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Physics

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Wednesday 24 June

Earth and Planetary Astrophysics

Using VLTI/GRAVITY+ to determine the identity of a third planet candidate in the PDS 70 system

David Trevascus, Wolfgang Brandner, Olga Balsalobre-Ruza et al. (+75 more)

Detections of protoplanets are rare and protoplanetary disk features mischaracterized as planets are common. PDS 70 is one of only two stars known to host multiple confirmed protoplanets, PDS 70 b and c, and repeat detections of a third point-like source in the system suggest the presence of third inner planet. However, previous observations of this third source are insufficient to distinguish whether it is a planet or a concentrated dust clump in Keplerian motion. Our observations with VLTI/GRAVITY+ did not re-detect this point-like source, suggesting that it is, in fact, a dust clump and not a planet. These observations demonstrate how the angular resolving power of VLTI/GRAVITY+ can be used to distinguish between protoplanets and protoplanetary disk features.
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All authors David Trevascus, Wolfgang Brandner, Olga Balsalobre-Ruza, Sylvestre Lacour, Karim Abd El Dayem, Nicolas Aimar, Anthony Berdeu, Jean-Philppe Berger, Guillaume Bourdarot, Valentin Christiaens, Carlos Correia, Richard Davies, Denis Defrère, Antonia Drescher, Andreas Eckart, Frank Eisenhauer, Maximilian Fabricius, Helmut Feuchtgruber, Simon Flesch, Natascha M. Förster Schreiber, Arianna Foschi, Quentin Fournier, Paulo Garcia, Rebeca Garcia Lopez, Reinhard Genzel, Stefan Gillessen, Iain Hammond, Sebastian F. Hönig, Mathias Houllé, Simran Joharle, Pierre Kervella, Laura Kreidberg, Lucas Labadie, Olivier Lai, Romain Laugier, Jean-Baptiste Le Bouquin, James Leftley, Ruancun Li, Bruno Lopez, Dieter Lutz, Gabriel-Dominique Marleau, Felix Mang, Antoine Mérand, Florentin Millour, Miguel Montargès, Nuno Morujão, Hugo Nowacki, Mathias Nowak, Juan Osorno, Thomas Ott, Sarah Pappert, Thibaut Paumard, Karine Perraut, Guy Perrin, Romain Petrov, Pierre-Olivier Petrucci, Nicolas Pourré, Sebastian Rabien, Diogo C. Ribeiro, Sylvie Robbe-Dubois, Matteo Sadun Bordoni, Joel Sánchez Bermúdez, Daryl Santos, Jonas Sauter, Jules Scigliuto, Jinyi Shangguan, Taro T. Shimizu, Ferréol Soulez, Christian Straubmeier, Eckhard Sturm, Matthias Subroweit, Calvin Sykes, Linda Tacconi, Paloma Thévenet, Irene Urso, Frédéric Vincent, Julien Woillez, the GRAVITY+ Collaboration

Quantum Physics

Optimal observables for quantum-enhanced sensing and applications in a Floquet time crystal sensor

M. A. Manya, Andrei Tsypilnikov and Fernando Iemini

In this work, we discuss how to determine and implement feasible optimal observables for a metrology protocol that saturates the quantum Fisher information (QFI) bound. In particular, we focus our study on a simple protocol, namely the method of moments (MoM). We first demonstrate that the symmetric logarithmic derivative (SLD) operator, a Hermitian observable, once implemented in the MoM, saturates the QFI bound. However, the SLD is generally too complex and typically non-local, rendering its direct experimental realization unfeasible. To overcome this limitation, we explore its structure in a specific sensing model - a Floquet time crystal (FTC) acting as an ac field sensor - and show that the SLD can be approximated by substantially simpler observables, such as the bare spin magnetization or a parity observable, for different relevant initial state preparations. We further corroborate our theoretical predictions in a nuclear magnetic resonance system operating as an FTC sensor, employing experimentally motivated parameters to simulate its performance in a state-of-the-art implementation. In general, our results establish a practical route toward near-optimal metrology in FTC sensors, where the inaccessible SLD operator can be replaced by simpler observables while retaining quantum-enhanced sensitivity.
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High Energy Physics (Phenomenology)

Double-real corrections to $e^+e^-\to q\bar{q}$ with partial fractioned scalar radiators and identified particle kinematics mappings

John M. Campbell, Stefan Höche and Max Knobbe

We present a new approach to local infrared subtraction for next-to-next-to-leading order QCD calculations in $e^+e^-\to q\bar{q}$. Overlapping singularities in the multipole radiation pattern are disentangled by partial fractioning, and the kinematics mapping corresponds to iterated next-to-leading order identified particle kinematics. We verify that the double-real remainder is rendered finite in the single and double unresolved limits and investigate the numerical convergence of the Monte-Carlo integral. We compute the phase-space integrals of the scalar counterterms in the back-to-back configuration, both analytically and with the help of numerical techniques based on sector decomposition.
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High Energy Physics (Phenomenology)

Axial-Vector Lattice Benchmarks Reveal a Common Medium Response of Meson Screening in Hot QCD

Jie Ren, Chen Chen, Fei Gao et al. (+1 more)

