Physics and Society
Cumulative suspicion and absorption dynamics in an agent-based Mafia game
Eduardo Velasco Stock and Roberto da Silva
The Mafia game, also known as Werewolf, describes a competition between a coordinated minority whose identities are concealed and a larger good faction composed primarily of uninformed civilians attempting to identify and eliminate them. We introduce an
agent-based formulation in which the daytime decision is not represented by uniform random voting. Instead, randomly paired
agents modify player-specific public suspicion scores according to their roles, and one surviving player is subsequently eliminated with probability proportional to their accumulated suspicion. These scores persist throughout the game, producing a history-dependent
stochastic process with two competing absorbing outcomes: elimination of the mafia or numerical parity between the mafia and the good faction. We investigate the effects of population size, initial mafia size, and the presence of perfectly informed detectives through extensive Monte Carlo simulations. In the absence of detectives, a random-execution approximation predicts that, in the dilute-mafia and early-time regime, the cumulative probability of mafia extinction behaves as $F(\tau)\sim (\tau/N)^{N_m}$, in agreement with simulations as $N_m/N$ decreases. The winning-probability curves also exhibit an empirical finite-size crossover characterized by a population scale $N_c$. Rescaling the population by $N_c$ approximately collapses the curves obtained for different initial mafia populations. Perfectly informed detectives substantially shorten mafia-survival times and introduce an additional dependence on population composition for which the same one-parameter rescaling is insufficient. The model provides a minimal connection between microscopic histories of accusation and the macroscopic absorption statistics of hidden-role games.
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Cosmology and Nongalactic Astrophysics
CosmoLattice 2.0
Jorge Baeza-Ballesteros, Daniel G. Figueroa, Adrien Florio et al. (+4 more)
This paper introduces $\tt {\mathcal C}osmo{\mathcal L}attice$ $\tt v2.0$, a major upgrade that substantially broadens the physical scope and computational capabilities of the code. It introduces
lattice implementations of scalar fields non-minimally coupled to
gravity through $\phi^2R$, as well as
axion-like fields coupled to Abelian gauge sectors as $\phi F_{\mu\nu}\widetilde F^{\mu\nu}$. It also provides new procedures for generating specialized initial conditions, including scaling networks of
cosmic defects ($\it e.g.$ strings and domain walls), and fields with arbitrary power spectra. The release also incorporates low-storage Runge-Kutta integrators for non-
symplectic systems (suitable $\it e.g.$ for non-minimal scalar kinetic terms as $\mathcal{G}_{ab}\partial_\mu\phi^a\partial^\mu\phi^b$), scalar-field simulations on reduced $(1+1)$- and $(2+1)$-dimensional
lattices, new optimized gravitational-wave
evolution, more flexible field and energy-density outputs, and GPU support that can accelerate simulations by a factor $\mathcal{O}(10)$ relative to CPU execution. Extensive documentation on the use of the code is provided on https://www.cosmolattice.com
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All authors Jorge Baeza-Ballesteros, Daniel G. Figueroa, Adrien Florio, Nicolás Loayza, Franz R. Sattler, Francisco Torrentí, Ander Urio
Astrophysics of Galaxies
The $\sigma_s^2-\mathcal{M}$ relation in the multi-phase ISM: Exploring the density PDF with the Cloud Factory simulations
Mairi Nonhebel, Rowan J. Smith and Ralf S. Klessen
The density probability distribution (PDF) of molecular clouds is a crucial component of analytical theories of
star formation. In idealised simulations of isothermal
turbulence, the width of the density PDF, $\sigma_s^2$, is dependent on the sonic Mach number of the medium, $\mathcal{M}$. The $\sigma_s^2-\mathcal{M}$ relation is widely used to connect cloud-scale
turbulence to the density PDF, and further to
star formation activity, yet its validity within individual phases of the multi-phase interstellar medium (ISM) remains untested. In this study, we evaluate whether the $\sigma_s^2-\mathcal{M}$ relation is applicable to individual phases of the ISM. We study the density PDFs of molecular cloud complexes in the Cloud Factory simulations; a suite of detailed zoom-in simulations that self-consistently generate a turbulent, multi-phase ISM. We test whether the $\sigma_s^2-\mathcal{M}$ relation holds in the hot ionised medium (HIM), warm ionised medium (WIM), warm neutral medium (WNM), cold neutral medium (CNM), the molecular phase, and the highly-shielded molecular phase traced by CO. We find the applicability of the classical $\sigma_s^2-\mathcal{M}$ relation to vary between phases and depend strongly on how $\sigma_s^2$ and $\mathcal{M}$ are measured. The relation fails to capture the widths of the WNM and CNM density distributions, with possible contributing factors including non-isothermality and large-scale coherent motions. In contrast, we find the $\sigma_s^2-\mathcal{M}$ relation to tentatively hold for the log-normal portion of the H$_2$ distribution. The width of the CO density PDF is systematically overpredicted by the classical relation, resulting from the selective nature of CO as a molecular gas tracer.
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Quantum Physics
Quantum reference frames beyond subsystems: a reconstruction and generalization of the perspective-neutral framework
Stefan L. Ludescher, Manuel Mekonnen, Thomas D. Galley et al. (+1 more)
We generalize the notion of
quantum reference frames (QRFs) to cases where the frame does not necessarily correspond to a tensor factor subsystem, but to a covariant
quantum instrument. This unlocks a variety of physical applications: "frames of labeling" for indistinguishable particles, suggesting explanations for the symmetrization postulate and the absence of parastatistics, and yielding a transparent description of the
entanglement of
bosons and
fermions; and relational clocks reproducing the Schrödinger equation exactly even when all subsystems are interacting or when there are frequency superselection sectors. Our work generalizes the perspective-neutral approach to QRFs pioneered by Höhn and co-authors, which we reconstruct from a simple operational scenario. We give a resource-theoretic grounding of this framework, and show how the notion of completely covariant operations explains the relevance of the charge-zero sector and the pure-state transformation behavior across perspectives. This also suggests operational clarifications of some aspects of constraint quantization, e.g. of the meaning of constraint equations such as $C|\psi\rangle=0$. Some of our results, such as our generalization of relationalization maps to instruments, apply more broadly to other QRF frameworks too, and they contribute to bridging the gap between operational
quantum information theory and the internal QRF research program.
