Statistical Mechanics
Stochastic Thermodynamics and SDE-based Generative Models
Yaowen Zhang
SDE-based generative models, including
diffusion models and the Schrödinger bridge, have found broad applications in signal processing tasks such as
speech enhancement, image restoration, and time-series generation. This note presents a modeling framework for such models within the context of
stochastic thermodynamics. The main results of this note are trajectory-level definitions of work, heat, and
entropy production, along with a generalized Jarzynski identity and a second-law-like inequality. The proposed framework extends the original Jarzynski setup to accommodate time-dependent bath temperature and nonconservative driving forces. This thermodynamic perspective may deepen our understanding of
diffusion models and the Schrödinger bridge from a nonequilibrium statistical mechanics viewpoint.
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Fluid Dynamics
Spectral perturbation theory for wall-admittance effects on compressible boundary-layer instability
Jiguang Yu, Louis Shuo Wang and Ye Liang
Thin wall treatments modify high-speed boundary-layer instability through the pressure they admit or absorb at the wall. This paper develops a unified admittance formulation for such effects on trapped compressible Rayleigh modes. For a simple rigid-wall eigenpair, we prove the spectral sensitivity law \[ c(A)=c_0+KA+\mathcal O(|A|^2), \qquad \delta\sigma=\alpha\Imag(KA)+\mathcal O(|A|^2), \] where \(A\) is the wall admittance and \(K\) is an explicit functional of the rigid-wall eigenfunction. The formula separates wall physics from outer-mode physics and yields a phase criterion for stabilisation. Matched asymptotics show that viscous and thermal wall layers, blind-pore coatings and shallow non-separating roughness all reduce to this same boundary condition, with additive leading admittances. Mach-4.5 computations validate the sensitivity coefficient and demonstrate porous damping, viscous-wall damping and sign-changing reactive roughness effects.
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Chemical Physics
Variational Quantum Eigensolver-Based Quantum Bootstrap Embedding for Molecules
Derek Peng
Simulating strongly correlated molecular systems on near-term
quantum hardware remains challenging because current hardware offers limited
quantum volume and moderate-fidelity
qubits. One way to address this challenge is through bootstrap
embedding (BE). Bootstrap
embedding partitions molecules into smaller fragments that are then embedded in the “bath” of other fragments iteratively. Bootstrap
embedding is appealing for
quantum simulation because fragmentation reduces the
qubit requirements of each fragment problem. In this work, we develop a
quantum bootstrap
embedding (QBE) workflow that uses variational
quantum eigensolver (VQE) fragment solvers and examines the algorithmic choices that determine the success of the overall VQE-QBE procedure. To improve efficiency, we introduce FastAdaptVQE, a sparse-
matrix-accelerated form of the adaptive variational
quantum eigensolver (ADAPT-VQE) that replaces symbolic commutator evaluation with direct statevector calculations, and MatrixFreeAdaptVQE, a
matrix-free extension that removes the sparse-
matrix memory bottleneck that arises for larger fragments. We also explore modifying the ADAPT-VQE operator-selection step by replacing the purely greedy choice with a lookahead strategy.
Benchmarks on H$_4$, F$_2$, and selected geometries of H$_6$ reach chemical accuracy, within 1 kcal/mol of BE results obtained with a full configuration interaction (FCI) solver. For $n$-butane, density-matching residuals converged, but energy errors remained outside chemical accuracy. These results show that combining QBE with VQE can accurately compute molecular energies, while density convergence alone does not ensure energy accuracy. This work lays the foundation for extending these energy calculations to larger molecular systems and
quantum materials on near-term
quantum hardware.
