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Monday 31 August

High Energy Physics (Theory)

Examples of Gribov copies in the presence of planar boundaries, and an emergent boundary gauge invariance in Yang-Mills theory

David Dudal, Luigi Rosa and Sebbe Stouten

First, we explicitly construct zero-modes of the Yang-Mills Faddeev-Popov operator in the presence of two parallel plates, with either perfect electric (PEC) or perfect magnetic (PMC) boundary conditions imposed. This establishes the existence of Gribov copies with finite action, and even finite L_2-norm, in Yang-Mills theory with non-trivial interfaces. We adapt Henyey's construction, although the boundary configuration imposes extra restrictions on the ansatz for the gauge field. Second, we discuss the phenomenon of an emergent boundary gauge invariance for PEC and PMC plates in Yang-Mills theory. This shall be important when applying the Gribov-Zwanziger procedure to parallel plate setups, of relevance for non-perturbatively studying the non-Abelian Casimir effect in the future.
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Mesoscale and Nanoscale Physics

Evanescent-mode Casimir-Josephson force and gate-controlled resonances in ballistic graphene Josephson junctions

Shahrukh Salim

We develop a microscopic scattering theory of the phase-dependent equilibrium mechanical response of a ballistic superconductor-graphene-superconductor Josephson junction. The calculation is based on an energy-dependent Dirac scattering matrix embedded in a normalized Matsubara determinant, so the reported force correction contains the complete Bogoliubov-de Gennes spectrum of the stated ideal model. At charge neutrality the full determinant approaches a closed-form evanescent-mode result proportional to $\Delta W/L^2$, reaching $2\ln 2\,\Delta W/(\pi L^2)$ at phase difference $\pi$ in the zero-temperature short-junction limit. Gate doping produces propagating channels and Fabry-Pérot structure, causing large oscillations and sign reversals of the phase-dependent force correction $\delta F=F(\phi)-F(0)$. We distinguish the interband-to-intraband Andreev crossover, controlled by $|\mu|/\Delta$, from the evanescent-to-propagating crossover, controlled by $|\mu|L/(\hbar v_F)$. Exact real-energy subgap poles obtained from the same energy-dependent scattering matrix are used to diagnose specular/interband and retro/intraband character; these labels are not treated as separately measurable thermodynamic forces in the mixed regime. We also quantify the difference between the complete determinant result and the frozen-scattering short-junction approximation without identifying that difference with a pure continuum force. The resulting gate- and phase-dependent mechanical signal provides a Dirac-material extension of earlier superconductivity-induced mechanical-force proposals.
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High Energy Physics (Phenomenology)

Two-loop QCD corrections to $CP$-even Higgs boson decays into $V\gamma$ in the Type-I Two-Higgs-Doublet Model

Lin-Qiao Qu, Zhong-Yuan Liu, Peng-Fei Duan et al. (+2 more)

We investigate the QCD corrections to the loop-induced decays of the heavy $CP$-even Higgs boson, $H \to V\gamma$ ($V = Z, \gamma$), within the framework of the Type-I Two-Higgs-Doublet Model (THDM). Owing to the similarity of the underlying loop topologies, the two decay channels exhibit closely correlated behaviour. After imposing relevant phenomenological constraints, we evaluate the decay widths for 5000 viable parameter points at next-to-leading order (NLO) in QCD under the alignment limit. The $H\to\gamma\gamma$ width exceeds that of $H\to Z\gamma$ by roughly a factor of four. Both are dominated by the top-quark loop: the $W$ contribution vanishes in the alignment limit, and the charged-Higgs loop is suppressed throughout most of the viable parameter region. The corrections exhibit a pronounced dependence on the heavy Higgs boson mass $m_H$, attaining a maximum in the vicinity of the $t\bar{t}$ production threshold. To elucidate the individual parameter dependences, dedicated benchmark scenarios are analysed, revealing that the decay widths diminish monotonically with increasing $\tan\beta$ while growing with $m_H$. The QCD corrections for both decay modes typically span approximately $-20\%$ to $+20\%$, with larger corrections in the non-alignment scenario: in the $H\to\gamma\gamma$ channel they reach up to $+38\%$ at large $\tan\beta$, and in the $H\to Z\gamma$ channel they cross zero to become positive. The $CP$ selection rule forces the $t\bar{t}$ pair into a $P$-wave configuration at threshold, which strongly suppresses the Coulomb corrections and secures the perturbative stability of the fixed-order prediction. A comparison with ATLAS limits shows that current data do not yet constrain the parameter space, whereas the $\mathcal{O}(15\%)$ NLO corrections may become relevant for interpreting exclusion bounds at the HL-LHC.
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All authors Lin-Qiao Qu, Zhong-Yuan Liu, Peng-Fei Duan, Yu Zhang, Wei-Long Duan

High Energy Physics (Phenomenology)

