Soft Condensed Matter
Influence of Rotational Diffusion on Macromolecular Self-Assembly Kinetics
Prabeen Kumar Pattnayak, Aloke Kumar and Gaurav Tomar
Macromolecular self-assembly underlies a plethora of biological processes and provides a versatile route for fabricating functional soft materials. The kinetics of self-assembly in solution are inherently
stochastic and are fundamentally governed by the interplay of translational and rotational
diffusion of the constituent macromolecules. While most computational studies model macromolecules as patchy spherical colloids, thereby neglecting the influence of
polymer architecture and internal conformational dynamics, the role of these factors in macromolecular self-assembly kinetics remains poorly understood. Here, we investigate the self-assembly of two patchy macromolecules with different architectures, namely linear chains and
star polymers with four and seven arms. The hydrodynamic radii of the macromolecules are chosen to be nearly identical, thereby matching their translational
diffusion coefficients and thus isolating the influence of rotational
diffusion on the self-assembly process. The binding probability of the patchy macromolecules is found to depend strongly on their internal architecture. Furthermore, reactive path density analysis reveals that self-assembly pathways are influenced by the rotational
diffusion coefficient of the individual macromolecules. Overall, this study establishes a bridge between the
equilibrium dynamics of macromolecules and their self-assembly kinetics, highlighting the importance of
polymer internal architecture in the process of self-assembly.
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High Energy Physics (Phenomenology)
Systematic derivation of the Boltzmann equation for electroweak baryogenesis
Motoi Endo, Yushi Mura and Tenta Tsuji
We derive the Boltzmann equation for electroweak baryogenesis within a field-theoretical framework. We first algebraically solve the Kadanoff–Baym equations by incorporating the effects of gradients of the CP-violating bubble-wall background order by order. We then apply approximations and assumptions appropriate for electroweak baryogenesis and identify the on-shell parts of the solutions, which describe quasiparticle states propagating in a
plasma. Using these on-shell solutions, we derive the Boltzmann equations for
flavor-diagonal quasiparticle modes, while neglecting the off-diagonal components describing
quantum coherence between different
flavor modes. Our derivation generalizes previous field-theoretical treatments by retaining self-energy corrections, and our results are consistent with the known Boltzmann equations when these corrections are neglected. This framework provides a systematic and transparent derivation applicable to multi-
flavor bosonic and fermionic systems.
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General Relativity and Quantum Cosmology
Post-Newtonian Roche-Lobe-Overflow Prescription for Compact Binary Mass Transfer and the Corresponding Gravitational Waveforms
Shuai Zhang, Jie Yang, Zi-Han Zhang et al. (+1 more)
Mass transfer in binary systems is central to many astrophysical phenomena, including the
evolution of compact interacting binaries. Starting from the first post-Newtonian hydrodynamic equations in the corotating frame, we derive the first post-Newtonian Roche potential and construct the corresponding post-Newtonian form of the Roche lobe overflow mass transfer prescription. We then include the time dependence of the component masses in the binary dynamics and compute the associated corrections to the equations of motion, gravitational-wave energy and angular-momentum fluxes, and far-zone polarization waveforms. Finally, we apply the model to representative ultracompact binary systems. We find that mass transfer can play an important role in the dynamical
evolution of compact binaries. For gravitational-wave observations, its main effect appears as a secular phase drift accumulated over long observation times.
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All authors Shuai Zhang, Jie Yang, Zi-Han Zhang, Shenghua Yu
Cosmology and Nongalactic Astrophysics
GGI Lectures on Large-Scale Structure Perturbation Theory (Effective Field Theory)
Mikhail M. Ivanov
These notes are an introduction to non-linear perturbation theory for cosmological large-scale structure. They are aimed at undergraduate and beginning graduate students and do not require any cosmology or
quantum field theory background. All necessary concepts are developed from scratch. The lectures are intended to explain all key ingredients needed to model the observed clustering of
galaxies in real and
redshift spaces. After a brief pedagogical introduction to the ideas of effective field theory (EFT), we develop large-scale structure EFT in the context of Newtonian cosmology using
symmetry principles. We discuss in detail the shortcomings of Standard Perturbation Theory, the non-linear
evolution of
baryon acoustic oscillations and its relation to the equivalence principle, counterterms and renormalization of the loop diagrams, and
stochastic effects. Then we develop EFT for
galaxy bias and
redshift space distortions. We also highlight some important facts about
redshift-space stochasticity, relevant for ongoing and future
galaxy surveys. Finally, we introduce Lagrangian Perturbation Theory.