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Plasma Physics · Cross-listed from cs.LG
Towards Data-Efficient Cross-Device Generalization of Grad-Shafranov Equilibria via Transfer Learning Neural Operator
Jay Phil Yoo, William Howes, Yashika Ghai et al. (+3 more)
Real-time reconstruction of magnetohydrodynamic
equilibria is essential for
plasma shaping, stability assessment and feedback control in
magnetic confinement fusion. However, Grad-Shafranov
equilibrium calculations remain largely device-specific and iterative, limiting their use in latency-constrained control settings. Existing neural approaches can accelerate individual
equilibrium predictions, but they do not generally provide reusable models across changing
plasma boundaries or tokamak geometries. Here we show that
equilibrium reconstruction can be recast as a cross-device operator learning problem. We develop a domain-specific neural operator framework that maps geometry and profile parameters directly to the poloidal flux field, replacing repeated solve-on-demand computation with amortized operator inference. Using the analytically tractable Solov'ev family as a controlled Grad-Shafranov testbed, we generate
equilibria across eight geometrically distinct tokamak-like configurations and
benchmark five neural operator architectures under four transfer-learning strategies. Single-geometry pretraining gives poor transfer to unseen devices, whereas multi-geometry pretraining enables data-efficient adaptation. The Wavelet Neural Operator gives the strongest cross-geometry performance, reaching mean relative L2 errors below 4% with 100 labelled target
equilibria and below 2% with full fine-tuning. The predicted
magnetic fields satisfy the divergence-free constraint to numerical precision, and four architectures achieve millisecond or sub-millisecond inference. These results identify neural operator pretraining as a route towards reusable, real-time
equilibrium inference across fusion device configurations.
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All authors Jay Phil Yoo, William Howes, Yashika Ghai, Kazuma Kobayashi, Souvik Chakraborty, Syed Bahauddin Alam
Mathematical Physics · Cross-listed from math.SG
Towards a Floer theory for Mars II – Floer Hessian field almost extends
Urs Frauenfelder and Joa Weber
In part I, \cite{Frauenfelder:2026c}, we showed that collisional periodic orbits of twisted Zeeman systems can be detected variationally by a non-local
Hamiltonian action functional. In this part II we show that the linearized gradient flow of this non-local functional is a Fredholm operator and prove a non-local
elliptic regularity result. These results are obtained with the theory of almost extendability of weak Hessian fields introduced in \cite{Frauenfelder:2025g}.
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Statistical Mechanics · Cross-listed from eess.SY
Positive-Real Identification of Sparse Mori-Hamiltonians from Partial Observations
Mohammad A. Ayoubi
Discovering the governing equations of a physical system from data is a central goal across the sciences, yet in most experiments only a few states are accessible while the rest stay hidden. Existing approaches treat this partial observability as an obstacle to be removed by first reconstructing the hidden state—a step that is ill-posed under noise and that discards the physical constraints, such as energy conservation, that the true dynamics obey. We show that for conservative (
Hamiltonian) systems no reconstruction is needed: projecting the dynamics onto the measured coordinates yields a
memory kernel that we prove to be a lossless positive-real rational
matrix, whose poles are the hidden natural frequencies and whose positive-semidefinite residues encode the couplings. From this kernel we recover a closed, interpretable governing equation for the observed dynamics—identified from output data alone, passive by construction, and validated by out-of-sample
forecasting. Under stronger conditions—an equipartitioned measure with position coupling, or a forced input–output experiment—the bare hidden frequencies and couplings of the underlying
Hamiltonian are additionally recoverable. We test the method on linear, nonlinear, and chaotic systems under realistic noise. Because it returns energy-conserving equations of motion from partial measurements, it offers a common tool for problems spanning mechanics, fluid and
plasma physics, and beyond.
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Mathematical Physics · Cross-listed from cs.FL
Assembly Spaces: Formal Definitions and Fast Methods for Approximating Assembly Indices
Gage Siebert, Redwan Chowdhury, Louie Slocombe et al. (+1 more)
Assembly theory is an experimental and theoretical framework that introduces a metrological approach to detecting life, with potential applications across diverse substrates. Its two central observables are assembly index and copy number. The assembly index is the minimum number of joining operations required to construct an object from its elementary parts; for molecules, it can be measured using mass spectrometry, infrared spectroscopy, and NMR. Copy number is the abundance of a given distinguishable object within a sample. A key empirical result of the theory is that high assembly index combined with high copy number constitutes a signature that cannot arise abiotically, and this has been validated experimentally in application to molecular biosignatures. The foundational theoretical concept underlying these results is the assembly space, which encodes the causal possibilities determinable from observed objects, with the assembly index the shortest path to them given the physical constraints of a given substrate. Here, we provide a generalized formalism to describe assembly spaces and tools for assembly index approximations. We begin by reviewing the applications of assembly theory across molecules, minerals and atmospheres, and then introduce a general, substrate-independent formal definition of assembly spaces and assembly indices. We develop a unified path hierarchy framework to clarify relationships among the various representations of assembly spaces and assembly paths that appear in the literature on molecular assembly. Finally, we show how formal grammar
algorithms can be adapted to efficiently bound assembly index calculations and provide clarification on the utility of such approximations, with the goal to increase the accessibility of tools to explore this emerging area for a broader group of researchers across chemistry, biology, and complexity science.
