High Energy Physics (Phenomenology)
Direct constraints on the agnostic $\nu$SMEFT from heavy-neutrino searches at the LHC
Lucía Duarte and Agustín Guillenea
The observation of
neutrino oscillations and masses motivates extensions of the Standard Model containing right-handed
neutrinos. If additional new physics exists at scales beyond the direct reach of present experiments, its effects can be systematically described within the
neutrino Standard Model Effective Field Theory ($\nu$SMEFT). In this framework, heavy neutral
leptons provide a promising target for
collider searches. In this work, we reinterpret a CMS search for heavy Majorana
neutrinos in the same-sign dimuon plus two jets final state to constrain the parameter space of the dimension-six $\nu$SMEFT. Using a detailed recast of the experimental analysis, we present results for both a pure-agnostic
benchmark and a
benchmark incorporating neutrinoless double-beta-decay bounds. For heavy-
neutrino masses in the range $200~\mathrm{GeV} \le m_N \le 15~\mathrm{TeV}$, the observed upper limits on the effective coupling strength range from $5.8\times10^{-7}\,\mathrm{GeV}^{-2}$ to $2.3\times10^{-6}\,\mathrm{GeV}^{-2}$. These results constitute the first experimental exclusion limits on the agnostic $\nu$SMEFT parameter space obtained from a dedicated recast of an LHC heavy-
neutrino search.
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Astrophysics of Galaxies
The AGORA High-resolution Galaxy Simulations Comparison Project. IX - Part 2: Effects of a Major Galaxy Merger on the Stellar Morphology of a Milky Way-mass Galaxy Progenitor
Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung et al. (+23 more)
Galaxy mergers, with their high sensitivity to initial conditions, provide a valuable setting for comparative studies of
galaxy simulation codes. Following our first paper focusing on merger-driven
star formation, we present a code comparison examining the morphological transformation impact of a major
galaxy merger at $z \approx 4.5$ on a Milky Way-mass
galaxy progenitor. Our analysis employs nine state-of-the-art codes from the AGORA CosmoRun cosmological zoom-in simulation suite. For this merger, we show that the adopted
stellar feedback type influences the
galaxy's compaction and
stellar disc formation. Codes with purely thermal feedback produce a merger remnant that forms a disc and becomes compact primarily during and after coalescence; codes that include kinetic feedback begin disc formation and compaction around the first periapsis; and codes with strong delayed cooling or superbubble feedback suppress disc formation and produce a more extended remnant. In contrast, the orientation of the remnant disc is code-independent. In all codes, the rotational angular momentum of the remnant disc aligns with the interaction's orbital angular momentum rather than the pre-merger rotational axis, implying that the infalling gas preserves its orbital angular momentum to form a new disc. Comparisons with the Santa Cruz semi-analytic model show reasonable agreement in
stellar mass and half-mass radius, yet the model underpredicts (overpredicts) the dark matter fraction and velocity dispersion for codes exhibiting strong compaction (expansion). The systematic dependence of our remnants' morphology on feedback schemes demonstrates that merger remnant morphology may serve as a powerful probe of
stellar feedback processes.
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All authors Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung, Ramón Rodríguez-Cardoso, Santi Roca-Fàbrega, Ji-hoon Kim, Joel R. Primack, Kentaro Nagamine, Renyue Cen, Daniel Ceverino, Weiguang Cui, Anna Genina, Hyeonyong Kim, Yuri Oku, Johnny W. Powell, Yves Revaz, Pablo Granizo, Alessandro Lupi, Ikkoh Shimizu, Héctor Velázquez, Tom Abel, Oscar Agertz, Avishai Dekel, Boon Kiat Oh, Thomas R. Quinn, the AGORA Collaboration
Astrophysics of Galaxies
The AGORA High-resolution Galaxy Simulations Comparison Project. IX - Part 1: Effects of a Major Galaxy Merger on Star Formation of a Milky Way-mass Galaxy Progenitor
Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung et al. (+23 more)
Given their highly nonlinear dynamics and sensitivity to initial conditions,
galaxy mergers are a compelling area to conduct a simulation code comparison. We perform a comparative study of a major
galaxy merger at $z \approx 4.5$ in cosmological zoom-in hydrodynamic simulations of a Milky Way-mass
galaxy progenitor. The comparison employs the AGORA CosmoRun suite of nine well-calibrated, state-of-the-art numerical codes, each adopting a different
stellar feedback scheme. We find that the
evolution of the
star formation rate (SFR) during the interaction is strongly shaped by the
stellar feedback type. Using kinetic feedback in the feedback model drives a pronounced merger-induced starburst that starts to subside before coalescence; using thermal feedback without kinetic feedback yields prolonged SFR growth even after coalescence; and using delayed cooling or radiation pressure results in highly fluctuating SFR. Tracking gas particles in particle-based codes reveals that kinetic feedback facilitates gas inflow from the secondary
galaxy onto the primary
galaxy between the first periapsis and apoapsis, thus producing an earlier and more prominent starburst. In contrast, thermal feedback, augmented by superbubble or delayed-cooling feedback, suppresses gas cooling, creates a more extended gas distribution, and hinders strong starbursts during the merger. We also observe an inverse correlation between burst fraction and pre-merger gas fraction that is independent of feedback models. Overall, these results highlight the sensitivity of simulated
galaxy mergers'
star formation response to
stellar feedback prescriptions. This study indicates that
galaxy mergers may serve as a good testbed for
stellar feedback processes in cosmological simulations.