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Mesoscale and Nanoscale Physics
Current-based RF charge sensing in a carbon nanotube
Marta Cagetti, Stefan Forstner, Victor Champain et al. (+8 more)
Ultra-sensitive charge detection is a widely used tool for
quantum electronics with applications in
quantum information processing and in probing the physics of condensed matter systems. Existing approaches require either an impedance-matched resonant
circuit, or millimeter-scale proximity between amplifier and sample, both adding complexity and constraining device design. In this work, we introduce a current-mode charge sensor in a suspended carbon nanotube, operating at the $1.25$ MHz resonance of an RLC tank
circuit and achieving a charge sensitivity of $0.15~\mu e/\sqrt{\mathrm{Hz}}$. We utilize it to measure a double
quantum dot (DQD) electrostatically defined in the same nanotube, revealing a highly regular charge stability diagram. We perform single-shot readout of the DQD charge state at an integration time of $3.56~\mu\mathrm{s}$, without any false assignments over $10^{7}$ measurements and a signal-to-noise ratio of 17 exceeding the state of the art.
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All authors Marta Cagetti, Stefan Forstner, Victor Champain, Roger Tormo-Queralt, Christoffer B. Møller, Sergio L. De Bonis, Chandan Samanta, Elsa Vázquez-Rodriguez, Eneko Mateos-Madinabeitia, David A. Czaplewski, Adrian Bachtold
Materials Science
Charge-to-spin conversion in epitaxial and polycrystalline Bi and Bi/Ag layers
Federica Nasr, Emir Karadža, Santos F. Alvarado et al. (+9 more)
Bi is predicted to be an efficient generator of
spin-orbit torques (SOTs), with charge-to-
spin conversion efficiency comparable to those of prototypical heavy metals, such as Ta, W, and Pt. However, experimental reports provide widely scattered interconversion efficiencies, while the origin of the large conversion signal in Bi/Ag
bilayers remains controversial. Here, we investigate charge-to-
spin conversion in epitaxial and polycrystalline Bi-based
magnetic heterostructures by measuring the damping-like SOT using magneto-optic Kerr effect magnetometry, complemented by structural and spectroscopic analyses and harmonic
Hall resistance measurements. We show that inserting an Ag spacer between Bi(001) and metallic ferromagnets (FeCo or Ni) enhances the SOT efficiency by more than one order of magnitude, reaching an effective
spin Hall conductivity of approximately $2 \times 10^5 (\hbar/2e)$ S/m, in excellent agreement with theoretical expectations for bulk Bi. This enhancement can be consistently explained by the preservation of the structural and chemical integrity of Bi, otherwise compromised by the direct deposition of a
ferromagnetic overlayer, rather than by Rashba
spin-orbit coupling at the Bi/Ag interface. Comparative studies across epitaxial, polycrystalline, and intentionally surface-oxidized Bi films, beyond oxygen doses known to destroy Bi(001) surface states, reveal that structural disorder has a negative impact on the SOT efficiency and indicate a dominant bulk contribution to
spin-current generation in Bi/Ag
heterostructures, yielding an effective Bi
spin Hall angle of approximately 1. By establishing a direct correlation between atomic-scale integrity and charge-to-
spin conversion, this study provides design principles to improve the reliability of Bi-based SOT devices and offers a robust framework for interpreting
spin-charge interconversion in Bi and Bi/Ag systems.
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All authors Federica Nasr, Emir Karadža, Santos F. Alvarado, Federico Binda, Tobias Goldenberger, Carlo Zucchetti, Myriam H. Aguirre, Paolo Moras, Andrey V. Matetskiy, Polina M. Sheverdyaeva, Paul Noël, Pietro Gambardella
Optics
Large-Time-Step Operation in a Volume Integral Equation for Dielectric Scattering
Sushil Kumar, Giampiero Gerini and M. C. van Beurden
In transient electromagnetic analysis, explicit time-domain solvers are restricted by the Courant-Friedrichs-Lewy (CFL) condition, making finely discretized dielectric scattering problems computationally expensive. This work investigates large-time-step operation in a marching-on-in-time time-domain current-density volume integral equation (MOT-JVIE) solver for dielectric scattering. For the considered band-limited excitations, accurate transient analysis is demonstrated for time steps up to 16 times larger than the reference CFL-limited time step associated with the voxel discretization. The study reveals a fundamental computational shift in the large-time-step regime. As the time-step size increases, the present-time causal interaction region expands, increasing the number of nonzero entries in the present-time interaction
matrix and causing the dominant computational cost to transition from history-term evaluations to repeated
matrix–vector products involving this
matrix. Consequently, the present-time interaction
matrix emerges as the principal scalability bottleneck in the large-time-step regime. To address this bottleneck, a
matrix-free FFT-based
matrix–vector-product strategy that exploits the multilevel Toeplitz structure of the Green-function-related volume-integral operator is employed for the present-time interaction
matrix. The proposed framework is evaluated through an inhomogeneous dielectric cube and an 8 X 8 array of inhomogeneous dielectric nanopillars representative of multiscale metasurface structures, demonstrating more than an order-of-magnitude reduction in computational cost. In single-threaded execution, the method is demonstrated for 15.6 million unknowns, providing a large-scale MOT-JVIE demonstration beyond 15 million unknowns on one CPU thread.
