Superconductivity
Electronic inhomogeneity in Cs- and Sb-terminated surfaces of CsV$_3$Sb$_5$ probed by scanning photoemission spectromicroscopy
T. Mizokawa, G. Tomassucci, M. Hattori et al. (+6 more)
Electronic structures of Cs- and Sb-terminated surfaces of a kagome
superconductor CsV$_3$Sb$_5$ have been elucidated by means of scanning photoemission microscopy (SPEM). The observed band structure of the Cs-terminated surface is rather close to that of the bulk while that of the Sb-terminated one is substantially modified around K/H point of the Brillouin zone. While the contrast between the Cs- and Sb-terminated regions is reduced below the charge density wave transition temperature, the Sb 5$p$ band of Cs-terminated region exhibits electronic inhomogeneity which slightly increases below it. The inhomogeneity of the Sb 5$p$ band would be related to disorders of the out-of-plane Sb and relevant for the band folding along $\Gamma$-A with the charge density wave. The SPEM results suggest that the less inhomogeneous Cs termination is more suitable for interface of kagome
superconductors. However, the inhomogeneity of Cs termination, which is significant at $\Gamma$/A, noticeable at K/H, and negligible at M/L, is expected to affect the Sb 5$p$-V 3$d$ hybridization at the interface.
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All authors T. Mizokawa, G. Tomassucci, M. Hattori, F. Minati, L. Tortora, A. Barinov, Z. Wang, J.-X. Yin, N. L. Saini
Materials Science
The substitutional atomic distance model for predicting lattice thermal conductivity in alloys
Zhicheng Zong, Tianhao Li, Shixian Liu et al. (+2 more)
Understanding
phonon transport in
alloys is crucial for the design of high-performance electronic and thermoelectric devices. However, conventional theoretical models fail to provide a clear physical picture of
phonon scattering caused by atomic disorder in
alloys, and their prediction accuracy is limited. In this work, a new substitutional atomic distance model for
alloys is proposed, providing an intuitive physical picture. SiGe and InGaAs
alloys are taken as representative systems, and their thermal conductivities are calculated, showing good agreement with previous experimental measurements. The results indicate that
alloy scattering plays a dominant role in reducing thermal conductivity. This study provides new insights into
phonon transport in
alloys and offers guidance for tailoring thermal properties through compositional engineering.
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All authors Zhicheng Zong, Tianhao Li, Shixian Liu, Haisheng Fang, Nuo Yang
Quantum Physics
Unbiased Hamiltonian Simulation by Reversing Trotter Error Dynamics
Keisuke Murota, Yuta Kikuchi, Enrico Rinaldi et al. (+2 more)
Owing to their simplicity and low overhead, Suzuki-Trotter formulas remain the de facto
Hamiltonian simulation methods on current
quantum computing platforms. Systematic Trotter errors, however, will quickly become limiting when scaling to larger problems and aiming for higher accuracy. We present a mechanism that removes the systematic error of any $k$-th order Suzuki-Trotter simulation, at the cost of a constant sampling overhead. The key insight is that the Trotter error is itself a coherent dynamics to be reversed, rather than a deviation to be bounded. By identifying the structure of this error in closed form, we carry out that reversal through quasi-probabilistic decompositions. The resulting
algorithm, called Probabilistic Trotter Error Reversal (PTER), is unbiased and still improves the gate-count scaling of Suzuki-Trotter formulas while retaining their simplicity. Numerical simulations of a Heisenberg
spin chain support the predicted resource advantage already at modest system sizes.
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All authors Keisuke Murota, Yuta Kikuchi, Enrico Rinaldi, Frédéric Sauvage, Synge Todo
Quantum Physics
Quantum complexity resource in Gaussian boson sampling: Core structure of the semidefinite program
Kunwar Kalra and Vitaly Kocharovsky
We present a rigorous analysis of the algebraic and
geometric structure of the
quantum complexity resource of a system of bosonic modes in Gaussian
boson sampling. This resource underlies the
quantum advantage of the system: its
photon-counting statistics require the evaluation of a hafnian of the resource covariance
matrix, and that computation is #P-hard. The resource covariance
matrix is the solution of a semidefinite program that extracts the minimum-trace physical
quantum part of the total covariance
matrix; the complementary part is positive semidefinite and can therefore be simulated classically. Earlier work characterized this resource only through the trace of the
quantum part, equal to its
photon number. We characterize the optimizer itself, as a
quantum state and as a
geometric object, beyond the scalar given by its trace. We prove that it is a unique pure Gaussian state and construct an explicit oracle map, obeying an algebraic Riccati identity, that reconstructs the resource. We prove that the full problem compresses exactly onto the active
symplectic sector that the dual program support generates. The passive-diagonalizable states are solved in closed form, the first explicit solvable class, and the whole program is shown to be equivalent to a minimization over the
symplectic group, that is, over the Siegel upper half-space. Together these results establish that the program determines a canonical localized pure Gaussian component of the resource, and they provide the structural foundation for its detailed analysis.