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All authors Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung, Ramón Rodríguez-Cardoso, Santi Roca-Fàbrega, Ji-hoon Kim, Joel R. Primack, Kentaro Nagamine, Renyue Cen, Daniel Ceverino, Weiguang Cui, Anna Genina, Hyeonyong Kim, Yuri Oku, Johnny W. Powell, Yves Revaz, Pablo Granizo, Alessandro Lupi, Ikkoh Shimizu, Héctor Velázquez, Tom Abel, Oscar Agertz, Avishai Dekel, Boon Kiat Oh, Thomas R. Quinn, the AGORA Collaboration
Disordered Systems and Neural Networks
Thermal avalanches in a quasiperiodic XXZ model
Paolo Molignini and Antonio Štrkalj
We study bath-induced thermalization in the many-body localized XXZ
spin chain subjected to a quasiperiodic
magnetic field. We engineer a thermal inclusion by setting the field strength in one part of the chain below the localization threshold and analyze thermalization via the avalanche mechanism. To study the nature of such avalanches, we use two complementary observables, namely the two-point connected correlation function and the particle-number
entropy. Surprisingly, the correlations alone show no signatures of avalanches. Instead, they display a logarithmic growth of the correlation length throughout the dynamics and predict localization lengths of the local integrals of motion that remain well below the avalanche threshold. In contrast, the particle number
entropy shows clear signatures of the thermal avalanche, with the avalanche front progressively propagating deeper into the localized subsystem for sufficiently large baths. The discrepancy between the two observables shows that two-point correlations are unreliable in identifying thermal avalanches in quasiperiodic systems, as opposed to the random case. On one hand, qualitative results are consistent with the analytical predictions of the standard avalanche theory. On the other hand, significant quantitative deviations persist, which could be due to short-range resonances generated by the quasiperiodic potential. Our results suggest that the standard avalanche framework requires revision to account for the short-range correlations of quasiperiodic potentials.
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Quantum Physics
Resolving topological order crossovers on NISQ hardware
Ruizhe Shen, Yin Zhong and Ching Hua Lee
Topological phases of matter provide a promising route toward robust
quantum information processing, but on present-day noisy intermediate-scale
quantum devices the experimentally relevant question is whether signatures of topological crossovers remain resolvable under realistic imperfections. Here, we address this question in the Wen–plaquette model through a two-stage strategy on the IBM
Quantum hardware. We first use a tractable system to systematically characterize crossover signatures. Using variationally compiled
equilibrium and quench-generated states, we resolve crossovers between stabilizer-dominated and trivial or disorder-dominated regimes through local plaquette stabilizers and a Wilson loop, and quantify their robustness against static disorder, deliberately amplified
circuit noise, and effective non-Hermitian fields. The quench dynamics further reveal that plaquette-sector signatures remain substantially more stable deep in the strong-stabilizer regime than near the finite-size crossover. Building on the properties established in the small system, we extend the implementation to a physical two-dimensional IBM processor using a layered representative-
qubit construction. The resulting
lattice-averaged plaquette response exhibits only weak degradation under intentionally amplified local coherent perturbations. Together, these results connect controlled finite-size characterization with a scalable hardware implementation, providing a practical route for preparing and probing topological signatures on near-term
quantum processors.
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Quantum Physics
Mixed-state topological order and error-correction thresholds in non-Abelian codes: rigorous results
Sun Woo P. Kim and Max McGinley
We present a versatile and mathematically rigorous technique for bounding recovery thresholds in topological codes subject to noise. Our method captures the effect of applying an arbitrary (possibly non-Pauli) local noise channel to the code state of a broad class of two-dimensional codes, including surface codes, non-Abelian
quantum doubles, and string-net codes. In each case, we prove that for noise strengths up to some explicit constant value, any initially encoded logical information can be recovered to high precision, and that the noise-corrupted state exhibits key hallmarks of mixed-state topological order: long-range
entanglement and emergent higher-form
symmetries. We also describe how these methods can be adapted to higher dimensions and correlated noise models.
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Strongly Correlated Electrons
Counting Edge Modes with the Higher Berry Curvature: A Bulk Topological Order Parameter for Quantum Spin Chains
Adam J. McRoberts, Joe Crossley, Chris Hooley et al. (+1 more)
We show that the higher Berry
curvature (HBC) can be used to count the gapless edge modes created by an
entanglement cut, and thus defines an integer-valued topological order parameter for
quantum spin chains. Given an individual
spin-chain
Hamiltonian, we construct an extending family by interpolating to a reference product Néel state, and show that the integral of the HBC over this extension is equal to the ordinary Berry phase of half of the chain swept out in response to an infinitesimal field. It thus counts the
spin of the gapless edge modes exposed by the cut, and a change in its integer value signals a phase transition. We illustrate this with several examples: $S=1/2$, $S=1$, and $S=3/2$
spin-Peierls chains, which undergo `singlet flop' transitions between different patterns of dimerisation; the bilinear-biquadratic chain, which clarifies the connection to the strict
symmetry-protected topological phases classification; and the staggered $J_1$–$J_2$ chain, which has both nearest-neighbour and third-neighbour patterns of singlets depending on the signs of the interactions.
