Fluid Dynamics
Finite basis physics-informed neural networks with hard constraints for viscous fluid flow in highly perforated domains
Jeeeun Lee, Denis Korolev, Miro Duhovic et al. (+1 more)
In this work, viscous fluid flow governed by the Stokes equations in highly perforated domains is studied using physics-informed neural networks (PINNs). Perforated microstructures induce complex boundary conditions and fine-scale flow features that are difficult for standard neural networks to resolve. Conventional PINNs, even when combined with advanced training techniques, can suffer from a loss of accuracy and efficiency as the number of perforations increases. One important source of this difficulty is the soft enforcement of boundary conditions through penalty terms, which can lead to stiffness, gradient conflicts, and poor resolution of near-boundary flow structures. Hard constraints provide an alternative by encoding boundary conditions exactly into the network ansatz, but may introduce undesirable non-local effects due to the global nature of the approximation. To address these challenges, finite basis PINNs (FBPINNs), which are based on domain decomposition and localisation principles, are used together with hard boundary constraints that efficiently encode perforation-related boundary conditions. This approach helps mitigate spectral bias, improves overall accuracy, and exhibits convergence that is only weakly affected by the number of perforations, thereby providing an efficient and highly parallelisable neural network framework. The proposed approach is further supported with theoretical arguments, specifically focusing on the localisation and approximation properties of FBPINNs.
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All authors Jeeeun Lee, Denis Korolev, Miro Duhovic, Seong Su Kim
Quantum Physics
Bell nonlocality with directly generated telecom-band spin-photon entanglement
Dong-Yu Huang, Jian Wang, Xiao-Long Zhou et al. (+8 more)
Quantum nonlocality, typically revealed through
entanglement distribution across
quantum networks, is a cornerstone of
quantum information science. Long-distance distribution of
entanglement requires the information carrier, i.e. flying
photons, to operate in the minimum-loss telecom band of optical fiber. While extensive efforts have been devoted to the direct generation of
entanglement between C-band telecom
photons and various stationary
spins, the verification of
quantum nonlocality remains an outstanding challenge. Here, utilizing a dipole transition in rubidium atoms with a wavelength of 1530 nm and a cavity-assisted protocol, we achieve resonant excitation and direct emission of C-band telecom
photons from a single atom, generating
spin-
photon entanglement with a measured Bell state fidelity exceeding 91.4%. We then verify Bell nonlocality by observing a Bell inequality violation of 2.455(77) > 2 using this high-quality entangled pair. These results extend the wavelength of a single-atom
quantum emitter to the telecom C-band, achieving sufficiently high-fidelity
spin-
photon entanglement to finally verify Bell nonlocality. This work thereby provides a promising building block for a large-scale atom-based
quantum network capable of distributed
quantum metrology and long-distance
quantum communication.
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All authors Dong-Yu Huang, Jian Wang, Xiao-Long Zhou, Ze-Min Shen, Si-Jian He, Qi-Yang Huang, Yi-Jia Liu, Yu-Shu Chen, Quan Jiang, Chuan-Feng Li, Guang-Can Guo
Mathematical Physics
Perturbation Theory for Time-Dependent Point Interactions with Discrete Spectrum
Kaya Güven Akbaş, Fatih Erman and O. Teoman Turgut
We develop a perturbative framework for time-dependent point interactions in
quantum systems with purely discrete unperturbed spectrum. In two and three dimensions the point interaction is described through the renormalized resolvent obtained from heat-kernel regularization, while in one dimension the diagonal Green function is finite and no renormalization is required. Time dependence is introduced either through the interaction parameter or through the motion of the support point. In both cases we expand the non-autonomous
Hamiltonian in the spectral basis of the corresponding static point-interaction problem and derive the first- and second-order pole shifts, projection corrections, and transition amplitudes. We also describe how finite degeneracies are treated by separating the coupled point-interaction direction from the unaffected orthogonal subspace in each degenerate eigenspace. The method is illustrated by explicit examples: point interactions with time-dependent coupling, harmonic oscillators perturbed by moving point interactions, and a particle on a sphere with a moving interaction center. We also discuss the one-dimensional harmonic oscillator with a moving delta potential, showing that in the non-renormalized case the present formulation reduces to the standard time-dependent perturbation theory. Finally, an exactly solvable delta center moving with constant velocity on a circle is used as a discrete-spectrum example for the local moving-center expansion and its velocity-dependent dynamical corrections.
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Disordered Systems and Neural Networks
Composite-State Localization Beyond the External Landscape in Non-Hermitian Quasicrystals
Tian Zhou, Xue-Bin Wang, Zhongmin Yang et al. (+1 more)
A composite excitation need not inherit the localization behavior of its constituents. We show that an interacting non-Hermitian quasiperiodic ladder realizes a controllable and reversible localization inversion between composite and unbound excitations, where internal configuration, rather than only the external potential, becomes a control parameter for localization. Opposite complex potentials on the two legs cancel at first order for a same-rung pair but act directly on separated particles, allowing extended composite states to persist while the unpaired sector becomes localized. A strong-coupling theory identifies the composite state as an emergent weakly modulated non-Hermitian quasicrystal generated by virtual unpaired configurations. Breaking the potential antisymmetry restores a direct modulation of the composite band and reverses the localization hierarchy. Engineering configuration-space pathways further stabilizes an extended composite band embedded within a localized continuum, the inverse of the conventional bound-state-in-the-continuum scenario. Our results establish internal configuration as a reversible control parameter for localization.
