Mathematical Physics
Structure-Informed Neural Operators for Long-Time Prediction of Parametric Hamiltonian PDEs
Victory C. Obieke, Christopher Chukwuemeka and Emmanuel E. Oguadimma
Hamiltonian partial differential equations (PDEs) often exhibit long-time dynamics governed by conserved quantities such as mass, momentum, and
Hamiltonian energy. Standard
Fourier neural operators (FNOs) provide efficient data-driven approximations of solution operators, but may not preserve these invariants during autoregressive rollout, and can develop drift in conserved quantities, phase error, and loss of qualitative accuracy. We propose an energy-projection
Fourier neural operator (EP-FNO), a structure-informed operator learning architecture that combines a residual FNO time-stepping update with an invariant projection for long-time prediction of parametric
Hamiltonian PDEs. We also provide a theoretical analysis showing that EP-FNO can approximate operators associated with PDEs efficiently, we also suggest a stability estimate. We evaluate the approach on the Zakharov–Kuznetsov, Kadomtsev–Petviashvili, and sine–Gordon equations. Numerical experiments show that the projected model improves long-time stability, and gives more accurate propagation of
soliton and coherent wave structures compared with a standard FNO baseline. Our results demonstrate that invariant projection improves the reliability of learned surrogates for long-time
Hamiltonian PDE simulation.
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Quantum Physics
Optimizing Entanglement Distillation Policies via Markov Decision Process Formulation
Jigyen Bhavsar, Rajni Bala and Siddhartha Santra
Entanglement distillation is a fundamental operation in
quantum information processing used to obtain higher-fidelity entangled pairs from a supply of less entangled
quantum states using local operations aided by classical communication (LOCC). In a physically relevant setting, where states with an initial fidelity of $f_0$, probabilistically generated over multiple, $m$,
memory pairs distributed between two parties, Alice and Bob, are pairwise distilled, the optimal policy identifies the system-configuration dependent sequence of
entanglement generation and
distillation operations that need to be performed in order to minimize the expected time to reach some target fidelity $f_T>f_0$. Here, we formulate and systematically analyze this task as a Markov decision problem and using a value iteration
algorithm, obtain optimal deterministic policies that minimize the expected waiting time required to reach a target fidelity. Our results show that the expected waiting time under the optimal policy decreases with increasing generation probability $p$ and number of
quantum memories $m$ - as expected. In contrast, it exhibits non-monotonic behavior with respect to $f_0$ for a fixed fidelity gap, $(\Delta f = f_T-f_0)$. While the optimal policy consistently outperforms baseline policies such as the greedy, nested and
entanglement pumping policies, its relative advantage is regime-dependent, being determined by the system parameters ($p,f_0,f_T,m$), and exhibits a nontrivial dependence on the fidelity gap $\Delta f$. Our results highlight the value of formulating
entanglement distillation as a Markov decision problem, enabling the systematic design of policies that achieve target fidelity thresholds for
quantum information tasks in realistic resource-constrained settings.
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Soft Condensed Matter
Many-body activity emerging in a monolayer of air-fluidized hollow pentagons
Wan-Jung Lin, Bohan Wu-Zhang, Rodrigo Fernández-Quevedo García et al. (+6 more)
Particles governed by many-body interactions exhibit remarkably complex structures and dynamics. We experimentally investigate a monolayer of pentagon particles subjected to an up-lifting air flow which induces many-body aerodynamic interactions and
stochastic motion akin to a thermal bath. To minimize air flow resistance, particles move collectively with interactions dictated by their geometry: hollow particles exhibit effective attraction, whereas solid particles repel each other. Under sufficiently large air flow, sparsely packed hollow pentagons overcome substrate friction and undergo long-time diffusive motion. Under lower air flow, we see a coexistence of isolated, static pentagons and densely packed, "active" clusters, whose particles display super-diffusivity. This "emergent activity" arises collectively when locally disordered structures interact with the air flow, resulting in correlated motion across broad temporal and spatial scales. Using Langevin dynamics simulations of two-dimensional attractive active pentagons, whose activity is an effective result of the local packing density, we further unravel the basic features of this emergent activity.
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All authors Wan-Jung Lin, Bohan Wu-Zhang, Rodrigo Fernández-Quevedo García, C. Miguel Barriuso G., Aayush Agarwal, Yue Fan, Miguel Ruiz-García, Chantal Valeriani, Hongyi Xiao
Mathematical Physics
A Reverse Hard-Core Model in $\mathbb{A}_2$: an Application of the Pirogov-Sinai Theory
A. Mazel, I. Stuhl and Y. Suhov
In this paper we use the Pirogov–Sinai theory to analyze a class of particle models of Statistical Mechanics on the unit triangular
lattice $\mathbb{A}_2$. The models are specified by two parameters: the particle activity $u\in(0,1)$ and a positive Löschian number $t$ interpreted as a maximal squared clearing radius. Admissible configurations are those in which every empty
lattice site has an occupied site within squared distance at most $t$, thereby forbidding empty disks of radius exceeding or equal $t$. The
Hamiltonian favors configurations with as few occupied sites as possible, while the admissibility condition enforces a positive density of particles. We prove that the periodic ground states of the model, i.e., the configurations achieving an optimal balance of two tendencies, are the ones whose occupied sites form triangular sublattices of explicitly determined squared side-length $d_*(t)$. Furthermore, for sufficiently small values of the activity parameter $u$, some (but not necessarily all) periodic ground states generate extreme Gibbs (DLR) measures. We describe the resulting phase structure and characterize the pure phases associated with stable ground states.