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All authors Stefan L. Ludescher, Manuel Mekonnen, Thomas D. Galley, Markus P. Mueller
Statistical Mechanics
Strongly-connected percolation on directed lattices
M. E. J. Newman, P. Grassberger and R. M. Ziff
We study percolation on
lattices with directed bonds, focusing on the behavior of strongly-connected percolation clusters – clusters in which every site is reachable from every other along a directed path. We consider the two-dimensional square
lattice and various globally isotropic arrangements of the directions of the bonds. Performing simulations using a range of algorithmic approaches, we calculate high-precision values for critical exponents, fractal dimensions, crossing probabilities, and percolation thresholds for bond percolation with each bond arrangement. We find that the critical behavior is in a distinctly different universality class from that of traditional undirected percolation, but that all bond arrangements appear to fall in the same universality class.
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Chemical Physics
Ultrafast configuration changes and anomalous diffusion of an aromatic adsorbate on rare-gas nanoparticles
Arne Morlok, Philipp Elsässer, Yilin Li et al. (+5 more)
Nanoparticles (NPs) exhibit tunable catalytic properties and serve as nanoreactors for controlled multimolecular chemistry. The kinetics and reactivity of such systems are critically governed by the surface binding configurations of adsorbates, their
stochastic fluctuations, and the adsorbate mobility across the nanosurface. However, resolving these properties with sufficient structural, spatial, and temporal resolution remains a major experimental challenge. Here, we study phthalocyanine adsorbates on rare-gas clusters as a test case. By combining high-resolution two-dimensional electronic spectroscopy and molecular dynamics simulations, we reveal the configurational dynamics of the adsorbates and establish a direct relation between these dynamics and the nanoscale properties of the clusters. Our findings indicate sub-diffusive surface motion and trapping of the adsorbate within single surface facets. Such dynamical behavior seems unexpected considering the weak adsorbate-surface interaction and cluster temperatures close to the sublimation point. These results provide direct insight into the ultrafast binding dynamics of molecular adsorbates on nanoscale objects, which is critical for our understanding of the chemistry of such systems.
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All authors Arne Morlok, Philipp Elsässer, Yilin Li, Ulrich Bangert, Felix Riedel, Tanja Schilling, Frank Stienkemeier, Lukas Bruder
Quantum Physics
A Kernel-Based Density of States Estimator for Quantum Computing
Julio Cesar Siqueira Rocha
We introduce a
quantum kernel method for estimating the density of states (DoS) of
quantum many-body systems. The method exploits the Rodeo
algorithm as a physical implementation, requiring no modification of its standard single-ancilla
circuit. Averaging the Rodeo response over Haar-random input states reconstructs the DoS convolved with a spectral kernel whose analytical form is determined entirely by the probability distribution of the sampled
evolution times. This establishes a direct
quantum analogue of the classical Kernel
Polynomial Method (KPM): Haar-random states perform
stochastic trace estimation, while the temporal sampling distribution plays the role of the reconstruction kernel. We derive the
estimator, quantify its statistical and systematic uncertainties, and establish an explicit correspondence between
quantum reconstruction kernels and classical signal-processing window functions, enabling concepts such as spectral leakage, side-lobe attenuation, and main-lobe width to guide kernel design. The method is validated numerically on the one-dimensional transverse-field
spin–$\sfrac{1}{2}$ and
spin–$1$ Ising models, where the reconstructed density of states and the resulting thermodynamic observables agree with exact diagonalization within the estimated statistical uncertainties.
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High Energy Astrophysical Phenomena
A radio view on Gamma-Loud Protostars: Derivation of jet mechanical luminosity
Javier Méndez-Gallego, Carlos Carrasco-González, Rubén López-Coto et al. (+5 more)
Context. Gamma-Loud Protostars (GLPs) have been recently reported as
Galactic hadronic accelerators whose acceleration site is situated in their protostellar jets. Theoretical and observational analysis situate
radio cm luminosity as a thermal tracer of jet activity, presenting an unique opportunity to study jet properties as accelerators. Aims. We aim to develop a way to estimate the kinetic power of protostellar jets and compare their energetics with those extracted from the non-thermal gamma-ray side of GLPs. Methods. We combine theoretical and phenomenological relations to estimate the jet mechanical luminosity based on the
radio cm luminosity. We relate the resulting values to the non-thermal contribution of GLPs, studying its behaviour and efficiency. Results. The derivation of the jet power successfully reproduces infrared and
radio observations. The
cosmic-ray energy correlates to the injected mechanical energy, implying an acceleration efficiency of 1–10%. Future
radio observations are needed to find the definite accelerators and obtain reliable efficiencies.
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All authors Javier Méndez-Gallego, Carlos Carrasco-González, Rubén López-Coto, Iván Agudo, Stefano Menchiari, Rubén Fedriani, Emma de Oña Wilhelmi, Guillem Anglada
Quantum Physics
Universal Optimization and Tighter Fidelity Bounds for Approximate Quantum Error Correction
Jing Wu, Michele Grossi, Doga Kurkcuoglu et al. (+1 more)
Approximate
quantum error correction (AQEC) extends the framework of discrete- and continuous-variable
quantum error correction beyond the Knill-Laflamme (KL) conditions, where the recovery performance is quantified by
entanglement fidelity. Recent studies have enabled efficient evaluation of near-optimal
entanglement fidelity using transpose-channel recovery. Yet, determining the global optimal recovery map and its
entanglement fidelity for general codes beyond the KL conditions remains a major computational challenge. Direct optimization becomes prohibitive as the number of noise Kraus operators grows rapidly with system size, and existing approaches lack rigorous guarantees for reducing this optimization to a tractable dimension. Here, we derive an explicit characterization of the optimal environmental state of complement channel, which transforms the optimization over recovery channels into an equivalent optimization over quotient
unitaries. For a broader class of codes that satisfy only the orthogonality part of the KL conditions, we show that the optimal recovery map admits an explicit analytical form. Building on this form, we derive novel rigorous lower bounds of
entanglement fidelity that strictly improve upon the transpose-recovery bound. We further develop a novel recovery strategy based on principle components, and derive a rigorous bound on the error introduced by noise truncation. Our approach enables efficient searches for approximate recovery maps for AQEC codes, avoiding the need to optimize over the full Kraus-operator space.