Meson screening masses trace the evolution of hadronic correlations toward quasi-free quark–antiquark screening in hot QCD. Combining lattice QCD (LQCD) benchmarks with a symmetry-preserving Dyson–Schwinger baseline, we identify a flavor-dependent axial-vector quasi-free onset, $x^\ast_{fg}=T^\ast_{fg}/T_c$: an operational high-temperature matching scale at which the axial-vector screening mass has approached the corresponding free-field value after ordinary chiral restoration or parity-partner convergence has set in. On the finite interval $1\le x\lesssim x^\ast_{fg}$, independent light/strange and charm-containing lattice benchmarks are organized by a common medium-response function with one flavor-sector parameter. One axial-vector point fixes this parameter; the remaining axial-vector data test its temperature dependence, and vector screening masses validate it without vector input. A reduced-mass interpolation then yields lattice-testable quasi-free onsets and screening spectra for light-charm and bottom-containing sectors. The resulting onset scales provide common reference points for future lattice and continuum studies of meson dissolution across flavor.
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All authors Jie Ren, Chen Chen, Fei Gao, Si-xue Qin

Strongly Correlated Electrons

Bobkingite, a new coupled sawtooth chain platform

P. Peter Stavropoulos, Aleksandar Razpopov, Harrison LaBollita et al. (+3 more)

We investigate the mineral bobkingite, \ce{Cu5(OH)8Cl2(H2O)2}, as a potential realization of the sawtooth chain. Using ab initio methods, we estimate the magnetic exchange couplings and find that bobkingite hosts quasi-one-dimensional sawtooth chains, with residual three-dimensional interactions strongly suppressed by the crystal geometry. Examining the full exchange network, we find that the classical model exhibits an extensive manifold of nearly degenerate states with emergent two-dimensional character, which spin-wave theory shows to persist to leading order in quantum fluctuations as Ising degrees of freedom. Unlike other sawtooth candidates, bobkingite has negligible vertical interchain coupling, preserving a one-dimensional degeneracy even in the presence of ordering, suggesting that any long-range order is weak. Thermal fluctuations may thus stabilize a finite-temperature classical spin liquid regime, with a cascade of transitions upon cooling into successively lower-dimensional degenerate states, making bobkingite a compelling platform for exploring sawtooth chain physics.
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All authors P. Peter Stavropoulos, Aleksandar Razpopov, Harrison LaBollita, Michael R. Norman, Antia S. Botana, Roser Valentí

Quantum Physics

Permutation asymmetry unlocks emergent advantage in randomized Bell tests

Wieslaw Laskowski, Tamas Vertesi and Jan Wojcik

All maximally entangled two-qubit states violate local realism with the same probability under uniformly random projective measurements, yet they need not behave identically in randomized Bell tests. We show that when measurement settings are exchanged between the parties in sequential Bell experiments, permutation symmetry of the shared state determines the statistical relation between the two realizations. Permutationally invariant states yield identical nonlocality outcomes in both experiments, whereas asymmetric states can violate local realism in one realization but not in the other. This distinction leads to two operational consequences. First, it enables the detection of correlations between the measurement choices of Alice and Bob through the joint violation statistics. Second, in Bell tests with finite measurement pools, asymmetric maximally entangled states can significantly increase the probability of observing nonlocality without requiring additional resources. Our results identify permutation asymmetry as a useful feature in randomized Bell experiments and highlight a new role of symmetry in quantum nonlocality.
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High Energy Physics (Theory)

An observer's quantization of 3d de Sitter

Andreas Blommaert, Damiano Tietto and Herman Verlinde

What is the density of states of the de Sitter static patch? We propose a definition and calculation of such a density in 3d dS. Our proposal involves a sum over an SL(2,$\mathbb{Z}$) set of Euclidean no-boundary Kerr-lens spacetimes sourced by a line-defect with given energy and spin - which in Lorentzian time represents an observer's worldline at the center of the dS static patch. We develop an exact quantum computation of the spectral density using a holographic duality between dS$_3$ gravity and two copies of $\mathbb{C}$LS, the complex Liouville string. The SL(2,$\mathbb{Z}$) Kerr-lens spacetimes map under the duality to an SL(2,$\mathbb{Z}$) family of generalized crosscap geometries. We compute the $\mathbb{C}$LS $\otimes$ $\mathbb{C}$LS crosscap amplitudes and show that they match the semi-classical gravity prediction. For the simplest non-trivial Kerr-lens space, the $\mathbb{C}$LS $\otimes$ $\mathbb{C}$LS description is, in turn, dual to two copies of the $G\Sigma$ effective field theory of the double scaled SYK model. The $G\Sigma\otimes G\Sigma$ theory lives on an observer's worldline in the static patch, setting the stage for developing a microscopic worldline hologram of 3d de Sitter.
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High Energy Physics (Phenomenology)

Constraining Multiple Kinetically Mixed Dark Photons

Joerg Jaeckel and Sebastian Monath

Extra U(1) gauge bosons under which Standard Model particles are uncharged, aka dark photons, are a simple and well-motivated extension of the Standard Model. There could be a single, but also several or even many such dark photons. However, most studies consider only a single dark photon. Here, we want to look at the more general case of multiple dark photons interacting with the Standard Model via kinetic mixing. We consider a range of standard probes, Cavendish experiments, light-shining-through-walls experiments, as well as energy loss in stars. To explore the rather high-dimensional parameter space of the masses and the kinetic mixing matrix, we pursue a statistical approach, considering different distributions for the kinetic mixing parameters.
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Mesoscale and Nanoscale Physics

Anomalous Hall viscosity of altermagnets

Iksu Jang, Rui Aquino, Jörg Schmalian et al. (+1 more)