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Geophysics
A Distributed Acoustic Sensing Dataset for Vessel Detection and Localization in Submarine Cable Protection
Erick Eduardo Ramirez-Torres, Javier Macias-Guarasa, Daniel Pizarro et al. (+7 more)
Recent incidents of accidental damage and suspected sabotage to submarine telecommunication and power cables, particularly in the Baltic Sea, have underscored their vulnerability and the need for continuous monitoring solutions. Distributed acoustic sensing (DAS) applied to submarine optical-fiber cables enables wide-area monitoring of
underwater acoustic activity. We present the Marlinks-NS DAS
dataset, comprising processed submarine DAS measurements and AIS-derived vessel information curated for cable-protection research. The
dataset defines two machine-learning tasks (vessel detection and vessel-to-cable distance estimation) allowing reproducible research under realistic marine conditions. The
dataset contains 74,771 labeled data instances from ten days of continuous recording along a 2,554 m segment in a 28 km buried fiber-optic cable in the North Sea. Each instance includes spectral-energy features from 250 sensing channels, together with anonymized distance measurements and metadata from AIS information. The released HDF5 data, documentation, processing description, and example code support reproducible development and evaluation of DAS-based vessel-monitoring methods for submarine cable protection.
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All authors Erick Eduardo Ramirez-Torres, Javier Macias-Guarasa, Daniel Pizarro, Javier Tejedor, Sira Elena Palazuelos-Cagigas, Pedro J. Vidal-Moreno, María R. Fernández-Ruiz, Sonia Martin-Lopez, Miguel Gonzalez-Herraez, Roel Vanthillo
Plasma Physics
Variational Formulation of a Hybrid Kinetic and Gyrokinetic Model for Astrophysical and Laboratory Plasmas
F. N. deOliveira-Lopes, S. C. Thatikonda, D. Told et al. (+5 more)
We present a Lagrangian model that encapsulates fully kinetic ions and gyrokinetic electrons for
solar wind electromagnetic
turbulence. Using a consistent method, where both electrons and
protons are treated with the same mathematical formalism, we derive and implement a model in which high-frequency waves and kinetic electron effects are described in a computationally cost-efficient way. Higher-order Lie-transform perturbation methods applied to
Hamiltonian formulation of guiding center motion are used to describe the dynamics of particles and fields. We use a variational approach to derive field equations for closure of the system.
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All authors F. N. deOliveira-Lopes, S. C. Thatikonda, D. Told, A. Mustonen, K. Pommois, K. Hagiwara, F. Jenko, R. Grauer
High Energy Physics (Phenomenology)
Charge-exchange reactions with pion and kaon beams in the NA64h experiment at CERN
Sergei N. Gninenko, Sergey Kuleshov, Valery E. Lyubovitskij et al. (+1 more)
We discuss a new approach to search for dark sector coupled to
quarks in the invisible decays and oscillations of light neutral
mesons produced in the charge-exchange (CEX) reactions with pion and kaon beams $\pi^-(K^-)+ (A, Z) \to \pi^0, \eta, \eta' (\bar K^0) + (A,Z-1)$ at
nuclei target $(A,Z)$ in the NA64h experiment at CERN for $P_{\rm Lab}$ running in the interval from 5 to 50 GeV. For estimating of the projection sensitivity for the proposed searches the knowledge of the
meson yield is crucial. This work is dedicated to the accurate evaluation of CEX cross sections for the wide range of energies and target
nuclei which could be also useful for other experiments.
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All authors Sergei N. Gninenko, Sergey Kuleshov, Valery E. Lyubovitskij, Alexey S. Zhevlakov
Mesoscale and Nanoscale Physics
Effects of gold cluster intercalation in graphene: stationary waves and modified QPI features
Cristina Bena, Marion Cranney, Poonam Kumari et al. (+2 more)
Gold intercalation beneath epitaxial
graphene on SiC produces a cluster phase with unusual standing waves and quasiparticle-interference (QPI) features concentrated near the
graphene M points. We show that this can be explained by Au intercalation below
graphene hollow sites, which induces a local scattering potential on the six surrounding carbon atoms. Within a T-
matrix treatment, this ring-like scatterer produces elliptical QPI structures centered near M, in agreement with the experimental FT-STS measurements. We further show that these QPI features naturally generate the nearly stationary standing-wave patterns observed in real space. Finally, we compute the local-density-of-states contrast on and off a small cluster and show that its sign and magnitude are strongly energy dependent, consistent with the experimental observations.