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All authors Gage Siebert, Redwan Chowdhury, Louie Slocombe, Sara Walker
Computational Physics
SelfTICA: contrastive learning of dynamical representations for rare-event sampling and characterization
Kai Zhu, Jintu Zhang, Pietro Novelli et al. (+2 more)
Rare events govern many important molecular processes but remain difficult to characterize within accessible simulation timescales. This challenge has motivated machine-learning methods to construct low-dimensional collective variables for specific objectives, including state discrimination, slow-mode identification, and committor-function approximation. Here we introduce SelfTICA, a self-supervised framework that uses contrastive learning on time-lagged configurations to learn a latent representation of the slow modes governing relevant transitions. Once learned, this representation is frozen and reused across downstream tasks, including collective variables construction, enhanced sampling, free-energy estimation, and committor learning. Compared with direct slow-mode optimization, SelfTICA improves training stability and provides collective variables even from limited and exploratory trajectories, accelerating rare-event sampling and enabling accurate free-energy estimation. The dynamical information encoded during pretraining also accelerates committor learning and enables characterization of transition-state regions. These results show that contrastive learning of slow dynamical representations provides a common foundation for rare-event sampling and mechanistic analysis.
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All authors Kai Zhu, Jintu Zhang, Pietro Novelli, Tingjun Hou, Luigi Bonati
Soft Condensed Matter
Underscreening and related phenomena in concentrated electrolytes
Diana Shvydka and Victor Karpov
We propose a heuristic model of underscreening phenomenon in high density Coulomb systems, such as concentrated electrolytes and electron hole conglomerates under ultra high dose rate (UHDR) radiation in biological tissues. It explains the data on screening length $L$ increasing with charge particle concentration and offers additional insights in understanding the conductivity and reduction potential of concentrated electrolytes. Also, it validates our current understanding of the FLASH radiation treatment of tumors (FLASH-RT) perceived as an analogous system. The underlying physics is that mutual binding creates
diffusion barriers which suppress the concentration of mobile particles thus increasing the screening length. Also, they slow down the rates of chemical reactions responsible for generation of biologically active radicals which explains the sparing effect observed under UHDR.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.DC
Is RISC-V Ready for Massively Parallel Astrophysical Codes?
Jenny Lynn Almerol, Nitin Shukla, Federico Ficarelli et al. (+5 more)
We present a performance and portability evaluation of three well-established astrophysical production codes, namely iPIC3D, PLUTO, and OpenGadget3, on a Sophgo SG2044 RISC-V processor (part of the Monte Cimone cluster), with comparisons to AMD EPYC 9554 (x86) and NVIDIA GH200 Grace (ARM) systems. These applications represent
memory-bound, compute-bound, and hybrid workloads, respectively. Numerical correctness is verified across all platforms, confirming portability. RISC-V shows consistently lower performance, with slowdowns of about $3-6\times$ relative to x86 and $5-9\times$ relative to ARM. The gap is mainly due to limited
memory bandwidth, shared cache constraints, narrower 128-bit vector units, and lower clock frequency, but also less-mature auto-vectorization capability of the GNU compiler suite.
Memory-bound kernels are the most affected, where early bandwidth saturation and L2 cache contention reduce scalability at higher thread counts. Hybrid MPI+OpenMP configurations reveal a trade-off between
memory contention and communication overhead, with intermediate configurations achieving the best performance. These results suggest that RISC-V is capable of supporting scientific workloads; however, additional improvements in both hardware and compiler technology, particularly in auto-vectorization, are required to achieve competitive performance.