We show that the phonon Hall viscosity at zero magnetic field is a natural probe of altermagnetism. First, we demonstrate that the finite elements of the Hall viscosity tensor unambiguously distinguish altermagnets from ferromagnets and conventional antiferromagnets. We then microscopically compute the Hall viscosity in models for d-wave and g-wave altermagnets, and find a strong sensitivity to electronic spectrum features such as gapped Dirac points and Lifshitz transitions. This sensitivity reflects a strain-space Berry curvature monopole, which contrast to the multipolar character of the standard momentum-space Berry curvature in altermagnets. Since the Hall viscosity can be probed experimentally through magneto-acoustic measurements, it provides a compelling method to probe the broken symmetries and topology of insulating altermagnets.
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All authors Iksu Jang, Rui Aquino, Jörg Schmalian, Rafael M. Fernandes

Soft Condensed Matter

Odd Diffusion in Three-Dimensional Isotropic Media

Viola Zixin Zhao, Andres Franco Valiente and David T. Limmer

Odd diffusion is a hallmark of chiral active matter, generating currents transverse to density gradients. Existing theories rely on a linear antisymmetric transport coefficient that exists only in two dimensions, raising the question of whether odd diffusion can occur in isotropic three-dimensional systems. Here we show that such transport is possible through a nonlinear constitutive law. Symmetry considerations reveal that the three-dimensional Levi-Civita tensor permits a leading order isotropic odd current at second order in the density gradient expansion and only in multicomponent systems. The resulting transport generates boundary-driven rotational currents, finite vorticity, and enstrophy despite the absence of external torques or preferred directions. We show how such a constitutive law derives from a microscopic model of particles interacting through nonreciprocal three-body forces using the Dean–Kawasaki coarse-graining procedure. These results establish a minimal framework for odd transport in isotropic three dimensions.
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Cosmology and Nongalactic Astrophysics

First full-shape joint analysis of the two- and three-point correlation functions on real data: $\Lambda$CDM cosmological constraints from BOSS DR12

Massimo Guidi, Michele Moresco, Alfonso Veropalumbo et al. (+3 more)

The three-point correlation function (3PCF) encodes cosmological information beyond the two-point correlation function (2PCF), yet a full-shape joint analysis in redshift space using real data has so far been lacking. We present the first full-shape cosmological constraints from a joint analysis of 2PCF and 3PCF in redshift space, using BOSS DR12 data, extending to real data, including Alcock–Paczyński and redsfhit space distortions, the full-shape configuration-space framework validated in real space for the first time by Euclid Collaboration: Guidi et al (2026). We model both statistics adopting the velocity difference generating function (VDG) framework, incorporating non-perturbative Fingers-of-God damping, a complete Eulerian galaxy bias expansion, and infrared resummation. Fast and accurate theoretical predictions are obtained using dedicated emulators, which enable a full-shape likelihood analysis of the 3PCF and its combination with the 2PCF, varying the cosmological parameters $10^9 A_s, \omega_{\rm cdm}$ and $h$, while the baryon fraction density $\omega_{b}$ is fixed to its fiducial value. The covariance matrix is estimated from 2048 MultiDark-Patchy mocks, and an optimal data-vector compression ensures a stable covariance inversion. The perturbative model is validated against goodness-of-fit tests across different scales, and provides a good description of the joint data vector down to $r_{\rm min}^{\rm 3PCF} \sim 60\,h^{-1}{\rm Mpc}$. We find that the joint 2PCF+3PCF analysis yields significant improvements over the 2PCF-only baseline, with gains of approximately 29%, 10%, and 24% on $\sigma(h)$, $\sigma(\omega_{\rm cdm})$, and $\sigma(A_s)$, respectively. The improvements mainly arise from the additional BAO cosmological information encoded in the 3PCF triangle configurations.
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All authors Massimo Guidi, Michele Moresco, Alfonso Veropalumbo, Lorenzo Cavazzini, Antonio Farina, Andrea Labate

Quantum Physics

Measures of Chirality in Mixed-State Topological Phases

Shijun Sun, Bader Aldossari, Rasmit Devkota et al. (+1 more)

What does it mean for a mixed-state topological phase to be chiral? Mathematically, chirality can be sharply characterized through the symmetry algebra of the mixed state. Physically, however, the question is far more subtle. In pure states, chirality in topological phase is tied to a web of familiar diagnostics, involving bulk-boundary correspondence, a gapless entanglement spectrum, a nontrivial modular commutator, and a quantized thermal Hall response. We show that none of these diagnostics remain reliable in mixed states. Instead, for decohered topological phases with a known error-free parent state, we propose two relative-entropy-based measures that can diagnose chirality, with one of them further extracting the chiral central charge. As a concrete example, we use these measures to analyze the $em^2$-decohered $\mathbb{Z}_3$ toric code, identifying the chirality transition to be in the random-bond Potts class for the particle-hole symmetric channel, and the polarized random bond Potts class for asymmetric channels. Our results emphasize how mixed-state topology demands intrinsically new diagnostics beyond direct analogues of pure-state probes.
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All authors Shijun Sun, Bader Aldossari, Rasmit Devkota, Zhu-Xi Luo

Cosmology and Nongalactic Astrophysics

Lyman-Alpha Forest and its Cross-Correlation with High-Redshift Galaxies in Effective Field Theory at the Field Level