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Optics
All-optical Synchronization of Breather Solitons in a Kerr Microresonator
Wang Liao, Stuart G. Murdoch, Stephane Coen et al. (+3 more)
Microresonator Kerr
solitons are promising candidates for the realization of miniaturized on-chip optical frequency combs. For specific system parameters, these
solitons are associated with oscillatory instabilities, leading to breathing dynamics characterized by periodically modulated temporal and spectral profiles. In this regime, the
solitons form a frequency comb comprised of primary comb lines surrounded by sidebands separated by the breathing frequency. Here, we numerically and experimentally demonstrate that the breathing sidebands can be all-optically synchronized to a weak monochromatic
laser injected into the cavity, thus providing direct control of the
soliton oscillation frequency. We judiciously characterize the synchronization process, and show that it is accompanied by a strong reduction of noise in the
soliton's breathing. Our results provide fundamental insights on oscillatory dissipative structures, and could enable new forms of composite optical frequency combs.
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All authors Wang Liao, Stuart G. Murdoch, Stephane Coen, Gregory Moille, Kartik Srinivasan, Miro Erkintalo
Cosmology and Nongalactic Astrophysics
Modeling survey-window and integral-constraint effects on PNG in the galaxy power spectrum with light-cone mocks
Shintaro Nakano, Masahiro Takada, Toshiki Kurita et al. (+1 more)
We develop an analysis framework based on light-cone
galaxy mock catalogs constructed from linear theory simulations in order to accurately model the impact of
primordial non-Gaussianity (PNG) on
galaxy power spectrum on large scales. These linear light-cone catalogs properly incorporate a variety of observational and cosmological effects, including the survey window function, the
redshift evolution of matter and
galaxy density fields, and
redshift-space distortions (RSD). When estimating the multipole moments of the power spectrum from each light-cone mock, we employ the same
estimator as used in actual analyses, thereby properly accounting for the effects of the discrete
Fourier transform, the line-of-sight dependence of the fields, and wide-angle RSD effects. Using light-cone mock catalogs that mimic the BOSS survey, we demonstrate that long-wavelength modes comparable to or larger than the survey window scale, namely super-survey modes, have a significant impact on the integral constraint (IC) in power spectrum measurements. In particular, we show that the analytical treatment of the survey-window convolution and IC, which has been commonly used in previous studies, begins to lose accuracy on scales of $k\lesssim k_{\rm eq}$ (the matter-radiation equality scale), and becomes invalid in the presence of PNG. The method developed in this work enables unbiased searches for PNG using the
galaxy power spectrum on long-wavelength scales probed by ongoing and future wide-area
galaxy surveys.
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All authors Shintaro Nakano, Masahiro Takada, Toshiki Kurita, Ryo Terasawa
Materials Science
Atomically Thin Amorphous Carbon with an Ultralow Dielectric Constant
Chee-Tat Toh, Artem K. Grebenko, Ugur Karadeniz et al. (+17 more)
Two-dimensional (2D) materials exhibit excellent properties at monolayer thickness and are viable replacements for various microelectronic components as scaling gradually approaches the atomic limit. Despite significant advancements in the ongoing 2D revolution of integrated
circuits, one crucial building block, namely a 2D ultralow-k (ULK) dielectric, remains unreported. The challenge lies in achieving a dielectric constant less than 3, as traditional low-k dielectrics are inherently unstable at the 2D limit due to their amorphous or porous nature. The realisation of ultrathin dielectrics with low-k is also needed to address current bottlenecks in integrated
circuits scaling. Specifically, low-k materials are necessary to minimise parasitic capacitances as the distance between conductive elements shrinks below 10 nm. Moreover, advanced architectures like gate-all-around field effect transistors (GAA FET) require even lower dielectric constants (k<2) at sub-3nm thickness. Here, we show that layer-by-layer grown multilayer amorphous carbon (ML-AC), as thin as 0.8 nm, is a mechanically robust 2D ULK dielectric with k of 1.35 and dielectric strength of 28-31 MV cm-1. The lack of any long-range order, its intrinsic 2D nature, sp2 carbon character and low density are all essential for minimising dielectric permittivity. Moreover, ML-AC overcomes the vulnerability of existing dielectrics to ion
diffusion degradation with a record metal ion
diffusion time to failure (TTF) of 10^10 s for even a single layer. Therefore, otherwise necessary additional layers occupying up to 3 nm can be eliminated, which is especially significant as metal line widths approach 10 nm. Combined with its low-temperature, direct and conformal growth even on a dielectric, these critical features enable substantial improvements in silicon-based
semiconductor electronics and ensure compatibility with future 2D electronics.
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All authors Chee-Tat Toh, Artem K. Grebenko, Ugur Karadeniz, Usha Bhat, Ya He, Hongji Zhang, Denis V. Vyalikh, Anna Makarova, Alexander Fedorov, Alena A. Alekseeva, Kostya Iakoubovskii, Lu Shi, Andrei Starkov, Chuan Chu Tee, Lucas M. Sassi, Michel Bosman, Naoto Kamiuchi, Yuta Sato, Kazutomo Suenaga, Barbaros Oezyilmaz
Instrumentation and Methods for Astrophysics · Cross-listed from cs.LG
ScaleAware-JEPA: Latent Representation for Discovery in Multiscale Physical Fields
Guang-Xing Li
Continuous physical fields represent a large fraction of data under scientific investigation. Their multiscale structures are central to discovery, yet useful coordinates are not known in advance. Standard self-supervised methods define context and targets in fixed image coordinates, posing a predictive task misaligned with fields organized across a continuous scale hierarchy. We introduce ScaleAware-JEPA, a framework that constructs dense, label-free latent coordinates for continuous scalar fields. Constrained
Diffusion Decomposition (CDD) separates each field into pixel-registered scale components and provides the scale coordinates that define the masking geometry. The resulting JEPA objective predicts hidden structure with a context footprint tied to the
diffusion scale of each component rather than to an arbitrary patch size. Across MHD
turbulence, interstellar molecular gas and urban nighttime-light structure, the learned geometry maps back to coherent morphology, forming dense structural atlases without labels or predefined
segmentation rules. By tying latent prediction to the scale hierarchy of a field, ScaleAware-JEPA constructs latent coordinates through which complex physical patterns can be inspected before their relevant structures have been prescribed. Code is available at https://github.com/gxli/SA-JEPA.