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All authors Tian Zhou, Xue-Bin Wang, Zhongmin Yang, Tao Liu
Strongly Correlated Electrons
Momentum-Selective Electron and Spin Dynamics under Ultrafast Photoexcitation
Gusein Bedirkhanov, Nagamalleswararao Dasari, Alexander I. Lichtenstein et al. (+1 more)
Recent advances in time-resolved spectroscopies have enabled direct access to the momentum-selective nonequilibrium dynamics of correlated
quantum materials, revealing a strongly momentum-dependent response of electrons and collective excitations. Interpreting these observations requires a real-time theoretical framework that consistently captures the interplay between strong local electronic correlations and nonlocal collective fluctuations, a capability that remains beyond state-of-the-art nonequilibrium approaches. Using a recently developed real-time many-body framework, we resolve the momentum-selective ultrafast dynamics of a photoexcited correlated electron system. We predict a transient nodal-antinodal anisotropy in electronic heating, providing a microscopic explanation for the momentum-dependent response debated in time-resolved photoemission and Raman experiments, and identify the nonthermal spectral-weight transfer responsible for the transient antinodal in-gap states observed in ultrafast photoemission. We further uncover a momentum-selective
magnetic response, in which
antiferromagnetic fluctuations undergo a strongly nonthermal, quench-like excitation far above the electronic temperature while preserving their correlation length, before relaxing through a momentum-space
magnon cascade toward lower-momentum modes. Finally, by tracking the real-time local
spin susceptibility, we identify a dynamical, experimentally accessible signature of local-moment formation and its photoinduced melting. Our results establish a unified microscopic picture of ultrafast electronic and
magnetic dynamics, providing a framework for interpreting momentum-resolved pump-probe experiments.
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All authors Gusein Bedirkhanov, Nagamalleswararao Dasari, Alexander I. Lichtenstein, Evgeny A. Stepanov
Space Physics
Skills for forecasting space weather
H.J. Austin and N.P. Savani
Coronal mass ejections (CMEs) from the Sun can have severe impacts on the Earth environment in the form of geomagnetic storms. These storms pose a risk to the global technological infrastructure, making the prediction of these events imperative. In this paper, we have broadened the statistical verification of the Bz4Cast tool, the first empirically-driven model to forecast
solar wind
magnetic vectors inside a CME prior to their Earth arrival. Twenty five CME events (between 2012 and 2016) have been tested with the Bz4Cast model, and the skills have been compared to the heuristic approach of NOAA's Space Weather Prediction Center (SWPC) G-scale for 3-day geomagnetic storm forecasts. For a broad range of scores, and within uncertainty, the Bz4Cast architecture provided the same skill as the experienced on-duty forecasters at SWPC. The most prominent difference is that the Bz4Cast architecture provides a slightly higher false alarm ratio than the SWPC 3-day forecast.
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Chemical Physics
A comparative study of sum-connectivity and product-connectivity Gourava indices for benzenoid hydrocarbons
Nagesh H.M, Vijaya Chandra Kumar U, Azghar Pasha B et al. (+1 more)
This study evaluates the sum-connectivity ($SGO$) and product-connectivity ($PGO$) Gourava indices as molecular descriptors for benzenoid hydrocarbons. Using a
dataset of 30 benzenoid structures, we compare least-squares regression models for predicting $\pi$-electronic energies ($E_{\pi}$) and find that $SGO$ yields a markedly better fit than $PGO$ across molecular edge types. The indices are further assessed using three validation designs: (i) correlation analysis, in which $SGO$ exhibits strong yet non-perfect inverse correlations with standard descriptors ($M_1, M_2, SO, DSO,$ and $ABS$; $r\in[-0.9923,-0.8936]$), suggesting complementary structural information; (ii) degeneracy analysis on Octane, Nonane, and order-$10$ tree
datasets, where $SGO$ attains low degeneracy rates (22.22%, 40.00%, and 42.45%); and (iii) structure-sensitivity analysis on trees of order $n=10$, showing 74% higher sensitivity than $DSO$ while maintaining a high structure-abruptness ratio ($SA = 0.474386$). Overall, $SGO$ offers a favorable balance between discriminative power and numerical stability, supporting its applicability in QSPR modeling and related theoretical studies.
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All authors Nagesh H.M, Vijaya Chandra Kumar U, Azghar Pasha B, Narahari N
Biological Physics
A minimal physical model of cochlear mechanics: Insights into active nonlinear feedback
Vidyunmathi N. A. and Toby Joseph
The remarkable sensitivity, compressive nonlinearity, and frequency selectivity of the mammalian cochlea arise from an active process that amplifies the passive mechanical response of the basilar membrane. Outer hair
cells are widely regarded as the primary effectors of this active process in the basal regions of the cochlea. This active contribution progressively decreases with increasing stimulus level. Motivated by these observations, a minimal cochlear model is investigated in which each location is represented by a forced damped oscillator with an exponential displacement-dependent active feedback. The oscillators are coupled through the cochlear fluid and also by elastic and dissipative longitudinal interactions to form a one-dimensional distributed model. The model reproduces key features of cochlear mechanics, including level-dependent amplification, compressive nonlinearity, frequency selectivity, traveling-wave propagation, and phase accumulation. Comparison with a simplified cubic nonlinear model has been carried out. Even though the cubic nonlinearity describes the response for weak stimuli, at higher stimulus levels it deviates from the exponential model and fails to reproduce the gradual transition towards predominantly passive behavior. Longitudinal coupling broadens the frequency response, modifies the traveling wave profile, and increases phase accumulation. The proposed model provides a simple physical framework for understanding how local active processes and longitudinal mechanical interactions together shape the nonlinear response of the cochlea.