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All authors Jenny Lynn Almerol, Nitin Shukla, Federico Ficarelli, Geray S. Karademir, Andrea Bartolini, Emanuele Venieri, Giacomo Madella, Elisabetta Boella
Quantum Physics
Orbital-optimized spin-adapted multistate contracted VQE for excited states and properties on quantum hardware
Erik Rosendahl Kjellgren, Karl Michael Ziems, Peter Reinholdt et al. (+3 more)
We introduce the orbital-optimized multistate contracted variational
quantum eigensolver (oo-MC-VQE) method with
spin-adapted operators for the computation of ground and excited states, as well as state-specific and transition properties. The use of
spin-adapted operators ensures that the
spin symmetry of the reference states is conserved throughout the VQE optimization. In multistate variational approaches, achieving a balanced description of an increasing number of electronic states places growing demands on the expressibility of the underlying ansatz, thereby introducing a fundamental trade-off between accuracy and
circuit complexity. We consider the effects of this trade-off explicitly and find that the number of
circuit parameters required to obtain accurate results is reported to scale approximately linearly in the number of states. We further present an explicit
quantum-
circuit implementation of the oo-MC-VQE method and demonstrate its integration with
quantum error mitigation techniques. Finally, we execute the method on real
quantum devices to compute absorption spectra for two
benchmark molecular systems.
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All authors Erik Rosendahl Kjellgren, Karl Michael Ziems, Peter Reinholdt, Stephan P. A. Sauer, Sonia Coriani, Jacob Kongsted
Fluid Dynamics
The Extended KdV Equation: Augmented Lagrangian and Variational Solitary Waves with Applications to Dispersive Hydrodynamics
Saleh Baqer and Hamid Said
In this work, we extend the method of averaged Lagrangian to the study of the general second-order (non-conservative) extended Korteweg–de Vries equation, known as the eKdV equation. Building on the framework introduced in [18], we construct a master (augmented) Lagrangian, modeled on Luke's Lagrangian, that incorporates the governing constraints at the appropriate asymptotic orders via the method of Lagrange multipliers. Averaging the resulting Euler-Lagrange equations in the traveling wave setting yields the existence of a (single) solitary wave solution with a $\operatorname{sech}^2$ profile. Explicit second-order formulas are obtained for the height of the solitary wave, together with the solitary wave velocity and inverse width, in terms of a fixed amplitude parameter. A key feature of the derived expressions is their asymptotic reduction to the classical KdV results when the first-order terms are retained. To assess the robustness and utility of the variational solitonic solutions, the derived formulas are subsequently applied, via the dispersive shock equal amplitude approximation method, to estimate the height and velocity of the leading solitary wave edge of dispersive shock waves governed by the eKdV Riemann problem. Theoretical predictions for the relevant wave parameters in both the eKdV solitary wave and dispersive shock wave problems are compared with direct numerical simulations and found to be in strong agreement.
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Quantum Physics
Zain H. Saleem
We investigate the speed at which
entanglement can be generated by an interaction parameter encoded in a two-
qubit Hamiltonian, quantified by the derivative of concurrence with respect to the coupling parameter. For arbitrary pure two-
qubit states evolving under a general nonlocal interaction, we derive a bound relating this
entanglement speed to the
quantum Fisher information (QFI). Specifically, we show that $|\partial_g C| \le \sqrt{F_Q^{(g)}} \sqrt{1-C^2}$, where $F_Q^{(g)}$ is the QFI associated with estimation of the parameter. This establishes $\sqrt{F_Q}\sqrt{1-C^2}$ as an upper bound on the speed of
entanglement generation in parameter space. We further derive the saturation conditions and identify the states and dynamical regimes for which equality is attained. At saturation, concurrence evolves at the maximum rate permitted by the distinguishability of the underlying
quantum state. These results reveal a direct connection between
quantum metrology and
entanglement generation, showing that the same information-theoretic quantity that governs parameter-estimation precision also limits the speed at which
entanglement resources can be created.