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Materials Science
Optimizing Expert-Designed Crystal Graph Networks for Band-Gap Prediction with an Autonomous LLM Research Loop
Chenmu Zhang and Boris I. Yakobson
Predicting a material's properties from its structure is a central, fast-advancing problem in computational materials science. A decade of work has produced standard public
benchmarks and many published machine-learning models for the task (Dunn et al., 2020). The task's fixed metric and these baselines make it a natural setting for autonomous
agent research (Karpathy, 2026). On the MatBench band-gap
benchmark ($>$100k
crystals), a general-purpose coding
agent autonomously built the most accurate model trained without external pretraining, ahead of all seventeen expert-designed models reported for the task. A closer analysis shows it reached this by implementing known methods: either already standard in
crystal neural-network models, or borrowed from other areas of machine learning. The contributing implementations include element-pair features on each message-passing edge and a
crystal space-group
embedding. The work not only demonstrates that LLM-
agent autonomous research can optimize an expert-designed machine learning model for material property prediction, but also investigates the limitations of such autonomous research.
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High Energy Physics (Phenomenology)
Size Dependence of the Sommerfeld Enhancement for Puffy Dark Matter
Wu-Long Xu, Jin Min Yang and Wen-Na Yang
We examine the size effects in the Sommerfeld enhancement factor for puffy dark matter annihilation. First, we use the partial-wave method to study the case of puffy dark matter for which only a charge density distribution is given without specifying its internal structure. We find that by using two dimensionless parameters, we can provide a characterization of the resonance structure of the Sommerfeld enhancement. Using this approach, we demonstrate that the finite size of dark matter particle is another fundamental factor, in addition to low velocity, that affects the Sommerfeld enhancement. Then, as an example of puffy dark matter with nontrivial internal structures, we perform the analysis for the nugget-type dark matter, whose Sommerfeld enhancement factor is found to exhibit a resonant behavior similar to that of point-like particles.
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Astrophysics of Galaxies
Globular cluster formation with multiple stellar populations: A comprehensive overview of a star-cloud interaction scenario
Kenji Bekki and Madeleine McKenzie
We present a new scenario of globular cluster (GC) formation with multiple
stellar populations (MPs) in which both the first and second populations (1P and 2P, respectively) of
stars form from
giant molecular clouds (GMCs) polluted by asymptotic
giant branch (AGB)
stars within and around the GMCs. Unlike previous GC formation scenarios with AGB
stars being the primary polluters, the new scenario alleviates tensions with the mass-budget and dilution-timing problems The principal results based on idealized analytic models of the formation scenario are as follows. The observed fraction of 1P
stars and the helium abundance spreads between the 1P and 2P as a function of GC masses can be well reproduced. The modelled GCs show O-Na, C-N, and Mg-Al anticorrelations and Si-Al, 25Mg-Al, 26Mg-Al correlations. The observed Mg-K anticorrelation can be reproduced, only if super AGB
stars make a significant contribution to chemical enrichment within GMCs. The lack of correlations of Li abundances with [Na/Fe] and [Al/Fe] can be reproduced, only if about 20% of the polluting AGB
stars produce Li-rich ejecta, which disfavours scenarios with polluters incapable of Li production. Iron-complex, Type-II GCs can be formed through merging of two GCs formed from two GMCs within a host
dwarf galaxy at different epochs. The new scenario predicts young massive clusters formed in
galaxy environments with surface
star formation rate densities well below 1 M_sun/yr/kpc^2 are unlikely to evolve into GCs with MPs. It also predicts low 12C/13C ratios of 2P (~5), a [Na/Fe]-[F/Fe] anticorrelation, and P-rich
star formation with [P/Fe]$>0.5$ and [N/Fe]>0.5. These predictions are tested against more than 30 observed properties of GCs with MPs, representing one of the most comprehensive observational
benchmarks against a specific GC formation scenario to date.
