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Tuesday 8 September

Quantum Physics

A Platform-aware Compilation Framework for Fault-tolerant Quantum Computation

Srushti Patil, Susan X. Chen, Andreas Juul Bay-Smidt et al. (+4 more)

The compilation of an algorithm can vary significantly with the choice of physical hardware platform and error correction model. Yet, current compilation frameworks typically commit to a single architecture-hardware configuration, making it difficult to assess resource estimates across platforms. We present a platform-aware compilation framework that re-compiles a quantum circuit into a hardware-compatible instruction set as well as fault-tolerant operations and provides end-to-end resource estimates in terms of physical-qubit count, time-to-solution, and classical processing time. We benchmark the framework by obtaining end-to-end resource estimates for different compilers, each tailored to the functionalities of specific hardware modalities: connectivity, clock speed, and noise model. As part of this framework, we introduce a transversal active volume (t-AV) compilation architecture designed for the efficient execution of fault-tolerant operations in platforms supporting long-range logical connectivity. We benchmark the framework for Hamiltonian simulation of the 2D Fermi Hubbard model as well as for eigenenergy estimation of a small molecule (trimethylenemethane) as a candidate for early fault-tolerant demonstration of quantum chemistry. For the latter, we show that end-to-end quantum simulations can be achieved with $\sim10^4$ physical qubits and runtimes ranging from $10^2$ ms (photonics, superconducting) to $10^5$ ms (neutral atoms).
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All authors Srushti Patil, Susan X. Chen, Andreas Juul Bay-Smidt, Stefan Alaric Schäffer, Peter Krogstrup, Stefano Paesani, Gemma C. Solomon

Quantum Physics · Cross-listed from cs.ET

Sparse Walsh-Pauli Correlation Encoding for MaxCut: A Quantum-Inspired Formulation with Quantum-Hardware Validation

Cesar Augusto do Amaral, Nicolás Legnazzi, Marcos Vinicius Reballo et al. (+3 more)

We introduce a sparse Walsh-Pauli correlation encoding for MaxCut, in which graph variables are represented by diagonal Pauli-string expectation values computed classically as normalized XOR autocorrelations of Walsh coefficients. The complete Walsh basis can reproduce the diagonal correlators of arbitrary quantum states, while a structured sparse support reduces the number of trainable coefficients to $m+1$ for $m$ graph variables. We evaluate the method on $1{,}400$ held-out random graphs with up to $7{,}000$ vertices, obtaining empirical approximation ratios near $0.98$ relative to MQLib heuristic references. On Gset instances G14, G23, G60, and G64, the sparse model achieves mean refined approximation ratios of $0.9828$, $0.9926$, $0.9781$, and $0.9369$, respectively, with $80.4\%$-$89.3\%$ fewer parameters than the complete Walsh representation. The trained coefficients are transferred without retraining to quantum circuits. Statevector simulations of the four Gset instances achieve fidelities above $0.99994$ and preserve all correlator signs. Separately, a seven-qubit experiment on a $15$-vertex graph executed on IBM quantum hardware achieves a correlator-sign agreement of $0.927\pm0.049$ relative to the corresponding noiseless circuit. These results demonstrate the potential of sparse Walsh-PCE for large-instance quantum-inspired MaxCut optimization while validating the transfer of classically trained parameters to quantum hardware.
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All authors Cesar Augusto do Amaral, Nicolás Legnazzi, Marcos Vinicius Reballo, Marcus Ritt, Alexsandro Santos da Rosa Júnior, Fernando Augusto Caletti de Barros

High Energy Astrophysical Phenomena

Resolving structure within the iron line profile of Serpens X-1 with XRISM and NuSTAR

Hayden Hall, Renee M. Ludlam, Edward Cackett et al. (+2 more)

We present the first simultaneous XRISM and NuSTAR observations of the neutron star low mass X-ray binary Serpens X-1. We perform spectral modeling on the joint observations of XRISM/Resolve, XRISM/Xtend, and NuSTAR, testing Comptonization and double thermal continuum model prescriptions. We find that a hybrid double thermal model adequately describes the underlying continuum of the source while the Comptonization models predict largely unphysical parameter values. We perform reflection modeling and confirm with tight constraints an inclination of 5^{\circ} \pm 1^{\circ} and inner disk radius of 6.6 \pm 0.6 Rg for the source. We show that the spectral resolution of XRISM/Resolve allows for the determination of a unique inner disk radius, which has the potential to constrain neutron star spin in other systems. We discuss discrepancies in spectral shape between XRISM/Resolve and NuSTAR above \sim 8 keV. We also present lightcurve and spectral analyses of 8 Type-I X-ray bursts that occurred during the observations.
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All authors Hayden Hall, Renee M. Ludlam, Edward Cackett, Jon M. Miller, Javier A. García

High Energy Physics (Phenomenology)

Relativistic spatial distributions of transverse angular momentum

Cédric Lorcé, Asmita Mukherjee, Ravi Singh et al. (+1 more)

In our previous work [C. Lorcé et al., Phys. Lett. B 868 (2025) 139792], we investigated the 2D spatial distributions of transverse total angular momentum, including orbital angular momentum and intrinsic spin, relative to the canonical center (or center of spin). In the present work, we extend this analysis in two directions. First, we study the corresponding transverse boost distributions relative to the canonical center. Second, since the definition of generalized angular momentum density depends crucially on the choice of pivot, we analyze how the spatial distributions of transverse total angular momentum and boost are modified when they are defined relative to different relativistic centers, viz.~the relativistic centers of mass, energy, and spin. Considering spin-1/2 targets, we derive the corresponding 2D spatial distributions in the transverse plane, and further investigate how the spatial patterns evolve under longitudinal Lorentz boosts. Additionally, we provide the corresponding light-front distributions in the transverse plane, establishing a clear connection between the instant-form and light-front descriptions of transverse angular momentum and boost.
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All authors Cédric Lorcé, Asmita Mukherjee, Ravi Singh, Ho-Yeon Won