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Quantum Physics
Generalized Kerr-Cat Qubit Codes
Alonso Viladomat, Shahram Dehdashti, Amin Kargarian et al. (+2 more)
We present a systematic study of Schrödinger cat codes constructed from Kerr-type coherent states, including displaced Kerr coherent states and Barut–Girardello Kerr coherent states, each admitting two distinct families determined by the sign of the Kerr nonlinearity. By tuning the Kerr parameter and coherent-state amplitude, these states interpolate between $\mathfrak{su}(2)$, $\mathfrak{su}(1,1)$ coherent states, providing a unified and versatile foundation for this type of bosonic
quantum error correction. Unlike standard two-component Schrödinger cat codes, where a single
photon-loss event induces an uncorrectable bit-flip, the nonlinear phase-space structure of Kerr cat states enables simultaneous detection and correction of both
photon-loss and dephasing errors within a unified recovery framework, with optimal recovery operations determined via convex optimization. We demonstrate that Kerr cat encodings significantly outperform conventional cat codes under combined loss and dephasing noise, and that judicious parameter optimization can suppress both error channels to a level that reduces the overhead of additional error correction layers. We further show that Kerr-deformed coherent-state
manifolds under engineered two-
photon driving emerge as effective steady states of driven-dissipative dynamics, with single-
photon decoherence strongly suppressed and leakage outside the protected
manifold appearing only as higher-order corrections in the deformation strength. Our extended formalism identifies generalized Kerr Schrödinger cat codes as promising candidates for fault-tolerant bosonic
quantum computation in experimental platforms such as nonlinear photonics.
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All authors Alonso Viladomat, Shahram Dehdashti, Amin Kargarian, Janis Nötzel, Peter van Loock
Instrumentation and Methods for Astrophysics
Direct High-Resolution Imaging of Earth-like Exoplanets with the Solar Gravitational Lens
Slava G. Turyshev
We present a scalar, aperture-averaged observability
benchmark for resolved
exoplanet imaging with the
solar gravitational lens (SGL). A real Earth luminance map is propagated through a scanned SGL image plane using source-to-image-plane compression, a finite-aperture SGL kernel, and an Einstein-ring
photon-count model. We inject
photon noise, finite-exposure smear, cloud-like temporal variability, coronal and detector-calibration residuals, optical-operator mismatch, and
navigation error, then reconstruct with a regularized
Fourier/Wiener inverse. For an Earth-radius
planet at 30 pc observed from 650 AU with a 1 m
telescope, the projected image cylinder is 1.338 km across; a $128\times128$ raster has 10.46 m image-plane pitch, 99.55 km source pixels, and convolved-image SNR 43.16 for 1800 s per sample. With the stated ring-extraction, temporal, background, calibration, and
navigation mitigations, the fiducial reconstruction reaches SNR 6.89, structural similarity 0.848, normalized RMS error 0.439, and a 232 km
Fourier-ring-correlation resolution proxy. A higher-count case reaches SNR 10.49, structural similarity 0.927, normalized RMS error 0.287, and the 199 km two-pixel grid floor. Controlled cloud tests show that a static inverse fails for rotating cloudy data, whereas phase-registered robust coadds recover persistent surface-proxy structure in the scalar model. The dominant requirements are temporal sampling, coronal and detector calibration, ring extraction, image-plane metrology, optical-operator knowledge, and dynamic inversion, not calibrated monopole SGL blur. The
benchmark demonstrates recoverable 200-230 km-class broadband spatial contrast in the stated scalar model, but does not validate propulsion, communications, coronagraphic or external-occulter propagation, physical
solar multipoles, physical cloud fields, or a full dynamic
retrieval pipeline.
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Astrophysics of Galaxies
Galaxy Spiral Arm Count vs. Concentration and Mass: A First Look with Euclid
Beverly J. Smith, Sydnie Bergner, Mark L. Giroux et al. (+1 more)
Using catalogued information from Euclid Quick Data Release 1, we compare 2-armed and 3-armed spiral
galaxies as classified by the Euclid Zoobot software. Two-armed
galaxies have larger concentrations, lower
stellar masses (M*), and lower
star formation rates (SFRs) on average than 3-armed
galaxies. For a given M*, 2-armed
galaxies have larger concentrations than 3-armed
galaxies. These trends have been seen before in nearby
galaxies; with Euclid we extend the patterns to
redshifts z = 0.4 - 1. Two-armed
galaxies have lower SFRs because they have lower masses; at fixed M*, 2-armed and 3-armed
galaxies have similar SFRs. We see a bend in the concentration-log M* relation for 2-armed
galaxies at M* = 10^10.3 M(sun). Above this mass, 2-armed
galaxies show significantly larger concentrations than their lower mass counterparts. The observed concentrations of 2-armed
galaxies decrease with increasing
redshift, perhaps from morphological K-corrections and resolution differences. About 60% - 70% of Euclid spirals are 2-armed, and about 15% - 20% are 3-armed. One-armed
galaxies are rare, with low masses compared to 2-armed spirals. We compare these statistics with
Galaxy Zoo Sloan Digital Sky Survey arm counts at low z, and tentatively with JWST at higher z. We discuss these results in terms of theoretical models of spiral arm generation and
evolution, and compare with statistics of grand design, multi-armed, and flocculent
galaxies. There is a need for more quantitative measurements of arm structure beyond arm counts provided by the Zoobot/
Galaxy Zoo or the three standard arm classes.