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General Relativity and Quantum Cosmology
Quasibound states of a charged Dirac field around regular black holes
Shao-Jun Zhang
Charged regular black holes can respond differently from Reissner–Nordström (RN) black holes to charged scalar perturbations, raising the question of whether their inner geometry also leaves a distinct imprint on fermionic fields, for which classical superradiant amplification is absent. We address this question by studying quasibound states of a massive charged Dirac field on the Ayón-Beato–García (ABG) regular black-hole background. We derive the separated radial equations and the far-field trapping condition $M\mu^2-qQ\omega_R>0$, compute the complex spectrum by two-sided shooting and matching, and independently identify the long-lived modes in time-domain evolutions. The identical Newtonian and Coulomb tails of ABG and RN produce the same leading hydrogenic spectrum, so their real frequencies differ only through subleading corrections and full radial matching. The damping rates are much more sensitive to the inner geometry: changes in the near-horizon potential barrier suppress or enhance the leakage of the fermionic cloud into the horizon, and some ABG modes live more than an order of magnitude longer than their RN counterparts despite having nearly identical real frequencies. All modes found in the explored parameter range remain damped. Thus the regular geometry changes the lifetime, rather than the leading binding energy, of the fermionic cloud without generating a Dirac superradiant instability.
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Atmospheric and Oceanic Physics
Routes to rare events with optimally timed perturbations: a Tent Map is all you need
Justin Finkel
Extreme weather events are difficult to understand for the same reason that they are dangerous: they happen rarely, catching victims unprepared when they do occur and scientists unable to assess risks confidently, given such limited precedent to learn from in the real world and high computational expense to simulate more examples. Rare event sampling (RES)
algorithms seek to reduce this expense by forcing simulations more directly towards the extremes and then compensating for that forcing in statistical analysis. But the performance of RES hinges on several hyperparameter choices which are ad hoc in practice, and must be better understood if RES is to be broadly useful. This paper addresses one particular parameter, the advance split time (AST), which prescribes when to perturb a simulation to split off the most informative possible ensemble of alternative extreme event scenarios. We prescribe the optimal AST as the time it takes for an initial perturbation to amplify into the size (inverse rarity) of the extreme event being targeted. For the Logistic and Tent maps, two archetypal examples of one-dimensional chaos, we rigorously derive and express the rule as a simple log-ratio between perturbation size and event rarity. The pair of examples also illuminates where the rule breaks down, and subsequently, we generalize the rule into a maximum-
entropy criterion that solidifies recent heuristic and empirical results. Despite the idealized setting, our results deliver theoretical clarity that can anchor future developments of principled RES methods applicable to real-world, high-impact weather and
climate extremes.
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Computational Physics
Verified residual-specific explicit derivative kernels for physics-informed learning and discretized PDE adjoints
Wenbo Cao, Zhe Lu and Weiwei Zhang
Derivative computation is central to scientific computing, from space-time derivatives in physics-informed neural networks (PINNs) to residual Jacobian actions and discrete-adjoint operators in computational fluid dynamics (CFD). General-purpose automatic differentiation (AD) reduces implementation effort, but can incur substantial runtime and
memory overhead for high-order residuals and complex discretized operators. Explicit derivative kernels can exploit problem-specific structure and provide efficient, controllable evaluations, but their use has been limited by derivation and implementation costs. This work revisits explicit differentiation (ED) as a residual-specific and verifiable route enabled by
agent-assisted implementation and stringent numerical verification. For PINNs, we propose residual-specific partial-jet propagation, which makes the derivative-state closure of the target PDE residual explicit and realizes it through specialized layerwise kernels, rather than relying only on nested AD or a generic Taylor-mode transform. Relative to nested AD, the resulting ED kernels achieve floating-point-level agreement in residual and parameter-gradient evaluations and accelerate complete PINN training, often reaching 2-4x speedups while reducing peak GPU
memory in most cases. For discretized PDE adjoints, we apply the same verification-driven strategy to a finite-volume CFD residual. The generated tangent-action and transpose-action kernels pass Taylor-remainder, inner-product, and reduced-gradient consistency checks, and are embedded into a GPU-resident discrete-adjoint workflow for freestream Mach-number and angle-of-attack inversion. These results suggest that verified explicit derivative kernels, supported by
agent-assisted implementation, can serve as a practical, structure-aware complement to general-purpose AD for derivative-intensive scientific computing.
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Chemical Physics
Thermal Fundamental Gap Predictions in DFT via Optimally Tuned Hybrids
Tim Gould, Leeor Kronik, Gil Amoyal et al. (+1 more)
Predicting electronic fundamental gaps at finite temperature has remained conceptually and practically challenging. We address this in three connected steps. First, we extend generalized Kohn–Sham hybrid density functional theory to thermal ensembles, deriving a Mermin generalized Kohn–Sham framework from a thermal one-particle auxiliary system and an exact density-functional remainder. Second, via an extension of Janak's
theorem that holds rigorously in this framework, we recast Hirata's thermal-quasiparticle picture as a thermal orbital gap
estimator and derive a closed low-temperature form, the error of which is controlled by the derivative discontinuity. Third, because optimal tuning eliminates this error, the auxiliary orbital gap matches the interacting gap at low temperature, upgrading optimal tuning from a ground-state strategy to the governing principle – mandatory, not optional – for accurate finite-temperature gap predictions obtained from gaps of orbital
eigenvalues within a hybrid functional framework. We present applications that validate the theory and demonstrate its consequences.