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All authors Jing Wu, Michele Grossi, Doga Kurkcuoglu, Silvia Zorzetti
Mesoscale and Nanoscale Physics
A.-F. Kalo, E. A. Rodríguez-Mena, J. C. Abadillo-Uriel et al. (+2 more)
Unstrained bulk germanium is a particularly attractive material for
circuit quantum electrodynamics with
spins (
spin-cQED). We show, through systematic modeling and comparison with state-of-the-art strained germanium
heterostructures, that hole
spins in bulk germanium double
quantum dots readily reach the strong-coupling regime with superconducting microwave resonators, achieving
spin-
photon coupling strengths $g_s/2\pi\gtrsim100$\,MHz. This enhancement originates from large
spin-orbit interactions beyond the perturbative regime. In addition, the coupling is much less sensitive to the orientation of the applied
magnetic field, which shall ease operation and limit the impact of device-to-device variability. Our results establish bulk germanium as a compelling platform for scalable
spin-cQED.
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All authors A.-F. Kalo, E. A. Rodríguez-Mena, J. C. Abadillo-Uriel, M. Filippone, Y.-M. Niquet
Astrophysics of Galaxies
Observational Tests of Sgr A*'s State of the Accretion Flow
F. Yusef-Zadeh, R. G. Arendt, H. Bushouse et al. (+4 more)
General relativistic magneto-hydrodynamic (GRMHD) simulations of the possibly magnetically arrested disk (MAD) of the
accretion flow of Sgr A* predict short and long time variability, lumpiness in the flow, strong
magnetic fields, reconnection driving flux eruptions and a jet aligned with its
spin angular momentum. We carried out simultaneous multi-wavelength observations with the objective of placing some constraints on these predictions. Our analysis supports most of the predictions of the MAD picture of the flow. It is not clear if there is evidence for a jet, but this could be the result of confusion in the complex region surrounding Sgr A*. Also, the geometry of the
magnetic fields, which accelerate particles to produce X-ray emission via inverse Compton Scattering (ICS), appears to be consistent with a hybrid state where the
accretion flow is represented by MAD-like
magnetic field strength and with Standard and Normal
Evolution-like (SANE-like)
magnetic field geometry.
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All authors F. Yusef-Zadeh, R. G. Arendt, H. Bushouse, C. J. Chandler, D. Kunneriath, S. M. Ressler, M. Wardle
Strongly Correlated Electrons
Chiral Magnons: Mechanisms and Research Progress
Wanxing Lin, Hanchen Deng, Bao-Tian Wang et al. (+1 more)
Chiral magnons are distinctive collective
spin excitations in
magnetic ordered systems, whose dispersion relations break momentum-inversion
symmetry, $\omega(\boldsymbol{k}) \neq \omega(-\boldsymbol{k})$, resulting in essential non-reciprocal
spin-wave propagation. This built-in directionality provides new opportunities for
spin information transfer, thermal-
spin interconversion, and low-dissipation non-reciprocal microwave devices, which complement but differ from topological magnonics. In recent years, the proposal and rapid development of altermagnetism have broadened the physical origin and research framework of
chiral magnons, making them a research frontier in condensed matter physics. This review presents a unified framework for
chiral magnons, covering
symmetry-breaking mechanisms, material implementation, experimental characterization, transport response, and many-body non-Hermitian dynamics, and evaluates routes toward room-temperature and device-related platforms. The discussion is based on
symmetry analysis, model
Hamiltonians, and
spin-wave theory, combined with first-principles calculations as well as recent spectroscopic (e.g., inelastic and polarized
neutron scattering, Brillouin light scattering) and transport measurements. This review further summarizes bulk-gap and Berry-
curvature induced
chiral magnon edge states, the enhancement of non-reciprocity via
chiral spin pumping and cavity-
magnon hybrids, as well as non-Hermitian features arising from multiparticle damping and gain-loss competition. This review provides a comprehensive reference for elucidating the underlying mechanisms of
chiral magnons, advancing the synthesis and experimental characterization of novel materials, and also guiding the design of next-generation non-reciprocal magnonic devices.
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All authors Wanxing Lin, Hanchen Deng, Bao-Tian Wang, Dao-Xin Yao
Quantum Physics
Non-Hermitian entropy production from fluctuation theorems
Vasco Cavina, Frank Ernesto Quintela Rodríguez and Donato Farina
We develop a first-principles thermodynamic framework for non-Hermitian dynamics based on a post-selected version of the fluctuation
theorem. This allows us to identify a quantity that remains positive throughout the non-Hermitian
evolution and can be interpreted as the
entropy production of the post-selected dynamics. We relate this quantity to previously proposed notions of non-Hermitian
entropy and derive an associated second law. Furthermore, we establish a connection with information-theoretic quantities, in particular the Petz-Rényi divergences, and leverage this connection to derive upper and lower bounds. Finally, we decompose the
entropy production into incoherent and coherent contributions, identifying distinctive features of the coherent term in the vicinity of exceptional points. We illustrate our results using a paradigmatic model of non-Hermitian
evolution based on a two-level system.