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All authors Beverly J. Smith, Sydnie Bergner, Mark L. Giroux, Curtis Struck
General Relativity and Quantum Cosmology
Tidal Stripping of Matter Bound to the Secondary in Extreme Mass-Ratio Inspirals
Sreejith Nair and Sayak Datta
Environmental studies of extreme mass-ratio inspirals (EMRIs) have focused almost entirely on matter surrounding the primary supermassive black hole. We instead consider matter bound to the
stellar-mass secondary (e.g., gas or dark matter); which can be progressively tidally stripped during the LISA-band inspiral. This changes the bound mass of the inspiraling object, modifying the gravitational-wave (GW) phase at leading order in the secondary mass. Furthermore, as the signal interpolates from an initially dressed inspiral to a nearly bare one, it can produce a characteristic inflection in the residual phase with constant mass waveform templates. Even for an environmental mass $\sim 10^{-3}\,M_{\odot}$, the cumulative dephasing relative to in band initial bound mass waveform can be larger than unity. In subsolar mass cases, the relative dephasing can reach $O(10^3)\, \rm rad$. Neglecting this effect may bias inferred EMRI parameters at the level of the fractional change in the in-band bound mass. The
tidal stripping phenomena carry information about the mass and the compactness of the bound matter, enabling probes of sub-AU, planetary- to subsolar-mass environments surrounding
stellar-mass black holes.
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Materials Science
Precipitation strengthening as a collective multi-dislocation phenomenon
Mahmudul Islam, Jason Ogbebor, Nicolas Bertin et al. (+3 more)
Precipitation strengthening is a cornerstone of physical metallurgy, delivering otherwise unattainable combinations of strength and ductility. The approach relies on nanoscale precipitates that impede the motion of dislocations, the primary carriers of metal plasticity. Historically, precipitation strengthening has been rationalized via two idealized, limiting mechanisms: dislocations either cut through or bow around precipitates. However, under many technologically relevant conditions, multiple dislocations can interact with a precipitate at the same time, potentially giving rise to distinct precipitate-dislocation dynamics that in situ experiments are yet to fully resolve. Here, using large-scale atomistic simulations (100 million atoms) that capture these dynamics, we demonstrate that in this regime, the cutting-versus-bowing dichotomy is incomplete: strengthening arises as an emergent phenomenon driven by concurrent multi-dislocation interactions. These interactions simultaneously induce dislocation accumulation at interfaces, storage within precipitates, and precipitate-mediated multiplication inside the
matrix. Our findings establish a distinct mechanistic regime of precipitation strengthening beyond traditional models and provide a quantitative foundation for predicting its behavior.
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All authors Mahmudul Islam, Jason Ogbebor, Nicolas Bertin, Sylvie Aubry, Vasily V. Bulatov, Rodrigo Freitas
Materials Science
Atomistic insights into the structural, thermal, and mechanical evolution of $Zr_{47.5}Cu_{47.5}Ag_{5}$ bulk metallic glass
N. Mendez, S. Jaroszewicz, M. P. Beccar-Varela et al. (+1 more)
Bulk metallic glasses (BMGs) are distinguished by amorphous atomic structures that confer superior mechanical performance; however, the
evolution of these properties in ternary bulk configurations remains insufficiently explored. In this study, we employed large-scale molecular dynamics simulations to investigate the structural, thermal, and mechanical properties of $Zr_{47.5}Cu_{47.5}Ag_{5}$ BMGs. Our thermodynamic and topological analyses, utilizing potential energy regression and the Modified Wendt-Abraham parameter, identified a glass transition temperature ($T_g$) of approximately $692\text{ K}$. Structural characterization via Voronoi tessellation and partial radial distribution functions reveals that the amorphous
matrix is stabilized by icosahedral clusters, with Ag atoms inducing significant chemical heterogeneity through localized nano-clustering. Thermal transport properties, computed via the Green-Kubo formalism, demonstrate a monotonic decrease in conductivity with temperature, consistent with structural scattering saturation in disordered
lattices. Mechanical tensile testing reveals that the material exhibits robust rate- and temperature-dependent behavior, with yield strengths reaching $\approx 2.3\text{ GPa}$ at room temperature. We show that macroscopic strain-softening is intrinsically linked to the thermally induced collapse of rigid icosahedral motifs, which facilitates shear band percolation. These findings provide a structural rationale for the beneficial role of Ag dopants in enhancing the resilience of multicomponent metallic glasses.