Meson gravitational D-form factors and symmetry breaking in low-energy QCD

Mamiya Kawaguchi, Kazuhiro Tanaka and Mitsuru Tanaka

We investigate meson gravitational D-form factors in the three-flavor linear sigma model and their connection to symmetry breaking in low-energy QCD. Within the scalar meson dominance picture, we examine the scalar meson exchange contributions and their relation to meson masses through scalar-meson couplings. In the three-flavor symmetric limit, we first derive analytical expressions for the D-form factors of pseudoscalar and scalar mesons. In the chiral limit, the forward-limit value of the octet pseudoscalar D-form factor is fixed to $-1$, whereas the $U(1)_A$ anomaly generates additional contributions to the singlet pseudoscalar and scalar-meson D-form factors. For realistic flavor breaking, the interaction introduced to reproduce the scalar-meson mass hierarchy below $1$ GeV significantly affects the scalar-meson D-form factors. We further compare the linear sigma model results with those obtained from a chiral perturbation theory Lagrangian including a dilatonic scalar field and show that their differences are governed by the canonical mass dimensions of the interaction terms contributing to meson mass generation. These results indicate that meson D-form factors provide sensitive probes of symmetry-breaking structures in low-energy hadron physics.
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Fluid Dynamics

A Physics-Informed, PIV-Based Method for Surface Pressure Reconstruction

Abbas Daliri and Fulvio Scarano

A physics-informed method for PIV-based surface pressure reconstruction that combines least-squares optimization with both local and global physical constraints is proposed. The standard deviation of the surface–normal pressure gradient is introduced as a physically meaningful weighting function in the optimization process. Moreover, a physical global constraint is also introduced to reconstruct surface pressure outside the suction region. The results show very good agreement with data obtained from pressure taps. Near the leading edge, the surface pressure reconstruction error has been reduced by one-third.
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Medical Physics

Imaging cellular-level brain microstructure with diffusion MRI

Xiaodong Li, Jing Zhao, Baolan Lu et al. (+4 more)

Noninvasive live-cell imaging in deep human tissues is crucial for exploring the cellular biological and pathogenic processes, but remains a significant unmet challenge. Diffusion magnetic resonance imaging (dMRI) promises to narrow this gap by noninvasively providing cellular-level microstructural information. Within a single crowded voxel containing millions of living cells, the intricate cellular-level microstructures create numerous microcompartments, each characterized by a specific diffusivity. However, conventional dMRI methods relying on voxel-averaged macroscopic parameters, merely reflect aggregate microstructural properties and fail to quantify this distribution of microcompartment-specific diffusivity within a voxel, thereby obscuring microstructural details. Here, we propose an intravoxel diffusivity probability distribution (IDPD) model to resolve a wealth of essential microstructural information via quantifying microcompartment-specific diffusivity distribution, thereby enabling direct cellular-level characterization. This exceptional capability is realized through a multi-tiered analytical workflow spanning targeted single-voxel or region of interest (ROI) analysis to global visualization using dynamic videos and statistic parametric maps. Ultimately, the IDPD model enables noninvasive cellular-level microstructure imaging, offering a promising avenue to evaluate living cell functions in vivo.
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All authors Xiaodong Li, Jing Zhao, Baolan Lu, Jinzhu Wang, Xinhua Wei, Qingxian Yang, Xuegang Xin

Statistical Mechanics

d'Q = TdS for Infinitesimal Irreversible Processes: On the Differential Form of the Clausius Inequality

Hiroshi Shimahara

Conventionally, the differential form of the Clausius inequality is adopted for infinitesimal irreversible processes. We show that the correct first-order form for infinitesimal quasi-static irreversible processes is the equality d'Q=TdS rather than d'Q < TdS. This provides a purely thermodynamic proof that internal entropy production is second-order or higher and confirms that entropy remains a well-defined state quantity even when quasi-static irreversible processes are included, without resorting to the Boltzmann relation.
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Lattice Field Theory

Bias-Corrected Machine-Learning Estimation of Chiral Condensate Cumulants: A Retrospective Lattice QCD Case Study

Benjamin J. Choi, Hiroshi Ohno and Akio Tomiya

We present a retrospective case study of bias-corrected machine learning (ML) estimates of traces of the inverse Dirac operator, $\text{Tr}\,M^{-n}$ ($n=1,2,3,4$), using a fixed lattice QCD dataset and examining how the results depend on the relative proportions of the labeled and training sets. Two supervised learning approaches are examined: one using $\text{Tr}\,M^{-1}$ as the input feature, and the other employing gauge observables such as the plaquette and rectangle. Beyond the direct estimation of $\text{Tr}\,M^{-n}$, we further investigate two derived applications of the ML estimations: the evaluation of the cumulants of the chiral condensate within a single ensemble and that obtained through multi-ensemble reweighting across ensembles with different quark masses. Within this fixed dataset, the bias-corrected estimates show close agreement with the full-data reference under the adopted evaluation criteria, while the uncorrected estimates can exhibit amplified deviations after the nonlinear cumulant and reweighting steps. For the approach using $\text{Tr}\,M^{-1}$ as the input feature, nominal solve-count accounting suggests that the Dirac-inversion cost could be reduced to approximately $25.75\%$ of that of the conventional calculation in the present setup. This value is a cost projection rather than an end-to-end benchmark: it assumes comparable costs for successive inversions and excludes model-training and analysis overhead.
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Earth and Planetary Astrophysics

Planar Three-Body Problem: theoretical predictions and simulation results

Yogesh Dandekar, Ethan Springer, Shoval Zard et al. (+3 more)