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General Relativity and Quantum Cosmology
Fast, accurate, and differentiable: a neural-network surrogate for NRSur7dq4 precessing binary black hole waveforms
Michael Pürrer, Ashwin Girish, Lucy M. Thomas et al. (+2 more)
We present a neural network surrogate model that emulates the NRSur7dq4 gravitational waveform model for precessing binary black hole mergers. The surrogate decomposes the waveform into constituent quantities and trains an independent multilayer perceptron (MLP) for each. We validate the surrogate against NRSur7dq4 on 10,000 waveforms spanning its full parameter space ($1 \leq q \leq 4$, $|\chi_{A,B}| \leq 0.8$). For representative total masses between 60 and 300 $M_\odot$, median sky-averaged frequency-domain mismatches range from $8.0 \times 10^{-5}$ to $1.7 \times 10^{-4}$, with 95th percentiles below $10^{-3}$. On an NVIDIA L40S GPU the JAX surrogate evaluates a single waveform in about 1 ms end-to-end, roughly 10 times faster than the LALSimulation C implementation of NRSur7dq4, and sustains about 140 times the LALSimulation throughput at batch size 64, making it well suited for both low-latency parameter-estimation samplers and large-scale waveform generation. The full NRSur7dq4 NN waveform-to-likelihood pipeline is implemented in JAX and is differentiable. This is the first neural-network surrogate of a precessing numerical-relativity waveform model to combine validated NR-faithful accuracy with a fully differentiable, GPU-accelerated inference pipeline, enabling gradient-based inference approaches via automatic differentiation including Fisher information
matrices, GPU-accelerated nested sampling, gradient-based MCMC and importance sampling.
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All authors Michael Pürrer, Ashwin Girish, Lucy M. Thomas, Scott E. Field, Vijay Varma
Solar and Stellar Astrophysics
Empirical H- and K-band Limb Darkening for 31 CHARA Stars: A Near-Infrared Benchmark for Stellar-Atmosphere Models
Narsireddy Anugu, John D. Monnier, Antoine Mérand et al. (+9 more)
Limb darkening, the decrease in
stellar intensity from the disk center to the limb, encodes the temperature structure and opacity of
stellar atmospheres. Direct spatially resolved measurements of this center-to-limb variation remain scarce, especially in the near-infrared. We present interferometric limb-darkening measurements for 31
stars observed simultaneously in the $H$ and $K$ bands with the CHARA Array. The sample spans spectral types F–M and luminosity classes IV–I. The targets are well resolved in $H$ and, for most targets, also in $K$. This coverage constrains the visibility
curvature associated with limb darkening in joint $H+K$ fits. We fit the combined $H{+}K$ squared visibilities with four analytic limb-darkening laws and compare the resulting coefficients with bandpass-matched predictions from five
stellar-atmosphere grids (Kurucz, MPS1, MPS2, Stagger, and spherical SATLAS, with reported coefficients placed on the Rosseland-radius convention) spanning one-dimensional plane-parallel, three-dimensional radiation–hydrodynamic, and spherical low-
gravity models. The associated limb-darkened angular diameters are measured with median formal precisions of $\simeq 0.2$–0.3%. The CHARA results show expected weaker limb darkening at longer wavelengths and also with increasing $T_{\rm eff}$. The clearest discrepancy with the atmosphere grids is in the wavelength dependence: the median fractional decrease in the power-law coefficient from $H$ to $K$ is $\simeq 39\%$ in the CHARA sample, compared with only $\simeq 17$–$22\%$ with model predictions. Relative to the MPS2 comparison, the empirical coefficients are higher by $\simeq 21\%$ in $H$ and lower by $\simeq 5\%$ in $K$. These results provide multi-band interferometric limb darkening as a near-infrared
benchmark for
stellar-atmosphere models.
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All authors Narsireddy Anugu, John D. Monnier, Antoine Mérand, Becky Flores, Alexandre Gallenne, Douglas R. Gies, Mayra Gutierrez, Robert Klement, Stefan Kraus, Jayadev Rajagopal, Rachael M. Roettenbacher, Gail H. Schaefer
High Energy Astrophysical Phenomena
Simulation of combined radio and radar signals at the Radar Echo Telescope for Cosmic Rays
K. Nivedita, I. Loudon, J. Loonen et al. (+29 more)
To explore
neutrino astronomy at high energies (> 10 PeV), the Radar Echo
Telescope for
Cosmic Rays (RET-CR) was developed to assess the feasibility of a radar technique for detecting particle cascades in ice, serving as a precursor to the Radar Echo
Telescope for
Neutrinos (RET-N). The main concept of RET-CR is that, as a high-energy
cosmic-ray air-shower core propagates into the high-altitude ice sheet, a dense secondary-particle cascade is created, which is very similar to that of an in-ice high-energy
neutrino-induced cascade. At RET-CR, the expected signal consists of three distinct components:
radio emission from the in-air particle shower, Askaryan
radio emission from the secondary in-ice cascade, and the radar signal itself arising from the reflection of the transmitted
radio signal from the ionisation trail of the in-ice secondary cascade. In this work, we present the first combined simulation-based package and study aimed at characterising the combined
radio and radar signals at the in-ice receivers at RET-CR. We describe the simulation framework and provide a detailed discussion of the salient features of the
radio and radar signals, including their spatial footprints and temporal characteristics, as predicted for the shallow in-ice detectors.