High Energy Physics (Experiment)

NOvA Dual-Baseline Search for Active-to-Sterile Neutrino Oscillations using Neutrino- and Antineutrino-Enriched Samples

NOvA Collaboration: S. Abubakar, M. A. Acero, B. Acharya et al. (+184 more)

We report a search for neutrino oscillations to sterile neutrinos in the NOvA detectors under a model with three active and one sterile neutrinos. This search simultaneously fits data in the two NOvA detectors and is the first from NOvA to use both neutrino- and antineutrino-mode beams, with exposures of $26.61\times10^{20}$ and $12.50\times10^{20}$ protons on target, respectively. There is no evidence for sterile neutrinos in the data and we are able to exclude regions of parameter space that were allowed by previous experiments, including most of the allowed region reported by IceCube.
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All authors NOvA Collaboration: S. Abubakar, M. A. Acero, B. Acharya, P. Adamson, N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, L. Asquith, A. Aurisano, N. Balashov, P. Baldi, B. A. Bambah, E. F. Bannister, A. Barros, J. Barrow, A. Bat, T. J. C. Bezerra, V. Bhatnagar, B. Bhuyan, J. Bian, A. C. Booth, B. Brahma, C. Bromberg, N. Buchanan, J. Burns, A. Butkevich, T. J. Carroll, E. Catano-Mur, J. P. Cesar, C. Chang, S. Chaudhary, H. Chen, S. Choate, B. C. Choudhary, O. T. K. Chow, A. Christensen, M. F. Cicala, T. E. Coan, T. Contreras, A. Cooleybeck, L. Cremonesi, G. S. Davies, P. F. Derwent, K. Dever, Z. Djurcic, K. Dobbs, D. Duenas Tonguino, E. C. Dukes, A. Dye, R. Ehrlich, E. Ewart, P. Filip, M. J. Frank, H. R. Gallagher, A. Giri, R. A. Gomes, M. C. Goodman, R. Group, A. Gusmao, A. Habig, F. Hakl, J. Hartnell, R. Hatcher, J. M. Hays, M. He, K. Heller, V Hewes, A. Himmel, X. Huang, T. Huynh, A. Ivanova, K. Kaess, G. Kufatty, I. Kakorin, A. Kalitkina, D. M. Kaplan, A. Khanam, B. Kirezli, J. Kleykamp, O. Klimov, L. W. Koerner, L. Kolupaeva, C. D. Kuruppu, V. Kus, T. Lackey, K. Lang, J. Lesmeister, A. Lister, J. A. Lock, W. A. Mann, M. Manrique Plata, A. Marathe, M. Martinez-Casales, V. Matveev, A. Medhi, B. Mehta, M. D. Messier, H. Meyer, T. Miao, R. Mohanta, A. Moren, A. Morozova, L. Mualem, M. Muether, C. Murthy, D. Myers, J. Nachtman, D. Naples, J. K. Nelson, O. Neogi, R. Nichol, E. Niner, G. Nissan, M. Nixon, A. Norman, A. Norrick, A. Olshevskiy, T. Olson, A. Pal, J. Paley, L. Panda, R. B. Patterson, G. Pawloski, R. Petti, R. K. Pradhan, L. R. Prais, S. Puhan, A. Rafique, M. Rajaoalisoa, B. Ramson, B. Rebel, C. Reynolds, P. Roy, D. Sagar, O. Samoylov, M. C. Sanchez, S. Sanchez Falero, P. Shanahan, P. Sharma, A. Sheshukov, S. Shukla, I. Singh, P. Singh, V. Singh, J. Smolik, P. Snopok, N. Solomey, A. Sousa, K. Soustruznik, M. Strait, C. Sullivan, L. Suter, A. Sutton, K. Sutton, S. K. Swain, A. Sztuc, N. Talukdar, P. Tas, T. Thakore, J. Thomas, E. Tiras, Y. Torun, D. Tran, J. Trokan-Tenorio, J. Urheim, B. Utt, P. Vahle, Z. Vallari, K. J. Vockerodt, A. V. Waldron, B. Wang, C. Weber, M. Wetstein, D. Whittington, D. A. Wickremasinghe, J. Wolcott, S. Wu, W. Wu, Y. Xiao, B. Yaeggy, A. Yahaya, A. Yankelevich, K. Yonehara, S. Zadorozhnyy, J. Zalesak, L. Zhao, R. Zwaska

High Energy Astrophysical Phenomena

Strong Polarization Signatures from Magnetically Stabilized Luminous Thin Accretion Disks

P. Chris Fragile, Peter Anninos, Madeline Breiling et al. (+2 more)

We utilize the Monte Carlo radiation transport capabilities of Cosmos++ to explore the polarization and Faraday rotation of radiation emitted from a set of general relativistic radiation magnetohydrodynamic simulations of magnetically stabilized, thin, black hole accretion disks. The guiding question is whether or not the Faraday rotation depolarizes the radiation to such a degree as to be inconsistent with the relatively high polarization measurements coming from the Imaging X-ray Polarimetry Explorer (IXPE). After first confirming that our code reproduces expected polarization results for electron clouds, planar scattering atmospheres, and AGN disks, we demonstrate the polarization and Faraday rotation capabilities using a Novikov-Thorne disk threaded with a purely toroidal magnetic field. We then analyze temporal snapshots from three different simulations of luminous, thin accretion disks threaded with different magnetic field configurations. We find that the effects of Faraday rotation are generally modest over the energy range of interest, since the strongest fields present in these simulations ($\gtrsim 10^8$ G) are mostly hidden beneath the photosphere. We can easily produce polarization degrees $\ge 4$% for sources seen mostly edge-on. As one example of a relevant target, we compare our results to an IXPE observation of Cyg X-1, finding that we can match the polarization degree quite well, though our polarization angle is rotated approximately $90^\circ$ with respect to the observed data. We speculate on a few possible explanations for this.
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All authors P. Chris Fragile, Peter Anninos, Madeline Breiling, Derrick Pickrel, Gabrielle Ruminski