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All authors Adam J. McRoberts, Joe Crossley, Chris Hooley, Joe H. Winter
High Energy Physics (Theory)
AdS Black Holes Are Short-Lived inside the Spectral Form Factor
José L. F. Barbón and Eduardo Velasco-Aja
We analyze the contribution of AdS black hole saddles to the spectral form factor of $d$-dimensional CFTs with a
gravity dual. At high temperatures, the analytically continued gravitational action of the large AdS black hole is expected to give a leading large-$N$ approximation to the 'slope' of the spectral form factor. When the CFT is put on a $(d-1)$-dimensional spatial sphere of radius $\ell$, we show that such an evaluation implies unphysical behavior of $Z(\beta +it)$ at large $t\gg \ell$ for $d\equiv5 \,({\rm mod}\; 4)$. A Picard–Lefschetz analysis of a minisuperspace approximation to $Z(\beta+it) $ does reveal the required Stokes phenomena that restore consistency. It is found that for $d>3$, the large AdS black hole saddle loses dominance and subsequently disconnects from the relevant integration cycle at $t=O(\beta)$. For $d=3$, dominance is lost at a time of order $\beta$, while the Stokes disconnection takes place at $t=O(\ell)$. After the large black hole saddle disconnects from the path-integral contour, the slope of the spectral form factor becomes dominated by the low-energy end of the spectrum.
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Quantum Physics
Frame-Dependent Traces and the Third-Particle Paradox
Alessandro Palumbo and Luca Apadula
The Paradox of the Third Particle arises when comparing subsystem descriptions across
Quantum Reference Frame (QRF) perspectives. We isolate two distinct origins of the Paradox: the QRF covariance of the partial trace and the failure of the physical
Hilbert space to inherit the kinematical tensor-product structure. We give an explicit counterexample to the Relational Trace (RT) resolution: an uncorrelated product state for which the RT statistical condition trivialises. We then introduce a new statistical consistency condition comparing subsystem discarding between external and internal QRFs, together with an associated frame-dependent map, the Perspective Relational Trace (PRT). We argue that our condition captures the operational content of the Paradox: rather than imposing consistency on the whole state space, we characterise exactly the states on which it holds in the Perspective-Neutral (PN) and
Quantum-Information (QI) approaches. This separates three levels of description: a PN subsystem of a PN whole, where consistency fails on a characterised set that includes product states; a QI subsystem of a QI whole, where it holds for all states; and a QI subsystem obtained from a PN whole by kinematical partial trace, where the full weakly invariant
algebra is recovered, yet consistency holds only on a proper subset. These results show that the PN approach can consistently describe only a closed, isolated system, while the QI approach can accommodate arbitrary subsystems. Tracing out a subsystem from a globally PN state yields a charge-superselected
algebra, reproducing in a minimal QRF model the boundary-charge structure of edge modes. We understand the Paradox not as a genuine contradiction, but as the consequence of comparing inequivalent physical layers without tracking which information is externally and which internally accessible.
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Cosmology and Nongalactic Astrophysics · Cross-listed from cs.LG
An Introduction to Bayesian and Frequentist Simulation-Based Inference with Machine Learning
Maximilian Dax, Theo Heimel and Gilles Louppe
Simulation-based inference (SBI) with machine learning is an increasingly important tool for solving inverse problems in science and engineering, including parameter inference and the inversion of detector effects. We provide an overview of the
Bayesian and frequentist statistical frameworks, describe how machine-learning-based SBI methods, such as neural posterior estimation and neural likelihood estimation, can be used for parameter estimation within these frameworks, and show that the same methods can also be applied to Empirical Bayes or unfolding tasks. We also discuss how to validate inference results and the limitations of SBI with machine learning.
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High Energy Physics (Phenomenology)
Formation and scaling of $\mathbb{Z}_N$ strings for global $\mathrm{SU}(N)/\mathbb{Z}_N$ symmetry
Masaki Yamada
We numerically investigate networks of global $\mathbb{Z}_N$ strings with multi-string junctions in a scalar field model whose
vacuum manifold is $\mathrm{PSU}(N)=\mathrm{SU}(N)/\mathbb{Z}_N$. The construction of the model is motivated by the
Higgs vacua of mass-deformed $\mathcal{N}=4$ supersymmetric Yang-Mills theory, commonly known as $\mathcal{N}=1^*$ theory, and provides a tractable effective description of string networks with
baryon-vertex-like junctions. We perform classical
lattice simulations of the formation and
evolution of these networks in a radiation-dominated universe. For $N=2,3,4,5,$ and $8$, we find that the networks approach a scaling regime rather than becoming frustrated. The normalization of the string density grows in proportion to the dimension of the adjoint representation, $N^2-1$, while non-minimal-charge components remain subdominant. These results imply that, at least for $N\lesssim 8$, the amplitude of the gravitational-wave energy density generated by the
cosmic-string network scales as $\Omega_{\rm GW}\propto \mu^2 (N^2-1)^2$, where $\mu$ is the tension of a unit-charge string.