We investigate the statistical properties of the non-hierarchical planar three-body problem, relevant to astrophysical systems with nearly planar dynamics, including protoplanetary disks and AGN disks. Using the Flux-based statistical theory of the three-body problem, previously studied in three dimensions, we derive theoretical predictions for several statistical observables in the planar case. Focusing on ergodic disintegration outcomes, we compare these predictions directly with numerical simulations and contrast the results with the corresponding unconstrained three-dimensional case. Our analysis is based on one million simulations for each of eight distinct mass sets. We examine escape probabilities, properties of marginal escape events, eccentricity distributions, lifetime distributions, and relative prevalence of prograde and retrograde escapes. While several of the theoretical predictions are in good agreement with the simulations, others exhibit unexpected discrepancies. We discuss possible explanations for these deviations.
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All authors Yogesh Dandekar, Ethan Springer, Shoval Zard, Alessandro Alberto Trani, Barak Kol, Ofek Birnholtz

Optics

Spatially or temporally resolved phase-based optoretinography with actively-tracked point-scanning optical coherence tomography

Léo Puyo, Jonas Franke, Felix Zeisberger et al. (+2 more)

Optoretinography is a promising approach to measure visual function but its clinical translation has remained confined to research settings due to demanding hardware requirements. Here, we demonstrate that high-quality phase-based optoretinography can be performed using conventional point-scanning spectral-domain optical coherence tomography. We show that the need for high imaging speed can be circumvented by accurate sampling of phase changes at consistent spatial location. Light-evoked outer-segment expansion could be temporally resolved in B-scan series acquired at a fixed position when filtering off-location B-scans, and spatially resolved in volumes acquired at rates as low as 1~Hz. These results indicate that the technical barrier for phase-based optoretinography is substantially lower than previously assumed and pave the way toward broad clinical translation.
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All authors Léo Puyo, Jonas Franke, Felix Zeisberger, Roland Rocholz, Gereon Hüttmann

Materials Science

Extending the Pnictide Chemical Space for Photovoltaics

Avaneesh Balasubramanian and Gopalakrishnan Sai Gautam

Developing novel and efficient materials that are beyond silicon for photovoltaic (PV) applications is required to meet the upcoming energy needs of our societies. To identify novel candidate materials that can act as PVs, we use first principles calculations to perform a systematic screening of the pnictide chemical space (i.e., nitrides and phosphides). Specifically, we explore three different ternary and quaternary pnictide classes, namely, ABCX$_2$, BB'B"X$_2$, and A$_4$BX$_2$ (A = Li, Na, or K; B, B', B" = Ca, Sr, Mg, or Zn; C = Al, Ga, or In; X = N or P), leading to a set of 104 possible pnictide compositions. Based on our evaluations of ground state structures, 0 K thermodynamic stabilities, electronic structures, carrier effective masses, dynamic stabilities, and intrinsic point defect formation energies, we arrive at three promising candidates, namely, NaCaInN$_2$, NaSrInN$_2$, and K$_4$ZnP$_2$. Notably, all the identified candidates are thermodynamically (meta)stable, exhibit direct (or nearest direct) band gaps that are optimal for PV applications, and are resistant to forming several types of point defects. We hope that our first principles driven workflow and the identified candidates will advance the development of novel PV materials and reinvigorate interest in the exploration of pnictides.
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Applied Physics

Towards an effective medium theory for in-vivo Magnetic Resonance: Characterizing Admissible Magnetization Dynamics

Alessandro Sbrizzi, Miha Fuderer and Ray Sheombarsing

The classical Bloch equation forms the foundation of magnetic resonance theory but may be insufficient to capture the complex effective dynamics observed in heterogeneous materials such as biological tissue. Here an effective-medium strategy is proposed to describe magnetic resonance dynamics from observations at macro-scale (order 1 mm$^3$). In this framework, the classical Larmor torque is retained while the relaxation term is replaced by a general nonlinear field (i.e. the effective medium term). This field is required to preserve key physical properties, including rotational symmetry, global stability of thermal equilibrium, and dissipativity. These requirements lead to a complete characterization of admissible relaxation fields and provide a constructive framework for generating nonlinear relaxation models. The resulting theory recovers classical Bloch dynamics as a special case and provides a principled foundation for effective-medium descriptions of magnetic resonance phenomena.
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Strongly Correlated Electrons

Pseudospin Dynamics of Charge Order

Ping Tang

Charge order is conventionally viewed as a static modulation of the electronic density, despite growing experimental capabilities to probe and manipulate its nonequilibrium evolution. In contrast to spin-ordered systems, a microscopic framework for charge-order dynamics and its control under external driving remains largely underdeveloped. Here, starting from an extended Hubbard model, we derive an effective pseudospin model in which the charge-ordered state maps onto staggered pseudospin order. The resulting charge-order dynamics is governed by Landau–Lifshitz–Gilbert-like equations for the pseudospins, closely analogous to those of a bipartite antiferromagnet. We show that an external electric field directly controls the staggered pseudospin order and, above a threshold field, drives coherent reversal of the charge-order polarity by destabilizing collective pseudospin excitations. Our results establish the charge pseudospin as a microscopic dynamical degree of freedom for coherent switching and control of charge order, providing a charge-sector analogue of the well-established framework for spin-order dynamics in spintronics.
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Soft Condensed Matter