Roger de Belsunce, Mikhail M. Ivanov, James M. Sullivan et al. (+2 more)

We present a field-level perturbative forward model for the Lyman-alpha (Lya) forest flux decrement. We validate it on two simulation suites: large-volume AbacusSummit N-body simulations with the Lya forest painted onto the dark matter field, and the Sherwood hydrodynamic simulations. Across the redshift range of the simulations (z=2.0-3.2), the 3D and 1D power spectra of the model match the simulated Lya fields at the 1% (5%) level up to k <= 0.3 (1.0) h/Mpc, with similar performance for the cross-correlation with massive dark matter halos. The counts-in-cells statistic shows excellent agreement down to cell radii of 2 Mpc/h. Leveraging cosmic variance cancellation, the model enables precision measurements of Lya bias parameters and robustly detects the full set of quadratic line-of-sight bias operators, consistent with the notion of naturalness in effective field theory (EFT). We quantify the stochasticity of the Lya forest (the analog to the one-halo term), and find it to be white (scale- and orientation-independent) on large scales, matching EFT predictions. We further find that phenomenological flux power spectrum models, based on modulations of the linear-theory power spectrum, fail at the field level even on quasi-linear scales. For the currently observing Dark Energy Spectroscopic Instrument (DESI), we generate large-scale clustering mocks of the Lya forest to validate cosmological parameter inference pipelines. Looking ahead to its successor, DESI-II, we produce large-volume mocks of representative samples of Lyman-break galaxies (LBGs) and Lya emitters (LAEs), calibrated on Astrid hydrodynamic simulations and matched to observations at z=3, enabling joint analyses of Lya forest and high-redshift galaxy data.
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All authors Roger de Belsunce, Mikhail M. Ivanov, James M. Sullivan, Shi-Fan Chen, Kazuyuki Akitsu

Quantum Physics

A fidelity metric for quantum annealing benchmarked by extreme scaling quantum Monte-Carlo simulations

Gabriel Gouraud, Miha Srdinsek and Xavier Waintal

Quantum annealers are supposed to follow adiabatically the ground state of a system as its Hamiltonian slowly interpolates between a trivial phase and a non-trivial one; the non-trivial ground state being the solution to an optimization problem. Overwhelmingly, their performances are measured in terms of how well or fast the optimization problem is solved. While pragmatic, this approach is inherently brittle as it strongly depends on the problem considered and the classical algorithm used as the reference benchmark. Here, we propose a quantity that not only measures the end result but also the quality of the actual quantum annealing process itself. Our metric is the quantum annealing counterpart of the fidelity-per gate of gate-based quantum computers. It takes the form of an accuracy $\epsilon$ for the equation of state of the annealer. We calculate benchmark values of $\epsilon$ using two variants of the simulated quantum annealing technique for Rydberg atoms systems. Our first approach uses variational quantum Monte-Carlo with an ansatz inspired by thermal annealing. It suggests that within $\epsilon \sim 10^{-2}-10^{-3}$, a quantum annealer is indistinguishable from its thermal classical counterpart. Critically, we could reach this precision up to $100,000,000$ atoms on a single CPU. Our second approach (based on Green function quantum Monte-Carlo) reaches accuracies around $\epsilon \sim 10^{-4}$ and we have run it up to $100,000$ atoms. These results outperform current Rydberg atom quantum annealing experimental platforms in both precision and size by orders of magnitude and put severe constraints for future hardware.
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Solar and Stellar Astrophysics

Modeling the curved dust sublimation front in protoplanetary disks: a potential probe of midplane turbulence

Ezequiel Manzo-Martínez, Ramiro Franco-Hernández, Nuria Calvet et al. (+3 more)

We present a new approach to calculate the geometry and emission of the dust inner wall in disks around T Tauri stars. This calculation follows a self-consistent approach given the disk structure and adopts a density-dependent sublimation temperature for the dust. We built spectral energy distributions (SEDs) of disk models with curved walls around a $0.5\,M_\odot$ star, finding that the curved wall starts at a radius of $\sim 0.11$ au and extends to $\sim 0.38$ au. The dependence on mass accretion rate, dust settling, and disk inclination on the resulting SEDs is explored, as well as the impact of the height of the midplane layer containing large millimeter-sized grains. To test our models, we compare synthetic near-IR colors from a grid of disk models with observed colors for a large sample of disk-bearing T Tauri stars located in Taurus, IC 348, and the Orion complex. Most of the observed colors can be explained by combinations of mass accretion rates, dust settling, and inclinations within the expected ranges for T Tauri stars. However, populating the regions where observed JHK colors are most concentrated, requires the millimeter-size grains be spread up to 0.5–3 scale heights above the midplane. This result contradicts expectations of rapid dust settling and suggests a high degree of turbulence capable of lifting large grains toward the upper disk layers. These findings provide insight into the dynamical conditions of the disk midplane near the star.
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All authors Ezequiel Manzo-Martínez, Ramiro Franco-Hernández, Nuria Calvet, Jesús Hernández, Paola D'Alessio, Rosa M. Torres

High Energy Astrophysical Phenomena

3D Kinematic Reconstruction of the Crab Nebula That Includes the Northern Ejecta `Jet'

Ziwei Ding, Dan Milisavljevic, Thomas Martin et al. (+4 more)