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High Energy Physics (Theory)
EFT (String) Tower Building
Alessandra Grieco, Ignacio Ruiz and Irene Valenzuela
We develop a bottom-up framework to reconstruct the asymptotic spectrum of light towers in four-dimensional $\mathcal{N}=1$ effective field theories directly from their Kähler potential. Our construction uses the Integral Scaling Relation, which relates the mass scales of towers becoming light at infinite distance to the tensions of EFT strings, together with the Emergent String
Conjecture applied recursively upon decompactification. These conditions organize the tower scaling vectors into a
lattice generated by the EFT-string vectors and select the globally consistent tower polytopes. When applied to Kähler potentials arising from string compactifications, our
algorithm precisely reproduces the known arrangements of towers and duality frames. We then classify the admissible polytopes for asymptotic Kähler potentials $K\sim-\log P(s)$, with $P(s)$ a homogeneous
polynomial of degree at most seven, and show that certain apparently consistent Kähler potentials are incompatible with the assumed
quantum-
gravity constraints. For general
polynomials, additional restrictions arise from gluing the tower arrangements across different growth sectors. Remarkably, every tower polytope allowed by our reconstruction can be obtained as a concrete slice of the polytope associated with M-theory on a Joyce $G_2$-
manifold. This provides evidence for a form of string universality in which EFT strings act as the fundamental building blocks of the UV tower structure in the EFT perturbative regimes.
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Mesoscale and Nanoscale Physics
Real-Space Imaging of Band Topology via Wavefunction Zeros
Julian Ingham and Raquel Queiroz
We prove that the wavefunction of a
crystal at a high-
symmetry momentum, $\Psi_{\boldsymbol{k}_*}(\boldsymbol{r})$, has
symmetry-enforced zeros at certain positions in the unit
cell, using a new invariant fixed uniquely by the symmorphic
symmetry representation of the wavefunction. This allows one to infer the
topology of an electronic band by probing zeros of the charge density, and in turn to connect scanning tunnelling microscopy to the group representation theory of bandstructure. We apply the
theorem to 1H transition metal dichalcogenides, where it detects the obstructed atomic limit of WSe$_2$, the Haldane model, where it detects the Chern number modulo three, and the Bernevig-Hughes-Zhang model, where it detects the $\mathbb{Z}_2$ index. In addition, the zeros have important consequences for interaction effects: in kagome metals, they fix the sublattice structure of Van Hove wavefunctions, and in twisted
bilayer graphene, they explain the qualitative interaction-induced reshaping of the flat bands.
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Quantum Physics
Non-Invertible Symmetries Mixing with Witt Non-Trivial Quantum Cellular Automata
Kansei Inamura, Oskar Wojdel, Lukasz Fidkowski et al. (+1 more)
Self-dualities and the stacking of
symmetry-protected topological (SPT) phases are basic operations on
quantum many-body systems. For a $\mathbb{Z}_p$ one-form
symmetry in 3+1d these correspond to the Kramers-Wannier-Wegner duality $S$, which is the gauging operation underlying non-invertible duality
symmetries, and the stacking of a 1-form
symmetry SPT $T$. In the continuum, they form a central extension of $PSL(2,\mathbb{Z}_4)$ for $p=2$, and of $SL(2,\mathbb{Z}_p)$ for odd
primes $p$, whose central elements are invertible theories with purely gravitational response. These central extensions are governed by a twisted, graded generalization of the Witt group of abelian anyon theories, which we determine. For $p=2$ the resulting group is the single-
qubit Clifford group, with duality and entangler acting as the Hadamard and phase gates. We realize this entire structure microscopically as
quantum cellular automata (QCA) acting on a certain local operator
algebra associated with a
spin lattice Hilbert space on a cubic
lattice. Specifically, our local operator
algebra is built by starting with all local operators commuting with a $\mathbb{Z}_p$ 1-form
symmetry, and taking the quotient by all the (local) 1-form
symmetry generators. The central elements can always be extended to the full tensor product
algebra with a uniquely defined QCA class. For $p=2$ they are generated by the non-trivial semion QCA, and for odd
prime $p$ they are generated by the non-trivial $\mathbb{Z}_p$ Clifford QCA. Consequently the
lattice fusion rules reproduce the continuum ones only up to these QCAs and
lattice translations, giving rise to fusion rules refined by QCAs.