Astrophysics of Galaxies

Turbulence Cascade in Cygnus X Revealed by Multi-point VDF Method

Junjie Huang, Yangjun Pu, Keping Qiu et al. (+3 more)

Turbulence plays a crucial role in regulating star formation activities within molecular clouds, yet few methods can directly reveal its properties and underlying processes. We use molecular line data from the Nobeyama 45m Cygnus X CO Survey to study the turbulence properties and their relationships with star-forming activities and/or other non-thermal motions. In this work, we apply the multi-point velocity dispersion function (VDF), rather than direct linewidth measurements, to investigate the non-thermal properties of molecular cloud motions. We filter out the large-scale ordered structure and isolate a relatively small-scale turbulence component. Through the Friends In Velocity (FIVe) algorithm, we identify 10 substructures of the clouds and derive the turbulent properties of each cloud using the VDF method. We find that both the cloud-complex regions and the 10 velocity substructures exhibit turbulence correlation lengths of $\sim 2$–5 pc. This plateau scale suggests a parsec-scale turbulence correlation or driving scale in Cygnus X. Below this scale, the rising VDFs trace the velocity scaling of the turbulent cascade, whereas larger-scale VDF variations likely reflect cloud-scale motions. The comparison between cloud complexes and substructures further suggests that, in observational data, the VDF may constrain the turbulence correlation scale more robustly than the turbulence velocity dispersion.
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All authors Junjie Huang, Yangjun Pu, Keping Qiu, Junhao Liu, Yingxi Li, Mengke Zhao

High Energy Physics (Phenomenology)

ALP-mediated inelastic dark matter and the LUX-ZEPLIN high-recoil candidate event LZ230616

Guan-Wen Yuan, Bo Zhang, Wen-Yu Cao et al. (+2 more)

The LUX-ZEPLIN (LZ) Collaboration has reported a high-energy candidate event LZ230616 with a reconstructed nuclear recoil energy $E_R=248\pm23_{\rm stat}\pm23_{\rm sys}~{\rm keV}$. We investigate a possible interpretation in terms of inelastic scattering between two Majorana dark matter states mediated by an axionlike particle coupled to gluons. The positive mass splitting suppresses low-energy recoils, while the momentum dependence of the interaction reshapes the high-energy spectrum. We treat the dark-sector and gluonic couplings independently and retain the momentum-dependent nucleon form factors and xenon nuclear responses. Using an approximate single-event likelihood, we find that, for $m_a=0.3~{\rm GeV}$, a narrow spectrum near the candidate energy arises at $m_\chi\simeq0.35~{\rm TeV}$ and $\delta\simeq330~{\rm keV}$, although this configuration requires a large coupling product and is highly sensitive to the Galactic halo speed cutoff. Our analysis establishes the kinematic and coupling requirements for subsequent tests using the thermal relic abundance and laboratory constraints on the mediator.
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All authors Guan-Wen Yuan, Bo Zhang, Wen-Yu Cao, Lei Feng, Ruizhi Yang

Applied Physics

Dynamic Sensing via Photomodulated Gas Desorption in Plasmonic Nanoparticle Chemiresistors

Lukas Mielke, Dahee Heo, Gabriele Carelli et al. (+1 more)

Quasi-static sensing, i.e., measurement of a sensor signal change induced by analyte presence with respect to a baseline signal observed in a reference gas beforehand, is the state of the art for qualitative and quantitative analyte identification in chemiresistive sensing. However, this approach is prone to baseline drift and, especially for inexpensive miniaturized point-of-care sensors, repeated calibration with reference gas is not feasible. To access reliable baseline information, active switching between analyte and reference gas would be required, causing a limitation for miniaturized implementation. Dynamic excitation of sensors offers an alternative: Via external stimuli the sensor is reversibly driven out of equilibrium in a controlled way, and the resulting transient sensor response, which is dependent on analytes present, is recorded and interpreted. Correlation of excitation and response signals can reduce effects of baseline drift and furthermore, dynamic features in sensor responses may contain valuable information. Especially light activation is a powerful and potentially miniaturizable approach to agitate sorption processes and therefore induce dynamics. In this work we report photothermal heating of hybrid, chemiresistive gold nanoparticle composites via LED excitation matching the plasmon resonance, to dynamically shift the analyte sorption equilibrium and induce dynamic sensor responses in a highly controlled way. We demonstrate that these sensor responses enable the detection of volatile organic compounds (VOC) via interpretation of differential signal components and that this approach improves the chemiresistors' baseline stability.
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All authors Lukas Mielke, Dahee Heo, Gabriele Carelli, Hendrik Schlicke

Mathematical Physics · Cross-listed from math.PR

Phase transition for strongly correlated percolation models on supercritical Bernoulli clusters

Alberto Chiarini, Zhizhou Liu and Maximilian Nitzschner

We consider the level sets of the Gaussian free field and the vacant set of random interlacements, both defined on a typical realization of the infinite cluster of supercritical Bernoulli bond percolation on $\mathbb{Z}^d$, $d \geq 3$. We prove that in the entire supercritical regime of Bernoulli bond percolation, both the level sets of the Gaussian free field and the vacant set of random interlacements undergo non-trivial percolation phase transitions at deterministic critical levels. A key aspect of the proof is the development of certain quenched controls over tree embeddings, permitting the application of a static renormalization scheme in the presence of spatial irregularities, which may be of independent interest.
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Materials Science