Optimal Transport of an Anisotropic Tracer in Dense Active Suspensions

Chandranshu Tiwari and Sunil P. Singh

The transport of anisotropic tracers in active fluids exhibits rich dynamical behavior arising from the interplay between particle shape, activity, and steric interactions. We employ Brownian dynamics simulations to investigate the motion of an elliptical tracer immersed in a suspension of active dumbbells. We find that both translational and rotational transport, characterized by the mean-square speed and diffusivity, are enhanced by more than an order of magnitude with increasing area fraction, $\phi$, of active dumbbells. Notably, tracer motion is enhanced along the major axis relative to the minor axis, with $\mathrm{v}_{\parallel}>\mathrm{v}_{\perp}$ and $D_{\parallel}>D_{\perp}$. Remarkably, both translational and rotational transport exhibit an optimum at an intermediate packing fraction of active dumbbells, with the corresponding transport coefficients decreasing at higher densities. We show that this non-monotonic transport arises from the anisotropic accumulation and aggregation of active dumbbells around the tracer, which control the non-equilibrium force and torque fluctuations. Thus, establish a direct connection between the collective organization of active dumbbells at the tracer surface and its emergent translational and rotational transport.
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High Energy Physics (Phenomenology)

First-principle predictions of fragmentation functions via quantum computing

Juan J. Gálvez-Viruet, Felipe J. Llanes-Estrada, Nicolas M. Arenaza et al. (+2 more)

We report on an algorithm to compute fragmentation functions from the first principles Quantum Chromodynamics (QCD) Hamiltonian quantized in Light-Front Gauge, opening a path for digital quantum computers to calculate these longitudinal jet-structure observables. Simulating the behaviour of such computers on a classical cluster (which is memory-limited to about 30 qubits, given the expansive Hilbert spaces of actual quantum computers), we run a demonstration of a heavy-quark leading parton fragmenting into quarkonium, which we benchmark against NRQCD computations. Future quantum computers, perhaps concurrently running with HL-LHC, would have ample opportunity to extract arbitrary parton-hadron combinations.
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All authors Juan J. Gálvez-Viruet, Felipe J. Llanes-Estrada, Nicolas M. Arenaza, María Gómez-Rocha, T. J. Hobbs

Quantum Physics

Marginal spectral distributions on regular bipartite unitary orbits

Lin Zhang

Fix the spectrum of a bipartite density matrix and randomize its eigenbasis according to Haar measure. We study the probability distributions induced on the spectra of the two marginal states. For arbitrary subsystem dimensions $m$ and $n$, the joint characteristic function of the reduced density matrices is expressed as a Harish-Chandra-Itzykson-Zuber integral whose external eigenvalues are the pairwise sums $x_i + y_j$. Repeated external eigenvalues are handled by confluent determinant limits. In the two-qubit case, we derive an explicit alternating-spline formula for the joint density of the two marginal Bloch radii. Its support is the Bravyi-Klyachko compatibility region. We also obtain a compact truncated-power formula for the Bloch-radius density of either individual qubit marginal. In the qubit-qutrit case, we derive a truncated-power formula for the qubit Bloch-radius density and a bivariate spline formula for the joint density of the largest and smallest eigenvalues of the qutrit marginal. The latter two variables determine the full qutrit spectrum because the trace is fixed. The derivations combine confluent HCIZ integrals, distributional Fourier inversion, orbital measures, and the SU(2) and SU(3) derivative principles. The resulting densities are piece-wise polynomial on chambers determined by subset sums of the fixed global eigenvalues, in agreement with the Duistermaat-Heckman description of projected coadjoint-orbit measures.
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Quantum Physics

Quantum Imaginary Time Evolution on an Infinite 1D Chain

Hao-Ti Hung, Tung Tsao and Ying-Jer Kao

We introduce a quantum-circuit algorithm for performing imaginary-time evolution on infinite one-dimensional lattice systems. The method uses a parameterized quantum circuit to represent a uniform matrix product state ansatz. We derive the ITE algorithm using the time-dependent variational principle and employ the quantum Lanczos algorithm to improve the ground-state energy estimate. As a benchmark, we simulate the transverse-field Ising model using both classical simulators and IBM Quantum devices. Our analysis includes a statistical study of the distributions of the cost function and energy density obtained from quantum measurements, illustrating the effects of finite-sampling noise on convergence.
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High Energy Physics (Experiment)

Search for proton decay into a single charged antilepton and a massless invisible particle using the full pure water data set of Super-Kamiokande

Super-Kamiokande Collaboration: Y. M. Liu, K. Terada, K. Abe et al. (+245 more)