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All authors Tim Gould, Leeor Kronik, Gil Amoyal, Stefano Pittalis
Quantum Physics
Alleviating the Sparse Matrix Scaling Bottleneck in Adaptive VQE via High-Order Taylor State Evolution
Hermawan Kresno Dipojono
The Variational
Quantum Eigensolver (VQE) is a leading
algorithm for noisy intermediate-scale
quantum (NISQ) devices, but its adaptive variants (e.g., ADAPT-VQE) suffer from severe classical simulation bottlenecks during the ansatz growth phase. Representing and exponentiating pool operators for multi-
qubit systems constructs massive sparse
matrices that quickly scale to millions of elements, choking classical
memory bandwidth and CPU/GPU cycle capacity. In this work, we present a resource-efficient software-layer framework that completely bypasses dense
matrix exponentiation by evaluating state updates through a deterministic fifth-order (O(5)) Taylor series expansion. This approach reframes the costly
unitary evolution into a chained sequence of five lightweight, successive sparse
matrix-vector multiplications scaling strictly as O(Nz), where Nz is the number of non-zero elements. We validate our framework using
equilibrium BeH2 (14
qubits),
equilibrium H2O (12
qubits), and strongly correlated asymmetrically stretched H2O molecular profiles under both Jordan-Wigner (JW) and Bravyi-Kitaev (BK) transformations. The simulation results demonstrate that the O(5) truncation maintains exceptional numerical fidelity, retaining a state fidelity > 0.999999 and matching absolute ground state energies down to subchemical accuracy, while effortlessly navigating
matrix spaces exceeding 268 million structural elements. This framework provides a scalable, high-performance pathway for executing deep variational simulations on hardware platforms with constrained computational budgets.
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High Energy Physics (Phenomenology)
Quark–hadron duality in inclusive electron–proton scattering at high $Q^{2}$: structure functions and truncated moments from CLAS12
Y. Wunderlich, A. Bulgakov, K. Joo et al. (+2 more)
We present a high-precision study of
quark–
hadron duality in inclusive electron–
proton scattering in the nucleon resonance region, extending to $Q^2\approx10~\mathrm{GeV}^2$, based on recent CLAS12 cross-section measurements at Jefferson Lab. The data, taken with a 10.6~GeV beam, span $2.55 \le Q^2 \le 10.4~\mathrm{GeV}^2$ and cover the full resonance region up to $W\approx2.5~\mathrm{GeV}$. To reach the CLAS12 kinematics, we develop a phenomenological high-$Q^2$ extension of the Argonne–Osaka (ANL-Osaka) dynamical coupled-channels framework, anchored to the original calculation at $Q_0^2=2.774~\mathrm{GeV}^2$ and constrained by the measured cross sections. This enables an ANL-Osaka-constrained longitudinal–transverse decomposition and determination of the
proton structure function $F_2(W,Q^2)$, from which we evaluate $W$-truncated Cornwall–Norton moments $M_2(Q^2)$. Comparison with the CJ15 global QCD analysis, including target-mass and higher-twist corrections, shows consistency at the cross-section, structure-function, and truncated-moment levels, providing quantitative evidence for both local and global
quark–
hadron duality at substantially higher $Q^2$ than previously explored. We further identify a threshold effect in the partonic calculation: the finite-$Q^2$ corrections do not enforce the physical pion-production threshold, and the residual discrepancy in the first resonance region is consistent with this effect rather than a breakdown of duality. Within the coupled-channel description, the single-pion channel alone underestimates the inclusive resonance-region strength above the $\Delta(1232)$, which is carried predominantly by the multi-
meson channels, as required for duality.
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All authors Y. Wunderlich, A. Bulgakov, K. Joo, T.-S. H. Lee, V. I. Mokeev
Quantum Physics
A Machine-Verified Proof of a Quantum-Optimization Conjecture
Uri Kol, Maor Ben-Shahar, Kfir Sulimany et al. (+1 more)
We report a machine-verified resolution of a problem open for over a decade in
quantum optimization: the Farhi, Goldstone and Gutmann (FGG)
conjecture that depth-$p$
Quantum Approximate Optimization
Algorithm (QAOA) on the ring of disagrees attains approximation ratio $(2p+1)/(2p+2)$ exactly. We found the proof using a large
language model, Claude Fable 5, and verified its correctness end-to-end by the Lean 4 proof assistant. Our methodology includes several ingredients: building on a substantial Lean library of
quantum information, we formalized the QAOA components and the known parts of the problem, and reduced the
conjecture to a single open mathematical statement. The model was then handed the library and our agentic toolkit, and tasked with closing that gap by constructing a proof in Lean. The resulting process is a feedback loop between the model's natural-
language reasoning and Lean's mechanical verification, which converged to a machine-verified proof. Human verification is required only for the structural scaffolding - that the formal statement faithfully encodes the intended claim - while the proof itself is supplied by the model and certified mechanically by Lean. The proof is nevertheless striking - the model uncovered a hidden dynamical
symmetry of the problem and exploited it, borrowing tools and machinery from an adjacent field to turn a hard existence problem into an explicit construction. This work paves the way for resolving open
conjectures in
quantum information science and beyond.