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All authors N. Mendez, S. Jaroszewicz, M. P. Beccar-Varela, M. C. Mariani
Mesoscale and Nanoscale Physics
Valley Valves at Domain Walls in Symmetry-Broken Rhombohedral Graphene
Vo Tien Phong, Francisco Lobo, Elsa Prada et al. (+3 more)
Rhombohedral multilayer
graphene polarized by a moderate perpendicular displacement field hosts a time-reversal-
symmetry-breaking valley-and-
spin-polarized metallic phase that may condense into a
chiral superconductor. Recent
magnetic imaging and transport measurements in this unconventional system suggest the presence of domain walls both in the metallic and superconducting phases. In this work, we show that valley domain walls are impenetrable barriers to transport in the metallic regime. Transmission through such a domain wall must therefore be mediated by intervalley interactions. We derive the
symmetry-allowed terms and show via microscopic numerical simulations that they enable the transmission of electrons across the domain wall. In the superconducting phase, we find that intervalley mixing is crucial for supporting an appreciable supercurrent through a SNS' Josephson junction that connects opposite-chirality superconducting regions. Taken together, our work elucidates the nature of domain walls in these experimentally relevant multilayer systems and emphasizes the critical role of intervalley hybridization in governing their transport properties.
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All authors Vo Tien Phong, Francisco Lobo, Elsa Prada, Pablo San-Jose, Francisco Guinea, Eugene J Mele
Data Analysis and Statistics
Peak-Based Nuclide Identification in HPGe $\gamma$-Spectrometry with Machine Learning and SHAP
Samuel Emmons, Kelly Truax, Maurice Lonsway et al. (+2 more)
High-purity germanium gamma spectra often require time-consuming analyses from subject matter experts. Photopeaks within these spectra are carefully fitted and numerical methods are employed to assist with nuclide identification (NID) and quantification. Amending the list of nuclides identified by analysis software can be nontrivial. When many samples need to be analyzed, it is therefore challenging to make timely and correct decisions. Supervised machine-learning-based NID can serve as an expert-informed, automated tool to improve the initial set of radionuclides suggested to an analyst and more effectively drive subsequent quantification. To that end, we implemented machine learning models that map photopeaks carefully fitted by analysts to NID results for experimental spectra containing various isotopic combinations drawn from a set of 65 isotopes. The best model achieved an F1 score of 0.97, markedly surpassing the F1 score of 0.84 achieved by traditional software when compared using a nuclide library comprising the same 65 isotopes assessed by the models. Finally, we illustrated the most important input features for model predictions using Shapley Additive Explanations. These explanations revealed that the models use physically relevant photopeaks when making predictions for the isotopes in our nuclide library.
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All authors Samuel Emmons, Kelly Truax, Maurice Lonsway, Bruce Pierson, Brian Archambault
Quantum Physics
Finite-Element Matrix Product States for Continuum Models in One Dimension
Akshay Shankar, Karel Van Acoleyen and Jutho Haegeman
We present a
matrix product state framework for simulating one-dimensional
quantum many-body systems in the continuum using non-orthogonal single-particle basis sets. By mapping the physical problem to an auxiliary computational space, we show that the resulting many-body overlap operator can be efficiently encoded as a
matrix product operator for sufficiently localized orbitals, thereby generalizing a construction that first appeared in [arXiv:2405.10285]. This construction recasts the variational ground-state search into a generalized
eigenvalue problem, which can be solved using a generalized density
matrix renormalization group
algorithm. As a primary application, we employ a first-order finite-element expansion to study the ground state properties of the Lieb-Liniger gas in the presence of inhomogeneities. This approach also provides a natural setting for exactly refining the
lattice, thereby enabling multigrid optimization strategies for
matrix product states.
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Mesoscale and Nanoscale Physics
Dominant spin Hall torque and negligible orbital Hall torque in {\alpha}-W/ferromagnet heterostructures with artifacts-free angular momentum detectors
Taiyang Zhang, Lujun Zhu, Qianbiao Liu et al. (+1 more)
{\alpha}-phased W was theoretically predicted to have a negative
spin Hall conductivity and a positive orbital
Hall conductivity at the same time, leaving the physical origin of the current-induced torque a critical open question. Here, we develop two angular momentum detectors of Cu/Ni/Cu and Cu/Fe60Co20B20/Cu that are free of artifacts torques (e.g., self-induced torque and
spin-vorticity torque) and clarify that the
spin-orbit torque contributed by {\alpha}-W remains negative and predominantly from the
spin Hall effect in the entire thickness regime. The damping-like torque exhibits a monotonic decay as the W thickness increases above 5 nm likely due to the thickness-dependent structural
evolution and resistivity reduction of the W layer. The negative torque in the entire thickness regime suggests negligible orbital
Hall torque from {\alpha}-W. This result is consistent with the theory that the orbital
Hall effect from simplified band structure calculations is not a non-local angular momentum source.