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Quantum Physics
Connecting entanglement growth with local integrals of motion in the disordered Fermi-Hubbard model
Ahad Nokhostin Helm, Brandon Leipner-Johns and Rachel Wortis
Generically a
quantum system initialized in an unentangled state will, under
unitary dynamics, rapidly become entangled, a process closely related to information transport and to thermalization. Disorder can suppress the growth of
entanglement and result in
memory of initial conditions. In non-interacting systems this arises from localization of single-particle states, the occupancy of which is fixed by the initial condition. In interacting systems similar localized conserved quantities persist, but with the added feature that they are coupled, resulting in
entanglement growth which is distinct from both non-interacting localized systems and from generic ergodic systems. The
Fermi-Hubbard model has two degrees of freedom per site – charge and
spin – and disorder may be present in both of these. We study the growth of
entanglement in two scenarios – disorder in charge equal and unequal to that in
spin, and determine the distinct contributions of charge and
spin degrees of freedom by expanding the
Hamiltonian in terms of a set of optimally localized conserved quantities with separate charge and
spin character. We find that coupling between charge and
spin is significantly weaker than charge-charge and
spin-
spin coupling. While this decoupling is present in all our results, it is only apparent when the strength of the disorder in the two sectors is different such that there is a separation between the characteristic timescales of the contributions to
entanglement made by charge and by
spin.
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Earth and Planetary Astrophysics
Low-spin ferrous iron suppresses mantle oxidation beyond Earth-like pressures
Alice Girani, Sylvain Petitgirard, Sergey Yaroslavstsev et al. (+5 more)
The Earth's mantle has elevated Fe$^{3+}$ relative to those of other rocky bodies, yet the oxidation- and electronic state of iron at extreme pressures is poorly known. We present in-situ energy-domain synchrotron Mössbauer spectra of $^{57}$Fe-enriched silicate glasses at 298 K from 1 bar to 174 GPa in a diamond anvil
cell. Glasses were synthesised with Fe$^{3+}$/[Fe$^{3+}$ + Fe$^{2+}$] from 0.02 $\pm$ 0.02 to 1.00 $\pm$ 0.02, as determined by colourimetry. While pure Fe$^{3+}$-basaltic glass shows minimal changes up to 174 GPa, the spectra of Fe$^{2+}$-peridotitic and basaltic glasses are fit by two doublets, D$_1$ and D$_2$. At 1 bar, their relative intensities are $\sim$92 % and $\sim$8 %, respectively, but the integral area ratio, D$_2$/(D$_1$ + D$_2$), reaches 0.65 by 172 GPa. Because this transition is reversible with pressure and no metallic iron is detected, the D$_2$ feature is Fe$^{2+}$ low
spin (LS), whereas D$_1$ is Fe$^{2+}$ high
spin (HS). Consequently, the Fe$^{3+}$/[Fe$^{3+}$+Fe$^{2+}$] of planetary mantles reach a maximum near $\sim$40 GPa, before decreasing at higher pressures due to the stabilisation of Fe$^{2+}_{\mathrm{{LS}}}$. This peak coincides with estimated core-mantle
equilibrium on Earth, implying that its uniquely oxidised mantle and habitable state may result from core formation within a Goldilocks pressure range. Secondary atmospheres are predicted to transition from H$_2$-rich for Moon-sized bodies, to CO-rich for Earth-like
planets and H$_2$- and CH$_4$-bearing around super-Earths and sub-Neptunes.
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All authors Alice Girani, Sylvain Petitgirard, Sergey Yaroslavstsev, Georgios Aprilis, James Badro, Antoine Bézos, Hugh St.C. O'Neill, Paolo A. Sossi
Physics and Society
Reducing health and climate impacts of the global food system
Koen van Greevenbroek, Steven J. Davis and Ken Caldeira
The global food system contributes to tens of millions of years of human life lost every year through unhealthy diets, and accounts for roughly a third of greenhouse gas (GHG) emissions. Researchers have thus often sought opportunities to simultaneously redress these large impacts on human health and
climate; "dietary shifts" are frequently identified as key to both improving health and reducing land-related GHG emissions. Here we develop a new, spatially-explicit, detailed model of the global food system, and use it to highlight enormous and low-cost opportunities to both improve dietary health and reduce food system emissions. However, we find that health and
climate goals are surprisingly independent; for example, reducing red meat intake benefits
climate, but may only modestly improve health outcomes. Similarly, there is very large potential both to achieve healthier diets that do not lead to emissions reductions and to reduce emissions without dietary change. Our results highlight both the potential for, and the separability of, food-related policies that advance public health and
climate goals.