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All authors Cristina Bena, Marion Cranney, Poonam Kumari, Alberto Zobelli, Laurent Simon
Mesoscale and Nanoscale Physics
An iterative method bridging DFT, disorder averaging, and experiment in intercalated materials: application to Au-intercalated graphene
Poonam Kumari, Alberto Zobelli, Igor de Melo Froldi et al. (+3 more)
Intercalation can strongly modify the electronic dispersion of a host material, as directly revealed by angle-resolved photoemission spectroscopy (ARPES). We develop a general iterative method combining density functional theory (DFT), tight-binding (TB), disorder averaging within the self-consistent T-
matrix approximation (SCTMA), and experiment, to construct an effective model of the intercalated system. DFT identifies the relevant microscopic degrees of freedom and constrains selected model parameters, while comparison of SCTMA calculations with experiment guides their further refinement. We apply this method to
graphene intercalated with Au clusters and show that it reproduces the main ARPES signatures of the Au-cluster phase, including the broadening of the V12an Hove singularity and the emergence of kink-like features in the dispersion. The essential microscopic ingredients identified by the analysis are the hybridization between selected intercalant orbitals and the
graphene states, together with an intercalation-induced local scattering potential.
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All authors Poonam Kumari, Alberto Zobelli, Igor de Melo Froldi, Adeline Crepieux, Laurent Simon, Cristina Bena
Materials Science
Intertwined magnetoresistance and Hall multifunctionality in a non-coplanar magnetic Weyl semimetal DyB4
Long Chen, Yulin Shen, Songxue Chi et al. (+4 more)
Anomalous magneto-transport responses provide complementary probes of orbital motion, momentum-space
topology, and real-space
spin chirality, yet their integration into a single material remains rare because their underlying requirements often compete. A promising materials-design strategy is to realize a
magnetic Weyl semimetal that combines linearly dispersive high-mobility bands with tunable non-coplanar magnetism while limiting
spin-dependent scattering. Here we identify DyB4, a frustrated rare-earth tetraboride, as a
magnetic Weyl semimetal candidate that embodies this strategy and hosts intertwined magnetoresistance and
Hall multifunctionality.
Neutron diffraction reveals a sequence of field-tunable
magnetic states, including non-coplanar
spin configurations and PT-
symmetry-broken phases. First-principles calculations identify steep linear dispersions and field-induced Weyl points near the
Fermi level. Magneto-transport measurements establish a rare fourfold combination of extremely large magnetoresistance,
chiral-anomaly-like negative magnetoresistance, large anomalous
Hall conductivity arising from cooperative intrinsic Berry
curvature and skew scattering, and scalar-
spin-chirality-driven topological
Hall responses. This multifunctionality arises from the distinct yet weakly coupled roles of itinerant carriers and localized 4f moments, which enable high-mobility transport, field-induced Weyl
topology, and non-coplanar magnetism. DyB4 therefore provides a 4f-electron platform for correlating orbital transport, momentum-space Berry
curvature, and real-space
spin chirality, suggesting a route toward multifunctional
magnetic topological materials.
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All authors Long Chen, Yulin Shen, Songxue Chi, Seunghoon Song, Yang Zhang, Jian Liu, Haidong Zhou
Mathematical Physics · Cross-listed from math.AP
On Sirakov's equal-frequency uniqueness conjecture
Hong-Ge Chen, Yong Liu, Juncheng Wei et al. (+1 more)
Let $N\in\{2,3\}$, $0<\mu _1\leq\mu _2$, and $0<\beta<\mu _1$. We prove that the equal-frequency two-component cubic Schrödinger system \[ -\Delta u+u=\mu _1u^3+\beta uv^2, \qquad -\Delta v+v=\mu _2v^3+\beta u^2v \quad\text{in }\mathbb{R}^N \] has exactly one positive solution in $H^1(\mathbb{R}^N)\times H^1(\mathbb{R}^N)$ modulo simultaneous translations. More precisely, every positive solution is a simultaneous translate of the synchronized state constructed from the unique positive radial solution of $-\Delta w+w=w^3$ in $\mathbb{R}^N$. This settles Sirakov's equal-frequency uniqueness
conjecture throughout the weak-coupling range. The main difficulty in the proof is to exclude radial solutions for which the ratio of the normalized components is nonconstant. After normalization, the two components satisfy scalar equations with a common potential. We construct a weighted Pohozaev functional for the system together with a correction term and prove that both the corrected functional and the associated weighted functional are strictly positive. Combining these sign properties with a radial flux identity and an auxiliary quotient associated with the component ratio forces synchronization.
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All authors Hong-Ge Chen, Yong Liu, Juncheng Wei, Wen Yang
Astrophysics of Galaxies
JWST's Constraints on the Substellar IMF in NGC 2024
K.L. Luhman
A recent study has reported the detection of a turnover in the initial mass function (IMF) below 12 Mjup and the possible detection of a minimum mass near 3 Mjup in the heavily embedded cluster NGC 2024 (<1 Myr), which was based on a sample of brown
dwarf candidates in NIRCam images from the James Webb Space
Telescope (JWST). I have used those NIRCam data in conjunction with archival spectra from JWST's Near-Infrared Spectrograph (NIRSpec) to constrain the substellar IMF in NGC 2024. I present NIRSpec data for 87 sources, 67 of which are within the NIRCam field. Based on those spectra and data from previous studies (e.g., X-ray emission), I have classified 45 of the NIRSpec targets as members of NGC 2024, 17 of which have spectral types indicative of brown
dwarfs (M6.5-L; 13 are within NIRCam). The latter have mass estimates as low as 4 Mjup according to theoretical evolutionary models. There remain a few photometric candidates lacking spectra that extend down to the completeness limit of the images (>=2 Mjup for Ak>=1), so the minimum mass of the IMF has not been detected. It is not possible to measure a reliable substellar IMF from the NIRCam images because of the small number of brown
dwarfs encompassed by them, a bias against objects at lower masses due to the high extinctions, and incompleteness at >=10 Mjup due to the saturation limit. Thus, there is no evidence in the JWST data for a turnover below 12jup.