A search for proton decay via $p\rightarrow l^{+}+X$, where $l^{+}$ is a positively charged lepton and $X$ is an invisible, massless, neutral particle, was performed using a 401~kton$\cdot$years exposure representing the entire pure water phase of Super-Kamiokande. No significant indication of a proton decay was observed beyond the expected atmospheric neutrino background. Lower limits on the partial lifetime of the proton were set to at $1.72\times10^{33}$ years for $p\rightarrow e^{+}+X$ and $0.61\times10^{33}$ years for $p\rightarrow \mu^{+}+X$ at the $90\%$ confidence level. These results improve on previous limits by factors of 2 and 1.5, respectively.
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All authors Super-Kamiokande Collaboration: Y. M. Liu, K. Terada, K. Abe, Y. Asaoka, M. Harada, Y. Hayato, K. Hiraide, T. H. Hung, K. Ieki, M. Ikeda, J. Kameda, Y. Kataoka, S. Mine, M. Miura, S. Moriyama, K. Nakagiri, M. Nakahata, S. Nakayama, Y. Noguchi, G. Pronost, K. Sato, H. Sekiya, R. Shinoda, M. Shiozawa, Y. Suzuki, A. Takeda, Y. Takemoto, H. Tanaka, S. Chen, Y. Itow, T. Kajita, R. Nishijima, K. Okumura, T. Tashiro, T. Tomiya, X. Wang, F. J. de Garay Arcones, P. Fernandez, L. Labarga, D. Samudio, C. Yanagisawa, B. Jargowsky, E. Kearns, J. Mirabito, L. Wan, T. Wester, B. W. Pointon, J. Bian, B. Cortez, N. J. Griskevich, Y. Jiang, M. B. Smy, H. W. Sobel, V. Takhistov, J. Hill, B. D. Xu, D. Jung, D. H. Moon, R. G. Park, B. S. Yang, K. Scholberg, C. W. Walter, O. Drapier, A. Ershova, M. Ferey, Z. Hu, E.~Le Blévec, T. Leplumey, Th. A. Mueller, P. Paganini, C. Quach, R. Rogly, T. Nakamura, J. S. Jang, R. P. Litchfield, L. N. Machado, F. J. P. Soler, J. G. Learned, K. Choi, S. Cao, T. V. Ngoc, L. H. V. Anthony, N. W. Prouse, M. Scott, Y. Uchida, V. Berardi, N. F. Calabria, M. G. Catanesi, N. Ospina, E. Radicioni, A. Langella, G. De Rosa, G. T. Burton, G. Collazuol, M. Feltre, M. Mattiazzi, L. Ludovici, M. Gonin, L. Périssé, B. Quilain, M. Fukazawa, S. Horiuchi, A. Kawabata, Y. Maekawa, Y. Nishimura, A. Oka, H. Tanigawa, R. Akutsu, M. Friend, T. Hasegawa, Y. Hino, T. Ishida, T. Kobayashi, T. Matsubara, T. Nakadaira, Y. Oyama, A. Portocarrero Yrey, K. Sakashita, T. Sekiguchi, N. Bhuiyan, F. Di Lodovico, T. Katori, R. Kralik, N. Latham, R. M. Ramsden, V. Siccardi, S. Aoyama, H. Bambara, Y. Inaba, H. Ito, M. Nishigami, T. Sone, A. T. Suzuki, Y. Takeuchi, S. Wada, H. Zhong, J. Feng, L. Feng, N. Fujimoto, S. Han, J. Hikida, M. Kawaue, T. Kikawa, F. Nakanishi, T. Nakaya, R. A. Wendell, S. J. Jenkins, N. McCauley, M. Fanì, M. J. Wilking, Z. Xie, Y. Fukuda, H. Menjo, Y. Yoshioka, J. Lagoda, J. Zalipska, T. Yano, M. Mori, J. Jiang, Y. Asano, K. Hamaguchi, H. Ishino, Y. Koshio, S. Ohshita, T. Tada, T. Ishizuka, G. Barr, D. Barrow, D. Wark, A. Holin, F. Nova, M. Jo, S. Jung, J. Yoo, L. Kneale, T. Peacock, P. Stowell, H. Okazawa, S. M. Lakshmi, S. Hong, E. Kwon, M. W. Lee, J. W. Seo, I. Yu, Y. Ashida, A. K. Ichikawa, S. Kobayashi, K. D. Nakamura, S. Abe, W. Cai, Y. Endo, S. Goto, S. Kodama, Y. Kong, H. Hayasaki, Y. Masaki, Y. Mizuno, T. Muro, K. Nakagiri, Y. Nakajima, M. Sekiyama, N. Taniuchi, T. Yamazumi, M. Yokoyama, P. de Perio, S. Fujita, C. Jesús-Valls, K. Martens, Ll. Marti, A. D. Santos, K. M. Tsui, M. R. Vagins, S. Izumiyama, M. Kuze, R. Matsumoto, C. Ise, M. Ishitsuka, M. Sugo, M. Wako, K. Yamauchi, Y. Nakano, A. Yankelevich, F. Cormier, R. Gaur, M. Hartz, A. Konaka, X. Li, B. R. Smithers, S. Chen, Y. Wu, A. Q. Zhang, B. Zhang, H. Adhikary, M. Girgus, P. Govindaraj, M. Posiadala-Zezula, Y. S. Prabhu, S. B. Boyd, R. Edwards, D. Hadley, M. O'Flaherty, B. Richards, A. Ali, B. Jamieson, C. Bronner, D. Horiguchi, A. Minamino, Y. Sasaki