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Quantum Physics
Hardy and Cabello Arguments in Spatial and Temporal Frauchiger-Renner Scenarios
Ehsan Erfani Maharat, Ali Ahanj and Mohsen Sarbishaei
We investigate Hardy- and Cabello-type logical structures within spatial and temporal extensions of the Frauchiger–Renner (FR) framework,
embedding these constructions directly into the FR multi-observer architecture. In the spatial multi-observer scenario, both Hardy and Cabello contradictions arise, with the Cabello construction yielding the stronger violation,$\(\Delta_{\rm Cabello}^{\max}=0.1078\)$, which exceeds the maximal Hardy probability $\(P_{H}^{\max}=\frac{5\sqrt{5}-11}{2}\approx 0.09017\)$. We then develop a sequential temporal FR protocol based on coherent multi-observer measurements performed on a single
spin-$\tfrac12$ system. In this temporal setting, the Hardy contradiction disappears identically due to dynamical constraints imposed by sequential state updates, whereas a finite Cabello-type violation survives, \(\Delta_{\rm Cabello}^{\max}\approx 0.0674\). Our results establish a fundamental structural distinction between spatial
entanglement and temporal multi-observer correlations in FR-type logical scenarios, and demonstrate that certain observer-independent description failures persist even without spacelike separation.
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Quantum Physics
Finite-Shot Operating Windows for Virtual Distillation and Symmetry Verification
Vicenzo Scavino Alfaro
Quantum error mitigation methods are usually compared by their infinite-shot bias, yet in an experiment the comparison is decided by a finite shot budget, by the instability of the
estimator, and by the cost of each shot. We derive finite-shot mean-squared-error laws for virtual
distillation (VD) and
symmetry verification (SV) whose leading terms predict when one method overtakes the other and whose remainders are bounded with explicit constants. For VD the law contains the statistical bias and denominator instability of the quotient
estimator, together with the sample size needed before the quotient can be trusted; for SV it separates the floor left by undetectable errors from the cost of postselection. A first-order decomposition of the noise generator shows which error components each method removes. Two such laws give a tie, a uniform dominance, or a trade-off whose crossing budget scales as $p^{-2}$ or $p^{-1}$ in the noise rate $p$; when the remainder bounds are sharp enough, they turn the leading crossing into a certified interval. In exact white-box QAOA simulations the predicted $p^{-2}$ scaling (fitted exponent $-1.97$) and the sign pattern of all pairwise comparisons ($300/300$
cells) are recovered, one pre-specified all-instance criterion is not met, and the crossings lie $3$–$13\%$ above the leading prediction; a certified interval containing the exact crossing is obtained only in a closed model. Gate-level simulations and runs on two IBM backends show why the ideal VD advantage disappears in the tested instances: interferometric overhead and denominator instability move its window beyond the tested budgets, where SV has the lower mean-squared error.
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Instrumentation and Detectors
DarkFlow: Hierarchical Digital SiPM Architecture with Low-Loss Dataflow Readout for Dark Matter Detection
Zirui Wang, Aras Repond, Shawn Westerdale et al. (+1 more)
Direct dark matter detection experiments require large-scale
photon sensing arrays with hundreds of thousands of synchronized readout channels. Silicon photomultipliers (SiPMs) have emerged as a leading candidate for these detectors due to their high integration density, low bias voltage, and superior radiopurity. However, existing digital SiPM readout architectures struggle to simultaneously preserve nanosecond-level temporal resolution for sparse scintillation events and sustain data integrity during high-intensity
photon bursts. We propose DarkFlow, a hierarchical digital SiPM architecture that features local data aggregation, compact relative-time encoding, consumer-driven backpressure, and occupancy-aware eDRAM burst buffering within a unified dataflow framework. We show that DarkFlow maintains ultra-low packet loss at billion-
photon event rates, where conventional architectures can exceed 80% data loss. Besides, the occupancy-aware refresh achieves a 2.14x improvement in effective refresh rate over conventional global refresh. Hardware evaluation in GlobalFoundries 22nm node confirms that the digital readout datapath accounts for less than 0.86% of the detector area and complies with the strict power budget in
liquid argon environments.