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Statistical Mechanics
Synchronization, Kinematic Waves and Spike-Phase-Separation in Feedback Ising Neural Networks on Heterogeneous Graphs
Anna Poggialini, Irem Topal, Fabrizio Lombardi et al. (+1 more)
Structural heterogeneity constrains collective dynamics in complex systems. However, its analytical tractability out of
equilibrium remains limited. In this work, we study a class of kinetic Ising neural networks driven out of
equilibrium by a homeostatic feedback loop between the neuronal excitability and the population firing rate. Using a Curie-Weiss heterogeneous mean-field approximation validated by Monte Carlo simulations, we provide an analytical characterization of how a macroscopic synchronized limit cycle emerges via an Andronov-
Hopf bifurcation on heterogeneous networks. We derive closed-form phase boundaries and show that the onset of oscillations is explicitly controlled by network heterogeneity through the degree moment ratio. Degree heterogeneity decouples the spiking rate per
neuron m from the spiking rate per synapse u, generating physical phenomena absent in homogeneous systems. These include (i) kinematic waves of sequential, degree-ordered activations propagating from the network periphery to the hubs, and (ii) a low-temperature phase-separated state emerging via a pitchfork bifurcation. We prove that for highly heterogeneous
topologies, this phase-separated fixed point stabilizes and dynamically destroys the synchronized limit cycle. These results provide a mathematical framework for understanding how heterogeneity regulates macroscopic oscillations and out-of-
equilibrium transitions in neural networks
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All authors Anna Poggialini, Irem Topal, Fabrizio Lombardi, Daniele De Martino
Data Analysis and Statistics
Unveiling Amplitude Distributions via the Ordinal Language of Random Walks
Alberto Mateos Roig, Luciano Zunino and Felipe Olivares
Ordinal patterns are widely used to characterize temporal organization in time series, yet they are often considered insensitive to the amplitude distribution of the data. In this work, we show that this limitation can be overcome by considering the ordinal structure of integrated time series. We investigate random walks generated from independent non-Gaussian increments and derive analytical expressions for the ordinal pattern probabilities associated with them. We show that for symmetric distributions, the probabilities of some ordinal patterns are fully determined by
symmetry arguments, while those for the remaining patterns depend explicitly on the shape of the increments distribution. Numerical simulations based on $q$-Gaussian increments validate the theoretical predictions. We further show that the construction of the random walk itself plays a fundamental role in the accurate characterization of non-Gaussian fluctuations, as different centering procedures may significantly affect the resulting ordinal statistics. Finally, we validate the proposed framework using financial time series, showing that the ordinal distributions of integrated logarithmic returns capture non-Gaussian features consistent with a cubic law.
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General Relativity and Quantum Cosmology
Ab Initio Real-Time Gravitational-Wave Parameter Estimation
David Yallup, Metha Prathaban, James Alvey et al. (+4 more)
We present a specialised GPU-native nested sampling kernel targeting rapid parameter estimation for gravitational wave inference problems. Building upon a Slice-within-Gibbs (SwiG) structure for rapid mixing, we investigate how far we can push baseline
stochastic sampling techniques on modern GPU hardware. We demonstrate that for typical long-duration binary
neutron star signals observed by the LIGO and Virgo detectors, we can achieve well calibrated posterior inference on the full uncompressed data of a three detector network in a median of twelve minutes on a single GPU. This falls to five minutes when sharded across four devices. Utilising heterodyning to compress the data reduces the median wall time across an injection campaign to 89 seconds – less than the length of the segment itself – and enables inference with precessing
spin,
tidal waveforms on GW170817 in around two minutes. This pushes
stochastic sampling techniques using full physical waveform calculations, launched from an uninformed prior state, towards real-time gravitational wave parameter estimation.
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All authors David Yallup, Metha Prathaban, James Alvey, Thomas C. K. Ng, Thibeau Wouters, Nikhil Sarin, Will Handley
Mathematical Physics
The reduced Dirac structure of General Relativity on manifolds with corners
Alberto S. Cattaneo, Filippo Fila-Robattino and Manuel Tecchiolli
In this paper, the corner Poisson structure of four-dimensional Palatini-Cartan
gravity is derived. Building on the classical description of
gravity on
manifolds with boundary, specifically on the boundary constraint
algebra, a pre-Dirac structure on the space of corner fields is obtained together with a reduction procedure that yields a maximal Dirac structure, identified as the graph of a Poisson bivector field, on the reduced space of corner fields. It is further shown that this Poisson structure admits an equivalent affine Poisson description, which naturally exhibits the reduced corner theory as a $BF$-like theory and leads to a BF$^2$V formulation. This provides the basis for a unified framework for the bulk, boundary, and corner structures of Palatini-Cartan
gravity.