Applied Physics

Arctic Dispersion Interruption Phenomenon and Sound Source Depth Estimation

Weng Jinbao, Yang Yanming, Chen Benqing et al. (+2 more)

The sound speed profile in the deep Arctic Ocean causes the surface layer to form a normal mode waveguide. When the depth of the sound source or receiver is near a node of the eigenfunction, the source cannot excite the mode, or the receiver cannot detect it, resulting in the modal amplitude at the receiver being approximately zero. This manifests as a dispersion interruption in the dispersion structure, which can be observed through time-frequency analysis of the received acoustic signal. Based on the interruption frequency identified from the received signal, combined with the relationship between node depth and modal frequency calculated from the ocean sound speed profile, the source depth can be estimated if the receiver depth is known. The phenomenon of dispersion interruption and the method of estimating source depth have been validated through simulations and experiments.
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All authors Weng Jinbao, Yang Yanming, Chen Benqing, Xu Dewei, Zhou Hongtao

Materials Science

Real-space overlap is not enough: ambiguity in nanobeam iterative ptychography

Stephanie M. Ribet, Mohsen Danaie, Willem P.M. de Kleijne et al. (+5 more)

High-resolution iterative ptychography typically relies on a well-aligned, high-convergence-angle electron probe. Here we explore whether it can instead be performed at small convergence angles, relaxing the need for probe correctors and enabling experiments at low accelerating voltages or with a de-excited objective lens, as in Lorentz mode. Through experiments and simulations, we show that once the convergence angle is small enough that no diffracted disks overlap, the resulting reconstruction is ambiguous, posing a significant challenge for robust interpretation of results. This challenge arises because of the lack of interference between Bragg disks in the recorded diffraction pattern intensity, leading to no phase information for each reflection. Reconstructions with these data lead to degenerate objects in which rigid translations of the lattice and reversals of contrast of the object produce the same error between experimental data and the ptychography forward model. Increasing the real-space overlap between probe positions does not lift this degeneracy. An amorphous substrate can supply the missing phase relationships by giving the Bragg beams support in the gaps between disks. This phasing is fragile, however, and survives only where the forward model matches the experiment. At fixed dose, either constraining the object to be a pure phase object or introducing thermal motion into the forward model is enough on its own to make the solution non-unique, highlighting why our experimental reconstructions below the overlap threshold are ambiguous despite ample dose and real-space redundancy. Most troublingly, the lattice spacing and orientation are always recovered correctly, so a non-unique reconstruction looks convincing and can be diagnosed only by repeating the reconstruction from different starting points.
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All authors Stephanie M. Ribet, Mohsen Danaie, Willem P.M. de Kleijne, Arthur R. C. McCray, Frederick Allars, Christopher S. Allen, Colin Ophus, Georgios Varnavides

High Energy Astrophysical Phenomena

Hunting the nature of the Seyfert 1 galaxy GRS 1734-292: can it be a gamma-ray emitter?

Luigi Foschini

It has been proposed that the radio-weak Seyfert galaxy GRS 1734-292 is the counterpart of 3EG J1736-2908 and of the nearby Fermi/LAT source. I examine this identification, considering that the radio weakness could result from free-free absorption of a relativistic jet. An association with the EGRET detections is plausible, whereas the latest Fermi/LAT localization no longer favors GRS 1734-292. New observations, especially at radio frequencies of tens of GHz, would help to settle the issue.
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Nuclear Theory

Quantum information in neutron-proton scattering from the $M$ matrix

Linjun Xie, Jinniu Hu, Ying Zhang et al. (+1 more)

We study quantum-information aspects of neutron–proton scattering in the spin-space $M$-matrix framework. Four representative classes of input states are considered, namely diagonal mixed states, separable pure states, general two-qubit pure states, and a special Schmidt-like entangled subclass. For each class, ensemble-averaged output mutual information, reduced-state linear entropy, negativity, and geometric quantum discord are calculated in the relative momentum– scattering angle plane. The results show that the outgoing spin correlations are governed jointly by scattering kinematics and by the structure of the incoming quantum ensemble. Input states with stronger intrinsic coherence or entanglement give larger maxima and higher minima in the mutual information, negativity, and geometric quantum discord. The enhanced regions of the mutual information and geometric discord depend on the input states, while the negativity maximum remains concentrated in the high-momentum backward-scattering region. These results extend earlier studies based on product-state entanglement power and provide an ensemble-based description of how spin correlations in neutron–proton scattering arise from the interplay between input-state structure and scattering dynamics.
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All authors Linjun Xie, Jinniu Hu, Ying Zhang, Hong Shen

High Energy Physics (Theory) · Cross-listed from math.RT

GIT for root stacks and 3d mirror symmetry

Swapnil Garg, Ruoxi Li and Yuji Okitani

Using window theory, Bodzenta–Donovan showed that the derived category of a root stack $\sqrt[n]{X/D}$ has a $2n$-periodic $2$-term semiorthogonal decomposition. We define a categorical generalization of the root stack construction and interpret this as a pullback on the B-side of the 3d mirror symmetry equivalence of Gammage–Hilburn–Mazel-Gee. We analyze this pullback using categorical representation theoretic results of Ben-Zvi–Francis–Nadler and Ben-Zvi–Nadler–Preygel applied to SODs. We also show that the pullback is equivalent to a pushforward of perverse schobers on the A-side, allowing us to deduce periodicity from a simple decomposition of an A-side Lagrangian skeleton. Additionally, we adapt the construction of Bodzenta–Donovan to a new GIT problem, which yields an embedding of Coh($\sqrt[m]{X/D}$) into Coh($\sqrt[n]{X/D}$) for $m<n$ coprime, and prove $2n$-periodicity of the resulting $2$-term SOD.
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High Energy Physics (Theory)

