Cosmology and Nongalactic Astrophysics
The Topology of the Universe
Craig J. Copi, Deyan P. Mihaylov, Anna Negro et al. (+14 more)
Is the Universe infinite in all directions? The only way to know is to look. A non-trivial
cosmic topology would imprint subtle signatures on the
cosmic microwave background (CMB) and on the three-dimensional distribution of matter, breaking statistical isotropy and, potentially, homogeneity at the largest scales. If the
topology scale is small enough, these signatures would be observable. Over the past three decades, successive space missions, most notably WMAP and $\textit{Planck}$, have enabled sophisticated searches for these signatures, using methods ranging from looking for matched circle pairs to full
Bayesian likelihood analysis based on
topology-dependent covariance
matrices. Although these searches have yielded no definitive evidence for non-trivial
topology, current constraints exclude only some
topologies, parameter ranges, and observer positions. Recent advances show that detectable signals may persist even when the
topology scale exceeds the size of the visible Universe. Planned CMB experiments, including LiteBIRD and $\textit{Taurus}$, and high-precision
galaxy and line intensity-mapping surveys, could expand the detectable parameter space by exploiting polarisation data, and by exploring
topology-induced correlations at all accessible
redshifts. Whether
cosmic topology is observable remains uncertain, but current and future data offer an unprecedented opportunity to probe the global structure of the Universe.
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All authors Craig J. Copi, Deyan P. Mihaylov, Anna Negro, Amirhossein Samandar, Glenn D. Starkman, Yashar Akrami, George Alestas, Stefano Anselmi, Javier Carrón Duque, Fernando Cornet-Gomez, Linn Htat Lu, Andrew H. Jaffe, Arthur Kosowsky, Mikel Martin Barandiaran, Thiago S. Pereira, Catherine Petretti, Andrius Tamosiunas
Mathematical Physics
Data-Based Dynamical Systems Reconstruction: An Adequacy/Reliability Test
Guillermo Capobianco, Ulises Chialva and Horacio G. Rotstein
In this work, we address the problem of validating the reconstruction of a
stochastic system from noisy data. We demonstrate the limitations of criteria based solely on the loss function or on standard metrics used for reconstructing deterministic dynamics. We also propose an exploratory approach, based on a two-step test, which allows for a general assessment of the reconstruction without relying on arbitrary error-tolerance thresholds. However, we discuss how system degeneracy and non-identifiability, together with features intrinsic to
stochastic dynamics, impose certain constraints on the application of this test.
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Quantum Physics
Rapid Cavity-Based Mid-Circuit Measurement and Feedforward in a Neutral Atom Array
Tsai-Chen Lee, Jacquelyn Ho, Yue-Hui Lu et al. (+4 more)
Measuring part of a
quantum system in the midst of its
evolution and acting on the result in real time is essential for numerous
quantum information protocols. Neutral-atom arrays are a leading platform for
quantum information processing, but their mid-
circuit measurement-and-feedforward cycle times have remained slow, typically exceeding 1 ms. Here we demonstrate fast mid-
circuit measurement and real-time feedforward in an array of atomic
qubits coupled to a high-finesse optical cavity. Local light shifts tune individual data
qubits out of resonance with the cavity, shielding their coherence, while a near-resonant probe drives a selected
qubit whose emission is collected with Purcell enhancement. Mid-
circuit measurements of four
qubits with sub percent infidelity reduce the coherence of a fifth unmeasured data
qubit by less than 2%. We implement real-time feedforward to correct measurement-induced phase shifts and to realize an adaptive
circuit for optimal
quantum state discrimination and conditional state preparation. Our approach reduces the measurement-and-feedforward cycle time to below 100 $\mu$s and establishes optical cavities as a route to fast control of neutral-atom
quantum systems.
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All authors Tsai-Chen Lee, Jacquelyn Ho, Yue-Hui Lu, Tai Xiang, Nathaniel B. Vilas, Zhenjie Yan, Dan M. Stamper-Kurn
Cosmology and Nongalactic Astrophysics
Exploring Gravitational Wave Signatures Due to Primordial Non-gaussianity and Large Scale Structure Using SKAO
H. V. Ragavendra, Giulia Capurri, Alina Mierna et al. (+8 more)
This chapter explores theoretical and observational strategies to use the
stochastic gravitational-wave background detectable by Square Kilometre Array Observatory (SKAO) as a probe of precision cosmology. We detail the critical phenomenon of scalar-induced gravitational waves, demonstrating their unique features and their sensitivity to
primordial non-Gaussianity on scales much smaller than those probed by the
cosmic microwave background and large-scale structure. We investigate the phenomenology of parity violation in the early Universe through the chirality imprinted in the
stochastic gravitational-wave background, demonstrating that a parity-odd
primordial trispectrum can generate a detectable scale-dependent helicity. On the observational side, we point out that the standard gravitational-wave angular auto-correlation analysis is significantly limited by astrophysical shot noise. We show that cross-correlating the gravitational wave signal with independent large-scale structure tracers enhances the signal-to-noise ratio and allows us to isolate the astrophysical and cosmological components in the background. These results can be achieved only thanks to the enhanced sensitivity of SKAO, extensive sky coverage, and high angular resolution, which together make such targets observationally feasible.