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Quantum Physics
Optimal T Counts under Sparsity: from QROM to State Preparation and Block Encoding
Tongyang Li, Fengning Ou, Xinzhao Wang et al. (+3 more)
Many
quantum algorithms require coherent access to classical data, often modeled by
quantum read-only
memory (QROM). We initiate the study of the $\mathrm{T}$ count of sparse QROM, in which only $s$ of the $2^n$ addresses store nonzero data. We prove that the optimal $\mathrm{T}$ count is $\Theta\left(n+\min\left\{s,\sqrt{s\left(m+\log(2^{n+1}/s)\right)}\right\}\right)$. Our upper bounds use a multilevel hashing scheme, while our lower bounds reduce sparse QROM to state preparation and use counting arguments for adaptive Clifford+$\mathrm{T}$
circuits. The lower bounds thus hold even when mid-
circuit measurements and classically controlled operations are allowed. As applications, we obtain matching $\mathrm{T}$-count bounds $\Theta\left(\min\left\{s,\sqrt{s\log(2^{n+1}/s)}\right\} +\sqrt{s\log(1/\varepsilon)}+\log(1/\varepsilon)\right)$ for $s$-sparse state preparation and $\Theta\left(\sqrt{2^n s\left(n+\log(1/\varepsilon_{\rm BE})\right)} +\log(1/\varepsilon_{\rm BE})\right)$ for block encoding of $s$-sparse
matrices, where $\varepsilon$ and $\varepsilon_{\rm BE}$ are the precision of state preparation and block encoding, respectively.
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All authors Tongyang Li, Fengning Ou, Xinzhao Wang, Penghui Yao, Pei Yuan, Shengyu Zhang
Materials Science
"Anomalous Solid Solution" in Ultra-High Melting Point Oxides: A New Strategy for Developing Ultra-High Temperature Thermal Protection Coatings
Yubo Wang, Hong Meng, Pengfei He et al. (+7 more)
The high-temperature performance of ultra-high temperature ceramics (UHTCs) in atmospheric environment is fundamentally governed by their melting points of oxidation products. Typical high-melting-point
oxides, such as ZrO2, undergo phase transformations at elevated temperatures, leading to structural instability. Although doping with rare-earth or transition-metal cations can suppress these transformations, it often results in a reduction in melting point, thereby limiting practical service temperature. Here, ytterbia-stabilized zirconia (YbSZ) coatings are prepared via atmospheric
plasma spraying, achieving a remarkable increase in the melting point of ZrO2 to approximately 2850 $^\circ\mathrm{C}$ and raising the ultimate
plasma and oxyacetylene ablation temperature up to nearly 2780 $^\circ\mathrm{C}$ and 3200 $^\circ\mathrm{C}$, which is the highest temperature resistance property as reported. Notably, this performance enhancement originates from a synergistic mechanism of strengthened ionic-covalent mixed bonding and improved oxygen vacancy stability. Based on these findings, the concept of "anomalous solid solution" is firstly proposed to be used in the area of ultra-high temperature protection, which provides new insights into the compositional design of UHTC systems.
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All authors Yubo Wang, Hong Meng, Pengfei He, Shujun Hu, Chuan Sun, Ximing Duan, Xiaopeng Lu, Dingwang Yuan, Wangyu Hu, Xiubing Liang
Statistical Mechanics
Interacting Quantum Symmetric Exclusion Process
Denis Bernard, Friedrich Hübner and Stefano Scopa
We introduce and solve the Interacting
Quantum Symmetric Exclusion Process (IQSEP), a family of models describing the
stochastic quantum hopping of charged particles along the edges of a
lattice, with hopping amplitudes that depend on the occupations of neighbouring sites. In the absence of interactions, they reduce to the standard
quantum simple symmetric exclusion process, exhibiting coherent diffusive transport. For interactions of order one, they capture incoherent diffusive transport and its fluctuations, characterized by density-dependent diffusivity and mobility, making contact with the macroscopic fluctuation theory. By rescaling the interaction strength appropriately with the
lattice mesh, we define a mesoscopic scaling regime that retains a finite coherence length in the continuous thermodynamic limit. This regime interpolates between coherent behavior at small length scales and incoherent behavior at large scales. The resulting scaling theory accounts for fluctuations of
quantum coherences in interacting diffusive systems, going beyond the scope of standard fluctuating hydrodynamics.