Controlling Hydrogen Isotope Retention at Helium Cavities through Radiation-Induced Segregation in Fusion Steels

Lihao Shi, Logan N. Clowers, Qing Peng et al. (+2 more)

Hydrogen isotope retention in plasma facing and structural alloys is a central materials challenge for deuterium-tritium fusion. Motivated by ion beam irradiation experiments and first principles calculations, we identify an irradiation-enabled mechanism whereby solute segregation to defect sinks enhances hydrogen isotope trapping. Triple-ion irradiation of reduced activation ferritic-martensitic steel F82H reveals pronounced segregation of Cr and Ta to cavity surfaces. Density functional theory shows that these segregants markedly increase H stability at cavities by strengthening binding energies and increasing migration barriers, leading to substantially higher attention. The effect originates from solute-tuned electronic structure: Ta promotes strong H 1s-metal d orbital hybridization, whereas Cr shifts the surface d-band toward a more favorable bonding configuration. These findings provide an atomistic link between irradiation-induced segregation and elevated-temperature hydrogen isotope retention and alloy chemistry routes to control tritium inventory in fusion environments.
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All authors Lihao Shi, Logan N. Clowers, Qing Peng, Gary S. Was, Fei Gao

High Energy Physics (Phenomenology)

How to choose a good rational basis for elliptic Feynman integrals?

Ekta Chaubey and Vasily Sotnikov

Representing multi-loop scattering amplitudes as linear combinations of multivalued transcendental functions with process-dependent rational coefficients has long been understood to be advantageous. In general, these transcendental functions satisfy a system of differential equations with coupled homogeneous blocks. When these coupled blocks can be removed through algebraic basis transformations, the relation between the rational and algebraic bases is universal and minimal. Here, we ask whether an analogous universal and minimal relation exists when decoupling requires transformations involving complete elliptic integrals. We elaborate on the method proposed in ref. arXiv:2504.20897, in which we suggested that a basis constructed using an elliptic generalization of leading singularities may provide an answer to this question. We extend this analysis to the off-diagonal blocks of the rational differential equations satisfied by the bases obtained through this construction. We find that the $\epsilon$ dependence of these blocks can be organized into a universal structure that is preserved under the decoupling transformation used to express the solutions in terms of iterated integrals.
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High Energy Physics (Theory)

Covariant Phase Space and Carroll-Weyl $\chi$ Symmetry of Carroll Non-BPS D$_p$-branes

Limin Zeng

We analyze the covariant phase space of Klusoň's canonical Carroll non-BPS D$_p$-brane actions. The Carroll limit is formulated as a contraction of the canonical phase space: the canonical one-form is invariant under the scaling of conjugate pairs, while the leading Hamiltonian constraint differs between the electric-like and magnetic-like sectors. This difference controls the weak closure of the electric-like constraint algebra and the stronger closure of the magnetic-like Hamiltonian brackets. We separate the generic non-BPS sector, which carries $D-1$ local phase-space degrees of freedom, from the tachyon-vacuum sector, which carries $D-2$ only after imposing second-class background conditions. We also identify the rank condition for the generic electric-like sector and its strengthening in the vacuum sector. Finally, we show that the Carroll–Weyl $\chi$ transformation, the matter-sector analogue of the null-string Carroll–Weyl symmetry, preserves the symplectic form and admits a charge, but is obstructed by the constraints and cannot be promoted to a first-class gauge generator except in highly restricted corners, a global vacuum sector or the singular potential $V\propto T^{-1}$ at $p=1$. The obstruction is algebraic in $\chi$, so no restriction of its spacetime profile can remove it. This contrasts with null string theory, where a restricted $\chi$-symmetry can be completed to an additional first-class constraint.
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Statistical Mechanics

Stochastic Processes as Non-Metric Geodesics in Information Geometry

T. Koide and A. van de Venn

We establish a one-to-one correspondence between geodesics associated with the one-parameter family of $\alpha$-connections on the Gaussian statistical manifold and a class of continuous stochastic processes characterized by a time-independent noise intensity. We demonstrate that geodesics in expectation parameters naturally classify into three distinct geometric categories, among which the Boundary-connecting class allows us to construct an explicit linear stochastic realization with constant diffusion, representing a generalized bridge process. This result demonstrates how continuous stochastic processes within this Gaussian class can be extended along geometric curves. Under appropriate operational limits, this generalized bridge process reduces to fundamental stochastic dynamics, either Ornstein-Uhlenbeck (OU) relaxation or free Brownian diffusion. Crucially, the physical restoring force governing the resulting OU relaxation directly determines the underlying connection parameter $\alpha$, providing a concrete physical observable to constrain the manifold geometry. Depending on the chosen affine connection representation, this restoring force can be attributed either to scalar curvature or purely to non-metricity, establishing a direct conceptual analogy with the Geometrical Trinity of Gravity. Furthermore, applying this framework to driven stochastic thermodynamics, we show that the work-minimizing optimal protocol in the slow-driving limit coincides precisely with an expectation geodesic of the statistical manifold with non-metricity equipped with $(g, {}^{(1/2)}\Gamma, {}^{(-1/2)}\Gamma)$, highlighting the active physical role of non-metricity in information geometry.
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Nuclear Theory

How strange: Phase diagrams with 3 critical points

Mateus Reinke Pelicer, Nikolas Cruz Camacho, Rajesh Kumar et al. (+2 more)