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All authors Kansei Inamura, Oskar Wojdel, Lukasz Fidkowski, Sakura Schafer-Nameki
Quantum Physics
Non-Clifford quantum cellular automata from invertible topological quantum field theories
Meng Sun, Zongyuan Wang, Bowen Yang et al. (+2 more)
Quantum cellular automata (QCAs) describe locality-preserving
quantum dynamics and link
quantum information, many-body physics, and topological
quantum field theory (TQFT). Constructing a QCA from a TQFT, however, remains challenging: although a topological action yields a
Hamiltonian with commuting terms that realizes the desired ground state, it does not by itself specify an
automorphism of the full operator
algebra. We develop a unified algebraic construction that extends such
Hamiltonians to complete separator-flipper
algebras on the full tensor-product
Hilbert space, thereby defining the corresponding QCAs microscopically. In 3 spatial dimensions, our framework unifies all previously known QCA constructions associated with the $\mathbb{Z}_8\times\mathbb{Z}_2$ subgroup of the Witt group, including the $U(1)_2$ and $U(1)_4$ QCAs. The same algebraic structure yields new infinite families of generalized $U(1)_2$ and $U(1)_4$ non-Clifford QCAs in spatial dimensions $d=4k-1$. We also reformulate the 4-dimensional $w_2w_3$ QCA and use it to construct QCAs from TQFTs associated with arbitrary products of Stiefel–Whitney classes. For example, we explicitly construct two infinite families: $w_2^nw_3^m$ QCAs in dimension $d=2n+3m-1$ and $w_2w_{4k-1}$ QCAs in dimension $d=4k$. For the 5-dimensional $w_3^2$ and $w_2^3$ QCAs, our construction gives finite-depth
quantum circuits, consistent with the cobordism classification. More generally, we show that our construction yields a finite-depth
quantum circuit whenever the corresponding Stiefel-Whitney number vanishes on every closed oriented
manifold. Overall, these results convert invertible TQFTs into microscopic QCAs, provide higher-dimensional constructions beyond the Clifford setting, and open a systematic route to characterizing their stable structures and boundary anomalies.
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All authors Meng Sun, Zongyuan Wang, Bowen Yang, Nathanan Tantivasadakarn, Yu-An Chen
Astrophysics of Galaxies
Different paths, same appearance: an intermediate-age red nugget at z~0.13
F. La Barbera, F. Buitrago, I. Ferreras et al. (+1 more)
Massive ultra-compact
galaxies are commonly regarded as nearby relics of the compact quiescent population at z~2-3, and detailed studies have focused so far only on old systems in dense environments. Here we present a spatially resolved analysis of G79071, an ultra-compact (R_e<2kpc), massive (M*~10^{11}MSun) ETG at z~0.13 residing in a low-mass group environment, based on deep VLT/X-Shooter long-slit spectroscopy. We extract
stellar kinematics out to ~4R_e and constrain
stellar population properties and the low-mass end of the
stellar IMF, by combining full spectral fitting, full-index fitting, and index fitting, using different
stellar population models. G79071 shows significant rotation, consistent with a fast-rotator-like kinematic structure, and is dominated by an intermediate-age
stellar population (~3-4Gyr) with a flat age profile and no evidence for a significantly old (>5Gyr) component. The central
metallicity is supersolar and decreases with radius, while most abundance ratios show flat radial trends and are consistent with typical massive, low-
redshift ETGs at similar velocity dispersion. Moreover,
metallicity and [Na/Fe] abundance are significantly enhanced, reflecting a very efficient chemical enrichment process.Our analysis suggests that the IMF remains bottom-heavy out to ~2R_e, implying a mass-excess factor alpha>~2. Jeans anisotropic models with an NFW
halo are consistent with the IMF-based
stellar mass normalization and with compactness-corrected (non-homologous) dynamical mass
estimators, yielding a modest projected dark-matter fraction within one effective radius, f_DM(<R_e)=0.18 \pm 0.07. These results show that at least some massive compact
galaxies with a bottom-heavy IMF can form and persist at lower
redshift and outside high-density environments, providing new constraints on the diversity of formation pathways for massive
galaxies.
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All authors F. La Barbera, F. Buitrago, I. Ferreras, C. Tortora
History and Philosophy of Physics
Dimensional Analysis is a Gauge Theory
Benjamin Muntz
I argue that dimensional analysis can appropriately be thought of as a gauge theory. This picture naturally leads to the usual quantity calculus through inherent properties of Lie groups, Lie
algebras, and representation theory. The gauge theory interpretation is perhaps strongest for non-constant units. I explain how Stevens's classification of scales of measurement can be understood by choices of different gauge groups. Finally, I reinterpret and rephrase the Buckingham-{\Pi}
Theorem in a way that also applies to typical gauge theories. Counting the number of ”{\Pi}”s becomes a well-known problem of invariant theory.