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Computational Physics
Nonadiabatic Molecular Dynamics on Real-time Excited-State Surfaces via Machine Learning Hamiltonians
Changwei Zhang, Yang Zhong, Zhi-Guo Tao et al. (+6 more)
Simulating the coupled, nonequilibrium dynamics of electrons and
nuclei is a central challenge in chemistry, physics, and materials science, governing phenomena from photocatalysis to
quantum information. The primary bottleneck has been the lack of a general, accurate, and efficient method for modeling the complete excited-state landscape: the potential energy surfaces, forces, and non-adiabatic couplings for multiple electronic states. While machine learning has revolutionized ground-state simulations and shown promise for excited states in molecules, a unified framework that solves the complete multi-state problem for general condensed matter systems has remained elusive. Here we introduce on-the-fly N${^2}$AMD (Neural network NAMD), a machine learning framework that makes on-the-fly NAMD in solids a reality. By employing an equivariant neural network to predict the system
Hamiltonian, the framework delivers excited-state energies, forces, and non-adiabatic coupling vectors at a fraction of the cost of ab initio calculations. Crucially, it allows simulations with hybrid functional accuracy, a level of approach previously inaccessible for NAMD. We showcase its capabilities with three topical examples: correcting order-of-magnitude errors in carrier dynamics predicted by conventional procedure in a MoS$_2$/WS$_2$
heterostructure, simulating previously inaccessible photoinduced ferroelectric switching, and capturing real-time polaron formation in TiO$_2$ at the hybrid-functional level. On-the-fly N${^2}$AMD moves beyond the limitations of
equilibrium theory, establishing a new paradigm for the predictive, first-principles design of materials operating far from
equilibrium.
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All authors Changwei Zhang, Yang Zhong, Zhi-Guo Tao, Yingzhou Li, Zhenggang Lan, Oleg V. Prezhdo, Xin-Gao Gong, Weibin Chu, Hongjun Xiang
Astrophysics of Galaxies
Diagnosing the Fe line complex of the intracluster medium by XRISM high-resolution spectroscopy
K. Fukushima, L. Hirata, N. Y. Yamasaki et al. (+17 more)
We aim to test the validity of the CIE framework in the ICM by performing line diagnostics based mainly on resolved Fe-K emission lines. Methods. We analyse Resolve full-array spectra of 17
galaxy clusters. Prominent Fe-K line components (the Fe xxv w, x, y, z, and Fe xxvi Ly{\alpha}1,2 lines) are removed from
plasma emission models and instead fitted with Gaussian profiles, enabling direct measurements of line fluxes without relying on synthetic spectral models. Some cool-core systems show w/z ratios lower than predicted by about 20 per cent, and a broader w than z, consistent with resonant scattering effects. The y/x ratios exhibit marginal deviations from model predictions for some objects, suggesting possible origins of cascade process due to electron recombination and contribution from low-ionised Fe. The Fe Ly{\alpha}2/Ly{\alpha}1 ratios are globally close to the expected value of about 0.5, and the samples with good
photon statistics prefer 0.55. This subtle excess is consistent with an unresolved contribution to Ly{\alpha}2 from the
magnetic-dipole (M1) transition, which is absent from one of the atomic codes considered here. More interestingly, systems at around 7 keV preferentially exhibit Ly{\alpha}2/Ly{\alpha}1 ratios above 0.55. Although the statistical significance of this trend is limited, it suggests that resolved Fe Ly{\alpha} spectroscopy may provide a sensitive probe of additional atomic processes to collisional excitation, including dielectronic and radiative recombination and polarisation effects.
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All authors K. Fukushima, L. Hirata, N. Y. Yamasaki, P. Chakraborty, S. Dupourqué, Y. Fujita, L. Gu, C. Kilbourne, K. Matsushita, F. Mernier, E. D. Miller, K. Nakazawa, Y. Omiya, N. Ota, A. Sarkar, K. Sato, M. Sun, Y. Uchida, I. Zhuravleva, H. Yamaguchi
Materials Science
Machine Learning Framework for Magnetic Candidate Discovery in Cerium-Based Compounds
Joshua A. Torres, Yaser M. Banad, Benjamin O. Tayo et al. (+1 more)
Cerium (Ce), the most abundant lanthanide, offers significant potential for addressing shortages in high-performance
magnetic materials, particularly through the discovery of compounds suitable for gap magnets. However, predicting Ce-based ferromagnets with uniaxial
magnetic anisotropy remains challenging because their
magnetic behavior depends strongly on
crystal structure, exchange geometry, and electronic interactions. Here, we present a physics-guided computational framework to screen known Ce-based
crystal structures and identify promising Ising ferromagnets for future synthesis. A Random Forest classifier uses seven structural and SOAP descriptors, including unit-
cell volume, density, atomic sites, space group, atomic density, Ce SOAP overlap, and transition-metal SOAP overlap, to prioritize candidate compounds. Selected crystallographic structures are then analyzed using Ising-model Monte Carlo simulations to characterize phase behavior and critical properties. Critical exponents extracted from simulated phase transitions provide quantitative insight into
magnetic regimes and anisotropy-related effects. We further employ autoencoders trained on affinity-based features from simulated
spin configurations to identify latent signatures of phase
evolution and transition behavior. Together, this framework integrates structural screening, statistical-mechanical simulation, and machine learning to accelerate the identification of promising Ce-based
magnetic materials and provide candidates for experimental synthesis and validation.