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All authors Zirui Wang, Aras Repond, Shawn Westerdale, Wantong Li
Earth and Planetary Astrophysics
Tracking low-velocity ejecta from the DART impact on Dimorphos
Isabel Herreros and Sébastien Charnoz
The DART impact on Dimorphos produced a large population of low-velocity ejecta (v < vesc), likely containing most of the excavated mass, whose early fate remains poorly constrained. We investigate the first 22 h
evolution of ejecta launched at 1-9 cm/s and assess how orbital dynamics and surface transport after first contact shape the surface distribution of the re-accreted ejecta blanket. We use RAVEL, a model that couples three-dimensional orbital dynamics in the Didymos-Dimorphos system with surface transport on a digital terrain model, including detachment, re-impact, rebound, and frictional sliding. Re-
accretion is rapid and asymmetric: more than 99% of the re-accreted mass returns to Dimorphos within 5 h. The slowest ejecta remain concentrated near the DART crater and dominate the primary ejecta blanket, whereas faster particles undergo orbital transport and preferentially populate antipodal and trailing regions. Surface motion strongly modifies the first-contact pattern, and the DART-derived rough terrain model produces elongated, topographically channelled depositional streaks dominated by the slowest ejecta, giving rise to a ray-like pattern. These results provide testable predictions for ESA's Hera mission and link ejecta-blanket morphology to orbital dynamics, re-
accretion, and surface topography.
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Fluid Dynamics
Sea Surface Roughness Dependence on Ocean Wave Parameters through Large Eddy Simulation with Local Subfilter Wave Drag
Hannah Hata Williams, Aditya K. Aiyer, Luc Deike et al. (+1 more)
Characterizing the Marine Atmospheric Boundary Layer (MABL) requires understanding the coupling between ocean waves and the turbulent atmospheric boundary layer above them. This coupling controls momentum exchange between the atmosphere and the ocean; it is of practical importance in the global
climate, flow of ocean currents, ocean engineering, and offshore wind energy. Computational study of the MABL is complex because it must resolve the coupled physics of waves and
turbulence over a wide range of spatial and temporal scales. This study expands on approaches for representing dynamic, local waves in Large Eddy Simulations (LES) of the MABL by developing a subfilter wave drag model to be local and scale-invariant. It explores the effects of different wave parameters (significant wave height and peak frequency of the wave energy spectrum) on the resulting momentum flux beyond monotonic relationships between surface stress through friction velocity $u_\ast$ and wind velocity above the surface $U_{10}$. Results are compared to field data and in a discussion on how representation of the MABL and associated momentum flux need to account for both wind and wave effects.
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All authors Hannah Hata Williams, Aditya K. Aiyer, Luc Deike, Michael E. Mueller
Nuclear Theory
Fast-reactor neutron sources in evaluated nuclear data library validation
Aaron Hurst, Emanuel Chimanski, Toshihiko Kawano et al. (+3 more)
Two different
neutron sources, based on $^{235}$U-fission
neutrons with different average energies, provide integral
benchmark data for validation of $\gamma$-ray production data in the evaluated
nuclear data libraries corresponding to fast-
neutron-induced inelastic-
neutron scattering reactions. Firstly, we consider the IRT-M Research Reactor, formerly located at the
Nuclear Research Institute just outside of Baghdad, Iraq, to demonstrate the validation methodology using the associated $\gamma$-ray data in the Evaluated
Nuclear Data File, version VIII.0 (ENDF/B-VIII.0), for several $\gamma$-ray transitions over a wide range of nuclides including $^{28}$Si, $^{32}$S, $^{56}$Fe, and $^{186}$W. Using the characterized
neutron flux of the Baghdad IRT-M Reactor, we find flux-weighted cross-sections deduced using the ENDF/B-VIII.0 $\gamma$-ray data to be in good agreement with the integral measurements performed at the Baghdad Research Reactor in addition to the corresponding results of different reaction-model calculations, {\tt CoH$_{3}$} and EMPIRE. Given the excitation thresholds for the $\gamma$-ray transitions involved in this investigation, these observations lend further support to the characterization of the IRT-M flux in the fast-
neutron energy region $0.862 \leq E_{n} \leq 5.0$ MeV. The additional detail devoted to the IRT-M source reflects the broader scope of the validation work carried out at that facility. A second
neutron source considered for this validation work is the Forschungsreaktor Münich (FRM-II), Garching, Germany. Again, the flux-weighted $\gamma$-ray data from ENDF/B-VIII.0 for $^{56}$Fe compare well to the integral FRM-II measurement and reaction-model calculations.