Generalised Symmetries, Anomalies, and Maximal Branches of 3d Chern-Simons Matter Theories

Fabio Marino, Francesca Pretto and Marcus Sperling

The generalised symmetries, 't Hooft anomalies, and their interplay with maximal branches are analysed for linear unitary three-dimensional $\mathcal{N}\geq 3$ Chern-Simons Matter quiver theories realised in Type IIB brane configurations. The 1-form symmetry, its self-anomaly and its maximal anomaly-free subgroup are determined independently from Wilson-line screening and from the string lattice. Fractional monopole endpoints of the generating Gukov-Witten defect are used to extract the anomaly data, while centre charges of integer monopoles determine the faithful 0-form symmetry group, its connected cover and possible 2-group structures. Mixed anomalies with non-abelian 0-form factors are found to cancel in the linear unitary theories considered. The effect of 1-form gauging on maximal branches is related to frozen D3-brane sectors, which flow to Chern-Simons TQFTs whose anyonic lines obstruct the required defect endpoint. This yields a criterion for affected branches and implies that at most two can be affected simultaneously. In such a case, a magnetic-quiver extension by non-simply laced edges is proposed, wherein the 1-form symmetry and its mixed anomaly with the branch isometry are reproduced.
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Quantum Physics

Exact quantum splitting and the structure of finite algebras

Muhammad Imran

For squarefree $f\in\F_q[x]$, Berlekamp's fixed-point algebra is $B\cong\F_q^r$, where $r$ is the number of irreducible factors. We give an exact quantum splitting procedure in a circuit model permitting efficiently computable, input-dependent single-qubit rotations. For a block with $s\ge2$ factors, a quadratic-character test (odd $q$) or absolute-trace test (characteristic $2$) is nonconstant with an exactly known probability $p_{q,s}\ge1/2$. Its value depends only on $q,s$, not on the hidden factors. An auxiliary-qubit reduction to success probability $1/4$ makes one Grover iteration exact. Thus factorization takes exactly $r-1$ splitting rounds and $O(n^3\log q)$ quantum $\F_q$-operations, with deterministic polynomial classical preprocessing and bookkeeping. The method also extracts primitive idempotents of arbitrary finite-dimensional commutative unital algebras given by structure constants in $O(n^4\log q)$ quantum $\F_q$-operations, staying over $\F_q$ throughout. Computing the radical and passing to the center extends it to the decomposition of $A/\Rad(A)$ into simple two-sided ideals, for an arbitrary finite-dimensional associative $\F_q$-algebra $A$.
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Computational Physics

Cartesian tensor equivariant machine-learning force field for spin-dependent atomistic simulations

Junjie Wang, Yijie Zhu, Zhongwei Zhang et al. (+5 more)

Magnetic materials exhibit an intricate coupling between atomic structure and spin degrees of freedom, posing a fundamental challenge for atomistic simulations across experimentally relevant length and time scales. Here we introduce HotPP-Spin, a spin-dependent extension of HotPP for magnetic machine learning interatomic potentials, built on Cartesian tensor equivariant message passing. Atomic magnetic moments are treated as explicit axial-vector degrees of freedom, while spatial-inversion and time-reversal parities are propagated through the tensor couplings. This construction provides a unified representation of exchange-dominated and spin-orbit-induced interactions without imposing predefined analytical interaction forms. A scalar spin-dependent potential energy surface yields energy-conserving atomic forces and magnetic effective fields through differentiation. Benchmarks spanning collinear magnetism, noncollinear magnetism, and spin-orbit-coupling-induced magnetic anisotropy show that HotPP-Spin accurately describes magnetic energy landscapes, magnetic forces, and magnetic-order-dependent energy-volume relations within the same general framework. For H-phase monolayer VSe\(_2\), stochastic spin-dynamics simulations using the learned magnetic effective fields locate the finite-size magnetic ordering crossover at 415–435~K, in close numerical agreement with the reported experimental value of \(418.5\pm7.8\)~K. These results establish Cartesian tensor message passing as a general route for connecting first-principles magnetic energetics with large-scale atomistic simulations of coupled structural and spin phenomena.
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All authors Junjie Wang, Yijie Zhu, Zhongwei Zhang, Zhiyue Guo, Xudong Zhu, Lixin He, Chi Ding, Jian Sun

Strongly Correlated Electrons

Holographic Representations of Topological Quantum Criticality: Emergent Symmetry Approach around the Bott Clock