We show that the Chiral Mean-Field model (CMF) can produce a phase diagram with three critical points: the nuclear liquid-gas transition, quark deconfinement, and a strangeness driven transition. The strangeness driven transition separates a mainly nucleonic phase from one dominated by hyperons and baryon resonances. We discuss the compositional change in these transitions and their possible signatures in heavy-ion collisions and neutron star mergers.
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All authors Mateus Reinke Pelicer, Nikolas Cruz Camacho, Rajesh Kumar, Veronica Dexheimer, Jacquelyn Noronha-Hostler

Quantum Physics

Distributed Quantum Property Testing with Quantum Carrier Pigeons

Kenny Chen, Mina Doosti, Ryan Sweke et al. (+1 more)

We introduce a framework for distributed quantum inference under communication constraints. In our model, $m$ distributed nodes each receive one copy of an unknown $d$-dimensional quantum state $\rho$, before communicating via a constrained one-way communication channel with a central node, which aims to infer some property of $\rho$. This framework generalizes the classical distributed inference framework introduced by Acharya, Canonne, and Tyagi [COLT 2019], by allowing quantum resources such as quantum communication and shared entanglement. Within this setting, we focus on the fundamental problem of quantum state certification: Given a complete description of some state $\sigma$, decide whether $\rho=\sigma$ or $\|\rho-\sigma\|_1\geq \epsilon$. Additionally, we focus on the case of limited communication between distributed nodes and the central node: we assume each communication channel is limited to only $n_c$ bits and $n_q$ qubits with $n_c + n_q \leq \log d$. When all nodes can make use of a shared source of randomness, we show that the copy complexity of distributed state certification is $\Theta(\frac{d^2}{2^{n_q} 2^{n_c/2}\epsilon^2})$. We further demonstrate that shared randomness is necessary to achieve the above complexity, by proving an $\Omega(\frac{d^3}{4^{n_q} 2^{n_c} \epsilon^2})$ lower bound in the $\textit{private-coin}$ setting. Moreover, we develop a private-coin algorithm that matches this bound up to a $\sqrt{\log d}$ factor, showing this complexity is near-optimal. Together, our work establishes a general framework for distributed quantum inference with communication constraints and characterizes the complexity of distributed state certification with limited communication.
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All authors Kenny Chen, Mina Doosti, Ryan Sweke, Chirag Wadhwa

Solar and Stellar Astrophysics

The role of specific entropy in the onset of the luminosity bump

S. Hekker

During their evolution, stars follow a distinct path in luminosity–temperature space. Low-mass stars that have exhausted hydrogen in their core follow the so-called red-giant branch which is predominantly in the direction of increasing luminosity and decreasing surface temperature. The luminosity bump is a temporary decrease in luminosity against this otherwise increasing trend. The bump is present in both observations and stellar evolution models. However, with canonical physics included in the models, the bump in computed evolutionary tracks appears at higher luminosities than the observed bump. To understand why the bump appears later in the models than in observations, the physics of the bump needs to be unravelled. The end point of the bump is well-understood; however, the onset of the bump is still an enigma. Here, we report on the physical origin of the onset of the luminosity bump. We show that the difference in specific entropy at the mean molecular weight discontinuity decreases due to the discontinuity moving in. This decrease is attributed to the decrease in the ratio of the temperature to the pressure at smaller radii. Upon reaching a critical value the specific entropy difference at the mean molecular weight discontinuity is reduced sufficiently to reduce the specific entropy in the convective envelope. The latter is a key signature of the bump. Hence the evolution of the specific entropy at the mean molecular weight discontinuity provides a viable description for the onset of the bump.
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Adaptation and Self-Organizing Systems

Double explosive transitions in adaptive multilayer networks with higher-order interactions

Anath Bandhu Das and Pinaki Pal

Can asymmetry between two interacting networks fundamentally change how they synchronize? We identify double explosive transitions in the forward direction, backward direction, or a combination thereof, with single or double hysteresis loops in an adaptive bilayer multiplex network of Kuramoto oscillators with pairwise and three-body interactions and asymmetric phase lags. Using the Ott-Antonsen reduction, we derive a low-dimensional system and perform a stability analysis. The reduced model accurately captures the full microscopic dynamics and enables analytical expressions for the bifurcation points. Systematic mapping across multiple parameter planes reveals eight distinct synchronization regimes. The relative ordering of saddle-node and pitchfork bifurcation points—controlled by phase-lag asymmetry, cross-layer adaptation, and the higher-order interaction strength—creates two distinct coherent branches (weak and strong), giving rise to double explosive transitions. Crucially, phase-lag asymmetry acts as a robust control knob: while symmetric phase lags suppress explosive transitions, layer-specific differences promote multistability and double explosive transitions. The higher-order interaction strength $K_2$ and adaptation strengths $q$, $p$, and $h$ further modulate these transitions in a complex, parameter-dependent manner. Excellent agreement between analytical predictions and numerical simulations confirms the robustness of our reduced description.
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High Energy Physics (Phenomenology)

Axion Hair and Pulsar Electrodynamics: modelling, discharge dynamics, and particle-in-cell simulations

Samuel J. Witte, Andrea Caputo, Stefan Stelzl et al. (+3 more)