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All authors K. Nivedita, I. Loudon, J. Loonen, P. Allison, J. J. Beatty, D. Z. Besson, A. Connolly, A. Cummings, C. Deaconu, S. de Kockere, K. D. de Vries, I. Esteban, D. Frikken, C. Hast, E. Huesca Santiago, C.-Y. Kuo, A. Kyriacou, U. A. Latif, V. Lukic, C. McLennan, K. Mulrey, J. Nam, S. Prohira, J. P. Ralston, M. F. H. Seikh, N. Shahid, R. S. Stanley, J. Stoffels, S. Toscano, D. van den Broeck, N. van Eijndhoven, S. Wissel
Astrophysics of Galaxies
Reaching the Metallicity Floor at $z\sim 10$: Lensed Star Clusters at Cosmic Dawn and Cosmic Noon
Raul Jimenez, Elena Tomasetti, Carmela Lardo et al. (+1 more)
Origins of globular clusters (GCs) are linked to the assembly of their host
galaxies. We analyze
star-cluster populations in two strongly lensed systems that bracket
Cosmic Dawn and
Cosmic Noon: the
Cosmic Gems arc (GEMS) at z=9.625, among the first
galaxies, and the Sparkler at z=1.378. New STARRED deconvolution photometry of GEMS provides SEDs for ten unique, doubly imaged cluster candidates, while a homogeneous
Bayesian analysis places both populations on a common cosmological timeline. The GEMS clusters formed at $z_{\rm form}\approx 10$–$11$ (median $\simeq10.2$), consistent with
halo assembly at or above the atomic-cooling scale. Their photometry requires low
metallicities: individual clusters are consistent with $[Z/{\rm H}] \lesssim -1.2$, and the data exclude $[Z/{\rm H}]\geq-0.5$, though they cannot distinguish reliably below $[Z/{\rm H}] \simeq -1.5$. This conclusion is unchanged when using
stellar-population models including binary
evolution—important for ultraviolet emission at this age—yielding similarly low
metallicities, $[Z/{\rm H}]=-2.2$ to $-2.7$. The formal estimate, $[Z/{\rm H}] = -2.3\pm0.3$, is consistent with the Milky Way GC
metallicity floor, though its value remains prior-dependent. The Sparkler clusters formed $\sim2.5$ Gyr later, at $z_{\rm form}\approx 2$–$3.5$ in a
Cosmic Noon
dwarf galaxy, and are more enriched ($[Z/{\rm H}] \approx -0.5$). Comparison with Milky Way GCs places GEMS in an exceptionally early, metal-poor regime and the Sparkler among later, more enriched populations, though neither association uniquely determines an in-situ or ex-situ origin. Closed-box and gas-regulator calculations show both systems are compatible with limited pre-enrichment followed by rapid enrichment and
accretion-regulated growth. Together, they probe distinct cluster-forming environments from
Cosmic Dawn to
Cosmic Noon.
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All authors Raul Jimenez, Elena Tomasetti, Carmela Lardo, Licia Verde
High Energy Astrophysical Phenomena
Gravitational Wave Modeling of White-Dwarf–Compact-Object Binaries and Observational Outlook
Tristan S. Weaver, David Radice, Donghui Jeong et al. (+1 more)
We investigate the end stages of circular white-
dwarf–compact-object binaries by developing a novel integrator implementing mass transfer and 2.5-order Post-Newtonian kinematics. White-
dwarf–compact-object binaries are subject to two phases: a slow inspiral during which binary
evolution is dominated by weak-
gravity radiation reaction and a quicker “outspiral" dominated by mass transfer. These systems have unique gravitational waveforms with several characteristic features including an accumulation of signal near the maximum cutoff frequency set by the transition between in- and outspiral. We investigate trends in gravitational wave parameters based on component masses. In particular, maximum cutoff frequency depends strongly on white
dwarf mass and compactness. It is unlikely that extragalactic binaries will be measured by LISA or current or future terrestrial detectors. However, white-
dwarf–compact-object binary end stages will be an important source for future decihertz detectors such as DECIGO and LGWA: The final inspiral of tens of white-
dwarf–
neutron-
star binaries will be detected annually by LGWA, and millions of inspirals along with thousands of outspirals will be detected by DECIGO. The ultimate fates of these binaries are diverse and dependent upon the intricacies of angular momentum loss. In particular, we show that white
dwarfs with partners of sufficiently low/high mass can end their lives in common envelopes/mergers, while white
dwarfs do not enter contact with partners of intermediate mass. The highest frequencies produced by white-
dwarf–compact-object binaries in our tests are 10–20 Hz—incapable of mimicking sub-
solar-mass compact object signals in terrestrial detectors or explaining S251112cm-like signals.
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All authors Tristan S. Weaver, David Radice, Donghui Jeong, Victor Liu
High Energy Physics (Phenomenology)
Beyond leading-logarithm photon production from two-loop diagrams in a hot QCD medium
Sumit, Ritesh Ghosh and Munshi G. Mustafa
We investigate high-energy
photon production from a
quark-
gluon plasma by evaluating the imaginary part of the two-loop
photon self-energies in thermal QCD. Working within the imaginary-time formalism, we derive analytical expressions for both the leading-logarithmic and the beyond-leading-logarithmic contributions to the
photon production rate. The rates obtained within the thermal field theoretical framework agree with those derived from kinetic theory calculations for the relevant
photon-production processes.
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Solar and Stellar Astrophysics
A Test of FeH Line Parameters using DR19 APOGEE spectra of Benchmark M Dwarfs
Anderson Silva-Andrade, Diogo Souto, Katia Cunha et al. (+9 more)
Recent studies have suggested a mismatch of up to 0.20 dex between iron abundances derived from Fe I and FeH lines in the H-band spectra of M
dwarfs, and in this work we investigate the nature of this possible offset. We analyze near-infrared H-band APOGEE spectra of
stars in 18 binaries composed of a G-
dwarf primary and an M-
dwarf secondary, together with four M-
dwarf stars having measured angular diameters from the literature, and six M-
dwarf members of the Hyades and Coma Berenices open clusters. These three families of
benchmarks were used to evaluate the FeH line list and check for possible systematic uncertainties in the FeH $gf$-values. Our tests used 1-D LTE plane-parallel model atmospheres, a radiative transfer code, and the baseline APOGEE spectral line list to derive
metallicities for the binary G-
dwarf primaries using Fe I lines, while
stellar parameters and
metallicities for the M
dwarfs used both FeH and Fe I lines. The mean
metallicity obtained for the Hyades M-
dwarfs was $\langle$[Fe/H]$\rangle$=+0.08$\pm$0.04, and for Coma Berenices $\langle$[Fe/H]$\rangle$=+0.02$\pm$0.08. The
metallicities of the G- and M-
dwarfs in binary systems showed excellent agreement (0.06 dex), and the mean
metallicities for the open clusters were also consistent with literature values from high-resolution optical analyses. We investigated the consistency between the spectroscopic and interferometric $T_{\rm eff}$ scales, finding agreement within the uncertainties. Forcing full agreement between the spectroscopic and interferometric $T_{\rm eff}$ scales resulted in a poorer match for the
metallicities in the binaries and the open clusters. We conclude that the best overall concordance is obtained when no adjustments are made to the FeH $gf$-values, which are based on the Hargreaves et al. (2010) line list.
