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Physics

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Wednesday 9 September

Statistical Mechanics

Infinite ergodic theory and functional statistics of non-confined Feller process

Vicenç Méndez

We study additive observables of a non-confined Feller process characterized by a non- normalizable stationary probability density and return times with infinite mean. The process is equivalent, after a deterministic rescaling, to a squared Bessel process, but we focus here on a question: the spatial structure of its local-time field. We show that the local time admits a fac- torization in the long time limit. Its spatial profile is governed by the non-normalizable stationary density, whereas its temporal fluctuations are controlled by a single Mittag-Leffler random ampli- tude. As a consequence, normalized spatial correlations of the local time converge to a universal constant independent of the two observation levels. Occupation times of finite intervals follow as corollaries and display Darling-Kac fluctuations. In contrast, non-integrable power observables exhibit self-similar squared-Bessel-type limits rather than Mittag-Leffler statistics. This spatial- field perspective provides a unifying framework for infinite ergodic theory under state-dependent multiplicative noise.
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Chemical Physics

Modeling electrolytes in nanopores by Monte Carlo simulations and the Bazant–Storey–Kornyshev model

Nader Nekoubin, David Fertig, Dezső Boda et al. (+1 more)

We study electrolyte-filled cylindrical nanopores through Monte Carlo (MC) simulations and the Bazant–Storey–Kornyshev model, for different ionic valencies, sizes, and bulk concentrations, pore radii and surface charge densities. Our model accounts for finite ion size through a Stern layer and we use de~Souza and Bazant's mechanical equilibrium principle to derive a boundary condition for the outer Helmholtz plane. For 1:1 electrolytes and moderate surface charge densities, we find that both the classical Poisson–Boltzmann–Stern (PB–Stern) and our Bazant–Storey–Kornyshev–Boltzmann–Stern (BSKB–Stern) model fit MC data well—for 2:1 and 3:1 electrolytes, the BSKB–Stern outperforms the PB-Stern model. Conversely, the BSKB–Stern model poorly fits MC data in other scenarios. First, BSKB–Stern does not capture drying and apparent like-charge attraction in 3:1 electrolytes and small surface charge densities. Second, BSKB–Stern only fits MC data for finely-tuned ionic diameters; for other ionic diameters, the ionic charge densities show oscillations or extended near-surface regions caused by ionic packing and strong Coulomb interactions, not captured by the BSKB–Stern model.
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All authors Nader Nekoubin, David Fertig, Dezső Boda, Mathijs Janssen

General Relativity and Quantum Cosmology

Black hole and wormhole branches in gravitational decoupling

Francisco Tello-Ortiz, Y. Gomez-Leyton, Vitalii Vertogradov et al. (+1 more)

Minimal Geometric Deformation (MGD) applied to a static Schwarzschild black hole seed generates a single decoupler function $h(r)$, obtained by solving the $\theta$-sector field equations together with an equation of state. Once $h(r)$ is fixed, the resulting one-parameter family is controlled by the coupling strength $k$ through $F(r;k)=1+k\,h(r)$. We show that, whenever the deformation develops a simple outermost root that crosses the seed horizon, the same fixed decoupler leads to two mutually exclusive branches associated with different global completions: on one side of the critical coupling the deformed metric preserves the seed horizon as a black hole, whereas on the other side the root $r_*>2M$ lies in the exterior and cannot be interpreted as an interior modification of the black hole geometry. We prove that this root forces a loss of Lorentzian signature on the interval $(2M,r_*)$, so that no smooth extension of the exterior metric through the seed horizon $r=2M$ exists once $r_*$ lies outside it. Within the static, spherically symmetric class considered here, the corresponding smooth Lorentzian completion is a two-ended wormhole obtained by excising $(2M,r_*)$ and doubling the region $r\geq r_*$ across the minimal sphere $\mathcal T=\{r=r_*\}$. No topology change of any single spacetime is claimed or required: $k>k_c$ and $k<k_c$ simply correspond to two different, non-diffeomorphic manifolds, and Lemma~1 below shows that the metric itself dictates which of the two is the admissible completion for a given $k$. We compute the second homology group of both completions explicitly, $H_2(\Sigma_{\rm BH},\mathcal H)=0$ for the black hole exterior relative to its horizon and $H_2(\Sigma_{\rm WH})\cong\mathbb Z$ for the completed wormhole manifold, giving a discrete invariant that distinguishes the two branches.
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All authors Francisco Tello-Ortiz, Y. Gomez-Leyton, Vitalii Vertogradov, Jean Baez Cuevas

Quantum Physics

In situ characterization of a photon-subtraction device via heralding counts and homodyne detection