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All authors H. V. Ragavendra, Giulia Capurri, Alina Mierna, Gabriele Perna, Federico Semenzato, Nicola Bartolo, Daniele Bertacca, Lorenzo Valbusa Dall'Armi, Sabino Matarrese, Matteo Pegorin, Angelo Ricciardone
Chemical Physics
Polyatomic Thermal Radiative Dissociation in Microcavities
Enes Suyabatmaz, Tuan Nguyen and Raphael F. Ribeiro
Blackbody infrared radiative dissociation (BIRD) activates molecules through successive absorption of ambient thermal
photons until the internal energy reaches a dissociation threshold. Because these radiative transition rates depend on the electromagnetic density of states (DOS), structured infrared environments provide a route to control thermal unimolecular dissociation. Here we develop a state-resolved master-equation framework for polyatomic BIRD in a planar Au/MgO multilayer cavity, where the reactive cluster $\mathrm{(H_2O)_2Cl^-}$ is studied. The cavity modifies the kinetics through the DOS sampled by anharmonic fundamental, overtone, and combination transitions. We show that MgO surface
phonon polaritons produce strong near-field enhancements in the central
vacuum reaction region of a microcavity. We find that short cavities with thick polar
crystal layers yield the largest BIRD enhancements due to enhanced evanescent surface
phonon polariton contributions. We further include collisions with a methane bath gas and show that cavity DOS engineering shifts the crossover between BIRD and collisional activation. These results establish Reststrahlen-band DOS engineering as a practical strategy for controlling polyatomic BIRD in infrared microcavities.
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High Energy Physics (Phenomenology)
Probing Invisible Fermions in $B \to D^{*}\ell X_{\text{inv}}$ via Angular Observables
Lipika Kolay, Soumitra Nandi and Shantanu Sahoo
Semileptonic decays $B \to D^{*} \ell X_{\text{inv}}$ provide a sensitive probe of light invisible particles, such as sterile
neutrinos or dark-sector
fermions. Within a general weak effective theory framework, we show that a massive invisible
fermion induces distinctive modifications in the angular distributions. We identify observables with enhanced sensitivity to the invisible particle mass, allowing a clear discrimination of such scenarios, and highlight angular structures that differentiate left- and right-handed
lepton-dark-sector currents.
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Quantum Gases
Universality beyond the Kibble-Zurek mechanism in the condensation of coherently coupled Bose gases
Subhadeep Patra, Paolo Comaron and Arko Roy
We study the universal spatial statistics of point-like topological defects formed during the nonequilibrium condensation of a coherently coupled Bose gas using the
stochastic projected Gross-Pitaevskii equation. The
symmetry-breaking transition is driven by a linear quench of the chemical potential, leading to
stochastic vortex nucleation in the individual condensate components. When the two components are considered together, these elementary defects may combine across components to emerge as composite topological defects known as full
quantum vortices. Beyond the mean defect density predicted by the Kibble-Zurek mechanism (KZM), we investigate the spatial organization of both the elementary and composite defects and show that their positions are well described by a Poisson point process, revealing a universal
stochastic geometry. This universality is further described through Voronoi tessellation, whose
cell-area statistics follow Poisson-Voronoi predictions. We also introduce the spatial form factor for characterizing the
vortex configurations and demonstrate the emergence of a characteristic dip-ramp-plateau structure. Our results establish universal
stochastic geometry of topological defects beyond conventional Kibble-Zurek scaling and identify it as a fundamental feature of nonequilibrium condensation in coherently coupled Bose gases.
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Earth and Planetary Astrophysics
Ultra-Precise Astrometric Search for Exoplanets with SKA-VLBI
Salvador Curiel, María J. Rioja, Richard Dodson et al. (+2 more)
The study of
exoplanets is a rapidly developing field, driven by the discoveries of Kepler and TESS, among others. The recent detection of Jovian planetary companions of low-mass
stars demonstrates that VLBI observations will be an excellent tool for indirect detection of planetary companions through precise
radio astrometry of the host
star. The anticipated sensitivity of SKA-VLBI and its capability to form multi-beam Tied Array Beams and MultiView analysis will allow us to achieve an order of magnitude increase in astrometric precision, providing much finer details for a wider range of
exoplanets and hosts, which will revolutionize the field of
exoplanets. Precise micro-arcsecond astrometric observations are crucial for detecting not only Jupiter-like
planets, but also lower-mass
planets. SKA-VLBI astrometric observations in L and C bands will open the possibility of indirect detection of thousands of planetary companions to
radio-bright ultra cool
dwarfs, M
dwarfs and young
stars. When a companion is also detected, the astrometric fit of the data will provide the dynamical masses of the components. In the case of binary systems with
planets, fitting the astrometric data will provide the individual masses of
stars and
planets, as well as the mutual inclination angle of the system, which will show whether the
planet is moving in prograde or retrograde orbit around its host
star. The search for
exoplanets at
radio wavelengths will be complementary to other techniques and will allow for the detection of a population of
exoplanets that is difficult to reach using other techniques.