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All authors Taiyang Zhang, Lujun Zhu, Qianbiao Liu, Lijun Zhu
High Energy Physics (Phenomenology)
Pre-Training for Simulation-Based Science: A Study on Jet Foundation Model Training Objectives
Ibrahim Elsharkawy, Joschka Birk, Vinicius Mikuni et al. (+3 more)
Foundation models (FMs) trained on large
datasets and fine-tuned on downstream tasks have emerged as a powerful paradigm in AI for science. Industrial FMs are typically trained using self-supervision with masking due to the lack of labels. In many scientific domains, accurate simulations are plentiful and facilitate large, labeled
datasets. This opens up new possibilities for pre-training. We present a systematic comparison of pre-training methods using the OmniLearned High Energy Physics FM framework. We test supervised classification, flow-matching generation, and self-supervised masked particle modeling. All models are pre-trained on the JetClass
dataset and fine-tuned on two representative downstream tasks, top jet classification and JetNet conditional generation. Among other observations, for classification tasks, we find that pure classifier pre-training is optimal when downstream labels and model capacity are plentiful, but combining it with self-supervised masked particle modeling (MPM) is uniquely powerful in the low-finetuning label regime. Flow matching-based generative pre-training seems to provide little benefit for downstream classification, and interestingly, for downstream generation, we find that flow matching must be in the pre-training objective to see a significant finetuning advantage, hinting at the orthogonality of classification and generation tasks. That is, for a model to transfer to both generative and classification downstream tasks, it must be pre-trained on both. This study provides a template for controlled scaling analysis of pre-training objectives for foundation models in simulation-based sciences.
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All authors Ibrahim Elsharkawy, Joschka Birk, Vinicius Mikuni, Wahid Bhimji, Gregor Kasieczka, Benjamin Nachman
Astrophysics of Galaxies
COSMOS-Web: A Multi-wavelength Morphological Catalog of ~780,000 Galaxies
Lilan Yang, Jeyhan S. Kartaltepe, Nicole E. Drakos et al. (+20 more)
We present multi-wavelength morphological measurements for all
galaxies in the COSMOS-Web survey, i.e., $\sim$780,000
galaxies contained in the COSMOS2025 catalog. We perform both parametric (e.g., single and double Sérsic modeling) and non-parametric (e.g., Gini-$M_{20}$) morphology analyses in four NIRCam bands, independently. Our parametric fits reveal a strong correlation between
galaxy structure and
star formation activity up to $z\sim4$, as evidenced by the dependence of the Sérsic index ($n_{\rm s\'ersic}$) and bulge-to-total ratio ($B/T$) on the position of the
star formation rate-
stellar mass plane. A tight correlation between $n_{\rm s\'ersic}$ and $B/T$ is observed. The
evolution of $n_{\rm s\'ersic}$ and $B/T$ depends on
stellar mass; for example, the median $n_{\rm s\'ersic}$ increases from $\sim1$ at $z\sim6$ to $\sim2.5$ at $z\sim2$ for massive
galaxies with $M_*>10^{10.5} M_{\odot}$, while lower mass
galaxies remain $n_{\rm s\'ersic}\sim1.2$ at all epochs. The UV $n_{\rm s\'ersic}$ values are systematically smaller than those in the optical, although both exhibit similar evolutionary trends. From non-parametric analyses, we demonstrate the distribution of
galaxies on the Gini-$M_{20}$ and asymmetry-concentration planes, and find that morphological classifications based on non-parametric indicators are consistent with those derived from the Sérsic index. The resulting catalog provides the largest and most detailed set of JWST multi-wavelength morphological measurements to date, serving as a valuable community resource for studies of structural transformation, bulge growth, and
galaxy-supermassive black hole coevolution across
cosmic time.
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All authors Lilan Yang, Jeyhan S. Kartaltepe, Nicole E. Drakos, Andreas L. Faisst, Carter Flayhart, Maximilien Franco, Anton M. Koekemoer, Olivier Ilbert, Hollis B. Akins, Caitlin M. Casey, Xuheng Ding, Ali Hadi, Santosh Harish, Ronaldo Laishram, Daizhong Liu, Georgios E. Magdis, Felix Martinez III, Henry Joy McCracken, Louise Paquereau, Jason Rhodes, Brant E. Robertson, Marko Shuntov, Greta Toni
Materials Science
Absence of orbital current torque in a magnetic metal/Pt/CuOx trilayer
Zhihao Yan, Lujun Zhu, Xiangrui Qin et al. (+2 more)
Naturally oxidized copper (CuOx) was cited as an exceptionally strong orbital-current source despite the keen debate over the concept of orbital current. Here, we report unambiguous experimental evidence for the absence of a detectable orbital-current torque in the Fe/Pt/CuOx trilayers. Using a
magnetic metal detector of Fe thin film with a negligible self-induced torque, the damping-like torque due to Pt/CuOx
bilayers is clarified to entirely arise from the
spin Hall spin current of the Pt. As the Pt thickness increases, the torque for Fe/Pt/CuOx and Fe/Pt/MgO increases coherently and monotonically, as exactly expected from the
spin Hall effect of Pt and the drift-
diffusion model of
spin angular momentum. These findings suggest poor generality or even universal absence of orbital current torque.
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All authors Zhihao Yan, Lujun Zhu, Xiangrui Qin, Zhengxiao Li, Lijun Zhu
High Energy Physics (Phenomenology)
Event generation for future DIS experiments
Peter Meinzinger, Daniel Reichelt and Federico Silvetti
In this contribution we discuss state-of-the-art
hadron-level predictions for the deep-inelastic scattering process at next-to-leading-order precision for several multiplicities, consistently merged in one sample. We focus on the physics at (potential) future
colliders, the Electron-Ion
Collider planned at BNL as well as the higher energy experiments discussed as future options at CERN, a LHeC and a DIS phase of the Future Circular
Collider dubbed FCC-eh.