We present new detailed three-dimensional kinematic reconstructions of the Crab Nebula created from hyperspectral cubes obtained with the SITELLE instrument mounted on the Canada–France–Hawaii Telescope. Our data cubes span a wavelength range from 3600Å to 7000Å, covering major emission lines including [O II] $\lambda\lambda$3726, 3729, H$\beta$, [O III] $\lambda\lambda$4959, 5007, [N II] $\lambda$5755, He I $\lambda$5876, [N II] $\lambda\lambda$6548, 6584, [S II] $\lambda\lambda$6717, 6731, and H$\alpha$. The field of view encompasses the “chimney" or “jet," a 45-arcsec-wide funnel-shaped structure that extends 100 arcsec beyond the northern limb of the nebula. Our 3D reconstructions confirm and geometrically resolve a cavity at the jet's base that was suggested by earlier kinematic studies, establishing a direct physical connection between the filamentary network and the jet funnel. The morphology and kinematics indicate that the early pulsar wind nebula (PWN) played a central role in forming the jet. Several formation scenarios, which are not necessarily mutually exclusive, remain viable, including a bipolar outflow shaped by a circumstellar disk, a breach or underdensity in the ejecta shell, and a pre-existing progenitor mass-loss trail acting as a low-density channel. Collectively, these scenarios exhibit differing abilities to account for the jet's pronounced collimation, the absence of a southern counterpart, and its near-ballistic motion. Discriminating among them will require fully three-dimensional hydrodynamic simulations that trace the remnant's evolution from the progenitor phase through late-time PWN expansion.
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All authors Ziwei Ding, Dan Milisavljevic, Thomas Martin, Tea Temim, John C.Raymond, Soham Mandal, Laurent Drissen

Cosmology and Nongalactic Astrophysics

Cutting with precision – Leveraging Collapse Volumes to generate the next generation of zoom-in initial conditions

Benjamin Seidel, Klaus Dolag and Jenny G. Sorce

Astrophysical processes happen across a wide range of scales. This poses a significant challenge from the perspective of modeling these processes. Modern cosmological simulations attempt to maximize the simulation volume to capture the full range of the density power spectrum while simultaneously optimizing spatial resolution for improved modeling of dynamics at galactic scales. Performing zoom-in simulations of galaxy clusters is a way to reconcile computational cost, mass resolution, and large-scale realism in simulations. To study the baryonic evolution of structures it is critical to ensure that the volume of interest is uncontaminated by high-mass particles from outside the zoom-in region. We introduce a new method of constructing stable boundaries for layered zoom-in initial conditions. Applying this method to clusters from the SLOW constrained simulation, we introduce the SLOW cluster zoom-in initial conditions. We select regions using a forward run of a gravity-only version of the parent box. We performed test simulations for a set of 20 regions created from the SLOW constrained simulations containing 30 local clusters. The simulations demonstrate these initial conditions to be stable against deformation and mixing of the boundary region. Consequently, they are uncontaminated to an unprecedented degree, reaching pristine regions of sizes exceeding 6 virial radii. These simulations will provide the basis for the first high-resolution simulations of a large set of directly comparable local galaxy cluster analogues and their environment to date. Their high fidelity in terms of stability and resolution in combination with the accuracy of the underlying local Universe model makes these simulations the first of their kind. They will enable comparisons with state-of-the art observations targeting both cluster properties and ICM physics as well as galaxy evolution in the local Universe.
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High Energy Physics (Phenomenology)

Magnetic monopole plasma oscillations and implications for TeV blazars

Mariia Khelashvili, Takeshi Kobayashi and Andrew J. Long

Magnetic monopoles arise in many beyond Standard Model scenarios, symmetrize Maxwell's equations, and their existence would be tied to the quantization of electric charge. It has been argued that, when placed in an astrophysical magnetic field, monopoles can induce a magnetic version of plasma oscillations. In this work, we explore monopole-induced oscillations of the intergalactic magnetic field (IGMF). We show that monopole-induced oscillations of the magnetic field lead to collimation of electrically charged particle trajectories, reducing the usual deflection by the magnetic field. The collimation effect impacts the deflection angle in the electromagnetic cascades of TeV blazars and leads to a decrease in the angular size of blazar secondary GeV halos. Therefore, the constraints on the secondary halo angular size from combined H.E.S.S. and Fermi-LAT observations translate into bounds on the magnetic monopole abundance. The bounds on the magnetic monopole flux obtained in this work from blazar 1ES 0229+200, depending on the IGMF strength, can be as strong as $F \lesssim 6 \times 10^{-23}\, \text{cm}^{-2} \text{s}^{-1} \text{str}^{-1}$ for low-mass monopoles $m \lesssim 10^6\, \text{GeV}$, stronger than existing laboratory and astrophysical bounds. The bound becomes subdominant to current constraints if the present-day IGMF value is stronger than $B \gtrsim 10^{-12}\, \text{G}$. At the same time, in the case of non-zero monopole abundance, the IGMF lower bound from TeV observations itself should be revised, resulting in a stronger lower bound at higher monopole number density.
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Data Analysis and Statistics

Interpreting "Interpretability" and Explaining "Explainability" in Machine Learning in Physics