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All authors Salvador Curiel, María J. Rioja, Richard Dodson, Huib Jan van Langevelde, Tao An
Statistical Mechanics
First-Order Recoverability Collapse in Self-Referential Information Decoders: The Operating Loop of an AI System as a Driven Nonequilibrium Steady State
Pieter van Rooyen
What kind of physical object is an artificial-intelligence system: a machine in the sense a refrigerator is – dissipating free energy while holding an order imposed from outside – or a dissipative structure in the sense a convection
cell is – an ordered state that exists only under throughput and loses stability past a critical drive? We argue the answer is split, as it is for the living
cell and the
star – the trained artifact is a machine, quenched and storable; the operating loop is a dissipative structure in the informational sense – and develop the framework in which the loop's classification becomes decidable. Modeling systems that couple inference to irreversible action as finite-capacity decoders under sustained informational driving, we characterize recoverable operation by a feasibility margin, local invertibility, and a stability diagnostic that diverges as capacity saturates. Making the feedback of uncertified output onto load explicit converts this continuous transition into a first-order one at mean-field level, sharpening in the fleet limit: lucid and collapsed states coexist in a cusp-organized bistable region with closed-form spinodals, collapse pre-empts the divergence, recovery is hysteretic, and for ungatedness alpha >= 1 load reduction alone cannot restore operation; reset restores only what is archived, making certification the operative stability lever. Cascades are subcritical branching with mean-field exponent 3/2 and a cutoff set by the grounded fraction of input. An instrumented real-workload pipeline experiment exhibits the collapse just below the spinodal computed from the measured service law, the backlog-delayed hysteretic recovery, and the cascade statistics. This supplies a statistical-mechanics account of the "metastable failures" documented in large-scale distributed systems, identifying recoverable dissipation as the stability criterion.
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Materials Science
Mechanism of Band Gap Formation in Beam Networks
Kwangmin Lee, Charles Emmett Maher, Katherine A. Newhall et al. (+1 more)
Band gaps are commonly attributed to Bragg scattering or local resonance, yet it remains unclear whether these mechanisms govern band gap formation in beam networks. In this work, we explain band gap formation in beam networks in terms of a new mechanism, geometry-induced coupling between deformation modes. Specifically, band gap onset arises from axial-bending coupling at
lattice nodes and scales with the axial cutoff frequency of a one-dimensional periodic beam, whereas band gap termination is primarily governed by high-frequency rotational branches associated with beam geometry. This mechanism holds for both periodic and disordered beam networks. In periodic
lattices, it manifests through beam orientations at
lattice nodes, whereas in disordered networks it manifests through short-beam statistics arising from variations in beam length. Together, these results establish a unified mechanism for band gap formation across both periodic and disordered beam networks, providing new insight into the physical origin of band gaps in beam-network materials.
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All authors Kwangmin Lee, Charles Emmett Maher, Katherine A. Newhall, Ryan C. Hurley
High Energy Physics (Theory)
Additional constraints for the tensor bootstrap
Samuel Laliberte and Reiko Toriumi
Recently, new positivity constraints were suggested to constrain arbitrary
unitary tensor integrals. In the present work, we explore two variants of these positivity constraints: one built from “open bubbles”, which are tensor-like objects found by removing a tensor from a bubble invariant, and the second built from “color
matrices”, which are
matrices found by removing a color contraction from a bubble invariant. Using these positivity constraints, we find sharp bounds on
unitary tensor integrals at finite $N$, and probe deviations from Gaussian universality in this limit.
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General Relativity and Quantum Cosmology
Non-perturbative, background independent Fock representations for canonical quantum gravity
T. Thiemann
A UV complete
quantum field theory of general relativity is believed to require a non-perturbative approach. Moreover, background independence of classical general relativity supplies a physical selection for suitable
Hilbert space representations of the
quantum geometry and matter fields. In this contribution we show that, contrary to common intuition, there exist rigorous, background independent Fock representations available for a non-perturbative canonical quantisation of geometry and suitable matter fields. This is interesting because the Fock
Hilbert space is separable while the
Hilbert space of other manifestly background independent and non-perturbative canonical quantisation programmes is not. Since non-separability is a source for quantisation ambiguities, such a Fock representation may help to arrive at a significantly more predictive theory. As a simple application we discuss the cosmological truncation and mechanisms for
quantum bounces. To make this manuscript concise we focus on the simplest incarnation of this idea. More details and many extensions are supplied in a companion paper.