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High Energy Physics (Phenomenology)
Towards a consistent perturbation theory at finite temperature
Passant Ali, Peter Lowdon and Owe Philipsen
The standard approach to perturbation theory for finite-temperature
quantum field theories has several issues, including the appearance of ill-defined on-shell contributions in the real-time formulation, and infrared divergences in massless theories. Earlier studies indicate that these issues all stem from the inconsistent thermal generalisation of the Gell-Mann-Low relation, which forms the foundation of perturbation theory in
vacuum. This inconsistency arises from the use of free scattering states in the relation, which are known not to exist in interacting thermal theories. In this work, we propose a generalisation of the Gell-Mann-Low relation for scalar theories based on non-perturbative spectral insights, namely that finite-temperature scattering states can be described by damped but stable particle-like excitations, so-called thermoparticles. The perturbative expansion of this generalised relation gives rise to contributions with exactly the same
topology as the standard finite-temperature approach, except that now the propagators appearing in this expansion are not those of a free field but of thermoparticles, which depend on the dynamics of the theory. We demonstrate that thermoparticle perturbation theory resolves the known problems of the standard approach. Furthermore, by comparing imaginary-time calculations at two-loop level with numerical
lattice simulations of two-point correlation functions in massive $\phi^{4}$ theory, we explicitly show that this framework gives rise to precise predictions, as in the
vacuum case, in stark contrast to the standard approach.
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Materials Science
Designing Strong and Broadband Nonreciprocal Thermal Radiation in Magnetic Topological Materials
Yiyang Jiang, Yufei Zhao, Linxiao Zhu et al. (+1 more)
Breaking reciprocity in thermal radiation opens opportunities for energy harvesting, sensing, and thermal management. Traditional nonreciprocal radiative
semiconductor devices need external
magnetic field. In this work, we predict a series of
magnetic topological materials for
magnetic-field-free nonreciprocal thermal radiation in the infrared regime, by combining first-principles calculations with Maxwell electrodynamics. We find strong and broadband nonreciprocity in
magnetic Weyl semimetals (e.g., Co$_3$Sn$_2$S$_2$), outperforming the conventional
semiconductor such as InAs. Furthermore, we propose universal material design recipes: strong nonreciprocity requires a large anomalous
Hall response relative to the optical loss, whereas the broadband response favors large optical loss and small dielectric dispersion. Our work establishes a predictive materials-discovery framework and quantitative design rules for next-generation magnet-free nonreciprocal thermal devices.
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All authors Yiyang Jiang, Yufei Zhao, Linxiao Zhu, Binghai Yan
Astrophysics of Galaxies
Physical characterization of the local system NGC 1313: A flattening in its chemical abundance by past interactions
Belén Ojeda-Díaz, Sergio Torres-Flores, Daniela E. Olave-Rojas et al. (+5 more)
Interacting
galaxies provide unique information on morphological transformation, enhanced
star formation, and chemical
evolution, and thus contribute to understanding the complex
evolution of
galaxies. We investigated the local interacting system NGC 1313 by analyzing its main physical and kinematical properties to understand how the interaction has influenced the evolutionary state of the
galaxy. We used multi-slit GMOS-S spectroscopy to study 19 regions across the
galaxy, encompassing its main body and the complex southwest region. We derived oxygen abundances using the N2 method and computed their chemical gradient. We derived electron densities using the S[II] ratio, ages from the EW(H-alpha), and
stellar masses of the regions from DR10 Legacy Survey images. We used H-alpha Fabry-Perot data to analyze the kinematics of the systems and search for signs of past interactions. The Baldwin-Phillips-Terlevich (BPT) and EW(H-alpha) versus N[II]/H-alpha (WHAN) diagnostics confirm photoionization by
star formation. The
galaxy has a low oxygen abundance (8.0<12+log(O/H)<8.2), with a mainly flat oxygen abundance gradient, suggesting gas mixing processes. Electron densities span $n_e$<10 to 142 cm$^{-3}$. The blue and red Wolf-Rayet bumps detected in two regions corroborate a young population. We find ages ranging from 2.7 Myr to 6.0 Myr. The velocity field shows complex kinematics in the northern region of NGC 1313, characterized by asymmetric line profiles. NGC 1313 thus provides an ideal laboratory for studying how minor interactions affect
star formation, chemical enrichment, and the kinematics of low-mass barred spiral
galaxies.
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All authors Belén Ojeda-Díaz, Sergio Torres-Flores, Daniela E. Olave-Rojas, Ciria Lima-Dias, Paulo J. A. Lago, Claudia Mendes de Oliveira, Philippe Amram, Bruno C. Quint
General Relativity and Quantum Cosmology
An inductive approach to $f(R)$ gravity and its application to extended sources
Federico Scali
In a previous work (Phys. Rev. D 110, 064042), a new family of $f(R)$ gravitational Lagrangians was constructed inductively using only
Solar System physics. Specifically, the modified Einstein equations were solved perturbatively on a Schwarzschild background, and the corresponding Lagrangian was reconstructed a posteriori from the solution. Classical
Solar System tests were then employed to constrain the fundamental length scale quantifying the deviation from general relativity. In the first part of this work, the construction of the model is critically reviewed, emphasizing the generality of the approach and the applicability to different modified
gravity frameworks. In the second part, the modified Newtonian potential produced by an extended source is derived within the new inductive $f(R)$ model, discussing the consistency of the Newtonian limit. In this context, the application to
galactic dynamics emerges as an intriguing perspective.