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Optics
Micro-electromechanical photonic integrated memristors
Matthew Zimmermann, Julia M. Boyle, Hardit Singh et al. (+7 more)
Programmable optical memristors embedded in photonic integrated
circuits (PICs) are emerging as an important technology for high-speed optical storage and in-
memory optical computing applications. These devices provide multi-level, non-volatile storage of optical phases that can be interrogated at the speed of light, enabling parallel data readout or energy-efficient multiply-accumulate operations in artificial neural networks. However, there remains several outstanding challenges with existing optical memristor technology including durability, material-induced optical losses, large-scale reconfigurability, or fabrication yield for realistic applications. Here we introduce an analog-programmable photonic memristor based on photonic integrated micro-electromechanical (MEMS) cantilevers produced in a CMOS foundry. The memristor consists of low-loss silicon nitride waveguides, requires no additional back-end materials integration, and is all electrically programmed with electrostatic-piezoelectric forces. We demonstrate up to 5-bit phase storage levels, 50 kbit/s programming speeds, strain-assisted non-
volatility lifetimes >1 hour, >1 billion cycle endurance, and stress-tested millions of write-read cycles with pseudorandom bit sequences. We further extend the
memory lifetime to several days with simple electronic refresh
circuits in a portable battery-powered module, demonstrating a proof-of-concept optical random-access
memory in static or dynamic configurations. Our MEMS-photonics technology represents an important step toward practical optical memristors.
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All authors Matthew Zimmermann, Julia M. Boyle, Hardit Singh, Alex Witte, Kevin Palm, Thuy-Linh Le, Andrew J. Leenheer, Daniel Dominguez, Matt Eichenfield, Mark Dong
High Energy Astrophysical Phenomena
Light Antinuclei Coalescence: Femtoscopic Constraints via Neural-Flow Surrogates
M. Korwieser, L. Fabbietti, B. Hashemi et al. (+4 more)
Precise predictions of
cosmic-ray antinuclei fluxes, a
prime dark matter signature, are limited by the lack of data constraining production rates of antinuclei. We mitigate this bottleneck with a fast, differentiable normalizing-flow surrogate for the femtoscopic source model (CECA), fit to 49 ALICE
proton-
proton correlation functions, and extrapolated via scaling laws to the low-multiplicity domain relevant for
cosmic rays. The surrogate reproduces CECA with sub-percent emulation fidelity, yielding data-constrained source functions that remove the dominant uncertainty in coalescence-based antinuclei production rates. The resulting uncertainties on the coalescence parameters $B_2$ and $B_3$ shrink from factors of 10-100 and ${\sim}$1000 to the few percent and ten-percent level, respectively, with an additional ${\sim}15\%$ wavefunction systematic for $B_{2}$.
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All authors M. Korwieser, L. Fabbietti, B. Hashemi, L. Heinrich, M. Mahlein, D. L. Mihaylov, C.S. Zeyn
Fluid Dynamics
Explainable quantum-compressed machine learning for complex fluid flows
Xiao Xue, Maida Wang, Mingyang Gao et al. (+2 more)
Machine-learning surrogates of physical systems face a paradox: explainable models facing the challenge of expressivity to capture complex nonlinear flows, whereas expressive deep surrogates match high-fidelity simulations only through massive parameterisations that turn the learned dynamics into a black box. Here, we introduce
quantum-compressed machine learning (QCML), which resolves this tension by compressing the latent propagator of a flow surrogate from $524{,}288$ trainable parameters to no more than $8$. This parameter reduction brings the learned dynamical law to the parameter scale of a physical constitutive relation rather than a black-box neural network, making the surrogate directly interpretable and controllable without sacrificing expressivity. The compression is realised by a structured
quantum circuit whose
unitary propagator constrains the latent spectrum to the unit circle exactly and by construction, replacing exponential error growth with linear accumulation over autoregressive rollouts. Classical regularisation only approximates this constraint: even a
quantum-inspired classical baseline penalised towards unitarity collapses within one Lyapunov time on turbulent channel flow, whereas QCML remains stable over the full rollout. Shared phase and coupling angles parameterising the
circuit correspond directly to modal frequencies and inter-mode interactions, giving the learned dynamics a physical interpretation in spectral space. On two patient-specific cardiovascular
benchmarks, the structured QCML propagator matches the predictive accuracy of its classical counterpart on surface pressure spectra, pressure drop, and wall shear stress. These results establish QCML as a working component of scientific machine learning and a concrete contribution towards practical
quantum advantage in real-world prediction.
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All authors Xiao Xue, Maida Wang, Mingyang Gao, Minh Chung, Peter V. Coveney
Accelerator Physics
X-Ray Transition Radiation
Grigor M. Garibian and Chi Yang
The monograph is devoted to theoretical and experimental studies of transition radiation produced by fast charged particles traversing media with interfaces. Particular
attention is paid to X-ray transition radiation (XTR) generated at a single interface as well as in a single plate or in a stack of plates. The foundations of the general theory of transition radiation are presented, and the results of experimental studies of XTR properties are given together with a comparison with theoretical predictions. TRDs of high-energy particles used at modern accelerators and in
cosmic-ray physics are described.