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Cosmology and Nongalactic Astrophysics
The 3D clustering of Lyman Alpha Emitters measured with DESI
Haruki Ebina, Martin J. White, Rongpu Zhou et al. (+44 more)
We present a clustering analysis of Lyman-$\alpha$ emitters (LAEs) using spectroscopic observations from the Dark Energy Spectroscopic Instrument (DESI) of candidates selected from the Blanco/DECam Intermediate-Band Imaging Survey (IBIS). We measure the two-point correlation function and the power spectrum, including cross-correlations with DESI
quasars. Using both analytical and
halo occupation distribution (HOD) simulation-based modeling, we find a linear bias of $b \sim 2.31$–$2.62$ for LAEs over the
redshift range $2.26 < z < 3.41$. The analytical modeling also provides constraints on the strength of radiative transfer effects, while the HOD analysis characterizes the LAE-
halo connection across multiple models. Finally, we quantify the magnitude of non-perturbative clustering effects such as Fingers of God in the LAE population, providing essential input for the accurate modeling of LAE-based cosmological analyses in forthcoming high-
redshift surveys such as DESI-II.
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All authors Haruki Ebina, Martin J. White, Rongpu Zhou, Arjun Dey, David Schlegel, Jessica Nicole Aguilar, Steven Ahlen, Davide Bianchi, David Brooks, Francisco Javier Castander, Todd Claybaugh, Kyle S. Dawson, Axel de la Macorra, Peter Doel, Simone Ferraro, Andreu Font-Ribera, Jaime E. Forero-Romero, Satya Gontcho A Gontcho, Alma Xochitl Gonzalez-Morales, Gaston Gutierrez, Julien Guy, ChangHoon Hahn, Hiram K. Herrera-Alcantar, Mustapha Ishak, David Kirkby, Anthony Kremin, Ofer Lahav, Martin Landriau, Dustin Lang, Laurent Le Guillou, Michael E. Levi, Marc Manera, Paul Martini, Aaron Meisner, Ramon Miquel, Seshadri Nadathur, Nathalie Palanque-Delabrouille, Will J. Percival, Francisco Prada, Ignasi Pérez-Ràfols, Ashley J. Ross, Graziano Rossi, Eusebio Sanchez, Michael Schubnell, Hee-Jong Seo, Gregory Tarlé, Benjamin Alan Weaver
Cosmology and Nongalactic Astrophysics
Using SKAO to Understand the Clustering of Gravitational Wave Sources
Michele Bosi, Sarah Libanore, Nicola Bellomo et al. (+4 more)
Coalescing Binary Black Holes (BBHs) trace the Large-Scale Structure (LSS) of the Universe, and their clustering properties can be extracted from Gravitational Wave (GW) data. Next-generation detectors, such as the Einstein
Telescope and
Cosmic Explorer, will enable statistical studies of GW sources thanks to the massive number of detected events. However, such events will still suffer from significant instrumental and theoretical uncertainties. Cross-correlating GW maps with other LSS surveys provides a promising strategy to mitigate these limitations. The SKA-Mid intensity mapping and
radio continuum surveys offer ideal
datasets for cross-correlation studies with GWs (SKAO$\times$ET2CE). Their wide sky coverage and deep
redshift sensitivity will allow precise probing of the epochs and environments where
stellar BBHs form most efficiently. In this chapter, we forecast the potential of cross-correlation angular power spectra to extract information on the distribution and clustering properties of GW events. First, we model the number density and bias of three independent tracers: GW sources, neutral hydrogen intensity maps, and
radio galaxies. We estimate the constraining power of SKA-Mid$\times$ET2CE on the GW clustering bias, which carries information on the origin of GW progenitors, e.g., whether they formed through
stellar evolution or are
primordial black holes. Finally, we develop a semi-analytic model for GW events hosted by SKAO
galaxies as a function of the time-delay distribution between the binary formation and merger, which is still largely uncertain to date. We forecast the signal-to-noise ratio of their cross-correlation with SKA-Mid, and demonstrate that SKA-Mid$\times$ET2CE will foster our understanding of the time-delay distribution.
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All authors Michele Bosi, Sarah Libanore, Nicola Bellomo, Caterina Scarpel, Federico Semenzato, Alvise Raccanelli, Michele Liguori
Astrophysics of Galaxies
Overview: Extragalactic Continuum Science with the SKAO
Catherine L. Hale and Fatemeh S. Tabatabaei
Radio continuum observations provide a powerful probe of energetic processes that drive
galaxy evolution across
cosmic time. The combined sensitivity, angular resolution, and survey speed of the SKAO's
telescopes will enable transformative advances in extragalactic astronomy by revealing important details into the interplay between
star formation,
accretion onto supermassive black holes,
magnetic fields, and
cosmic rays in
galaxies and their environments. In this article, we summarize the key science goals of the Extragalactic Continuum Science Working Group and the contributions of related chapters to Advancing Astrophysics with the SKA II (AASKAII). For
star forming
galaxies, this includes using multi-band SKA continuum observations to provide
dust-unbiased measurements of the
cosmic star-formation history and enable robust spectral energy distribution analyses of
star-forming
galaxies (SFGs) across
cosmic time. This is alongside studies which will be crucial to uncover the physics and duty cycles of active
galactic nuclei (AGN), clarify the origin of
radio emission in
radio-quiet AGN, and probe the co-
evolution of black holes and their host
galaxies. Moreover, the SKA's sensitivity will also reveal diffuse synchrotron emission in
galaxy clusters and the
cosmic web, tracing
cosmic-ray acceleration within large-scale
magnetic fields. Extragalactic continuum studies with the SKA will combine wide area continuum surveys, multi-band studies and imaging over those fields which have an abundance of data across the electromagnetic spectrum. The capabilities of the SKA
telescopes will position it as a cornerstone facility for addressing fundamental questions in
galaxy formation and
evolution.