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All authors Anderson Silva-Andrade, Diogo Souto, Katia Cunha, Verne V. Smith, Carlos Allende Prieto, Ricardo P. Schiavon, Verónica Loaiza-Tacuri, Aida Behmard, Dmitry Bizyaev, Ilija Medan, Dan Qiu, Bárbara Rojas-Ayala
Quantum Physics
Realizing Error Suppression in Partially Fault-Tolerant Quantum Simulations with IBM Quantum Computers
Henry Froland, Dorota M. Grabowska, Sebastian Grieninger et al. (+8 more)
Quantum error-detecting codes offer a near-term path for improving the performance of
quantum simulations on noisy hardware. Using IBM's superconducting
quantum computer ibm_boston, we show that partially fault-tolerant encoded
quantum simulations of the Ising model in 1+1D and 2+1D outperform their unencoded counterparts in estimating local observables. To represent 42 logical
qubits on the heavy-hex
quantum processor, 21 blocks of the [[4, 2, 2]] Iceberg code and up to 136 physical
qubits are used. By pairing fault-tolerant syndrome extraction with non-fault-tolerant logical operations, this scheme preserves many of the benefits of error detection while avoiding the overhead typically required for a fully fault-tolerant logical gate set. The encoding's square logical connectivity, together with the freedom to place logical
qubits within each block, enables simulations of a 2D spatial
lattice with lower
circuit depth than the unencoded implementation requires. We introduce Observable-Ranked Postselection, a selective-filtering technique based on syndrome correlations that recovers reliable results without the prohibitive shot loss of full syndrome postselection. Under the cumulative effect of device errors, this encoding improves local-observable accuracy over the unencoded baseline by 2-6% at intermediate times in 1+1D simulations, growing with
circuit depth to over 200% in 2+1D at the latest times studied.
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All authors Henry Froland, Dorota M. Grabowska, Sebastian Grieninger, Jeremy Hartse, Anne L. Lashbrook, Zhiyao Li, Ziyuan Li, Sarah J. M. Powell, Martin J. Savage, Xiaojun Yao, Nikita A. Zemlevskiy
Quantum Physics
Numerical Modeling of Quasiparticle-Induced Dissipation in Fluxonium Qubits
Kate Azar, Max Hays and Kyle Serniak
Nonequilibrium quasiparticles (QPs) generated by stray infrared and ionizing radiation can limit the performance of superconducting
quantum processors and present challenges for
quantum error correction schemes. Models of QP-induced energy relaxation commonly assume that the characteristic energy of the QPs and the
qubit transition energy are both small relative to the superconducting gap. Under these assumptions, certain
qubits such as the fluxonium would exhibit protection against QP-induced dissipation at specific bias points. Here, we show that this is not necessarily the case, numerically analyzing the predicted rate of QP-induced dissipation in fluxonium
qubits for different QP energy distributions and for QPs created via
photon-assisted tunneling processes. We find that accounting for small numerical factors, existing theoretical models predict sensitivity to QP-induced errors at bias points previously thought to be protected. We find that inclusion of asymmetry in the superconducting gap energy across the junction can reintroduce suppression of QP-induced relaxation, as expected. Additionally, for QPs created by
photon-assisted tunneling, we predict that $T_1$ protection will only occur for a specific energy of pair-breaking radiation. This understanding of fluxonium sensitivity to QP-induced dissipation informs the development of fluxonium-based processors and future QP-mitigation strategies.
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Materials Science
Organizing Principles for Moiré Quantum Matter
Qiaoling Xu, Yifan Gao, Tao Zhang et al. (+16 more)
Moiré flat bands in van der Waals
bilayers are usually discussed through a small set of mechanisms associated with the $\Gamma$ and $K$ valleys of hexagonal
crystals, and more recently with $M$-valleys systems. Here we show that this view is incomplete. The momentum-space location and effective local orbital character of the monolayer's band edge, in conjunction with the moiré
symmetry and the
symmetry representations of the resulting bands, provide a general set of organizing variables for the emergent low-energy moiré
Hamiltonian. Applying fully relaxed first-principles calculations, band unfolding and
symmetry-representation analysis to more than 600 commensurate twisted
bilayers spanning all 2D
lattice classes, we identify several routes to moiré
quantum matter beyond the conventional single-orbital paradigm. The resulting flat bands realize trigonal, honeycomb, square, checkerboard and kagome-like Hubbard models with single-orbital, multi-orbital and multi-site
Hilbert spaces;
spin-orbit-coupled multi-orbital flat bands exhibit
symmetry-indicated
topology beyond the conventional $K$-valley setting; and nonsymmorphic moiré
symmetries enforce semimetallic flat-band connectivity. Analogous quasi-one-dimensional flat-band structures are found in $M$-valley hexagonal systems and $X$-valley square or rectangular systems resulting from emergent momentum-space nonsymmorphic
symmetries. Separately, coupled multi-valley
manifolds with kagome-like connectivity are identified in several systems whose parent band edges lie at non-high-
symmetry points. These results establish a valley-orbital-
symmetry framework for connecting parent-material electronic structure to emergent moiré
Hamiltonians relevant to correlated, topological and
symmetry-enforced moiré phases.