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All authors Uri Kol, Maor Ben-Shahar, Kfir Sulimany, Dirk Englund
Atomic Physics
Low-lying $D$ states in yttrium and actinium ions highly sensitive to variation of the fine structure constant
Akio Kawasaki
Whether fundamental constants vary over time or space is one of the key questions in metrology and cosmology. Among them, variation of the fine structure constant $\alpha$ is intensively investigated. Yttrium ions Y$^+$ and actinium ions Ac$^+$ have low-lying $D$ states that are suitable for this search, with a proper path for
laser cooling and detection. Theoretical calculations show that the sensitivities of the transitions between the ground state and the lowest $^3D_1$ states are $K=9.40$ and $K=9.73$, respectively. By driving the transition between the ground state and the $^3D_1$ states with a two-
photon transition, the transition can be used for a high-sensitivity search for time variation of the fine structure constant. The high efficiency of a detection scheme using the transition between the $7s6d~^3D_1$ states and the $7s7p~^3P_0$ state also suggests that Ac$^+$ ions are potentially useful as a platform for
quantum information processing.
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Disordered Systems and Neural Networks · Cross-listed from cs.LG
I-BBS: Coordinate-Free Inference of Latent Sub-Manifolds Using Random Distance Matrix Theory
Igor Halperin
Bogomolny, Bohigas and Schmit (BBS) found that the spectrum of the pairwise distance
matrix on N points sampled from a smooth d-dimensional
manifold encodes a signature of the underlying geometry. We develop I-BBS (Inference-BBS), a coordinate-free method that identifies a low-dimensional latent sub-
manifold embedded in a high-dimensional ambient distance
matrix alone, without accessing an ambient high-dimensional vector space. It therefore applies even when that space is only partly observable or undefined. We model the ambient
embedding by two classes of generative noise, model-based and model-free. The noise mixes the latent signal with off-
manifold components, so the
eigenvalues reorganise collectively and the latent geometry cannot be read off
eigenvalue by
eigenvalue. We recover it instead from two integer-stable signatures that survive the noise: the multiplicity of the top non-Perron multiplet, which fixes $d$, and a parameter-free law for how the multiplet positions shrink as the noise grows. On synthetic spheres $S^1$, $S^2$ and $S^3$ these integer signatures are far more stable under noise than the continuous spectral slope, and a blind test recovers both the
manifold and the noise model from a single distance
matrix. Applications to neural-network representations and to the dynamic training regime are developed in two companion papers.
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Earth and Planetary Astrophysics
Deuterated water and the formation of the satellites of Uranus
Michael E. Brown, Matthew Belyakov, Swaroop Chandra et al. (+5 more)
The satellites of Uranus orbit in a low-eccentricity, equatorial plane that is tilted by 98 degrees relative to the
solar system – a geometry that mirrors Uranus's extreme axial tilt. Although a
giant impact could have tipped Uranus, how the satellites came to share this orientation remains uncertain. Proposed formation pathways include
primordial accretion followed by reorientation, formation from debris generated by the tilting impact, and reaccretion from a massive ring produced by the
tidal disruption of passing bodies from the outer
solar system. Current observations do not discriminate among these scenarios. Using the James Webb Space
Telescope, we measured the deuterium-to-hydrogen (D/H) ration in the water ice of the five regular satellites of Uranus. We find an average D/H ratio of $2.1\pm 0.2 \times 10^{-4}$, nearly five times higher than that of Uranus and comparable to the values measured in comets. This enrichment is inconsistent with with any formation scenario in which substantial Uranian material was incorporated into the satellites, thereby excluding models that require significant mixing in an impact-derived vapor disk. The observed D/H ratios are instead compatible with models in which the satellites accreted from material that remained largely separate from Uranus, such as debris from a disrupted pre-existing satellite system or from a tidally captured outer
solar system body. The innermost regular satellite, Miranda, exhibits a marginally elevated D/H ratio (2.8 $\sigma$ above the average of the other satellites), potentially indicating a distinct formation history or source of water and offering an important clue for distinguishing amount competing models.
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All authors Michael E. Brown, Matthew Belyakov, Swaroop Chandra, M. Ryleigh Davis, Merritt McDowell, Ashma Pandya, Kevin T. Trinh, Samantha K. Trumbo
High Energy Astrophysical Phenomena
VLBI Astrometry of Magnetars
Takuya Akahori, Sujin Eie, Kei Amada et al. (+8 more)
The origin of the strongest
magnetic fields in the Universe, i.e., the origin of magnetars, is a longstanding question. An enhanced dynamo effect in an irregular
supernova explosion is a possible origin, which implies a stronger kick velocity and a higher proper motion of the magnetar compared to those of ordinary
pulsars as well as an irregular morphology of the host
supernova remnant (SNR). However, this hypothesis is not well studied yet, because there is a lack of precise measurement of the proper motion of magnetar and of identification of the host SNR. VLBI astrometry of magnetars is a unique tool to examine the hypothesis. In this chapter, we introduce the MONSTER (Monitoring Observations of the
Neutron Stars That Evolve Rapidly) Project. SKA-VLBI's unprecedented sensitivity and the highest angular resolution will allow us to dramatically expand the survey volume in which we can measure the proper motion of magnetars within a
radio outburst period of a few months.