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Mathematical Physics · Cross-listed from math.DG
From $L_\infty$ algebroids to $L_\infty$ spaces: Part I
Alberto S. Cattaneo and Shuhan Jiang
The notion of $L_\infty$ spaces over dg
manifolds is developed. An equivalence between the category of transitive $L_\infty$ algebroids and that of $L_\infty$ spaces is established, and this equivalence detects weak equivalences. Moreover, a faithful functor from $L_\infty$ algebroids to $L_\infty$ spaces is constructed, which also detects weak equivalences.
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General Relativity and Quantum Cosmology
Quintic Modification to Lifshitz Quasi-topological Black Holes
A. Bazrafshan, A. R. Olamaei and M. Ghanaatian
We extend the analysis of Lifshitz black holes to quintic order in five-dimensional quasi-topological
gravity coupled to a massive Abelian vector field. Starting from a static ansatz with a constant-
curvature horizon, we derive the reduced field equations and identify the radially conserved quantity of the one-dimensional effective system. We then analyze the algebraic conditions that permit Lifshitz backgrounds, both in the absence and in the presence of the massive vector field. Since closed-form black-hole solutions are not available for the generic quintic theory, we construct numerical solutions by integrating the field equations outward from regular near-horizon data. We present solutions for the relativistic branch \(z=1\) and the Lifshitz branch \(z=2\), covering the three horizon
topologies \(k=-1,0,+1\). The numerical profiles remain qualitatively consistent with those found previously in cubic and quartic quasi-topological Lifshitz
gravity. A controlled planar comparison through the genuine quartic point \(\hat\mu_5=0\) further shows that the very small quintic couplings used in the representative examples produce nearly quartic profiles, whereas larger admissible values of \(\hat\mu_5\) lead to clearly resolved changes in both the normalized radial profiles and the Hawking temperature. We also compute the Wald
entropy and Hawking temperature and examine the thermal behavior through dimensionless logarithmic temperature–
entropy plots. For the representative branches considered here, the heat capacity is positive. For a fixed-theory planar \(z=2\) family, the conserved radial charge is further used to determine the energy density; the differential and integrated first laws are verified numerically to the precision of the computation, and the corresponding Helmholtz free-energy density is found to be negative relative to the Lifshitz
vacuum normalization adopted here.
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Mesoscale and Nanoscale Physics
Anyon Exchange Phase from Antidot Interferometry
Matthias Thamm, Felix Puster and Bernd Rosenow
Quasiparticles in fractional
quantum Hall systems are anyons, carrying a fraction of the electron charge. Exchanging two of them gives rise to a fractional exchange phase. While the fractional charge and the braiding phase – twice the exchange phase – have been measured, the exchange phase itself has remained inaccessible. We study a
quantum antidot embedded in a Fabry-Perot interferometer. Within a systematic non-
equilibrium Keldysh treatment that consistently includes the occupation and level broadening of the antidot, we find that the transmission phase evolves non-monotonically when a gate voltage tunes the antidot through a resonance, in contrast to the monotonic
evolution for electrons. The bare exchange phase can be extracted from the difference between the phase plateaus.
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Mathematical Physics
Long-time asymptotics of the autocorrelation function of the transverse Ising chain at the critical magnetic field Revisited
Noah Hout, Kenta Miyahara, Dustin Newland et al. (+1 more)
Following the work of Deift and Zhou (DOI:10.1007/978-1-4615-2474-8_15), we analyze the long-time asymptotics of the autocorrelation function of the transverse Ising chain at the critical
magnetic field (a special case of the
spin-$\frac12$ XY model in a
magnetic field) via the associated Riemann-
Hilbert problem. We refine the original Deift-Zhou's result by determining the subleading growing term in the asymptotics.