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Instrumentation and Detectors
Chopping and distilling variational autoencoders for real-time anomaly detection in high energy physics
Max Cohen, Rajat Gupta, Sterre Hoogendoorn et al. (+3 more)
Anomaly detection (AD) has recently emerged as an exciting alternative to conventional search strategies in high energy physics using artificial intelligence (AI) and machine learning (ML). The integration of these techniques into trigger systems is even more recent, but represents a crucial step in expanding the coverage of LHC triggers. In this paper, we explore the direct comparison, as well as combination, of two compression techniques for variational autoencoder (VAE) AD trigger
algorithms: utilizing only latent-space derived variables and therefore requiring only half of the VAE that we call "chopping" and applying knowledge
distillation (KD) to distill the VAE into a student architecture that we call "
distillation." We demonstrate the feasibility of deploying such techniques on an FPGA within the resource and latency constraints of an LHC trigger environment and further find that a combination of the two leads to the smallest models that maintain, and in some cases, improve, performance with respect to the original VAE architecture.
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All authors Max Cohen, Rajat Gupta, Sterre Hoogendoorn, Sergey Scoville, Tae Min Hong, Dylan Sheldon Rankin
Quantum Physics
Magic transfer in quantum spin chains
Antonio Palamara, Chad Nelmes, Enrico C. Domanti et al. (+1 more)
Quantum communication protocols based on
spin chains have been extensively studied, yet their ability to transmit nonstabilizer resources has not been systematically addressed. We investigate the transport of
quantum magic in
spin chains through the natural dynamics of systems initialized in nonstabilizer states, and quantify the transported resource via the stabilizer norm. We analyze three experimentally feasible state-transfer protocols, ranging from noisy to (quasi-)perfect transfer, including one realizable in trapped-ion platforms. We find that the geometry of the injected state strongly influences transport: states in the lower Bloch hemisphere achieve higher transfer quality, whereas states in the upper hemisphere give rise to an efficient magic transport only beyond a threshold value of the parameter controlling the tendency towards perfect transfer. These features are robust across all protocols and identify the
Hamiltonian and state properties that favor high-quality transfer. Moreover, we identify a parameter region, relevant to the initial state preparation, in which the transported magic exceeds the initial encoding, indicating that such
spin systems can act as magic-amplification channels. Our results establish the conditions for efficient transport of nonstabilizer resources and demonstrate
quantum magic as a sensitive probe of
quantum transport beyond population dynamics.
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All authors Antonio Palamara, Chad Nelmes, Enrico C. Domanti, Francesco Perciavalle
High Energy Physics (Phenomenology)
Event Generation with Parallel Langevin Sampling and Learned Stein Diagnostics
Rob Verheyen
Efficient event generation is a major computational challenge for precision
collider phenomenology, especially for high-multiplicity final states where
matrix-element evaluations are expensive and rejection-sampling efficiencies are low. We study an alternative approach based on many parallel underdamped Langevin chains, retaining one terminal state from each chain to obtain unweighted events while avoiding within-chain autocorrelation. A learned Stein discrepancy is used as a convergence diagnostic, providing a data-driven estimate of the relaxation time. We apply the method to tree-level $u\bar u\to Z+n g$ event generation and find that relaxation requires only a modest number of exact-target Langevin steps, with mild growth over the multiplicities studied. Finally, we show that simple neural-network surrogate initialization can substantially reduce the required number of exact
matrix-element and gradient evaluations.
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Cosmology and Nongalactic Astrophysics
The limits of lattice inflation: a cautionary tale
Will Barker, Benjamin Gladwyn and Sebastian Zell
Cosmological
lattice simulations have become important tools for studying non-perturbative dynamics in the early Universe. Many widely used codes, however, approximate the gravitational background by an exact Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime and neglect metric perturbations. We show that, during inflation, this approximation prevents the freezing of superhorizon modes. During slow roll, the
curvature power spectrum decays as $H^4$, while the deviation becomes substantially stronger during ultra-slow roll. As a result, inflationary observables can be significantly distorted. In contrast, reheating studies appear to be considerably less sensitive to the omission of metric perturbations. We propose a practical criterion for assessing the validity of FLRW simulations based on the inclusion of first-order metric perturbations, and implement it in CosmoLattice.