Rikab Gambhir, Luisa Lucie-Smith and Jesse Thaler

We review the concepts of interpretability and explainability as they apply to machine learning in physics. We define interpretability as concerning the structural transparency of a model (the ability to understand or approximate its inner workings) and explainability as concerning the scientific content of a model (the ability to map it onto domain knowledge). We discuss the trade-offs each entails (interpretability vs. expressivity; explainability vs. adaptability), the contexts in which each is needed, and the intrinsic and post-hoc tools available for achieving them. Throughout, we emphasize that machine-learned models are subject to the same scientific questions as classical models, differing only in scale, and that interpretability and explainability are best understood as deliberate modeling choices rather than inherent properties. We also emphasize the importance of task specification and intervention plans as a core aspect of model design.
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Astrophysics of Galaxies

Latent thermal instability

Prakriti Pal Choudhury and Archie F. A. Bott

Multiscale temperature fluctuations are abundant in the intracluster medium (ICM) outside of galaxy cluster cores ($\sim 100~{\rm kpc}$). Their origin is often attributed to turbulent stirring by subhalos or accreting baryons crossing the virial radius. However, their apparent resistance to mixing and thermal conduction in a collisional medium has not been explained. We propose a new mechanism by which steady-state temperature fluctuations can form and persist outside the cluster core. Local thermal instability, or Field instability, is used to explain filamentary condensates in cluster cores but is usually dismissed outside them because thermal conduction should suppress instability. In weakly collisional or collisionless plasmas, however, thermal conduction can be anomalously suppressed by heat-flux-driven plasma instabilities triggered in presence of a local magnetic field, leading to two effects: (i) condensates form in a new parameter regime that overlaps with conditions outside the core, and (ii) condensates reach a steady state as in the hydrodynamic limit. This extends the regime of instability-driven fluctuations to over $\gtrsim50\%$ (depending on hot plasma temperature) of the cluster. We use one-dimensional hydrodynamic simulations of condensates to test our analytical ideas.
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Strongly Correlated Electrons

Toric code made subsystem: a framework for topological subsystem codes using anticommuting quantum spin liquids

Vaibhav Sharma and Sumiran Pujari

We introduce a framework of constructing topological subsystem codes based on the class of anticommuting quantum spin liquids described in [Phys. Rev. B 113, 064402 (2026)]. A canonical model from this class can be considered as a spatial modification of the toric code that voids its stabilizer code property. Rather, these models contain an extensive set of anticommuting local conserved operators that lead to an extensive ground state degeneracy. This degeneracy forms the basis of the subsystem degrees of freedom in the associated quantum error correcting code. The code inherits the many-body topological order of the quantum spin liquid, making it a topological subsystem code. We present two concrete and detailed examples for constructing these codes on a square lattice and a kagome lattice geometry, requiring weight-4 and weight-3 local check operator measurements respectively. In contrast to other subsystem codes, a unique property of these codes is the presence of an extensive number of local gauge qubits that are left undisturbed by the check operators apart from the logical qubits. Our construction provides a template for generating this new category of topological subsystem codes on different lattice or graph geometries, suitable for implementation on various quantum hardware platforms.
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Quantum Gases

The odd fermion at the edge: odd-even staggering in the trapped, unitary Fermi gas

Silas R. Beane, Domenico Orlando and Susanne Reffert

We investigate the odd-even staggering in the harmonically-trapped unitary Fermi gas at large particle-number charge $Q$. Using both a large-$N$ BdG description and a complementary large-charge EFT method, we show that for odd particle number the extra fermion forms an edge-localized quasiparticle near the Thomas-Fermi surface rather than a bulk excitation. In the edge limit, the microscopic BdG problem reduces to a universal coupled Airy system whose lowest positive eigenvalue fixes the leading odd-even splitting energy, $\chi\,\xi^{1/6}(24Q)^{1/9}\,\hbar\omega + \cdots$ where $\xi$ is the Bertsch parameter, and $\chi$ is a universal edge coefficient. The associated EFT describes a fermionic mode confined to the boundary and coupled to the superfluid Goldstone field, reproducing the same $Q$ scaling while introducing a dependence on two low-energy constants. Finally, we numerically compute the spectrum and confirm the predicted scaling and localization properties.
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High Energy Physics (Theory)

Conserved charges and $L_\infty$ algebras

Vinícius Bernardes, Theodore Erler and Atakan Hilmi F{\i}rat

We give a formula for conserved charges in an arbitrary Lagrangian field theory expressed in the framework of $L_\infty$ algebras. The formula is determined by the theory's $L_\infty$ data alone, without reference to the derivative structure of the Lagrangian. Therefore conserved charges can be computed in nonlocal models, such as string field theory, where conventional methods break down. The formula also gives the correct expression for the Hamiltonian of general relativity as a surface integral of the Brown-York stress tensor. Related computations in Yang-Mills theory suggest that spatial boundaries are dealt with in a natural fashion.
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Cosmology and Nongalactic Astrophysics