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All authors Noah Hout, Kenta Miyahara, Dustin Newland, Maxim Yattselev
Statistical Mechanics
Exact log-odds representation and mean-field criticality of a growing social group model
Xingfu Ke and Fanyuan Meng
We present an exact analytical reformulation of a growing social group model – a
Hamiltonian-free nonequilibrium process in which a group grows by noisy, consensus-driven admission. Cast as a gradient flow on logarithmic time, the fixed-point structure collapses to a single self-consistent equation: $\arctanh(\phi^*) = m \cdot \arctanh(\alpha\phi^*)$, where $\phi$ is the polarization, $\alpha=1-2\eta$ the evaluation reliability, and $m$ the number of evaluators. The equation has a direct log-odds interpretation: each verdict contributes log-likelihood ratio $2\arctanh(\alpha\phi)$; unanimity accumulates $m$ independent evidence pieces. The dynamics thus constitutes an exact mean-field theory of self-consistent inference, ordering when the collective gain $m\alpha$ overcomes the dilution of growth. We develop a systematic three-layer framework: core theory (Landau-like effective potential, comparison with the mean-field Ising model, and features without
equilibrium counterpart), mathematical foundations (criticality from correlated verdicts, Pólya-urn martingale convergence, and an RG-like flow with group size as scale), and complementary perspectives on irreversibility and information geometry. A frozen-$N$ Freidlin–Wentzell quasipotential yields Kramers-type escape estimates for metastable states, while Monte Carlo simulations collapse onto a parameter-free deterministic master curve on logarithmic time. Systematic comparison with the mean-field Ising model reveals shared critical exponents but a nested arctanh structure unique to growth. These results provide a detailed analytical characterization of a minimal model of growth-driven collective behavior and map which elements of the
equilibrium critical toolbox – suitably reinterpreted – survive without a
Hamiltonian.
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General Relativity and Quantum Cosmology
The Bondi–Sachs gauge, BMS frames, and memory in black hole perturbation theory
Andrew Spiers, Adam Pound and Jordan Moxon
As LISA and other next-generation detectors demand increasingly accurate waveform models, there is a growing need for these models to precisely control gauge freedoms that had previously been inconsequential. One such intrinsic freedom is the choice of the asymptotic Bondi–Metzner–Sachs (BMS) frame. The need to control the BMS frame is particularly pronounced in black hole perturbation theory, where there has been little work to this end – most glaringly in gravitational self-force calculations, which are in an unknown frame and encounter infrared, far-zone gauge singularities at second perturbative order. Here we present a framework for iteratively transforming to the Bondi–Sachs gauge and fixing the BMS frame on a Kerr background. This includes an extension of the Bondi–Sachs formalism to the multiscale expansions that underpin most self-force-based waveforms, introducing soft hair and a concept of “forgetful gauges” in the process. Our framework evades infrared divergences and naturally incorporates
memory effects that had previously only ever been added “after the fact” in self-force waveforms, including the recently discovered “
memory distortion”. Our formalism could also be used for ringdown analysis, and we expect it to be vital for comparisons with numerical relativity and post-Newtonian theory.
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General Relativity and Quantum Cosmology
Radial Mirror Scattering and the QNM Convergence Region
Alex Kehagias and Antonio Riotto
We revisit the convergence region of the quasinormal modes expansion of Schwarzschild retarded Green functions from a radial scattering viewpoint. The tortoise coordinate admits a natural reflection about a distinguished point, which maps the original Regge-Wheeler problem to a mirror radial problem with the same quasinormal mode spectrum. Although this reflection is not a spacetime
symmetry and does not leave the potential invariant, it gives a simple image interpretation of the second lightcone distance that controls convergence. Equivalently, after folding the radial line at the reflection point, the direct and mirror contributions arise as diagonal and off-diagonal propagation channels of a two-component half-line problem. We also relate this structure to the AdS$_2$ Green function, where the same direct-plus-image lightcone structure arises from a genuine boundary-bouncing null geodesic. This provides a spectral interpretation of the convergence condition and clarifies the role of the reflection point in the Schwarzschild radial Green function.
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High Energy Physics (Phenomenology)
Hyperon-pair spin tomography beyond scalar spin correlations
Lei Wang
Spin correlations measured after hadronization probe how
quantum information is transported through confinement. We formulate a process-independent
spin-
tomography framework for $\Lambda\bar{\Lambda}$ pairs in which the weak-decay angles determine the full two-
spin tensor rather than only its scalar trace. Applied to the short-range
STAR correlation in unpolarized $pp\to\Lambda\bar{\Lambda}X$, the framework shows that the published scalar $P_{\Lambda\bar{\Lambda}}$ leaves a continuous density-
matrix degeneracy: separable tensor completions and completions that violate the positive-partial-transpose (PPT) criterion can have the same trace. The missing observables are the transverse and longitudinal tensor components and their anisotropy $A_C=C_\perp-C_\parallel$. A local ${}^{3}P_0$ string-breaking
benchmark turns the
STAR trace into the falsifiable pattern $C_\perp>0$, $C_\parallel<0$, and $A_C>0$. We further show that feed-down must be treated as a tensor response rather than as a universal scalar dilution. In the complementary $e^+e^-$ calibration channel, the same
benchmark predicts a centrally enhanced $A_C$ of order $0.3$ in Belle II kinematics, measurable with about $10^4$ selected pairs for nominal
spin-transfer parameters. A claim of
entanglement requires the reconstructed two-
spin density
matrix, not the scalar trace alone, to violate the PPT bound.