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Instrumentation and Methods for Astrophysics
Detecting habitable exoplanet atmospheres with LIFE, the Large Interferometer for Exoplanets
Sarah Rugheimer, Aiden Weatherbee, James Fecanin et al. (+21 more)
A key goal of astronomers with the next generation
telescopes is to detect signs of life in
exoplanet atmospheres. NASA's next flagship is the Habitable Worlds Observatory (HWO). In the context of ESA's Voyage 2050 program, the Senior Committee report prioritises detecting habitable
exoplanet atmospheres in the mid-IR. The most suited mission for this is the Large Interferometer for
Exoplanets (LIFE) which can detect an even wider range of biosignatures than HWO and at lower concentrations. LIFE is a global science collaboration based out of ETH Zürich. With the UK's expertise in building infrared instruments we could play a leading role in realising an ambitious European-led mission. Notably, LIFE is able to detect necessary planetary context like surface temperature and pressure, along with a key discriminator molecule for biosignature false positives, methane, which will be much harder or impossible with HWO. Also, LIFE will be able to investigate many of the nearby rocky
exoplanets known from radial velocity searches that are inaccessible to HWO due to its limited spatial resolution.
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All authors Sarah Rugheimer, Aiden Weatherbee, James Fecanin, Alistair Glasse, Paul Rimmer, Eleonora Alei, Esther Wang, Marrick Braam, Sascha P. Quanz, Adrian Glauser, Alexander Archibald, Beth Biller, Mark Booth, Tereza Constantinou, Gregory Cooke, Daniel Dicken, Trent Dupuy, Mei Ting Mak, Paul Palmer, Tim Pearce, Vito Squicciarini, Amaury Triaud, Floris van der Tak, Sergey Yurchenko
Materials Science
Symmetry-Adapted Physical and Vibrational Properties of Ferroelectric Perovskite Oxides: Application to PbZrxTi1-xO3
Sumit Ranjan Maity and Brajesh Tiwari
Crystal symmetry governs macroscopic physical properties and
lattice dynamics in functional materials. We present a systematic application of tensor analysis and group theory to determine allowed physical-property tensors, vibrational-mode
symmetries, and Raman selection rules directly from crystallographic point-group
symmetry. The approach is applied to the prototypical ferroelectric PbZrxTi1-xO3 (PZT).
Symmetry lowering across the PZT phase diagram increases the number of independent pyroelectric, dielectric, and piezoelectric tensor components and modifies the
symmetry classification of Raman-active vibrations. These mode classifications enable
symmetry-based decomposition of reported room-temperature powder Raman spectra as a function of composition (x) across the morphotropic phase boundary, revealing the tetragonal-to-rhombohedral transition as a continuous redistribution of spectral intensity rather than emergence of new Raman modes. Persistent subpeak structure in selected modes indicates local
symmetry breaking due to cation disorder and
lattice anharmonicity, underscoring the importance of crystallographic
symmetry analysis for interpreting functional and vibrational properties of ferroelectric perovskite
oxides.
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Solar and Stellar Astrophysics
Echoes of Star Stories: Integrating Indigenous narratives into modern stellar astrophysics
Dionysios Gakis
Indigenous narratives have long preserved observations of celestial phenomena, offering insights that resonate with modern astrophysical research. Deeply embedded in cultural traditions, these stories describe events such as
stellar variability,
supernovae, eclipses, and planetary
alignments. Indigenous communities have also used the
stars for
navigation and calendar systems, reflecting a sophisticated understanding of celestial patterns. These narratives not only complement historical records but offer human-centric perspectives on
stellar life cycles that often parallel modern models. Drawing from traditions from diverse Indigenous communities - including Aboriginal Australians, Pueblo peoples, Inuit, and Polynesians - this paper highlights the profound connections between Indigenous knowledge and
stellar astrophysics. Integrating these traditions acknowledges their value, safeguards their relevance in the Space Age, and fosters mutual learning through cross-cultural collaboration. We explore how such narratives can enrich education, public engagement, and even inspire scientific hypotheses, bridging cultural heritage and modern astrophysics.
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High Energy Physics (Phenomenology)
Higher-order chiral Lagrangians with vector meson nonet in different representations
Wei Guo, Qin-He Yang and Shao-Zhou Jiang
In this paper,
chiral Lagrangians with vector
meson nonet are constructed across multiple representations, including those to the next-to-leading order in the vector-field representation, as well as to the next-to-next-to-leading order in the tensor-field and hidden local
symmetry representations. For the next-to-leading order octet, redundant terms in the other literature are also identified in both the tensor-field and hidden local
symmetry representations. Additionally, the equivalence between the tensor-field and hidden local
symmetry representations is examined.
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Quantum Physics
Hash-QNeRF: Multiresolution Hash Encoding for Quantum Neural Radiance Fields
Digonto Biswas, Tana Ballove, Anjan Bandyopadhyay et al. (+2 more)
Neural Radiance Fields (NeRF) have revolutionized novel view synthesis, yet their classical implementations remain computationally intensive for high-fidelity rendering. QNeRF recently demonstrated the feasibility of training NeRF on gate-based
quantum computers by combining amplitude
embedding, parameterized
quantum circuits (PQCs), parity-based measurements, and volumetric rendering. However, QNeRF relies on classical sinusoidal positional encoding for spatial coordinates, which scales poorly with scene complexity and resolution. In this work, we replace the sinusoidal positional encoding for spatial coordinates with the multiresolution hash encoding from Instant-NGP while keeping the view-direction encoding, amplitude MLP,
quantum circuit, parity measurement, output scaling, and volumetric rendering pipeline unchanged. This hybrid design, Hash-QNeRF, retains the
quantum radiance prediction step while benefiting from the fast convergence and
memory efficiency of learnable hash grids. On a synthetic Blender scene, we achieve a final training loss of 0.003534, corresponding to approximately 24.5 dB PSNR on the fitted batch. Noise resilience experiments using Qiskit FakeKyiv and FakeTorino backends yield state fidelities of 0.93 to 0.98, indicating that hash encoding does not degrade the
quantum circuit's noise tolerance.