Cross-correlation of SPT-3G D1 CMB lensing and DES Y3 galaxy lensing

A. Ouellette, Y. Omori, E. Anderes et al. (+92 more)

Measurements of the weak lensing of galaxies and of the cosmic microwave background (CMB) provide direct probes of the cosmic matter density field, but the two observables are sensitive to different spatial scales, redshift ranges, and survey systematics. Their cross-correlation thus enables consistency checks of the theoretical model and of potential systematics in either dataset. We present measurements of the cross-correlation between CMB lensing and cosmic shear over $\sim$1,300 deg$^2$ of the sky using the SPT-3G D1 CMB lensing maps and the Dark Energy Survey Year 3 (DES Y3) shear catalogs. For the first time, we measure this cross-correlation at high significance ($\sim 14\sigma$) when using a polarization-only CMB lensing reconstruction that is expected to be robust against biases induced by extragalactic foregrounds. We test a variety of other CMB lensing estimators that include temperature information and exhibit different tradeoffs between foreground biases and noise, as well as a shear sample that consists of blue, star-forming galaxies and has been shown to be less impacted by galaxy intrinsic alignments. Assuming $\Lambda$CDM and marginalizing over uncertainties in intrinsic alignments, baryonic feedback, and various nuisance parameters, we obtain a constraint on the amplitude of matter clustering $S_8 \equiv \sigma_8 \sqrt{\Omega_m / 0.3} = 0.833^{+0.047}_{-0.061}$, consistent with both the primary CMB results from Planck and shear-only results from DES Y3. By combining our measurement with Planck, we find mild constraints on the astrophysical processes that impact the cross-correlation. We obtain a constraint on the intrinsic alignment amplitude of the DES sample that is competitive with that from shear-only analyses, and we find a lower limit on the strength of baryonic feedback.
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All authors A. Ouellette, Y. Omori, E. Anderes, A. J. Anderson, B. Ansarinejad, M. Archipley, L. Balkenhol, D. R. Barron, K. Benabed, A. N. Bender, B. A. Benson, F. Bianchini, L. E. Bleem, S. Bocquet, F. R. Bouchet, E. Camphuis, M. G. Campitiello, J. E. Carlstrom, J. Carron, C. Chang, C. L. Chang, P. M. Chichura, A. Chokshi, T.-L. Chou, A. Coerver, T. M. Crawford, C. Daley, T. de Haan, K. R. Dibert, M. A. Dobbs, M. Doohan, D. Dutcher, C. Feng, K. R. Ferguson, N. C. Ferree, K. Fichman, A. Foster, S. Galli, A. E. Gambrel, A. K. Gao, F. Ge, F. Guidi, S. Guns, N. W. Halverson, E. Hivon, G. P. Holder, W. L. Holzapfel, J. C. Hood, A. Hryciuk, N. Huang, T. Jhaveri, F. Kéruzoré, A. R. Khalife, L. Knox, K. Kornoelje, C.-L. Kuo, K. Levy, Y. Li, A. E. Lowitz, C. Lu, G. P. Lynch, T. J. Maccarone, A. S. Maniyar, E. S. Martsen, F. Menanteau, M. Millea, J. Montgomery, Y. Nakato, T. Natoli, Z. Pan, P. Paschos, K. A. Phadke, A. W. Pollak, K. Prabhu, W. Quan, M. Rahimi, A. Rahlin, C. L. Reichardt, M. Rouble, J. E. Ruhl, A. C. Silva Oliveira, A. Simpson, J. A. Sobrin, A. A. Stark, J. Stephen, C. Tandoi, C. Trendafilova, J. D. Vieira, A. G. Vieregg, A. Vitrier, Y. Wan, N. Whitehorn, W. L. K. Wu, M. R. Young, J. A. Zebrowski

Strongly Correlated Electrons

The fate of odd-parity magnetism in one dimension

Kasper Rettedal Eikeland, Sondre Duna Lundemo and Asle Sudbø

We consider a one-dimensional model for a $p$-wave magnet within the bosonization framework. The model consists of itinerant electrons described by an extended Hubbard model coupled to a chain of localized moments through the Kondo exchange. The classical ground state of the local-moment system captures the salient features of an odd-parity magnet. By bosonizing the coupled system, a description in terms of coupled Luttinger liquids follows, giving rise to a rich weak-coupling phase diagram. It is shown that the spin chain develops quasi long-range order consistent with the combined time-reversal and translation symmetry defining the $p$-wave magnet. We highlight the peculiar role played by this order in establishing a commensurability condition on the electronic filling under which additional interactions appear in the bosonic field theory. It is demonstrated that these interactions endow the electron spectral function with a pronounced $p$-wave character. Away from commensurate filling, these interactions are rendered irrelevant and the ensuing $p$-wave character is lost.
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High Energy Physics (Theory)

De Sitter Representations

Kurt Hinterbichler

We review the representations of so(1,D), the algebra of isometries of D dimensional de Sitter space. We cover the representations in all D, including mixed symmetry representations and fermionic representations, and connect them to the various types of fields that can propagate on de Sitter space. The presentation is from a physics point of view, favoring concrete constructions over abstract considerations.
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Quantum Physics

Interpretable rule-based learning in an autonomous thermodynamic network

Sparrow Suderman and Giulia Rubino

Machine learning is typically described in terms of deterministic logical operations, whereas physical systems generally operate in the presence of noise, dissipation and irreversibility. Here, we turn these physical effects into computational resources for an autonomous, interpretable learning architecture. We develop a classifier based on thermodynamic neurons, which are autonomous quantum thermal machines that implement logical operations through heat flow, and use these to construct a stochastic version of the Tsetlin machine, an interpretable rule-based learning architecture. By combining thermodynamic AND, NOT and OR gates with an autonomous coupling mechanism, we realise a learning system whose computation unfolds without the need for external time-dependent control. Despite its noisy components, the resulting classifier achieves classification accuracy that is statistically comparable to that of the standard Tsetlin machine. Reliability arises from architectural mechanisms such as thresholding and redundancy, rather than exact logical operations. Our results highlight that accurate and interpretable learning can emerge from autonomous stochastic dynamics, and establish thermodynamic computation as a viable framework for physical machine learning.
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Solar and Stellar Astrophysics