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All authors Joshua A. Torres, Yaser M. Banad, Benjamin O. Tayo, Tej Nath Lamichhane
High Energy Physics (Phenomenology)
Neutrino Mass and its Impact on Gravitational Waves from Domain Wall Collision
Victoria Puyam and Mrinal Kumar Das
The $A_{4} \times Z_{4}$
symmetry models are constructed to study
neutrino masses and mixings, as well as the gravitational-wave spectrum from domain-wall annihilation. The first
neutrino mass model is constructed with the flavon's
vacuum expectation value and
alignment obtained from the self-interacting potential terms, while the second model uses a new
vacuum expectation value arising from a potential containing both self-interaction and mixed terms. The resulting
neutrino mixing patterns for both models are in good agreement with current
neutrino oscillation data with different mixing values. Further, the flavon mixing terms lift the
vacua degeneracy that often shows in the spontaneous
symmetry breaking of the discrete
symmetry. These mixing terms and the modified
neutrino mass
matrix of the second model are considered to produce the necessary bias for analysing the gravitational waves spectrum. The spectrum predicted by the model could be detected by current and near-future experiments when the flavons have the
vacuum expectation value of $10^4$ TeV.
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Superconductivity
Effects of high-pressure synthesis on phase formation and superconducting properties of PrFeAsO1-xFx
Priya Singh, Konrad Kwatek, Tatiana Zajarniuk et al. (+3 more)
Motivated by recent reports of enhanced superconducting performance in several families of iron-based
superconductors (IBS) processed by high-pressure (HP) synthesis, we investigate the influence of high gas pressure and high-temperature synthesis (HP-HTS) process on the structural, microstructural, electrical transport, and
magnetic properties of Pr-based oxypnictide PrFeAsO1-xFx (Pr1111) using the processing conditions of 0.5 GPa for 1 h previously optimized for other IBS families. Representative underdoped (x = 0.2), optimal doped (x = 0.3), and overdoped (x = 0.5) compositions from the ambient-pressure electronic phase diagram of Pr1111 are selected to evaluate its composition-dependent effects of HP-HTS. The results demonstrate that HP-HTS enhances fluorine incorporation, improves phase formation, and produces a denser microstructure with improved grain connectivity in the underdoped and optimal doped compositions.
Magnetic measurements reveal increased in the superconducting transition temperature (Tc) of ~1 K for x = 0.2 and ~6 K for x = 0.3, whereas only a marginal improvement in the critical current density is observed. Electrical resistivity measurements of the underdoped composition show a slight increase in Tc accompanied by a broader resistive transition, indicating residual structural inhomogeneity. In contrast, the overdoped composition exhibits increased
impurity phase segregation, accompanied by suppression of superconductivity. These results demonstrate that the effectiveness of HP-HTS in Pr1111 is strongly composition dependent and governed by the interplay among fluorine incorporation, phase stability, and microstructural
evolution, highlighting the need for further optimization of the HP-HTS processing conditions.
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All authors Priya Singh, Konrad Kwatek, Tatiana Zajarniuk, Tomasz Cetner, Jan Mizeracki, Shiv J. Singh
Optics
Spectral Mixing, Skin Localization, and Linear Optical Response in Dissipative Photonic Lattices
Chen-Huan Wu
We study the linear optical response of a finite dissipative Hatano–Nelson photonic
lattice. The response between selected input and output ports is resolved into a phase-coherent intensity and an incoherent modal-weight contribution using the biorthogonal Green function. Their comparison isolates interference among non-Hermitian modal residues, while a response-weight
entropy and the associated participation number $\Neff$ quantify how broadly the measured signal is distributed over the complex modes. The numerical results show that loss broadens the modal distribution, periodic-boundary spectral winding increases modal participation, and onsite disorder reduces it. Time-domain
quantum-walk dynamics independently display the drift and right-edge accumulation produced by non-reciprocal hopping under open boundaries. A parameter map in the $(g,W)$ plane, supplemented by disorder-ensemble averages, identifies a finite-size crossover in which $\Neff$ responds to disorder before the response-weighted center is displaced from the skin boundary. The analysis applies to coupled waveguides, microring arrays, driven cavity
lattices, and other linear photonic platforms with loss, gain, or non-reciprocal coupling.
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Statistical Mechanics
Low-frequency output fluctuations in an open exclusion process with particle pausing
Quentin Thommen
Slow internal states reshape both the mean throughput and the temporal organization of a driven
lattice gas. Exit-counting statistics reveal this effect in a finite open totally asymmetric simple exclusion process whose particles reversibly switch between active and paused states. Increasing pausing lowers the mean current smoothly, whereas the long-window Fano factor is strongly nonmonotonic. At the reference boundary rates, the maximum remains near a measured mean paused population \(N_p=L\rho_{\rm paused}\simeq1.5\)–\(2\) across
lattice lengths L=50-500, while the corresponding pausing rate scales as \(k_p^{\rm max}\propto L^{-1}\). A minimal constant-birth, linear-death approximation translates an order-one collective crossover into this finite-size displacement and gives \(N_p^\star\simeq1.50\) in the independent-pause, strong-blocking limit. The simulations delimit this approximation: the pause number is overdispersed, and at fixed \(N_p\), slower unpausing increases both the correlation time and the noise amplitude. Residence-time and structural analyses further separate the relevant slow variables. The pause-free versus pause-containing residence-time scale tracks the fitted output-correlation time, whereas the noise amplitude follows fluctuations, rather than the mean size, of the largest particle cluster. Low-frequency output noise therefore identifies an intermittent finite-size regime shaped jointly by slow-defect kinetics and traffic-jam reorganization.