In a companion paper, we demonstrated that static axion field gradients sourced by dense nuclear matter (axion hair) can dominate the near-field electrodynamics of old rotation-powered pulsars, leading to new constraints on light QCD axions and on CP-violating axion-nucleon interactions. This article provides the extended theoretical and numerical framework underlying those results. We begin by providing a detailed description of the sourcing of axion hair from dense nuclear matter, computing self-consistent field profiles for each interaction across the relevant parameter space. We then study the modification to the electrodynamics induced in the polar gap region by these axion gradients; this is done at the analytic level by studying the modification induced by axion field gradients on the effective discharge parameter (computed in the force-free limit of the split monopole magnetic field configuration, and looking at leading deviations from the force-free limit for dipolar field configurations), and numerically by developing dedicated 1D particle-in-cell simulations which capture the leading order dynamical behavior near the star. Our results demonstrate that axion hair serves to either enhance acceleration, or enhance screening, where the relevant effect changes between the northern and southern hemispheres of the star, and between the field lines which support out-flowing and return currents.
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All authors Samuel J. Witte, Andrea Caputo, Stefan Stelzl, Alexander Chernoglazov, Alexander A. Philippov, Surjeet Rajendran

Mesoscale and Nanoscale Physics

Non-perturbative theory of valley splitting in Si qubits from variational wave function: periodic effects of shear strain and asymptotic freedom in the wiggle-well potential

Johannes L. P. Steinschuld, Hendrik J. Bluhm and Seyed Akbar Jafari

Valley splitting sets the energy scale at which spin and valley degrees of freedom hybridize in silicon quantum-well qubits, but its sensitivity to interface structure makes it difficult to predict. Using the valleyor basis, we formulate a two-band effective-mass model for intervalley coupling in a finite quantum well and develop an analytical framework for treating non-perturbative effects of shear strain and wiggle-well potentials. For a $z$-independent coupling $V_s\tau_2$, corresponding to uniform shear strain, we construct a variational state from the exact plane-wave valleyors and a hard-wall envelope. This yields closed-form expressions for the two lowest states and their splitting, including the characteristic oscillatory $|\sin(k_{\rm min}L)|$ dependence. The variational result agrees with exact diagonalization to within $\sim1\%$ for realistic couplings, and provides a simple prescription for tuning the shear strain away from the nodes to enhance the valley splitting. We further show that finite barrier heights primarily renormalize the effective width of the quantum well while preserving the oscillatory dependence. For a wiggle-well coupling $V_w\cos(k_wz)\tau_1$, the valleyor representation reveals a crossover near the $k_w=2k_1$ resonance from wiggle-dominated splitting to orbital quantization. Remarkably, at high wiggle-well amplitudes, the empty-box energy scale predominantly dictates the near-resonant valley splitting, while the wiggle-well potential enters only as a sub-leading correction. This behavior can be viewed as asymptotic freedom for spin qubits. Away from resonance, the splitting exhibits a broadly peaked resonance with diffraction-like side-lobes as a function of detuning.
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Chemical Physics

Orbital choice in constructing model Hamiltonians

David W. O. Sousa and Elvira R. Sayfutyarova

Model Hamiltonians (e.g., the Hubbard or Heisenberg models) provide a simple yet physically meaningful description of complex electronic phenomena through a small number of parameters, such as electron hopping integrals or magnetic exchange couplings. Their construction typically exploits the local nature of electron correlation effects and therefore relies on localized orbitals. Although many localization schemes are available, the resulting localized orbitals depend not only on the chosen localization functional but also on the orbital space to which the localization procedure is applied. These choices are often treated as technical details and are rarely discussed explicitly. Here, we demonstrate that different, chemically reasonable choices of localized orbitals can lead to substantially different model Hamiltonian parameters, even when they produce nearly identical electronic energies. Using Density Matrix Downfolding, we systematically investigate how the localization functional and, more importantly, the choice of model orbital space affect effective Hamiltonians derived from ab initio calculations for representative $\pi$-conjugated systems and transition metal complexes.
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Nuclear Experiment

Indirect Measurement of the $\rm S^*(E)$ Factor for $\rm {}^{12}C({}^{12}C,\mathit{p}){}^{23}Na$ at Gamow Energies via the Trojan Horse Method with Near-0 degree Spectator Detection

Chengbo Li, Huiming Jia, Qungang Wen et al. (+8 more)

The astrophysical S*(E) factor for the 12C+12C reaction within the Gamow window plays a pivotal role in modeling stellar carbon burning and explosive nucleosynthesis scenarios. However, direct measurements or even simple extrapolations at these energies are severely hindered by Coulomb suppression and the possible presence of narrow resonances. To address this challenge, we performed an indirect measurement of the 12C(16O,ap)23Na reaction at the HI-13 Tandem Accelerator, employing 16O=(12C+a) as the Trojan Horse nucleus. A key innovation of this Trojan Horse Method (THM) study is the implementation of a copper beam-stopper foil, which enabled the detection of spectator particles near 0, the angular region where their yield is maximized under quasi-free kinematics. The S*(E) factor for the 12C(12C,p)23Na reaction in the astrophysically relevant energy range was extracted using the THM formalism based on the DWBA. Our results confirm the presence of resonant structures within the Gamow window around 1.5 MeV in both the p0 and p1 proton channels. No evidence of a hindrance effect is observed in the measured energy range. Without considering the resonance details, the overall trend of our results is qualitatively in reasonable agreement with the THM-Tumino2018 and TTIK2025 data, but differs significantly from the trend of the Modified-THM-Muk2019 data.
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All authors Chengbo Li, Huiming Jia, Qungang Wen, Chengjian Lin, Lei Yang, Feng Yang, Nanru Ma, Tianpeng Luo, Xuepeng Sun, Shangkun Shao, Xuejian Wang

Atomic Physics

Hyperfine-driven polarization effects in elastic muon scattering by atomic nuclei

Ivan A. Moiseev, Daria M. Vasileva, Konstantin N. Lyashchenko et al. (+3 more)

