tracking is a fundamental tool for particle-accelerator design and optimisation. Conventional tracking routines provide high accuracy but are computationally demanding, especially when simulating large particle ensembles or long time spans. As a result, optimising moderate- to high-dimensional parameter spaces is challenging, and real-time surrogate models remain out of reach for many applications. This contribution introduces a surrogate-modelling approach based on conditional flow matching (CFM). A CFM model is trained on tracking simulations of CERN's Proton Synchrotron (PS) over a 10-dimensional parameter space. The trained model reproduces final phase-space distributions with a median squared maximum mean discrepancy MMD$^2$ of $3\times 10^{-4}$ and mean inference time of 0.04 s, a speed-up of three orders of magnitude over conventional tracking. To capture distribution-dependent dynamics that vanilla CFM cannot represent, we extend the model with cross-attention over the initial particle ensemble (Cross-Attention-CFM) and demonstrate that this extension recovers performance on a space-charge benchmark in the PS, where vanilla CFM degrades. Finally, we introduce Hybrid-CFM, in which a small number of conventionally-tracked particles are used to inform the model. On the same 10-dimensional PS task, Hybrid-CFM with 100 auxiliary particles trained on 200 distributions matches the vanilla CFM trained on 1500, and improves the worst-case (90th-percentile) MMD$^2$ by roughly a factor of four, substantially reducing the upfront cost of building a surrogate.
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Soft Condensed Matter

Active Reinforcement of Jammed Emulsions by Living Microswimmers

Marie Corpart, Hugo Le Roux, Daniel Bonn et al. (+1 more)

We show that living microswimmers mechanically reinforce dense emulsions. Castor-oil-in-water emulsions laden with the microalga Chlamydomonas reinhardtii are compared in three states: without algae, with immobilized algae, and with motile algae, over a broad range of oil fractions spanning the jamming transition. Oscillatory rheology reveals that motile algae systematically increase the yield stress, by up to a factor of two, whereas immobilized cells at the same concentration leave it essentially unchanged. The reinforcement thus originates from activity rather than from the mere presence of inclusions. Single-cell tracking shows that the droplet network confines the swimmers in pores that shrink as the oil fraction increases, and confinement is known to amplify the propulsion force of C. reinhardtii. A simple estimate based on this confinement-enhanced force accounts for the measured excess yield stress and indicates an effective, activity-induced depletion-like attraction between the passive droplets. These results identify a feedback loop: the microstructure confines the swimmers, confinement amplifies the forces they exert, and these forces stiffen the microstructure. Active emulsions thus emerge as a model platform for programming the mechanics of disordered soft solids through activity.
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All authors Marie Corpart, Hugo Le Roux, Daniel Bonn, Antoine Deblais

High Energy Astrophysical Phenomena

EWOCS VII : Unveiling the faint diffuse X-ray emission in Westerlund 1

Albacete-Colombo J.F., Andersen M., De Becker M. et al. (+16 more)

Westerlund 1 (Wd 1) is the closest supermassive star cluster to the Sun, with over 100,000 stars of all spectral types down to brown dwarfs. This population strongly heats the surrounding interstellar medium (ISM), making Wd 1 a key site to study stellar feedback on intracluster gas. We present the most detailed X-ray study to date of its diffuse emission, aiming to separate and quantify the point-source contribution to the true diffuse emission. We analysed 36 Chandra ACIS-I observations within an 8x8 arcmin window. After removing 4922 point sources with ACIS Extract using energy-dependent PSF models and adaptive 99% enclosed-energy masks, we subtracted PSF-wing contamination and corrected for background, then applied adaptive smoothing in soft, medium, and hard bands. Spectral fitting suggests a shocked thermal plasma, with diffuse X-rays correlating spatially with massive stars. The core (Region #2) fits an APEC+PSHOCK model, with temperatures of 1.81+/-0.24 and 4.11+/-1.98 keV and a 6.7 keV Fe K-alpha line. The outer Region #1 shows charge-exchange emission, fitting a CXE+NEI model with softer temperatures of 0.27+/-0.04 and 1.09+/-0.05 keV. Column densities range from 1.84-2.24x10^22 cm^-2, and the total (0.5-8.0 keV) diffuse luminosity is ~9.6(+/-0.3)x10^33 erg/s. Near the core, hard emission likely arises from thermalised Wolf-Rayet winds and wind-wind collisions, softened by adiabatic expansion and turbulent mixing with cooler ISM. The soft component extends farther out, possibly from CXE in lower-extinction regions. No non-thermal contribution is found. A cluster-wind model predicts a luminosity ~2.2 above that observed, consistent with a low-density, partially evacuated intracluster medium. The resulting wind-to-X-ray efficiency, eta ~4.3x10^-6, is about two orders of magnitude below Cygnus OB2, yielding comparatively subluminous diffuse X-ray emission.
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All authors Albacete-Colombo J.F., Andersen M., De Becker M., Mackey J., Larkin C.J.K., Guarcello M.G., Anastasopoulou K., Sciortino S., Greco E., Miceli M., Sapienza V., Flaccomio E., Filócomo A., Stevens I.A., Bayo A., Drake J.J., Gennaro M., Gunderson S.J., Fraschetti F

Instrumentation and Detectors

Reconstruction Bias in Timepix4 Subpixel Centroiding for Electron Imaging

Nina Dimova, Richard Plackett and Daniela Bortoletto

Subpixel centroiding is widely used to improve the spatial resolution of hybrid pixel detectors for electron imaging by estimating the true interaction position within an entry pixel. Existing centroiding strategies are typically optimised using localisation accuracy. However, observations show that improved localisation does not necessarily translate into improved modulation transfer function (MTF) or reliable virtual-pixel rebinning. This work proposes a unified interpretation of these observations based on the ambiguity of the centroid reconstruction problem. We show that observable-based centroid estimators solve an intrinsically non-unique inverse problem using deterministic reconstruction rules, which can introduce entry-phase-dependent reconstruction bias that governs the spatial distribution of reconstructed subpixel coordinates. This framework explains why localisation accuracy alone is insufficient to predict imaging performance and identifies approximate intra-pixel translational symmetry as a prerequisite for faithful virtual-pixel imaging. The proposed interpretation is evaluated using simulated 200 keV and 300 keV electron data together with measured 200 keV data acquired with a Timepix4 detector. Comparisons of charge-weighted, timing-based, and morphology-dependent centroiding strategies demonstrate that estimators with similar localisation performance can exhibit markedly different MTFs and rebinned flat-field behaviour. The results suggest that future centroid optimisation should consider subpixel phase bias and rebinnability alongside localisation accuracy.
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Chemical Physics

Intracavity Photon Statistics from Correlated Molecular Electronic Structure

Kurt R. Brorsen

Quantum optics characterizes light through photon correlations, but ab initio cavity quantum electrodynamics (QED) has only calculated raw field moments at present. In this study, intracavity photon statistics of cavity-coupled molecules are computed from QED coupled-cluster (QED-CCSD-22) densities and validated against exact diagonalization of the Pauli-Fierz Hamiltonian. A change of coordinate origin or dipole convention displaces the ground state coherently, so second-order and higher cumulants of the cavity field are well defined even for molecular ions. The photon subsystem of QED Hartree-Fock is exactly coherent, so the invariant statistics measure electron-photon correlation. The field fluctuations are super-Poissonian, and their degree of second-order coherence is set by the cavity frequency rather than by the coupling strength, falling from 18.5 to 4.9 for H2 as the cavity is detuned from 5 to 20 eV. A parity selection rule makes the sign of the third cumulant a probe of the orientation of the molecular charge asymmetry along the cavity polarization.
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