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Materials Science
Multimodal deep learning framework to predict strain localization of Mg/LPSO two-phase alloys
Daiki Kuriki, Fabien Briffod, Takayuki Shiraiwa et al. (+1 more)
This study proposes a method for predicting three-dimensional (3D) local strain distribution under compressive deformation of as-cast Mg/LPSO two-phase
alloys from 3D microstructure images. The 3D local strain distribution was obtained by applying the digital volume correlation method to X-ray CT images before and after compression tests. Three microstructure descriptors were extracted from the 3D microstructure images around each strain measurement point: volume fractions of the phases, persistent diagrams that can express the connectivity of the phases, and two-phase spatial correlation that can express the spatial distribution of the phases. A deep learning model was then constructed to predict local strain from the three microstructure descriptors. Since two types of descriptors were used in this study, numerical data and image data,
multimodal deep learning was employed to make predictions. Thus, the use of multiple microstructure descriptors enabled predictions to be made with higher accuracy than when predictions were made from a single descriptor. Feature importance of the descriptors was assessed through correlation analysis and occlusion sensitivity analysis. The results revealed that high strain tended to occur in the region where the hard phase, LPSO phase, had a large elongated phase oriented at a 45{\deg} direction to the loading direction. This result is consistent with other previous studies and indicates that the proposed method is effective in elucidating the relationship between the microstructure and the deformation behavior of the material.
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All authors Daiki Kuriki, Fabien Briffod, Takayuki Shiraiwa, Manabu Enoki
Quantum Physics
Time-reparameterisation invariant quantum evolution law: the lack of absolute time does not imply a stationary global state
Ognyan Oreshkov and Denis Bouvy
We challenge the common belief that if there is no absolute time parameter in physics, a
quantum system described without reference to an external clock can be assumed to be in a stationary state of its
Hamiltonian. We present a time-reparameterisation invariant
quantum evolution law, which for a given initial condition predicts the same trajectory in state space as the Schrödinger equation, except that for nontrivial trajectories it does not predict the speed at which the trajectory is traversed. The solutions of this
evolution law are all time-reparameterised solutions of the Schrödinger equation. We show how the predictions of the Schrödinger equation are recovered relative to an internal clock in this framework. In contrast to the Page-Wootters formalism or Dirac's quantisation of the
Hamiltonian constraint, here the global sate is not stationary. We discuss the assumptions leading to the common conclusion that the state can be taken stationary and suggest that they need to be revisited.
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High Energy Physics (Theory)
Gauge transformations in Z-space in (anti)holomorphic sector of HS theory
D.A. Batyaev and A.V. Korybut
We consider a consistent deformation of the (anti)holomorphic generating system of [arXiv:2209.01966], aiming to provide a map to the (anti)holomorphic truncation of the Vasiliev theory. In our new formulation, the previously rigidly defined master-field $\Lambda$ can be shifted by $\mathrm{d}_z$-exact projective one-forms. The class of projective one-forms is described comprehensively, and corresponding projective identities are proven. $\mathrm{d}_z$-exact forms of the order $n$ in $C$ induce field redefinition of order $(n+1)$ and beyond. Explicit expression for the $(n+1)$-th order field redefinitions are provided. An analysis of the gauge transformation of the second order in $C$ in zero-forms is performed, identifying necessary and sufficient conditions for the part of the field redefinition of the second order that can be gauged away. The field redefinitions induced by the shift of $\Lambda$ are proven to be nontrivial.
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Mathematical Physics · Cross-listed from math.QA
Non-semisimple open-closed 3d TFT
Ingo Runkel and Yilong Wang
Given a spherical finite tensor category C, not necessarily semisimple, and a two-sided modified trace on its projective ideal, we define an open-closed three-dimensional topological field theory with values in vector spaces. The bordism category has as morphisms three-dimensional bordisms with corners, whose boundary is partitioned into the gluing boundary, parametrised by source and target surface, and the unparametrised free boundary. The free boundary is equipped with an embedded C-coloured graph satisfying an admissibility condition. Our construction starts from a new three-
manifold invariant based on the multi-handlebody invariant of [arXiv:1809.07991] and the chromatic maps of [arXiv:2302.04509]. The open-closed topological field theory is then obtained via the universal construction.
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High Energy Physics (Phenomenology)
Hadronic photon correction to $\gamma^{\ast} \gamma \to f_{2}(1270)$ at next-to-leading order
Bing-Xin Liu and Shen-Qiang Ren
Within the framework of light-cone sum rules, we calculate the hadronic
photon corrections to the $\gamma^*\gamma \to f_2(1270)$ transition form factors induced by the leading-twist
photon distribution amplitude of the real
photon. We establish the factorization formula for the
vacuum-to-
photon correlation function at next-to-leading order in $\alpha_s$, and extract the perturbative hard matching coefficients by applying the method of regions. The parametrically large logarithms appearing in the hard functions are resummed to next-to-leading logarithmic accuracy by solving the two-loop
evolution equation for the corresponding light-ray tensor operator. Combining the resulting light-cone sum rules with the known leading-power contributions from QCD collinear factorization, we provide updated theoretical predictions for the three helicity form factors $T_0(Q^2)$, $T_1(Q^2)$ and $T_2(Q^2)$, including an estimate of the theoretical uncertainties.