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Astrophysics of Galaxies
Intermediate-mass black hole seeding in galactic nuclei from star cluster migration
Stefano Torniamenti, Nils Hoyer, Nadine Neumayer et al. (+2 more)
Nuclear star clusters are one of the most favorable sites to host hierarchical black hole (BH) mergers, potentially bridging the gap from
stellar-mass to massive BHs. However, their assembly and the
evolution of their BH populations remain poorly constrained. We investigate the process of intermediate-mass BH (IMBH) seeding in
galactic nuclei from
star cluster migration. We introduce inSpyral, a new semi-analytic model that draws
star cluster populations from a
galaxy formation model (L-
Galaxies 2020),and integrates their
evolution across a wide range of spatial scales, from BH core dynamics to the orbital motion in the host
galaxy. We find that dynamical friction drives the inspiral of the most massive clusters in
galaxies with $M_{\mathrm{\star, gal}} \lesssim 5 \times 10^{10} \,\mathrm{M_\odot}$, seeding their
nuclei with IMBHs as early as $z \sim 6$. The BH mass distribution from BH mergers in migrating clusters extends to $\sim 300 \, \mathrm{M_\odot}$, a factor of five above the upper limit from in-situ formation. If clusters form with sub-parsec scale radii ($\lesssim 0.5 \, \mathrm{pc}$), hierarchical mergers significantly enhance BH mass growth before migration, and seed
galactic nuclei with IMBHs above $10^4 \, \mathrm{M_\odot}$. The most massive and highly spinning gravitational-wave events are well reproduced by BH mergers involving second-generation remnants that experienced relatively small relativistic kicks ($\lesssim 100 \, \mathrm{km \, s^{-1}}$). GW231123 is consistent with BH mergers between a third-generation primary and a second-generation secondary, which occur in
star clusters with mass $> 2 \times 10^{6} \, \mathrm{M_\odot}$.
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All authors Stefano Torniamenti, Nils Hoyer, Nadine Neumayer, Peter J. Smith, Manuel Arca Sedda
Strongly Correlated Electrons
Jahn-Teller effect in $j = 3/2$ Mott insulators: Ground states and thermal fluctuations
Kathleen Hart, Ruairidh Sutcliffe and Arun Paramekanti
The interplay of strong atomic
spin-orbit coupling with Jahn-Teller (JT)
lattice distortions is an important theme in
quantum materials hosting heavy atoms. A prototypical example of such a system is a degenerate $j = 3/2$ multiplet coupled to local
phonon modes. Here, we study the multipolar ground states of this system as realized in Mott
insulators, explore its thermal phase diagram via an $SU(4)$
spin Monte Carlo approach coupled to JT
phonons, and study the temperature dependent splittings of the $j = 3/2$ multiplet as relevant to spectroscopic probes. Our work sheds light on coexisting distinct multipolar orders engendered by
phonon coupling, role of thermal JT fluctuations, and the
entropy of the coupled multipole-
phonon system. We discuss broad implications for double perovskites $\rm Ba_2MgReO_6$, $\rm Ba_2NaOsO_6$ and lacunar spinels such as $\rm GaTa_4Se_8$ and $\rm GaNb_4Se_8$.
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Astrophysics of Galaxies
An Analytic Model for Stellar Metallicity Gradient Residuals in Cold, Phase-Mixed Galactic Disks
Shaunak Modak, Zoe Hackshaw and Keith Hawkins
The distribution of
stellar metallicities over phase space in
galactic disks is sculpted by both
star formation and secular orbital transport processes. As a result, chemo-dynamical models that infer radial heating and migration histories from observations typically rely on sophisticated numerical modeling of
stellar distribution functions,
star formation histories, and various dynamical perturbations. Here, we develop a complementary minimal analytic model for constraining radial migration, using
stellar metallicity residuals relative to overarching
galactic metallicity gradients. Incorporating residuals imprinted during formation and produced dynamically, and assuming a cold, phase-mixed
stellar disk, we derive a closed-form expression for the resulting residual distribution. Applying our model to observed [Fe/H] residuals for
stars in the
Galactic thin disk, we find the root-mean-square amplitude of radial migration for
stars of age $\tau$ to be $\langle (\delta R_\mathrm{g})^2 \rangle^{1/2} \approx (2.79 \pm 0.07)\,\mathrm{kpc} \times [\tau/(6\,\mathrm{Gyr})]^{1/2}$, consistent with results derived from more complex numerical frameworks. Our results clarify the physical origins of covariances and degeneracies common across chemo-dynamical transport models, and demonstrate that
metallicity residuals provide a flexible, interpretable probe of radial migration in
galactic disks.
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Cosmology and Nongalactic Astrophysics
Constraints with CMB lensing on dark matter decays to massive decay products
Anna Bencke, Nanoom Lee and Marc Kamionkowski
Motivated by the recent measurements by the Dark Energy Spectroscopic Instrument (DESI) which suggest a late-time matter density approximately 5% lower than that inferred from Planck we investigate models in which dark matter decays to two less massive, and thus warm, states. The decaying dark matter (DDM) models are parameterized by the fraction $f$ of dark matter that decays, the decay rate $\Gamma$, and the fraction $\varepsilon$ of the mass retained by the decay products. To efficiently explore the warm decay product regime, we employ CLASSIER-DDM, a modified version of the public Boltzmann solver CLASS that solves the perturbation equations with DDM via an integral-equation method. We consider DESI DR2
baryon acoustic oscillations and Planck 2018 CMB data including
lensing, and find that DDM models are not favored over the $\Lambda$CDM model. This result arises because CMB
lensing tightly constrains the velocity kicks imparted to decay products. For example, for $f\simeq0.5$, we find $1\sigma$ constraints to the decay-product kick velocities an order of $10^{-2}$ to $10^{-3}$ times the speed of light for decay
redshifts from shortly after recombination until today. Nonetheless, the allowed parameter space includes models with sufficient power suppression at small-scales to potentially address
dwarf galaxy anomalies. Our results also suggest that explanations for DESI that involve dark-matter decays to one massive and one massless particle will be constrained by CMB
lensing.
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