We present a theoretical study of polarization dynamics in the elastic scattering of muons and antimuons by high-magnetic-moment atomic nuclei, using ${}_{83}^{209}$Bi as a benchmark. The analysis tracks the evolution of (anti)muon polarization and its transfer to the nucleus, emphasizing nuclear-structure corrections. These corrections significantly alter both the differential cross sections and the polarization observables. Our results demonstrate that measuring scattered muon polarization serves as a sensitive probe for nuclear charge radii and magnetic dipole moments.
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All authors Ivan A. Moiseev, Daria M. Vasileva, Konstantin N. Lyashchenko, Igor A. Zhosan, Deyang Yu, Oleg Yu. Andreev

Physics Education

From Local Context to Climate Science: Low-Cost Experimentation in the Initial Training of Physics Teachers

André A. A. Marinho, Edson R. L. Lopes, Jhon KF V. Silva et al. (+2 more)

Climate change poses a major scientific, environmental, and educational challenge, requiring approaches that connect physical concepts, empirical evidence, and socially relevant environmental issues. This study presents and analyzes a low-cost experimental investigation developed within the "Physics and the Environment" course of a Physics teacher training program at the State University of the Tocantina Region of Maranhão (UEMASUL), Brazil. The experiment involved constructing a simplified thermal simulator using accessible materials and comparing a confined system with an open control system, both exposed simultaneously to solar radiation. The results showed that the average temperature inside the simulator was $45.91^{\circ}\mathrm{C}$, compared to $38.58^{\circ}\mathrm{C}$ in the external control system, corresponding to a mean temperature difference of $7.33^{\circ}\mathrm{C}$ (among other analyses). These results demonstrate that the experimental setup was capable of producing and measuring a significant thermal difference between the two systems. However, the observed temperature rise should not be interpreted as a direct measure of the atmospheric greenhouse effect, given that the experimental apparatus involves both radiative and non-radiative heat transfer mechanisms. The study emphasizes the educational potential of low-cost experimentation as a strategy to integrate electromagnetic radiation, energy balance, temperature, heat transfer, and climate science into the initial training of physics teachers. It also highlights the importance of explicitly discussing the limitations of experimental models and distinguishing local experimental evidence from conclusions regarding global climate processes.
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All authors André A. A. Marinho, Edson R. L. Lopes, Jhon KF V. Silva, Mariana S. Costa, Maria A. Morais

High Energy Physics (Theory)

Splitting Dynamics of Multiply Quantized Vortices in Holographic Superfluid of Finite Temperature

Shanquan Lan, Xin Li, Jiexiong Mo et al. (+3 more)

We study the splitting dynamics of multiply quantized vortices with winding numbers $n=5,6,7$ and $8$ in a two-dimensional holographic superfluid at finite temperature, by combining linear perturbation analysis of quasinormal modes with fully nonlinear real-time numerical simulations. Three new physical phenomena are revealed. First, the number of unstable modes no longer strictly follows the $2n-3$ formula as $n$ increases. For the vortex with $n=8$, the unstable mode with $p=2(n-1)$ is absent throughout the entire temperature range, so that only $2n-4$ unstable modes exist. Second, the transition of the dominant unstable mode with increasing temperature exhibits new characteristics. For vortices with $n\le 6$, the dominant mode changes sequentially as $p=2,3,\dots,n$, whereas for $n\ge 7$ jump-like transitions occur-for instance, for $n=7$ the dominant mode jumps from $p=2$ to $p=4$ at $T=0.325T_c$ and then directly to $p=7$ at $T=0.359T_c$, and for $n=8$ it jumps directly from $p=2$ to $p=8$ at $T=0.302T_c$. Third, a single splitting pattern of high-winding-number vortices can contain multiple sub-splitting patterns with distinct topological structures, as exemplified by the $l=4$ pattern of the $n=8$ vortex, which exhibits three sub-patterns at low, intermediate and high temperatures. The nonlinear simulations confirm the predictions of the linear stability analysis, and the implications of our results for cold-atom experiments are discussed.
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All authors Shanquan Lan, Xin Li, Jiexiong Mo, Yu Tian, Yu-Kun Yan, Hongbao Zhang

Cosmology and Nongalactic Astrophysics

Why Azimuthal Averaging Works in Halo Lensing: Symmetry and Power Counting for Nonlinear Shear and Magnification

Keiichi Umetsu

Cluster weak-lensing analyses often compress two-dimensional lensing fields into azimuthally averaged radial profiles and evaluate nonlinear observables from the averaged convergence and shear. However, the ring average of a nonlinear observable generally differs from the mean-field prediction formed from the averaged fields. This difference, divided by the mean-field prediction, defines the fractional residual. For a complete ring, the difference begins at second order in angular fluctuations. For centered elliptical halos, rotational symmetry makes the shape contribution even in signed ellipticity, while the leading miscentering dipole is orthogonal to the shape quadrupole. We test these predictions using projected triaxial NFW halos at six mass-redshift grid points spanning $3\leq M_{200\mathrm c}/(10^{14}\,h^{-1}M_\odot)\leq20$ and $0.2\leq z_l\leq0.5$, for $z_s=1$. For the reference offset model, centering offsets follow a Rayleigh distribution with scale $0.05r_{200\mathrm c}$. For $0.366\leq R/r_{200\mathrm c}\leq1$, where at least $95\%$ of each population satisfies a conservative subcriticality criterion, we calculate the median of the fractional residuals across the retained halos for each population and radius. The largest population-median magnitudes are $0.90\%$ for reduced shear, $0.0093\%$ for inverse magnification, $0.64\%$ for magnification, and $0.18\%$ across the two magnification-bias cases $\mu^{\alpha-1}$ ($\alpha=0.3, 1.4$). In the paired calculation at $z_s=2$, the maximum magnitude increases for every observable, consistent with weak-lensing power counting. Across both source planes and the common radial domain, every population median remains below $2\%$ in magnitude. This accuracy follows from first-order cancellation, rotational symmetry, and harmonic orthogonality, with further weak-lensing suppression of the remaining nonlinear terms.
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High Energy Astrophysical Phenomena