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Quantum Physics
Quantum Decision Theory for Displacement Detection with Finite-Energy GKP States
Seid Koudia and Symeon Chatzinotas
We develop a
quantum-decision-theoretic framework for detecting phase-space displacements with finite-energy, $d$-level Gottesman-Kitaev-Preskill (GKP) probes. For single-mode and
entanglement-assisted architectures, we derive the
Bayesian minimum-error probability, the optimal Neyman-Pearson receiver-operating characteristic, and the corresponding minimum detectable displacement. Finite-energy effects are treated through exact theta-series displacement kernels, while pure loss followed by
quantum-limited amplification is mapped to an effective Gaussian random-displacement channel.
Entanglement removes preparation-dependent blind directions and preserves both logical displacement labels, although it does not surpass the pointwise optimized single-mode strategy in the noiseless pure-state setting. We
benchmark the resulting protocols against coherent-state, direction-matched squeezed-
vacuum, and twin-beam schemes at equal nominal squeezing. Numerical results identify finite-squeezing and lossy regimes in which GKP probes achieve both a lower
Bayesian error and a smaller minimum detectable perturbation than the selected Gaussian receivers.
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Chemical Physics
Oxygen Reduction Reaction on Platinum Nanocatalysts Produces Long-Lived, Hysteretic Oxygenated Adsorbates
Jaehyeon Kim, Lalith Krishna Samanth Bonagiri, Fujia Zhao et al. (+1 more)
Aqueous electrocatalysis generates oxygenated intermediates at catalyst surfaces. While intermediate species on single-
crystal catalysts have been observed, the nature and
evolution of surface oxygenated species on industrially relevant nanoparticle (NP) catalysts remain largely unknown. Here, using in situ Raman spectroscopy, we tracked the formation and potential-dependent
evolution of oxygenated adsorbates in alkaline media on NP catalysts with an active platinum (Pt) surface. By comparing spectroscopic features in Ar- vs O2-saturated electrolytes, we determined three key intermediates produced by the oxygen reduction reaction (ORR): adsorbed OOH, OH, and O2. In contrast to the conventional wisdom that intermediates exist only during catalytic reactions, we found these oxygenated adsorbates to be highly long-lived and hysteretic, and to persist even after the termination of ORR. This adsorbate-retention effect exhibits a modest dependence on the surface oxidation state and the electrolyte cations (K+ vs Li+), and is likely facilitated by the heterogeneous nature of the catalyst surface. The results highlight the complexity of surface adsorption structures on realistic catalysts, which often extends beyond that captured by measurements or simulations on model single-
crystal surfaces.
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All authors Jaehyeon Kim, Lalith Krishna Samanth Bonagiri, Fujia Zhao, Yingjie Zhang
Strongly Correlated Electrons
Quantum geometric localization length and localization criticality in an ideally flat Chern band
Xu-Cheng Wang and Yang Qi
We propose that the localization length in an isolated, ideally flat Chern band is set by
quantum geometry. We explore the corresponding localization transition and its critical scaling by applying transfer
matrix calculations in the maximally localized hybrid Wannier basis, whose spatial spread is exactly characterized by a
quantum geometric length. Remarkably, upon tuning the
quantum metric of the Chern band, we observe a crossover from a universal regime controlled by the Dirac fixed point to a non-universal regime with continuously varying critical exponents. Within the universal regime, the localization length exhibits a pronounced linear dependence on the
quantum geometric length, supporting its
quantum geometric nature. These findings provide a novel
quantum geometric perspective on the localization in
quantum Hall systems such as twisted moiré superlattices, and shed new light on the long-standing controversy over the criticality of the integer
quantum Hall transition.
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Plasma Physics
Beam experiments for reactive ion etching of silicon (Si)-based materials by silicon halide ions
Kazuhiro Karahashi, Tomoko Ito and Satoshi Hamaguchi
Etching yields of Si, SiO2, and Si3N4 have been determined for silicon ion (Si+), halogen ions (F+, Cl+, and Br+) and silicon halide ions (SiF+, SiF3+, SiCl+, SiCl3+, SiBr+, and SiBr3+) irradiation in 300 to 1000 eV using a mass-selected ion beam apparatus that can irradiate a single species ion to sample surfaces under an ultra-high
vacuum condition. Si+ irradiation below 1000eV deposits silicon atoms on Si, SiO2, and Si3N4 surfaces. The etching yields of silicon tri-halide ions (SiF3+, SiCl3+, and SiBr3+) above 1000 eV are larger than those of halogen ions, respectively, and these etching yields depend on the incident ion energy and the etching material (especially Si3N4). At low incident energy, silicon mono-halide ions (SiF+, SiCl+, and SiBr+) deposit silicon on substrates, and the etching threshold energy depends on the halogen species. This information contributes to a database of experimental values needed to increase the precision of an etching process and a profile simulator.