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All authors Takuya Akahori, Sujin Eie, Kei Amada, Sangita Kumari, Kohei Kurahara, Hiroto Masaoka, Hao Ding, Teruaki Enoto, Shota Kisaka, Keiichi Maeda, Kotaro Niinuma
Astrophysics of Galaxies
Takuya Akahori, Kohei Kurahara, Shin-ya Nitta et al. (+4 more)
Galaxy clusters contain an intra-cluster medium (ICM) with temperatures of tens of millions of Kelvin. Cosmological structure formation simulations show that this diffuse gas is heated not only by adiabatic gravitational compression but also by shock waves and
turbulence generated during mergers of
galaxy groups and clusters. These processes are expected to produce
magnetic fields and
cosmic rays, observed through synchrotron polarization. One structure formed during cluster
evolution is the cold front, a contact discontinuity created when colder gas moves transonically through hotter gas. Using MeerKAT, GMRT, and ATCA, we recently discovered
radio emission along cold fronts in two
galaxy clusters, with spectra indicating re-acceleration at the discontinuity. This presents a new puzzle because the standard mechanism in
galaxy clusters,
Fermi acceleration, is not naturally expected there. We propose
magnetic reconnection as the re-acceleration mechanism. Compression and stretching of magnetized
plasma at the discontinuity can generate current sheets that trigger reconnection, as also suggested by simulations. With AA*, we will probe broadband
radio spectra at high spatial resolution to constrain where re-acceleration occurs. Polarization measurements will reveal
magnetic-field structures and clarify the conditions required for
magnetic reconnection.
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All authors Takuya Akahori, Kohei Kurahara, Shin-ya Nitta, Haruka Sakemi, Hiroki Akamatsu, Mami Machida, Motokazu Takizawa
High Energy Physics (Theory)
Understanding Color Confinement through Quantum Reference Frames and Relational Observables
Kei-Ichi Kondo
We present a formulation for color confinement on the basis of
quantum reference frames (QRFs) and relational observables. In the QRF approach to color confinement, colored quantities are not defined as isolated local fields, but rather as relational observables with respect to a color frame or a dressing field. The Gauss law removes compactly supported local color charge from the physical bulk
algebra, while boundary fluxes, Wilson lines, and holonomies may remain as semi-local data. This separates gauge invariance from frame independence. Color confinement is characterized under the fixed protocol by the absence of a finite-energy, physically accessible, asymptotically isolated nontrivial color-charged representation in the infinite volume limit. A failure to globalize a long-distance color frame is one possible mechanism contributing to this absence, which clarifies the role played by topological defects in color confinement. As concrete examples, we examine $(1+1)$-dimensional $SU(2)$ Yang–Mills theory and $(1+1)$-dimensional $U(1)$ gauge–
Higgs model. We also take up the two-dimensional U(1) gauge–
Higgs model on $\mathbb{H}^2$ (Euclidean $AdS_2$) and three-dimensional $SU(2)$ gauge–
Higgs model on $\mathbb{H}^3$ (Euclidean $AdS_3$) which are obtained based on conformal equivalence by dimensional reduction of four-dimensional SU(2) Yang–Mills theory restricted to symmetric-instanton sectors. Through explicit calculations in these examples and in controlled sectors, we provide nontrivial checks for internal consistency of the present formulation. We also discuss prospects for four-dimensional Yang–Mills theory and gauge–
Higgs theories.
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Materials Science · Cross-listed from cs.CV
MatMMExtract: An Open-Source Pipeline for Panel-Level Extraction of Grounded Image-Text Pairs from Materials Science Literature
Subham Ghosh, Shubham Tiwari, Mohammad Ibrahim et al. (+1 more)
The materials science literature encodes decades of experimental knowledge in figures, yet this visual record remains locked away and inaccessible to AI at scale. The core difficulty is structural: most scientific figures are compound, with a single caption describing multiple sub-panels simultaneously, making direct image-text pairing unreliable. We present MatMMExtract, an end-to-end open-source pipeline that resolves this by decomposing compound figures into individual sub-panels and generating structured, grounded annotations using a large
language model guided by a curated materials science taxonomy. Applied to 14,810 open-access articles, MatMMExtract produces MatSciFig; 391,606 panel-level image-text pairs from 180,571 figures, each annotated with a sub-caption, a two-level visualisation category spanning 19 classes and over 100 subtypes, and a scientific summary. To enable accurate panel localisation, we introduce MaterialScope, a domain-specific detection
dataset of 2,811 manually annotated materials science figures, on which a fine-tuned YOLO12-m detector achieves mAP_50 of 0.9227. Among six benchmarked
language models, Gemini 3.1 Flash Lite delivers the best cost-quality trade-off for annotation generation, with 82% of outputs rated good and a
hallucination rate of 4.8%. A dual-encoder
retrieval baseline on MatSciFig achieves a 4.4 times improvement in R@1 over zero-shot CLIP, demonstrating the
dataset's immediate utility for
vision-
language learning. All resources are released openly to the community.