Priyanka Sharma, Matteo G. A. Paris and Stefano Olivares

Photon subtraction is one of the most important techniques for generating non-Gaussian optical states and constitutes a key resource for quantum information processing and quantum metrology. The practical performance of a photon-subtraction device is primarily determined by the transmissivity of the beam splitter and the quantum efficiency of the heralding detector. Accurate knowledge of these parameters is therefore essential for assessing the quality of the generated non-classical states. In this work, we propose an experimentally feasible in situ scheme for the simultaneous estimation of these two parameters using only the measurement data produced during the operation of the device. Our protocol combines the click statistics of an on/off heralding detector with homodyne measurements performed on the transmitted mode of the beam splitter when fed by a displaced squeezed state. Within the framework of classical multi-parameter estimation theory, we derive the corresponding Fisher information matrix and investigate both joint and sequential estimation strategies. For simultaneous measurement of parameters, we evaluate the sloppiness of the underlying statistical model and analyze its dependence on the measured quadrature, probe photon number, squeezing fraction, beam splitter transmissivity, and detector efficiency. Our analysis proves that an appropriate choice of the homodyne quadrature substantially reduces parameter degeneracy and enables efficient simultaneous estimation. Furthermore, we show that the joint estimation strategy consistently provides a lower estimation bound than the sequential estimation approach over a broad range of experimentally relevant parameters.
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Astrophysics of Galaxies

The JWST Emission Line Survey (JELS): Multi-wavelength properties of Paschen line-emitters at Cosmic Noon

Malte Brinch, Edo Ibar, Luis Ossa-Fuentes et al. (+14 more)

Context: Narrowband JWST/NIRCam selection isolates star-forming galaxies in well-defined redshift slices, while ALMA and archival far-IR/submm data reveal obscured growth. We combine these to measure Paschen-line SFRs, infer nebular extinction from EAZY Av, and probe FIR-to-submm emission via weighted-median stacking, to constrain galaxy growth at cosmic noon. Aims: We characterize stellar, nebular, and FIR properties of Paschen-selected galaxies in COSMOS, in two ensembles at z~1.50 (Pa-alpha) and z~2.65 (Pa-beta), quantifying short- vs long-timescale SF and dust attenuation, and constraining obscured SFR and gas masses. Methods: We select robust narrowband-excess samples from the JELS F466N/F470N mosaic (Pa-alpha: 77, Pa-beta: 31 sources), remove AGN via X-ray/radio matching, and assemble multiwavelength photometry (JWST, HST, Spitzer, Herschel, SCUBA-2, AzTEC, ALMA). Photo-z/stellar properties come from EAZY/STARDUST; line SFRs use recent Paschen calibrations, with nebular extinction from EAZY Av. Results: EAZY fits show stellar masses log(Mstar/Msun)~7.4-10.3 and modest SFRs (0.1-27 Msun/yr). Line SFRs are 0.1-22.0 and 0.7-47.9 Msun/yr for Pa-alpha/beta. Most sources show short-term bursts (line SFRs exceed SED SFRs), weakly decreasing with mass. Nebular attenuation correlates with mass and SFR. Stacking gives no >3sigma detections beyond MIRI. The weighted-median SED gives SFR_UV,med = 0.48+-0.11 and 3.92+-0.47 Msun/yr for Pa-alpha/beta. ALMA Band 4 gives the tightest constraints: median 3-sigma limits SFR_IR<53 (Pa-alpha) and <44 Msun/yr (Pa-beta); gas mass <10^11.2 (Pa-alpha) and <10^10.6 Msun (Pa-beta). Conclusions: Paschen-selected samples show widespread short-timescale star formation, but FIR/sub-mm data give only upper limits on obscured SFR/ISM mass. Deeper spectroscopy and ALMA continuum data are needed to constrain obscured SF and gas reservoirs.
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All authors Malte Brinch, Edo Ibar, Luis Ossa-Fuentes, Corey Pirie, Philip Best, R. K. Cochrane, Kenneth Duncan, James Dunlop, Sophia Flury, Catherine Hale, Jorryt Matthee, Derek McLeod, Joshua Selfridge, David Sobral, Harry Stephenson, J. P. Stott, A.M. Swinbank

High Energy Physics (Phenomenology)

Zero-locus diagnostic of the direct contact term in $\phi\to\pi^+\pi^-\pi^0$

Seung-il Nam and Jung Keun Ahn

We formulate, within a fixed FSI-improved amplitude convention, a zero-locus diagnostic for the direct contact term in $\phi\to\pi^+\pi^-\pi^0$. The resonant $\rho\pi$ contribution is dressed channel by channel with the complex Omnès function, the direct term is multiplied by the averaged Omnès factor, and a real constant background is retained as a smooth residual amplitude. In this convention, $F^{\rm FSI}=R+c e^{i\delta_{\rm dir}}D$ with $c=g_{\phi3\pi}^{\rm eff}$, and the difference of two constrained invariant-mass gradients of the reduced Dalitz density gives a local quadratic identity for $c$ on the zero-contour. The construction provides a closure and stability diagnostic complementary to a global Dalitz-plot fit. For the benchmark input $g_{\phi3\pi}^{\rm eff}=-24.0~{\rm GeV}^{-3}$, we identify a numerically stable zero-contour branch around $M_{+0}=0.460\pm0.025~{\rm GeV}$ and $M_{+-}\le0.560~{\rm GeV}$, where the tight-contour median estimator reproduces $g_{\phi3\pi}^{\rm est}\simeq -24.0~{\rm GeV}^{-3}$, a closure recovery of the injected coupling within the chosen FSI-improved convention rather than an independent extraction. We further vary the mass-window selection of the branch. The median remains close to the injected value under shifts of the $M_{+0}$ window and moderate changes of its width, while the mean and standard deviation are more sensitive to outlier points near unstable quadratic branches. The method therefore identifies Dalitz-plane regions where the direct-term interference is locally well-conditioned and provides useful guidance for control-region choices and systematic variations in future global fits.
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High Energy Astrophysical Phenomena