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Astrophysics of Galaxies
Breathing Fire: Hot Dust in the Big Three Dragons at z = 7.15
Gitanjali Rajulal, Hiddo S. B. Algera, Yuma Sugahara et al. (+25 more)
We present new Atacama Large Millimeter/submillimeter Array (ALMA) Band 9 ($\lambda_\mathrm{obs} = 0.45\,\mathrm{mm}$) and 4 ($\lambda_\mathrm{obs} = 2.2\,\mathrm{mm}$) observations towards the Big Three Dragons, a pair of merging Lyman-break
galaxies (LBGs) at $z=7.15$. The system was previously detected in ALMA Bands 6, 7 and 8 ($\lambda_\mathrm{obs} = 0.73 - 1.32\,\mathrm{mm}$), which, combined with our new observations, allows us to robustly constrain its
dust temperature and obscured SFR. The unresolved Band 4 observations yield a $3.5\sigma$ detection, and the $0.4''$ Band 9 observations detect the Eastern and Western LBGs at $3.7$ and $3.5\sigma$, respectively. Through modified blackbody fitting, we infer a global
dust temperature of $T_d = 78_{-23}^{+35}\,\mathrm{K}$ for the system, which implies a high IR luminosity of $\log(L_\mathrm{IR}/L_\odot) = 12.32_{-0.41}^{+0.43}$. This makes the Big Three Dragons one of the most IR-luminous systems known at $z>7$, with a total $\mathrm{SFR}_\mathrm{UV+IR} = 267_{-153}^{+418}\,M_\odot\,\mathrm{yr}^{-1}$ that is almost completely obscured ($f_\mathrm{obs} = 0.94_{-0.09}^{+0.04}$). Using resolved ALMA observations in Bands 6, 8 and 9, we confirm both LBGs have hot
dust temperatures ($T_d \approx 67 - 84\,\mathrm{K}$) and correspondingly high obscured fractions ($f_\mathrm{obs} \approx 0.88 -0.95$). We find the Western LBG to fall $\sim1\,\mathrm{dex}$ above the canonical IRX-$\beta_\mathrm{UV}$ relation, suggesting patchy
dust obscuration. The compact Eastern component, on the other hand, is consistent with a Calzetti- or SMC-like
dust screen within the uncertainties. Together with the similarly hot
dust temperature recently reported for the $z=8.31$
galaxy MACS0416-Y1, our results suggest a non-negligible fraction of
star formation at the bright end of the UV luminosity function is highly
dust-obscured, even at $z\gtrsim7$.
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All authors Gitanjali Rajulal, Hiddo S. B. Algera, Yuma Sugahara, Tom J. L. C. Bakx, Takuya Hashimoto, Suzuka Arai, Akio K. Inoue, Ikki Mitsuhashi, Manuel Aravena, Karin Cescon, Chian-Chou Chen, Elisabete da Cunha, Pratika Dayal, Ilse De Looze, Andreas Faisst, Yoshinobu Fudamoto, Rodrigo Herrera-Camus, Hanae Inami, Anton M. Koekemoer, Shoichiro Mizukoshi, Michael Romano, Lucie Rowland, Sander Schouws, Renske Smit, Livia Vallini, Wei-Hao Wang, Giovanni Zamorani, Anita Zanella
Astrophysics of Galaxies
First detection of C2H+ in the interstellar medium
Arshia M. Jacob, Karl M. Menten, Sandra Brünken et al. (+10 more)
Despite the detection of nearly 350 molecules in the interstellar medium, almost half of which are carbon chains, the pathways that build molecular complexity remain poorly understood. Observed abundances of carbon-chain and aromatic species are difficult to reconcile with existing top-down or bottom-up formation scenarios, due in part to limited observational constraints and incomplete theoretical understanding. In particular, small intermediary ions, key drivers of ion-molecule reactions capable of seeding larger hydrocarbons and aromatic rings, could provide critical support for the bottom-up formation scenario. Constraining the abundance and chemistry of these ions is therefore essential to test whether bottom-up growth can operate efficiently under interstellar conditions. Here, we report the first detection of the small hydrocarbon cation ethynylium, C2H+, toward the Orion Bar, based on observations with the APEX 12m sub-mm
telescope of its lowest-lying J=3-2 rotational transition near 211GHz, which exhibits a unique spectroscopic fingerprint through resolved Lambda-doubling and hyperfine splitting components, as recently measured in the laboratory. Meudon PDR models successfully reproduce these values, placing C2H+ formation at the outer edges of PDR fronts. Our results link C2H+ production to CH+ and CH3+ within a network of ion-molecule reactions driven by vibrationally excited H2, a scenario now further supported by recent detections of these species in PDRs like the Orion Bar with JWST observations. The importance of C2H+ lies in its role as a key intermediate: it produces C2H2+ and subsequently C2H3+, effectively channelling small C2 building blocks toward larger hydrocarbons and facilitating bottom-up growth at the PDR surface. Targeted searches for C2H+ in other regions promise to provide a potentially decisive probe of ion-driven bottom-up chemistry in the ISM.
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All authors Arshia M. Jacob, Karl M. Menten, Sandra Brünken, Arnaud Belloche, Friedrich Wyrowski, Weslley G. D. P. Silva, Oskar Asvany, Sarwar Khan, Slawa Kabanovic, Kim Steenbakkers, Gerrit C. Groenenboom, Britta Redlich, Stephan Schlemmer
Cosmology and Nongalactic Astrophysics
Implicit Likelihood Inference and $z$-Binned Reconstruction of Dark Energy $w(z)$
Ke Wang, Jia-Yi Feng and Jianbo Lu
In this paper, to reconstruct the equation of state (EOS) of dark energy (DE) $w(z)$ with the
redshift binning method, we first introduce a $w_i$CDM model with a piecewise-constant EOS in $7$
redshift bins. Then, we turn to the Learning the Universe Implicit Likelihood Inference (LtU-ILI) pipeline to perform a multi-round ILI of $w_i$ from the cosmological data combination, including $TT$, $TE$, $EE$ and
lensing power spectra of Planck 2018, distance ratios of DESI DR2 and corrected apparent magnitudes of SNIa from Pantheon+ sample. More precisely, we build the
Cosmic Microwave Background (CMB) power spectrum,
Baryon Acoustic Oscillation (BAO) distance ratio and Type Ia
Supernovae (SNIa) apparent magnitude simulators by $\mathtt{CLASS}$ and embed them into the LtU-ILI pipeline. And, using Sequential Neural Likelihood Estimation (SNLE), we sequentially train neural networks with $6$ rounds of total $6\times20000$ simulations to target a “black box” likelihood of our forward model $w_i$CDM. Finally, with the estimated posteriors of $w_i$, we find that except for the unconstrained $w_5$ and $w_6$ (the last two bins), our reconstruction of $w(z)$ marginally favors dynamical DE in the first bin and is consistent with the cosmological constant at $68\%$ C.L. in the other bins.