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All authors Digonto Biswas, Tana Ballove, Anjan Bandyopadhyay, Sutanu Mangal, Arun Kumar Pati
Quantum Physics
Tunable Mpemba Effect in a Prethermal Many-Body Spin Network
Chaitali Shah, Cooper M. Selco, Leo Joon Il Moon et al. (+1 more)
Relaxation in an interacting system is determined not only by its initial distance from
equilibrium, but also by the relaxation modes populated by the initial state. Here we experimentally observe and control the Mpemba effect, in which a state farther from
equilibrium overtakes one initially closer, in an extended, disordered $^{13}$C
nuclear-
spin network in diamond. Field cycling allows us to prepare distinct spatial polarization profiles by independently controlling hyperpolarization and defect-mediated relaxation. We then track their
evolution under Floquet driving, which stabilizes a long-lived prethermal regime. We observe reproducible Mpemba crossings and tune the crossing time over several orders of magnitude, from late-time thermalization into the prethermal plateau. Semiclassical simulations show that randomly positioned paramagnetic defects create fast-relaxing regions and defect-poor regions that support the slowest collective relaxation mode. The Mpemba crossings are set by the initial state overlap with this mode. Our results demonstrate anomalous relaxation within a prethermal many-body regime and identify disorder, transport, and mode-selective state preparation as resources for controlling relaxation in extended
spin networks.
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All authors Chaitali Shah, Cooper M. Selco, Leo Joon Il Moon, Ashok Ajoy
General Relativity and Quantum Cosmology
Bulk Viscosity and Thermodynamic Approaches to Singularity Resolution in Non-Metric Gravity
M. Sharif, M. Zeeshan Gul and Nusrat Fatima
This manuscript investigates the impact of bulk viscosity on the viability of
cosmic bounce solutions in the context of $f(\mathcal{Q})$ theory, where $\mathcal{Q}$ is a non-metricity scalar. To complete this objective, we study the behavior of an isotropic homogeneous universe filled with a perfect fluid and consider a innovative parametrization of bulk viscosity coefficient with an arbitrary constant $\zeta_0$ as $\zeta=\zeta_{0}H$. We consider the particular functional form of this modified theory to explore how this gravitational framework influences the
cosmic evolution and explore a range of cosmological parameters to assess the existence and physical viability of bounce solutions. We also investigate the
evolution of
entropy through the second law of thermodynamics. The positive trend of energy density, negative pressure profile and violation of energy conditions support the existence of viable cosmological bounce scenario and highlights the significance of bulk viscosity in this framework. These results demonstrate that $f(\mathcal{Q})$
gravity provides a compelling alternative to standard
cosmic models and provides deep insights into the nature of gravitational interaction and the early cosmos.
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Quantum Physics
Quantum Correlations in Frustrated Three-Body Systems
Chaitali Shah and Apoorva D. Patel
Many physical systems are not understood from first principles due to the presence of multi-body
quantum correlations. The effort taken to simulate such systems on classical computers increases exponentially with increase in the system size. We study simple, yet non-trivial, three-body frustrated systems that can help in understanding the underlying
quantum correlations. First we investigate the ground state of helium-like atoms using the variational method and physically meaningful ansatze, revealing how
quantum entanglement arises due to frustration in the system. Next we consider another frustrated three-body system, the hydrogen molecular ion, and analytically demonstrate the nature of its wavefunction arising from the
quantum tunneling phenomenon. Finally, we extend these results to model yet another physically important system, the hydrogen bond.
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General Relativity and Quantum Cosmology
Thermal bath induced suppression of Hawking radiation
Hong Wang and Jin Wang
The
cosmic microwave background radiation or particles surrounding a black hole can be modeled as a thermal bath coupled to the black hole. In this study, we investigate the effects of such a thermal bath on black hole radiation. The model involves Hawking radiation particles that are bilinearly coupled to the thermal bath. In this framework, the Hawking radiation particles are treated as the system, and the bath serves as the environment. We analytically derive the effective Keldysh action and the dynamical equation of the system, which are essential for studying the effective dynamics of Hawking radiation. For the specific case of a bath weakly coupled to the radiation particles from a Schwarzschild black hole, we numerically solve the effective dynamical equation. The results indicate that the bath suppresses Hawking radiation. Consequently, an observer located far away from the black hole will detect radiation that is weaker than Hawking's original prediction.
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