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Astrophysics of Galaxies
Measuring Magnetic Fields Near and Far with the SKA via the Zeeman Effect
Timothy Robishaw, Marta Nowotka, Tao-Chung Ching et al. (+7 more)
Zeeman splitting in spectral lines – both in emission and absorption – provides direct estimates of
magnetic field strength and direction in magnetized gas in our own Milky Way and in external
galaxies. We discuss the potential for using the Square Kilometre Array (SKA) to measure the Zeeman effect in targets spanning an enormous range of distance: from cometary comas in the
solar system, through
Galactic molecular clouds, HI filaments in the cold neutral medium, high-velocity clouds, the
Fermi Bubbles, and photodissociation regions (PDRs) traced by
radio recombination lines, to OH masers and megamasers in nearby and distant starburst
galaxies, and to cold neutral gas in damped Ly-alpha absorbing systems at cosmological
redshifts. We update the sensitivity calculations of Robishaw et al. (2015) and indicate, for each science goal, whether it will be achievable with Array Assembly 4 (AA4) of SKA-Mid, with the staged delivery of AA*, or only with the full SKA buildout. Zeeman measurements will probe the
magnetic field in situ in the warm and cold neutral interstellar medium, complementing SKA Faraday rotation programs;
radio recombination lines, stackable across hundreds of transitions, extend this reach to HII regions and PDRs. In external
galaxies, SKA-Mid will enable Zeeman studies of OH kilomasers in nearby starburst systems, substantially expand the census of megamaser Zeeman detections beyond the Arecibo sky, and probe
magnetic fields in damped Lyman-alpha systems to field limits well below those currently achievable, opening a new window on the role of
magnetic fields in
galaxy formation and
cosmic evolution.
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All authors Timothy Robishaw, Marta Nowotka, Tao-Chung Ching, James A. Green, Anita M. S. Richards, Sandra Etoka, Malcolm Gray, Susan E. Clark, Tyler L. Bourke, Vincent Fish
Soft Condensed Matter
Optical mapping of phases and phase boundaries in nanoconfined fluids
Lauriane Pierrot Deseilligny and Susan Perkin
In confined space, deviations from bulk structure and properties are expected due to additional thermodynamic variables. In particular, composition variations arising from surface interactions may lead to additional phases and altered phase transitions. Here, we introduce a non-invasive method for nanoscale composition mapping in confined
liquids using the surface force balance (SFB). The method extends conventional SFB analysis from apex measurements to spatially resolved reconstruction of refractive index profiles within confined fluids. When multiple phases are present, the refractive index profiles provide direct access to the position and geometry of the nanoconfined fluid interfaces. We describe the interferogram analysis in detail and establish its range of validity through two model scenarios. First, measurements in air demonstrate the precision of the method and allow detection of a nanometric wetting capillary. Second, we analyse dynamic evaporation of a confined heptane droplet down to 0.1 pL volume. The method provides a time-resolved reconstruction of the meniscus geometry throughout the evaporation process. Although evaporation continuously drives the system out of
equilibrium, the meniscus remains well described by a catenoidal geometry down to heights of approximately 80 nm. At smaller separations, systematic deviations from the catenoidal profile emerge, indicating a crossover from a surface tension-dominated regime to a confinement-dominated regime. Overall, we demonstrate composition profiling as a framework to analyse confinement-induced composition variations and to quantify interfacial thermodynamic effects at the nanoscale.
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Quantum Physics
Large-Language-Model Discovery of Quantum LDPC Codes through Structured Concept Evolution
Zidu Liu and Florian Marquardt
Quantum low-density parity-check codes promise low-overhead error correction, but high-performing constructions remain hard to find. Here we introduce structured concept
evolution, in which a large
language model (LLM) evolves construction programs and their internal search strategies by modifying the finite group, protograph shapes or entry-assignment rule. We search for codes with fewer than $600$ data
qubits and check weight at most $12$, optimizing $kd^2/n$ or the
circuit-level logical error rate. Our method improves on published lifted-product
benchmarks in selected parameter regimes, with exactly certified distances for the leading results.
Circuit-level optimization typically yields lower logical error rates than $kd^2/n$ optimization, often despite smaller code distances. With the same
evolution framework and step budget, the best LLM outperforms all random-mutation and hill-climbing runs on both objectives. Our results point to LLM-driven program search as an approach to designing general
quantum LDPC codes.