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All authors Qiaoling Xu, Yifan Gao, Tao Zhang, Ammon Fischer, Yi Jiang, Hanqi Pi, Zike Fan, Dongdong An, Kun Zhou, Yingjian Li, Yongqing Li, Yuhao Fu, Lei Wang, Lijun Zhang, B. Andrei Bernevig, Dante M. Kennes, Enge Wang, Angel Rubio, Lede Xian
Astrophysics of Galaxies · Cross-listed from cs.LG
Multiclass Classification without Labels via Posterior Simplex Geometry
Raphaël Bonnet-Guerrini, Johann Ioannou-Nikolaides, Troels Petersen et al. (+1 more)
In many classification problems, reliable instance-level labels are unavailable. However, it is often possible to construct weakly enriched unlabeled samples:
datasets selected by different cuts, sources, populations, or experimental conditions that change latent class proportions without revealing them. Classification without Labels (CWoLa) shows that, in the binary case ($K=2$), a classifier trained to distinguish two impure mixtures with different class proportions can recover an optimal class discriminator without knowing the mixture proportions. We extend this principle to multiclass learning from several unlabeled mixtures ($K>2$), where the learner observes only mixture identity and neither latent class labels nor class-prior
matrices. We prove that, for a multiclass mixture model, the Bayes-optimal mixture classifier $g^\star$ maps data points into a $(K-1)$-simplex embedded in mixture-posterior space. The $K$ vertices of this simplex are induced by the latent classes through the unknown mixing
matrix. Leveraging this geometry, we propose prior-free procedures that train a standard classifier to distinguish mixture identities and then extract latent class structure using either post-hoc simplex fitting or a bottleneck architecture. Experiments on MNIST, CIFAR-10, and
Galaxy10 DECaLS show that mixture identity alone can recover latent classes and their fractions in the mixture. By narrowing the gap between weakly supervised and fully supervised performance, we provide a mathematically grounded, scalable tool for multiclass discovery in label-scarce domains.
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All authors Raphaël Bonnet-Guerrini, Johann Ioannou-Nikolaides, Troels Petersen, Vincenzo Piuri
Solar and Stellar Astrophysics
Investigating the Observational Progenitor Mass Gap in the White Dwarf Initial-Final Mass Relation. I. Cluster Census and Characterization of the First White Dwarfs in the Gap
David R. Miller, Jeremy Heyl and Pier-Emmanuel Tremblay
In recent years,
Gaia has been the primary driver of the expansion of the white
dwarf (WD) initial-final mass relation (IFMR) in open clusters. The increased sample size has highlighted a pronounced observational gap at progenitor masses of $\simeq2$–$2.7\,M_\odot$, with no spectroscopically confirmed cluster-member WDs in this range. Analysis of the Milky Way open cluster census shows that this absence is primarily driven by the scarcity of appropriately aged, nearby clusters capable of hosting
Gaia-detectable WDs, implying that deeper, targeted photometry will be required to build a substantial sample in this progenitor mass range. We further searched for previously unexamined
Gaia WD candidates in clusters with ages consistent with producing gap progenitors and identified two viable targets, which we observed spectroscopically with Gemini GMOS-N. Both targets yield inferred progenitor masses within the observational gap, making them the first spectroscopically confirmed cluster-member WDs in this progenitor mass range. The NGC 6991 candidate, in particular, is confirmed as a DA WD with an inferred progenitor mass of $2.12^{+0.04}_{-0.15}\,M_\odot$, providing further support for a non-monotonic trend in the IFMR.
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Cosmology and Nongalactic Astrophysics
EFT-Ramses: a code to simulate the effective field theory of dark energy
Nathaniel Ota Woodcock, Sownak Bose, Yunhao Gao et al. (+1 more)
While the standard $\Lambda$CDM paradigm is in excellent agreement with most current cosmological observations, theoretical challenges surrounding the cosmological constant ($\Lambda$) have strongly motivated the exploration of dynamical dark energy (DE) and modified
gravity (MG) models. Investigating the physical nature of the
cosmic acceleration requires N-body simulations to probe the non-linear growth of
cosmic structure and prepare for the high-precision data from Stage-IV surveys. In this paper, we present EFT-RAMSES, a comprehensive extension of the ECOSMOG cosmological simulation code designed to explore non-linear structure formation in DE and MG scenarios. We embed the effective field theory of dark energy (EFTofDE) framework into this new numerical pipeline, utilising the $\alpha$-basis parameterisation to provide a versatile, model-agnostic, computational engine. By consolidating diverse scalar and vector-tensor theories—including the normal and self-accelerating Dvali-Gabadadze-Porrati (DGP) models, cubic Galileons (cubic scalar Galileon (csG), cubic vector Galileon (cvG) and generalised cubic covariant Galileon (GCCG)), and generic effective field theory (EFT) parameterisation—into a single "master" Vainshtein equation, this pipeline bypasses the need for model-specific solvers and easily specialises to any particular model. As validations, we perform high-resolution N-body simulations for the normal-branch DGP (nDGP), csG, GCCG, and EFT models, comparing the resulting matter power spectra against dependent and independent codes such as legacy ECOSMOG and HiCOLA, as well as linear theory, and find excellent agreement. EFT-RAMSES provides a robust and versatile computational tool for precision cosmological tests of DE and MG using upcoming cosmological surveys. The code is available for download from the GitHub EFT-RAMSES repository.
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All authors Nathaniel Ota Woodcock, Sownak Bose, Yunhao Gao, Baojiu Li
Cosmology and Nongalactic Astrophysics
Primordial Physics in the Nonlinear Universe: Revealing the oscillating halo bias from cosmological collider models
Dhayaa Anbajagane and Neal Dalal
The initial conditions of our Universe contain a wealth of information about the particle physics of very high energies. One such class of signatures, called cosmological
colliders, generates oscillations in the three-point correlations (or bispectra) of the
primordial density field, and these imprint scale-dependent oscillations in the
halo bias. We develop a new method for simulating cosmological
collider models that foregoes traditional template-based basis-decomposition methods and can reproduce the scale-dependent signals of the input template at percent-level accuracy. Using this method, we produce simulations for one class of
collider models and present the first measurements of oscillating
halo bias in simulations. The amplitude and phase of the oscillations show a clear dependence on
halo mass, with a factor of ten shift in
halo mass causing a factor of two shift in the location of the oscillations. Increasing the frequency of the
primordial bispectra model suppresses the signal in the
halo bias, as the oscillations average down over the window function of the
halo. The phase of the signal is also sensitive to assembly bias. In all cases, the scale-dependent
halo bias can be accurately modeled using a simple peak background-split theory. The oscillations and their mass/selection-dependent phase offsets are a unique signature that is not easily mimicked by known observational systematics and is therefore a more robust target. Our simulations and underlying initial conditions code are both made publicly available.