Phase-Resolved Ultra-High-Energy Emission Defines an Energetic Boundary for Compact-Object Engines and Dense-Matter Structure

Marlon M. S. Mendes and Cesar H. Lenzi

We show that phase-resolved ultra-high-energy emission from LS I \(+61^\circ303\) defines a critical energetic boundary linking the compact-object engine, circumstellar interaction depth, and dense-matter structure. Combining the GeV–TeV–UHE spectral transition with an orbital acceleration–transparency sieve and branch-resolved stellar sequences for 116 certified EoS, we find that the measured \(25\)–\(100\) TeV component remains energetically viable for all 116 canonical-mass EoS and therefore does not discriminate among them. EoS discrimination arises only in the deliberately more demanding pure-hadronic \(>1\) TeV stress-test construction: at 2.0 kpc and \(1.4\,M_\odot\), this boundary gives \(I_{45,\rm crit}=1.5504\), with 82 of 116 EoS satisfying the energetic condition at\(\dot P_{\rm ref}=3\times10^{-15}\,{\rm s\,s^{-1}}\). A separately applied tidal diagnostic, \(\Lambda_{1.4}\leq580\), is satisfied by 43 EoS, with nine satisfying both conditions. These models span several microscopic classes but occupy a narrow structural region, indicating structural overlap rather than selection of a unique EoS family. A separate GeV power-budget test requires \(\dot P_{\rm rot}\gtrsim 5.65\times10^{-14}f_\Omega\,{\rm s\,s^{-1}}\) at 2.0 kpc. For \(f_\Omega\sim1\), the source lies well above the UHE crossing and the EoS discrimination disappears. The UHE observation therefore identifies the engine–environment regime in which differences in neutron-star structure can become observationally discriminating, rather than defining a universal dense-matter selector.
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General Relativity and Quantum Cosmology

Neutral scalar particle in a charged wormhole background

Matheus D. de Oliveira and Alexandre G. M. Schmidt

We investigate the dynamics of a neutral scalar particle in a charged traversable wormhole background, considering harmonic and modified harmonic oscillator couplings. By solving the Klein–Gordon equation, the radial problem is reduced to a generalized Heun equation, whose polynomial truncation yields the bound-state energy spectrum and quantized oscillator frequencies. Although the particle is electrically neutral, the energy spectrum depends indirectly on the wormhole charge through the geometric deformation of spacetime. We also analyze the dependence of the oscillator frequency on the angular momentum, throat parameter, electric charge, and the additional interaction parameter $V_{0}$. The appropriate limits recover the corresponding results for the uncharged wormhole and the standard harmonic oscillator.
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Statistical Mechanics

When does nonreciprocity matter? Scale-dependence and nonequilibrium signatures

Sarah A.M. Loos and Robert L. Jack

Nonreciprocity is increasingly recognized as a unifying concept linking diverse nonequilibrium phenomena found across physics, chemistry, and biology. It gives rise to distinctive behavior including run-and-chase dynamics and spatio-temporal patterns, often associated with a breaking of time-reversal symmetry. However, nonreciprocity and its nonequilibrium signatures are fundamentally scale-dependent, and may emerge or disappear under coarse-graining. A central challenge is therefore to understand when and how nonreciprocity manifests itself on different scales, for example via irreversible fluctuations or macroscopic currents. In this Perspective, we discuss the physical origin and fate of effective nonreciprocal interactions and the characteristic irreversible dynamics they give rise to across scales.
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Nuclear Experiment

$\rm S^*(E)$ measurement of the $\rm {}^{12}C({}^{12}C,\alpha){}^{20}Ne$ reaction at astrophysical energies via the Trojan horse method with $\rm ^{16}O$ quasi-free breakup

Chengbo Li, Huiming Jia, Qungang Wen et al. (+9 more)

The 12C(12C,a)20Ne reaction at astrophysical energies is crucial for understanding the carbon burning process in massive star and explosive astrophysical scenarios like Type Ia supernovae and X-ray bursts. However, directly measuring or simply extrapolating its S*(E) factor is extremely challenging due to Coulomb suppression and potential complex resonance structures near the Gamow window (1.5+-0.3 MeV). The THM can circumvent the Coulomb barrier, providing data within the Gamow window without extrapolation. Strong resonances near 1.5 MeV were previously reported by Tumino et al. using THM with 14N=(12C+d), a result that generated significant interest and debate, underscoring the need for further experimental verification. In this work, we selected 16O=(12C+a) as the Trojan-horse nucleus due to its lower binding energy, which favors quasi-free reactions. We performed an indirect measurement of 12C(16O,aa)20Ne at the HI-13 Tandem Accelerator at CIAE. Employing a copper beam-stopper foil, we measured the spectator a-particle within a small angular range around 0, where the quasi-free mechanism predicts its highest concentration. The S*(E) factor of 12C(12C,a)20Ne in the astrophysical energy region was extracted from the measured three-body reaction using THM based on DWBA. Our results confirm the existence of resonances within the Gamow window around 1.5 MeV in both the a0 and a1 channels. Without considering the details of the resonance structures, the overall trend of our results is qualitatively in reasonable agreement with the THM-Tumino2018 and TTIK2025 data, but differs significantly from the trend of the Modified-THM-Muk2019 data. We observe no evidence for hindrance effect in our results.
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All authors Chengbo Li, Huiming Jia, Qungang Wen, Chengjian Lin, Lei Yang, Feng Yang, Nanru Ma, Peiwei Wen, Tianpeng Luo, Chang Chang, Xuepeng Sun, Xuejian Wang