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All authors Subham Ghosh, Shubham Tiwari, Mohammad Ibrahim, Abhishek Tewari
Earth and Planetary Astrophysics
TOI-6884b: A low-mass brown dwarf transiting a slightly evolved star
Akanksha Khandelwal, Shubhendra Nath Das, Rishikesh Sharma et al. (+42 more)
We report the discovery of a low-mass transiting brown
dwarf orbiting TOI-6884 (TIC~156514476, $T_{\rm mag}=11.4$) from NASA's Transiting
Exoplanet Survey Satellite (TESS) mission. The TESS light curves initially suggested an orbital period of $\sim$14.42~days; however, our high-precision ground-based radial velocity measurements and multi-epoch time-series photometry reveal this to be a harmonic alias. We determine the true orbital period to be $4.808264^{+0.000015}_{-0.000014}$~days and confirm the substellar nature of the companion. TOI-6884b has a mass of $26.32^{+0.98}_{-0.93}\,M_{\mathrm{J}}$, a radius of $0.927^{+0.51}_{-0.52}\,R_{\mathrm{J}}$, and resides on a nearly circular orbit ($e=0.067^{+0.010}_{-0.012}$). Its host
star is a late F-type slightly evolved
star with $M_\star = 1.410^{+0.075}_{-0.069}\,M_\odot$,\msun, $R_\star = 1.840^{+0.072}_{-0.073}\,R_\odot$, $\log{g} = 4.057^{+0.045}_{-0.039}$, $[{\rm Fe/H}] = 0.094^{+0.073}_{-0.068}$~dex, and $T_{\rm eff}=6330^{+180}_{-160}$,\mathrm{K}$. TOI-6884b is a key addition to the small population of well-characterized transiting brown
dwarfs orbiting host
stars that have evolved off the main sequence. The detection of such systems will contribute to our understanding of the dynamical histories and structural
evolution of short-period substellar companions around evolved
stars.
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All authors Akanksha Khandelwal, Shubhendra Nath Das, Rishikesh Sharma, Abhijit Chakraborty, Churchil Dwivedi, Sanjay Baliwal, Karen A.Collins, David W. Latham, Allyson Bieryla, Cristilyn N. Watkins, Felipe Murgas, Norio Narita, Enric Palle, Steve B. Howell, Mark E. Everett, Catherine A. Clark, Polina A. Budnikova, David Ciardi, Nikitha Jithendran, Akihiko Fukui, Ashirbad Nayak, Bob Massey, Boris Safonov, Florence Libotte, Francis P. Wilkin, Gregor Srdoc, Howard M. Relles, Ivan Bonilla-Mariana, Izuru Fukuda, Jason D. Eastman, Jerome de Leon, Jesus Higuera, Kapil Bharadwaj, Keith Horne, Kendra Nguyen, Kevikumar Lad, Manuel Pichardo Marcano, Micaela Magno, Neelam JSSV Prasad, Noriharu Watanabe, Richard P. Schwarz, Sam Quinn, Santiago Paez, Toshi Suganuma, Y. Gomez Maqueo Chew
Mesoscale and Nanoscale Physics
Length–Velocity Gauge Equivalence of Quantum Geometric Nonlinear Conductivity in the Adiabatic DC Limit
Shakeel Ahmad and Fei Xue
Nonlinear transport has emerged as a sensitive probe of
quantum geometry beyond the Berry-
curvature physics of linear response. However, the intrinsic second-order dc response remains conceptually subtle: different
quantum and semiclassical formulations can appear to give different static limits, with different assignments of
Fermi sea and
Fermi surface contributions. Here we resolve this ambiguity by developing a gauge-consistent density-
matrix theory of intrinsic nonlinear conductivity in both the length gauge, where the electric field couples through the position operator, and the velocity gauge, where it enters through the vector potential. We show that the two gauges give the same adiabatic dc response when the same retarded continuation is used for all external frequencies and when the velocity gauge current includes all field-dependent vertices. The apparent
Fermi sea terms cancel in the full expression, leaving a
Fermi surface
quantum geometric contribution determined by the band-normalized
quantum metric. This result implies that a fully gapped
insulator has no residual dc nonlinear
Hall current in the adiabatic clean limit. The reactive part of the
Fermi surface term agrees with the original semiclassical Berry-connection-polarizability response, while the dissipative Ohmic sector requires a more careful treatment of relaxation and
impurity scattering. Our work establishes the length-velocity gauge equivalence for
quantum geometric nonlinear response and provides a foundation for using nonlinear transport to probe
magnetic quantum geometry, especially in PT-symmetric antiferromagnets.
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History and Philosophy of Physics
What Naturalness Measures: Fine-Tuning and Informational Invariants in Cosmology and Dark Matter
Stefano Profumo
Naturalness is commonly presented as an objective constraint on physical theories: a model requiring fine-tuning is judged implausible. This presentation conflates a representation-dependent quantity with an invariant one. A fine-tuning verdict depends on the choice of fundamental parameters, the prior, and the measure convention, so it does not by itself fix a feature of the world. Here, I argue that what is objective is structural: the universality class of the map from parameters to observables, invariant under admissible changes of parametrization and measure convention, and independent of any prior over parameter space; it constitutes an informational invariant. On this account naturalness is neither an aesthetic preference nor an objective probability, but a statement about the distinguishability geometry of the representations through which physics encodes observation. I trace the certainty of naturalness verdicts to a tradition, from Ockham through Dirac and Weinberg, in which parsimony and beauty are taken as guides to truth; modern naturalness inherits that tradition's authority without its successive justifications. The argument is developed in the gravitational and cosmological sector, where naturalness
reasoning is sharpest and its effective-field-theory grounding is weakest. A uniform analysis across gravitational and particle dark matter candidates shows that fine-tuning tracks the analytic structure of the abundance map, not the nature of the candidate; that the resulting classification is invariant across measure conventions while the tuning number is not; and that this decomposition instantiates informational structural realism. I situate the position against the autonomy-of-scales account, which the argument largely accepts, and against the deflationary reading, which identifies the borrowed authority but discards the structural residue.
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