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General Relativity and Quantum Cosmology
Logarithmic corrections to black hole entropy from minimum-assumptions discretization
Pelayo V. Calzada, Ana Alonso-Serrano, Ernesto Contreras et al. (+1 more)
We introduce here a general model, under agnostic and minimum assumptions, to uniquely find the
entropy area law with a corresponding fixed logarithmic correction term. In this approach, the horizon is discretized into generic Planck-scale
cells representing coarse-grained indistinguishable
geometric structures, and it is just the statistical combinatorial counting that determines the form of the
entropy terms. We highlight the role of the assumptions and their comparison with known models providing fixed logarithmic contributions to the
entropy.
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All authors Pelayo V. Calzada, Ana Alonso-Serrano, Ernesto Contreras, Pedro Bargueño
Materials Science
Negative Thermal Expansion in Cubic Ice: A Collective Quantum Effect of the hydrogen-bond network
Loan Renaud, Tomasz Poreba, Richard Gaal et al. (+3 more)
We report
neutron powder diffraction measurements and path-integral molecular dynamics simulations of stacking-disorder-free cubic ice I$_c$, produced by topotactic degassing of C2 hydrogen hydrate. Across the cryogenic stability range, ice I$_c$ exhibits a density maximum near 70 K, closely matching that of hexagonal ice I$_h$ despite their different long-range stacking sequences. Negative thermal expansion in ice I is therefore not specific to hexagonal stacking, but arises from the shared open tetrahedral hydrogen-bond network. Simulations with the MB-pol potential quantitatively reproduce the experimental anomaly only when
nuclear quantum effects are included. The density maximum coincides, within the temperature resolution, with maximal anisotropy of the
proton quantum distribution.
Neutron-derived displacement parameters independently reveal a strongly enhanced transverse
proton displacement, while
phonon calculations identify low-frequency transverse modes with the most negative Grüneisen parameters. Together, these results establish the negative thermal expansion of ice I as a collective
quantum effect governed by
nuclear statistics and the dynamics of the hydrogen-bond network.
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All authors Loan Renaud, Tomasz Poreba, Richard Gaal, A. Marco Saitta, Michele Casula, Livia Eleonora Bove
Physics and Society
High-fidelity inference of power grid frequency distributions
Alessandro Lonardi, Benjamin Schäfer and Christian Beck
Precision measurements of power grid frequency track energy supply-demand imbalances, with persistent fluctuations indicating strain that can lead to outages. Characterizing the statistical properties of grid frequency fluctuations is therefore essential to achieve efficient control and stable operations. Existing models had limited success in reconstructing the complex non-Gaussian features of observed frequency distributions. Here, we introduce a method for statistical inference of an interpretable
stochastic process governing frequency fluctuations, modeling frequency through a coarse-grained power imbalance signal combined with nonlinear generator control and Gaussian white noise. We develop an efficient
algorithm to infer these latent variables via maximum likelihood estimation, combined with superstatistics. We test our method on a large
dataset of new measurements from Great Britain and South Africa. Although these grids have markedly different properties, our predictions for frequency distributions match measurements excellently. Our method uses only frequency data for inference, thus offering an alternative to data-intensive approaches.
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Quantum Physics
Displaced photon helicity states: a quantum realization of Arago-Fresnel interference
Yan Zhang, Xiang Liu and Hou Ian
The laws of Arago and Fresnel relate the polarization of light to its capacity for interference. We investigate their
quantum counterpart at the level of the fundamental helicity states of a single
photon. To this end, we introduce displaced
photon helicity states (DPHS), constructed by coherently displacing single-
photon helicity eigenstates. The displacement bridges the microscopic
spin degree of freedom and macroscopic polarization observables, enabling interference effects that would otherwise be inaccessible to isolated
photons. We derive analytical expressions for the Stokes parameters associated with the interference between DPHS and coherent optical fields and show that opposite helicities generate distinct parameter dependences in the resulting fringe structure. The interference constitutes a
quantum realization of Arago-Fresnel interference and permits the helicity of an unknown
photon to be inferred from the Stokes response of the combined field. Beyond this application, DPHS generalize the framework of displaced nonclassical states from
photon-number excitations to the helicity degree of freedom of light.
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Atmospheric and Oceanic Physics
Weather Emulators at the Frontier of Heat Extremes Predictability
Cas Decancq, Thomas Mortier, Jessica Keune et al. (+1 more)
Atmospheric predictability declines rapidly beyond the next ten days, such that forecasts at longer lead times primarily convey large-scale trends rather than specific states. Yet in a warming world, improving early warnings of extreme heat is an increasingly critical challenge. Here we evaluate six state-of-the-art deep learning weather emulators - Pangu-Weather, FuXi, ArchesWeather, AIFS, GraphCast and Aurora - alongside leading dynamical systems and statistical baselines in
forecasting global near-surface temperature and extreme heat at lead times of 10-15 days. We find that several emulators rival or even surpass physics-based forecasts in deterministic temperature skill, but do so at the cost of reduced spectral fidelity, in a process widely known as blurring. While all models show some degree of predictive skill for extreme heat, most emulators under-represent peak intensities, and IFS recall is greater than that of any of the emulators. These results highlight both the emerging potential of AI to enhance extended range temperature prediction, and the remaining challenges in delivering reliable, actionable early warnings in a changing
climate.