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General Relativity and Quantum Cosmology
Tidal deformation of an accreting compact object
Avijit Chowdhury, Chiranjeeb Singha, Kazuharu Bamba et al. (+1 more)
Tidal deformation of a compact object serves as a sensitive probe of the strong-
gravity regime and nature of the compact object. It captures how a compact object responds to the external perturbing field of a companion. In realistic astrophysical settings, compact objects are typically immersed in matter-rich environments, which can significantly alter the response. In this work, we investigate the static deformability of Schwarzschild-like exotic compact objects (ECOs) embedded in a quasi-stationary, self-gravitating thin
accretion disk. By modelling the external spacetime with a relativistic thin-disk solution, we isolate environmental contributions to the scalar and
spin-1 response while maintaining analytical control. We show that, for perfectly reflecting ECOs, the characteristic logarithmic dependence of the scalar and
spin-1 response on compactness, set by near-horizon physics, remains intact even in the presence of
accretion. The disk primarily amplifies the overall magnitude of the response significantly. These findings highlight that environmental effects can seriously impact
tidal signatures, while still permitting, under suitable conditions, the distinguishability of horizonless compact objects from black holes in gravitational-wave observations.
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All authors Avijit Chowdhury, Chiranjeeb Singha, Kazuharu Bamba, Sumanta Chakraborty
Quantum Physics
Resolving Structure in Prethermal Floquet Dynamics with Precision Quantum Computation
Eyal Leviatan, Tasneem Watad, Roy Perry et al. (+38 more)
Periodically driven interacting
quantum many-body systems can exhibit long-lived prethermal dynamics, where local observables retain coherent structure even as
entanglement and operator complexity grow. Accessing this regime at the system sizes and times needed to determine physical properties of the prethermal state remains a central challenge: state-of-the-art classical methods become unreliable, while noise in
quantum hardware degrades observable expectation values. Here we overcome these limitations for a Floquet Ising magnet realized on a heavy-hex
lattice. Using the advanced error mitigation software QESEM on an IBM Heron r3 superconducting
quantum processor, we measure magnetization dynamics with percent-level precision and resolve long-lived subharmonic prethermal oscillations in systems of up to 74
qubits. These experiments reach regimes for which leading tensor-network simulations fail to converge, while sparse Pauli-path simulations remain strongly truncation dependent despite extensive computations on advanced GPUs and the Fugaku supercomputer. Leveraging this
quantum-accessible regime, we extend finite-size scaling to larger systems and find an unexpectedly slow decrease of the oscillation amplitude with system size, providing strong evidence that this oscillatory response persists in the thermodynamic limit of heavy-hex ladders. A hierarchy of mitigation and validation tests, including unbiased error mitigation, agreement between independent mitigation
estimators, noise-model validation on the superconducting hardware, and cross-platform corroboration at selected Floquet cycles on Quantinuum System Model H2 and Quantinuum Helios trapped-ion hardware, supports the reliability of these findings. Our work establishes error-mitigated
quantum processors as quantitative scientific instruments for discovering new physics in non-
equilibrium quantum matter.
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All authors Eyal Leviatan, Tasneem Watad, Roy Perry, Lukas Broers, Mohammed Zuhair Mullath, Ori Alberton, Itai Arad, Yosi Atia, Eyal Bairey, Shaul Barkan, Matan Ben Dov, Asaf Berkovitch, Ewout van den Berg, Itsik Cohen, Omri Golan, Ilya Gurwich, Avieli Haber, Barak A. Katzir, Oded Kenneth, Roei Levi, Yotam Y. Lifshitz, Yaron Lukovsky, Ron Melcer, Adiel Meyer, Boris Muratov, Aviad Panahi, Gili Schul, Tali Shnaider, Maor Shutman, Alireza Seif, Tomonori Shirakawa, Asif Sinay, Vincent P. Su, Hayk Tepanyan, Omri Trebitch, Assaf Zubida, Dorit Aharonov, Hrant Gharibyan, Abhinav Kandala, Seiji Yunoki, Netanel H. Lindner
Strongly Correlated Electrons
Momentum-Selective Two-Component Excitations in Electron-Doped Mott Insulators
Zeyu Han, Can Cui, Jia-Xin Zhang et al. (+1 more)
Experimental studies reveal a striking asymmetry in low-energy single-particle excitations between electron- and hole-doped cuprates. Electron-doped cuprates display a nontrivial dichotomy:
Fermi-
liquid-like behavior (suggesting weaker electronic correlations) coexists with correlation-driven features typical of hole-doped systems. This dual nature challenges a unified description within a doped Mott
insulator framework. The present work addresses this issue by establishing that the ground-state wave function of the $t$-$t'$-$J$ model generically possesses a two-component structure, comprising a coherent quasiparticle and an incoherent composite component. The kinetic energy arises from both the intrinsic propagation of the coherent quasiparticle and the resonance between these components. Using variational Monte Carlo at the level of a single hole, we show that for hole doping ($t'<0$), this resonance between components dominates and concentrates in the nodal region at low energies. This emergent propagation induced by resonance can be physically interpreted as originating from the recombination of fractionalized degrees of freedom, which drives various phenomena associated with strong correlations. Conversely, for electron doping ($t'>0$), the coherent quasiparticle propagation, which exhibits conventional properties of a
Fermi liquid, is selectively enhanced in the antinodal region at low energies. This produces a separation in momentum space for systems with electron doping: the antinodal spectral weight at low energies is governed by the coherent quasiparticle, fundamentally differing from the nodal region, which remains dominated by the incoherent composite component. Motivated by such a structure and guided by experimental observations, we propose a phenomenological Green's function at finite doping, yielding spectral features consistent with experiments.
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All authors Zeyu Han, Can Cui, Jia-Xin Zhang, Zheng-Yu Weng