Connecting Stellar Population Surveys to Stellar Evolution with Delay-time Distributions: Application to LMC Classical Cepheids

Sumit K. Sarbadhicary

The progenitors of many stellar-origin phenomena such as supernovae, evolved giants and supergiants, planetary nebulae, AGB stars and other post-main-sequence exotica remain poorly understood due to stellar evolution uncertainties such as mass-loss, binary evolution, rotation, mixing, and overshooting. A promising technique for investigating stellar progenitor scenarios with resolved stellar population surveys of galaxies is the delay-time distribution (DTD). Given a survey of stellar phenomena of interest, the DTD extracts the progenitor age distribution and production rates of the phenomena from star-formation history (SFH) maps of galaxies. Here we test the potential of DTDs as a stellar evolution diagnostic by applying to stars with known ages – Classical Cepheids in the LMC. We use the high-completeness OGLE-IV survey of Cepheids, and LMC SFH maps from optical and near-infrared surveys. The measured DTDs from optical SFH maps show significant detections at ages of 20-200 Myr for FU Cepheids, and 125-200 Myr for FO Cepheids. These are consistent with independently measured ages from the period-age-color relations, with the DTD peak being more consistent with relations from non-canonical models that include effects of overshooting, rotational mixing etc. An outlier population of 0.5-0.8 Gyr of FU Cepheids is also detected in the DTD, though its veracity is debatable given the brightness and pulsation periods of FU Cepheids, and because the signal is not recovered with DTDs derived from near-infrared SFH. For upcoming surveys (e.g. with Roman), DTDs of stars with well-constrained progenitors such as Cepheids and RR Lyrae can provide independent verification of the derived SFHs.
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Astrophysics of Galaxies

Dark Matter in Draco and Boötes I: Hints of a Core in an Ultra-Faint Dwarf from Simulation-Based Inference

Tri Nguyen, Lina Necib, Ting S. Li et al. (+8 more)

The density profiles of dwarf spheroidal galaxies are among the most sensitive probes of dark matter physics, yet extracting them from noisy stellar kinematics remains a fundamental obstacle. We present GraphNPE, a simulation-based inference method for dynamical mass modeling that incorporates measurement uncertainties and spectroscopic selection functions in the forward model. Using mock data, we show that methods relying solely on line-of-sight velocity dispersion are biased toward cuspy density profiles, even in the absence of the mass-anisotropy degeneracy. By accessing higher-order velocity moments, particularly line-of-sight kurtosis, GraphNPE breaks key degeneracies and recovers density profiles with substantially less bias. We apply GraphNPE to Draco and Boötes I using MMT/Hectochelle and DESI for Draco, and the S5 survey for Boötes I. For each, we report density profiles and dark matter $J$- and $D$-factors. For Draco, GraphNPE yields consistent results across datasets, marginally preferring a cuspy inner profile ($\rho_{150} \sim 1.6-1.9 \times 10^8\,\mathrm{M}_\odot\,\mathrm{kpc}^{-3}$) in agreement with literature. On DESI, however, second-order Jeans modeling fits the dispersion but fails to reproduce the kurtosis, demonstrating higher-order moments are essential. For Boötes I, limited statistical power prevents definitive determination of the inner slope. GraphNPE recovers $\rho_{150} = 0.36^{+0.15}_{-0.11} \times 10^8\,\mathrm{M}_\odot\,\mathrm{kpc}^{-3}$, significantly lower than literature and consistent with a cored inner profile. This places Boötes I among the lowest density dwarfs at comparable stellar masses.
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All authors Tri Nguyen, Lina Necib, Ting S. Li, Justin Read, Andrés Bañares-Hernández, Claude-André Faucher-Giguère, Kohei Hayashi, Kevin McKinnon, Andrew B. Pace, Nathan R. Sandford, Hao Yang

Instrumentation and Methods for Astrophysics

Nautilus Space Observatory: The Evolution of Planets and their Atmospheres

Ilaria Pascucci, Noah Tuchow, Yifan Zhou et al. (+11 more)

We are just beginning to explore the billion-year evolution from nascent planets in disks to mature planetary systems. Recent discoveries hint at demographic and atmospheric differences between young planets and their Gyr-old counterparts, but current facilities are limited - particularly in their ability to conduct statistical atmospheric studies over a broad period range. This white paper outlines compelling science achievable with the Nautilus Space Observatory, a proposed constellation of large-diameter space telescopes. We identify four primary scientific objectives: (1) determining the timescales over which planets evolve into sub-Neptunes and super-Earths; (2) tracking the temporal evolution of atmospheric mass-loss rates; (3) characterizing the evolution of the atmospheric mean molecular weight and C/O ratio; and (4) identifying the emergence of Helium-dominated worlds. Answering these questions requires the high spatial resolution, broad-wavelength coverage, large effective area, and parallelized multiple units that Nautilus provides. By isolating the physical processes that govern the evolution of planets and their atmospheres, these science objectives directly support NASA's Cosmic Origins and Exoplanet Exploration Programs.
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All authors Ilaria Pascucci, Noah Tuchow, Yifan Zhou, Daniel Apai, Chaucer Langbert, Ana Glidden, Luis Welbanks, Chia-Lung Lin, Adina D. Feinstein, Benjamin V. Rackham, Peter Plavchan, Kevin Wagner, Raymond Pierrehumbert, Robin Wordsworth