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All authors Aaron Hurst, Emanuel Chimanski, Toshihiko Kawano, David Brown, David Matters, Lee Bernstein
Mathematical Physics · Cross-listed from math.PR
A Concavity Theorem for the Parisi PDE
Fu-Hsuan Ho
We prove that the map sending the
diffusion profile to the solution of a time-changed Parisi PDE evaluated at time-space $(0,0)$ is concave. This result strengthens the raywise concavity result proven by Auffinger and Chen (2016). As an application, for the balanced multispecies Ising
spin glasses, the lower bound of Bates and Sohn (2025) matches the
Hopf-type upper bound given by the Hamilton–Jacobi framework developed by Mourrat, Chen and Xia.
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Earth and Planetary Astrophysics
Comprehensive Statistical Validation of TOI-7701.01: A Sub-Saturn Companion at the Giant Planet Boundary
Biel Escolà-Rodrigo
We present the formal statistical validation of TOI-7701.01 (TIC 122522333), a sub-Saturn transiting companion candidate orbiting a bright F-type subgiant host
star ($V=11.09$). Initially detected via an automated machine-learning transit survey by Salinas et al. (2025), the planetary nature of this signal remained unclear. We implement an independent vetting and statistical pipeline leveraging multi-sector space kinematics and the triceratops
Bayesian framework to compute false positive scenarios. A key methodological finding is the structural convergence of the companion's physical scale; despite utilizing un-detrended Simple Aperture Photometry (SAP) with a raw depth of $2417$ ppm to preserve field dilution metrics, the triceratops MCMC engine naturally converges on a physical radius of $7.86\,R_\oplus$ under the dominant Target
Planet scenario ($\mathcal{P}_{\rm TP} = 78.1\%$). This independent statistical derivation matches the
geometric radius of $8.07\,R_\oplus$ inferred directly from the instrumentally corrected Pre-Search Data Conditioning (PDCSAP) data. By aggregating our multi-iteration ensemble to suppress MCMC stochasticity, we derive a robust global False Positive Probability ($\mathrm{FPP} = 0.00191$) and a Nearby False Positive Probability ($\mathrm{NFPP} < 10^{-6}$), firmly validating the companion well below the rigorous $1.5\%$ threshold established for this
Bayesian framework. While the derived $7.8\text{--}8.1\,R_\oplus$ radius places the object at the boundary between
giant planets and low-mass brown
dwarfs, such a radius is highly atypical for a brown
dwarf, pointing to a planetary nature. We report TOI-7701.01 as a validated companion and encourage
prompt radial velocity characterization.
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Pattern Formation and Solitons
Anisotropic Cylindrical Waves in a Square Lattice of Acoustic Waveguides
Ioannis Ioannou Sougleridis, Olivier Richoux, Vassos Achilleos et al. (+2 more)
We investigate the propagation of cylindrical waves in a square network of acoustic waveguides. We establish, both theoretically and experimentally, the anisotropic dispersion relation governing wave propagation in the network, and demonstrate excellent agreement between experimental measurements and theoretical predictions. Owing to this anisotropic band structure, each propagation direction exhibits distinct dispersive properties. Consequently, the network supports anisotropic cylindrical waves at both low- and high-amplitudes, with waveforms that vary markedly with direction: from nearly dispersionless pulses to Airy-like wave packets in the linear regime, and from sharp shock-like fronts to smooth solitary-like profiles in the nonlinear regime. The theoretical results are further corroborated by numerical simulations based on the two-dimensional Westervelt equation.
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All authors Ioannis Ioannou Sougleridis, Olivier Richoux, Vassos Achilleos, Georgios Theocharis, Dimitrios Frantzeskakis