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Solar and Stellar Astrophysics
JWST Reveals a Galaxy-Wide Association of Red Supergiants with OB Stars in NGC 5584
Min Dai, Shu Wang and Biwei Jiang
The spatial relationship between young and evolved massive-
star tracers offers a means of probing recent
star formation across
galactic disks. We combine JWST/NIRCam, $Swift$/UVOT UVW2, and GALEX FUV/NUV images to investigate the spatial association between red-supergiant (RSG) candidates and UV-selected
star-forming complexes (SFCs) in the spiral
galaxy NGC 5584. We identify 5,310 RSG candidates using colour–magnitude criteria and define 106 UV-selected SFCs from the UVOT/UVW2 morphology, with their FUV and NUV luminosities measured independently using the GALEX images. We find that 82% of the UV-selected SFCs overlap significant RSG overdensities, indicating a
galaxy-wide statistical association between UV-bright SFCs and the evolved massive-
star population. Among the 93 SFCs with reliable JWST coverage, the UV-$\beta$-corrected FUV and NUV luminosities correlate tightly with the JWST/NIRCam luminosities, with Pearson correlation coefficients of $r=0.962$–$0.971$. MIST isochrone comparisons for 43 RSG-rich SFCs indicate a characteristic age of $\log(\mathrm{age/yr})\simeq 7.16$. These results show that RSG overdensities and UV-selected SFCs trace related but distinct phases of recent massive-
star formation. Their spatial correspondence is statistical rather than one-to-one and likely reflects differences in
stellar age,
dust extinction, spatial resolution, aperture coverage, and local
star-formation history.
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Applied Physics
Measured LWC-Specific Fog Attenuation and Frequency Scaling in Low-THz Channels
Jiabiao Zhao, Xiaoxiang Li, Kefeng Huang et al. (+6 more)
Fog can reduce the link margin of terahertz (THz) wireless systems. Earlier channel measurements mainly relied on visibility, and almost no
liquid water content (LWC) referenced attenuation coefficients have been reported. This letter reports controlled fog measurements at low-THz frequencies (120, 140, and 160 GHz) over a 22 m channel. LWC is retrieved from a time-aligned droplet size distribution (DSD) and paired with the fog-induced attenuation to obtain the relationship between attenuation and LWC at each frequency. The comparison with ITU-R P.840 is posed as an errors-in-variables problem. This separates the absolute coefficient from its frequency dependence - how the coefficient grows with frequency. Expressed as a power law of frequency, the measured exponent is 1.347, matching the value of 1.343 implied by P.840 at 20 oC. The results provide reference data and a compact scaling law for fog link budgeting at low-THz frequencies.
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All authors Jiabiao Zhao, Xiaoxiang Li, Kefeng Huang, Yapeng Ge, Hanchen Liu, Jie Yang, Weidong Hu, Houjun Sun, Jianjun Ma
Materials Science
Local coordination and migration-network topology shape Li-ion transport and delithiation in the low-energy $\varepsilon$-LiMnO$_2$ polymorph
Fukuan Wang, Busheng Wang and Yong Liu
In rocksalt-derived
oxide cathodes, the local Li-migration environment around an O$_4$ tetrahedral intermediate is commonly classified by the number of face-sharing transition-metal (TM) neighbors. In LiMnO$_2$, the TM species is Mn, and 0-TM denotes the absence of face-sharing Mn neighbors. However, migration and delithiation may also depend on higher-shell coordination and tetrahedral connectivity. Using the recently reported low-energy $\varepsilon$-LiMnO$_2$ polymorph as a model, we examine these factors through bond-valence site-energy and bond-valence pathway analyses combined with first-principles calculations. The resulting migration maps and tetrahedral statistics reveal distinct
topologies across four LiMnO$_2$ polymorphs. Although the $\varepsilon$ phase and the lithiated-spinel phase Li$_2$Mn$_2$O$_4$ (hereafter spinel) have identical tetrahedral-type fractions, their 0-TM motifs form quasi-one-dimensional chains and a three-dimensional network, respectively. Climbing-image nudged elastic band calculations yield $\varepsilon$-phase barriers of 0.35–0.36~eV, compared with 0.41–0.53~eV in spinel, a difference that may be associated with distinct next-nearest corner-sharing shells. Ab initio molecular dynamics yields an apparent activation energy of 0.32~eV, while direction-resolved mean-squared displacements show preferential Li migration along $c$, supporting low-barrier quasi-one-dimensional
diffusion. Delithiation calculations further show that differences in 0-TM connectivity and Li–Li separation between the $\varepsilon$ phase and spinel are associated with Li-site
evolution and calculated voltage steps. These results link local environments and the spatial connectivity of 0-TM motifs to Li migration and delithiation, providing a structural perspective for metastable cathode design.
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