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All authors Cas Decancq, Thomas Mortier, Jessica Keune, Diego G. Miralles
Cellular Automata and Lattice Gases · Cross-listed from q-bio.PE
Hash Chemistry: Minimal Models for Evolutionary Growth of Complexity
Ilya Horiguchi and Hiroki Sayama
Hash Chemistry is a family of minimalistic evolutionary models in which a deterministic hash function assigns a scalar score to entities of arbitrary size, opening a combinatorially vast possibility space (a “cardinality leap”). Since its introduction, the idea has been realized in several settings, from the original spatial formulation to a fast non-spatial variant and then to structural cellular models. Here we review the Hash Chemistry family as a coherent modeling framework and use it to explore how minimal systems can demonstrate the mechanisms behind multiscale open-ended evolutionary dynamics. The most recent model, Structural Cellular Hash Chemistry (SCHC), successfully demonstrated multiscale ecological interaction/adaptation and complexity growth of replicators in a computationally efficient manner. In this study, we first extend SCHC to incorporate spatial locality and dyadicity of competitive interactions among replicating structures. We show this extension substantially enhances SCHC's evolutionary dynamics. Furthermore, we explore SCHC in a significantly larger spatial domain using a GPU-accelerated implementation. We show that the size of the space acts as a control parameter for a
stochastic, nucleation-like transition between a compact-replicator regime and a runaway size-dominance regime, and we separate the responsible mechanism into a non-spatial, size-biased sampling feedback and a finite-size spatial effect. Altogether, these results illustrate the rich potential of Hash Chemistry as a minimal, mechanistically transparent testbed for studying open-ended
evolution across scales.
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Instrumentation and Methods for Astrophysics
Exploring generative design AI tools for astronomical instrumentation: a CubeSat chassis case study
Younes Chahid, Tassos Aretos, Will Cochrane et al. (+12 more)
Generative design artificial intelligence (AI) tools are currently used in multiple scientific fields, yet their adoption in mechanical engineering computer-aided design (CAD) remains limited due to a lack of disseminated case studies, limited availability of accessible tools, insufficient training in CAD data, the absence of universal editable file formats and more. Mechanical design for astronomical instrumentation faces increasing complexity in thermal, vibrational, and mechanical requirements alongside tight project deadlines. This paper presents a practical evaluation of an AI and FEA based generative design tool applied to chassis design for the Active Deployable Optical
Telescope (ADOT) CubeSat mission. Our analysis showcases the workflow steps including the setting of design, manufacturing and objective constraints. This study also shows the clear benefits of these types of tools, especially in the early brainstorming stages of multi-constrained mechanical structures, while also highlighting clear limitations like their black-box nature, the non-manufacturing-ready state of the results, and the time-consuming setup, limiting the tangible gain of these tools to high-value mechanical components.
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All authors Younes Chahid, Tassos Aretos, Will Cochrane, Katherine Morris, David Isherwood, Zeshan Ali, Graham Wilks, Noah Schwartz, Anmol Goyal, Marcell Westsik, Alastair Macleod, Steve Watson, Anjali Bhatt, David Lunney, Bradley Frank
Cosmology and Nongalactic Astrophysics
Domain walls through different cosmologies
I. Dankovsky, D. Gorbunov, S. Ramazanov et al. (+1 more)
We study properties of domain walls (DWs) arising in the model with a double well potential assuming different early universe cosmologies: from
dust through stiff matter domination to the limit of effective Minkowski space. Using
lattice simulations we demonstrate that
evolution of DW networks exhibits an approximate universality with respect to the cosmological equation of state (EoS). Namely, the wall area inside a given large volume is mainly determined by the particle horizon, while details of
cosmic expansion play a subdominant role. As it follows, particle horizon rather than the inverse Hubble rate is pivotal in DW
evolution defining the network correlation length and hence its phenomenology, e.g., the characteristic wavelength of emitted gravitational waves (GWs). Formation of closed DWs is shown to be very sensitive to the cosmological EoS and hence violate the universality, but their contribution to the total network is too small to change the overall picture. The universality breaking is also observed in the spectral properties of GWs from annihilating (biased) DWs: i) the IR slope of the spectrum depends on the EoS parameter; ii) there is a plateau in the UV part of the spectrum, which gets more pronounced as one stiffens the EoS. However, the dependence on the EoS is rather weak in the near peak region, which is most relevant from the viewpoint of
pulsar timing arrays and other searches for the
stochastic GW background. For a selection of
primordial cosmologies, we provide fitting formulae for the spectra near the peak.
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All authors I. Dankovsky, D. Gorbunov, S. Ramazanov, A. Vikman