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Instrumentation and Methods for Astrophysics
The Impact of Host Galaxy Properties on Supernova Classification with Hierarchical Labels
V. Ashley Villar, Sebastian Gomez, Edo Berger et al. (+1 more)
With the advent of the Vera C. Rubin Observatory, the discovery rate of
supernovae (SNe) will surpass the rate of SNe with real time spectroscopic followup by three orders of magnitude. Accurate photometric classifiers are essential to both select interest events for followup in real time and for archival population-level studies. In this work, we investigate the impact of observable host
galaxy information on the classification of SNe, both with and without additional light curve and
redshift information. We find that host
galaxy information alone can successfully isolate relatively pure (>90%) samples of Type Ia SNe with or without
redshift information. With
redshift information, we can additionally produce somewhat pure (>70%) samples of Type II SNe and superluminous
supernovae. Additionally with
redshift information, host
galaxy properties do not significantly improve the accuracy of SN classification when paired with complete light curves. In the absence of
redshift information, however,
galaxy properties significantly increase the accuracy of photometric classification. As a part of this analysis, we present the first formal application of a new objective function, the weighted hierarchical cross-
entropy, to the problem of
supernova classification. This objective function more naturally accounts for the hierarchical nature of
supernova classes and, more broadly, transients. Finally, we present a new set of SN classifications for the Pan-STARRS Medium Deep Survey of SNe that lack spectroscopic
redshift, increasing the full photometric sample to >4400 events.
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All authors V. Ashley Villar, Sebastian Gomez, Edo Berger, Alex Gagliano
Strongly Correlated Electrons
THz-induced phonon mode mixing and collective dynamics in a polar nanolattice
Elizabeth Skoropata, Peter M. Derlet, Hiroki Ueda et al. (+13 more)
Manipulating
phonons through
symmetry is a fundamental approach to alter the dynamic responses of materials. Most often new phases are sought through control of the unit-
cell (e.g. via strain, doping, light, etc.). By comparison, there is vast potential to look beyond the unit-
cell into higher-order architectures to control wave scattering and interference effects that remains less explored. We describe the THz-induced dynamics of an SrTiO$_{3}$ thin film with a nanoscale ordered interfacial dislocation network probed with 2- and 3-dimensional time-resolved x-ray diffraction and classical molecular dynamics simulations. We find that
symmetry breaking at all scales is an effective approach to create a dynamical electric polarization and to control
phonon mixing that generates previously unreported collective modes in the THz regime with circular
vortex-like displacements. This work opens a new pathway to explore dynamical functional properties that can be extended to
magnetic, electric, and ferroelectric systems by controlling the real-space
topology via epitaxy.
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All authors Elizabeth Skoropata, Peter M. Derlet, Hiroki Ueda, Roman Mankowsky, Mathias Sander, Henrik T. Lemke, Rafael T. Winkler, Yunpei Deng, Milan Radovic, Matteo Savoini, Biaolong Liu, Martina Basini, Vladimir Ovuka, Steven L. Johnson, Marta D. Rossell, Urs Staub
Strongly Correlated Electrons
Introduction to matrix-product states and tensor networks
Grégoire Misguich
These notes provide an introduction to tensor-network methods in
quantum many-body physics, with an emphasis on
matrix-product states (MPS). They develop the basic tensor-network
language, including graphical notation, virtual indices, bond dimensions, gauge freedom, canonical forms, QR and singular-value decompositions, and the role of
entanglement in controlling the efficiency of the representation. The main MPS
algorithms are then introduced, including contractions, correlation functions,
matrix-product operators, DMRG, and time-
evolution methods. The notes also briefly discuss projected entangled-pair states (PEPS) as a higher-dimensional generalization of MPS, together with the basic ideas behind approximate PEPS contraction. Finally, tensor-network representations of mixed states,
quantum channels, and Lindblad dynamics are presented, with applications to thermal states and open
quantum systems. The presentation is accompanied by short Julia code examples based on ITensor, ITensorMPS, and TensorMixedStates. These notes were written for the 9th Les Houches Summer School on Computational Physics: Open
Quantum Systems, held in June 2026.
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Astrophysics of Galaxies
Opening new parameter space windows on galaxy/AGN co-evolution with SKA radio continuum surveys
Isabella Prandoni, Mark T. Sargent, Matteo Bonato et al. (+11 more)
In this chapter we provide an overview of the science enabled by the SKAO, focusing on
galaxy/AGN co-
evolution studies. In particular we discuss a number of
radio continuum `reference' surveys with the SKAO, highlighting the role they can play in advancing this research field with respect to the pre-SKAO era. Alongside well-explored scenarios for wedding cake-like, tiered extragalactic surveys at specific frequencies, we also address the scope for complementary efforts to obtain deep multi-frequency imaging over parts of (an) extragalactic field(s). In addition to providing key information on the physical properties of the emitting sources, such multi-frequency imaging will make important contributions to the calibration of observables from surveys with sparser
radio spectral coverage. In this context, we explore possible pathways that can fully exploit the SKAO from initial (AA*) to baseline capabilities (AA4). Finally, we highlight observational synergies with other major facilities – for wide field and targeted follow-up science – that will be operational in the 2030s, and for which joint coverage of extragalactic fields will generate significant legacy value
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All authors Isabella Prandoni, Mark T. Sargent, Matteo Bonato, Dharam V. Lal, Mahdiyar Mousavi-Sadr, Masoumeh Ghasemi-Nodehi, Nicholas Seymour, Fatemeh S. Tabatabaei, Gianfranco De Zotti, Ivano Baronchelli, Elisabetta Liuzzo, Nicola Marchili, Marcella Massardi, Rosita Paladino