Fan Yang and Fei Zhou

In this article, we apply the idea of emergent symmetries to construct holographic representations of a broad class of topological quantum critical points (tQCPs) that appear in fermionic classes in the Bott clock. We show explicitly that around the Bott clock, an emergent symmetry $U_{EM}$ exists at a tQCP between different symmetry protected gapped phases with protecting symmetry $G_p$ in $d$ spatial dimensions. This emergent symmetry can be used to construct a $(d+1)$ spatial dimensional lattice model with a properly upgraded symmetry such as $U_{EM}\times G_p$ or $U_{EM} \rtimes G_p$, etc. By doubling the degrees of freedom of the adjacent topological class in $d$-dimensions, we successfully show that the $(d+1)$-dimensional lattice models constructed in this way have the desired enlarged symmetry groups that precisely belong to the adjacent topological classes, counterclockwise around the Bott clock. Furthermore, $d$-dimensional boundaries of these $(d+1)$ dimensional lattice models of gapped topological classes are shown to exhibit identical infrared dynamics as the corresponding tQCPs in the $d$-dimensional adjacent topological phases in the Bott clock, with lower symmetries.
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Mesoscale and Nanoscale Physics

Scalar Spin Chirality from Dissipative Pumping and Lamb-Shift Precession

YuanDong Wang and JianHua Wei

How electrical driving generates and reverses scalar spin chirality in an interacting system with a real Hamiltonian and no magnetic flux remains a fundamental open question. We show that dissipative tunneling prepares an orbital pseudospin, while virtual charge fluctuations generate a noncollinear Lamb field that rotates it toward the chiral direction. Bias changes their relative orientation and thereby reverses the current. This reservoir-induced orbital Hanle effect converts a nonchiral orbital polarization into scalar spin chirality. Within the ground-state space, the circulating current is determined by the scalar spin chirality. Hierarchical-equations-of-motion calculations show that the low-bias reversal survives beyond the second-order weak-coupling description, while the quadratic growth of chirality after a sudden voltage switch identifies precession. More broadly, time-reversal-odd responses can emerge in open quantum systems from the interplay between dissipative state preparation and coherent precession.
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Quantum Physics

Quantum-interference metrology of dissipative Kerr solitons

Yun-Ru Fan, Yong Geng, Ji Liu et al. (+9 more)

Dissipative Kerr solitons in optical microresonators underpin chip-scale frequency combs with applications ranging from coherent telecommunications to precision spectroscopy. Yet the characterization of their intrinsic femtosecond temporal structure remains challenging, as the low pulse energy and broad spectral bandwidth necessitate optical amplification and careful dispersion compensation in conventional ultrafast diagnostics, both of which can significantly distort the waveform. Here we demonstrate a quantum-interference metrology of microcomb solitons based on Hong-Ou-Mandel interference. By attenuating the soliton stream to the single-photon level and measuring fourth-order interference, we directly retrieve near transform-limited pulse durations without amplification or dispersion management, remaining accurate even after propagation through 25 km of standard fiber. The same interferogram also provides direct access to the temporal separations in multi-soliton states by converting inter-soliton separations into additional interference dips at corresponding delays, enabling sub-picosecond characterization of their intracavity temporal structure. This quantum-inspired paradigm introduces a fundamentally new metrological approach that is immune to amplification and dispersion distortions, offering a powerful tool for the characterization of complex soliton physics.
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All authors Yun-Ru Fan, Yong Geng, Ji Liu, Yong-Jun Huang, Hai-Zhi Song, Hao Li, Li-Xing You, Heng Zhou, Kun Qiu, Kai Guo, Guang-Can Guo, Qiang Zhou

Astrophysics of Galaxies

Testing SALT Approximations with Numerical Radiative Transfer Code. II. Thermal and Microturbulent Line Broadening

Cody Carr, Renyue Cen, Leo Michel-Dansac et al. (+2 more)

Forward models that connect galactic winds to their predicted spectral-line profiles have proved effective for inferring wind properties in controlled settings, but important limitations remain. In particular, many models rely on the Sobolev approximation to solve the radiative transfer equation and neglect line broadening caused by thermal and turbulent motions within the wind. In the first paper of this series, we demonstrated that neglecting this broadening in Semi-Analytical Line Transfer (SALT) models can bias the recovery of fundamental wind properties from mock observations. Here, we extend the SALT framework to incorporate this motion by solving the radiative transfer equation in the single-scattering limit. We treat re-emission using an escape-probability approach similar to that adopted under the Sobolev approximation, while allowing photons to escape from resonance regions of finite thickness. We validate the model and investigate parameter degeneracies by fitting mock spectra generated with Monte Carlo radiative transfer simulations assuming identical outflow configurations. We identify a degeneracy between the Doppler-broadening parameter and the radial density and velocity profiles: shallower density and velocity gradients can mimic the effects of greater velocity dispersion. Nevertheless, integrated quantities are well recovered. Over the range $13 \leq \log(N_{\mathrm{Si}^+}/\mathrm{cm}^{-2}) \leq 18$, the recovered ionic column densities have a scatter of 0.26 dex and are systematically overestimated by 0.22 dex. Mass-outflow rates evaluated at the terminal wind radius have a scatter of 0.88 dex and are systematically overestimated by 0.51 dex. These results represent substantial improvements over previous versions of the model.
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All authors Cody Carr, Renyue Cen, Leo Michel-Dansac, Claudia Scarlata, Alaina Henry