Search for refractive substructure in active galactic nuclei using ground-based VLBI observations

Tatiana A. Koryukova, Alexander V. Plavin, Alexander B. Pushkarev et al. (+1 more)

We present the results of the first systematic search for refractive scattering substructure in active galactic nuclei (AGN) using ground-based very long baseline interferometry (VLBI) data. We selected 1074 AGNs showing a steep frequency dependence of their angular sizes and compared the observed long-baseline visibility amplitudes with the predictions of the refractive substructure model for scatter-broadened images. Nine sources showed consistency with the expected level of refractive noise, including the quasar TXS 2005+403 (J2007+4029), which confirms previously reported results for this source. Remarkably, the majority of these AGNs are located in the Cygnus region – one of the key “hotspots” of strong Galactic scattering. For five selected AGNs, we identified at least two epochs with sufficiently high data quality showing long-baseline detections, suggesting the presence of scattering substructure. We showed that refractive scattering substructure in AGN is a rare effect, requiring high sensitivity, sufficient source brightness, and lines of sight with particularly strong turbulence in the interstellar medium. Nevertheless, AGNs can serve as powerful probes of the turbulent interstellar medium. We discuss strategies for improving the sensitivity of VLBI observations and identify the most promising sources for reliable detection and investigation of refractive substructure in future observations.
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All authors Tatiana A. Koryukova, Alexander V. Plavin, Alexander B. Pushkarev, Yuri Y. Kovalev

Mathematical Physics · Cross-listed from cs.CE

Joint nonlinearity in a stiffened aluminium wingbox panel and what it requires of a reduced basis

Nikolaos D. Tantaroudas and Evangelos Papatheou

A shell finite-element model of a stiffened aluminium wingbox panel, a laboratory structure shared by several experimental studies, is built with its plate-to-stiffener joints at the $78$ physical fastener positions and calibrated against measured modal data, a six-parameter sensitivity update of the substructure moduli within $\pm20\%$ reproducing the first five measured modes to $1.1$–$4.3\%$ with modal-assurance values of $0.88$–$1.00$. Making the fasteners nonlinear, at equal mesh, mass and damping, shows that joint nonlinearity enters the response strongly asymmetrically. Hardening is almost invisible, at most $+1\%$ in frequency, whereas softening or slipping the joints moves the first three resonances by $-2.1$, $-4.9$ and $-9.2\%$, and friction removes up to $80\%$ of the resonant peak before it recovers. Newmark integration of all $18{,}804$ degrees of freedom and a harmonic balance condensed exactly onto the joints and continued in arclength agree to $5.5\times10^{-4}$. A projection-based nonlinear model order reduction then locates the criterion that a jointed structure imposes on a reduced basis. The binding quantity is not the linear response, which eleven vectors reproduce to better than $0.01\%$, but the receptance of the structure between the joints, of which $126$ global eigenvectors carry about $2\%$, and without which the reduced model overpredicts the hardening shift of the fundamental by a factor of thirty and returns a value beyond the rigid-joint limit of the panel.
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Optics

Laboratory X-ray Microscopy Using Fresnel Zone Plate: Method and Practice

Yongshuai Ge and Yuhang Tan

This book was written to share our experience in developing a Fresnel zone plate (FZP) based X-ray microscope. The research began in September 2020, when we were going to build such a scientific imaging instrument from scratch in our laboratory. At that time, we could not find a textbook that systematically explained the entire development process step by step. We therefore had to make progress through trials and mistakes. After nearly five years of hard effort, we finally managed to build such an X-ray microscope in April 2025. Through this experience, we came to realize how challenging it can be to develop a new FZP-based X-ray microscope without systematic guidance. We therefore believe that it is worthwhile to share the learned lessons with readers who may be interested in developing their own FZP-based X-ray microscopes in the future. I would encourage readers to treat this book as a practical manual rather than a traditional textbook. Readers are not expected to be experts in X-ray imaging. Instead, a basic background in college-level physics should be sufficient to understand most of the material. Inevitably, the current edition has limitations and may contain omissions or inaccuracies due to the authors' limited experience and perspective. I sincerely welcome comments, suggestions and discussions from readers, please feel free to contact me at geyongshuai1987@qq.com. Your feedback will be greatly appreciated and will help make future editions of this book more complete.
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Fluid Dynamics · Cross-listed from math.AP

Finite-time divergence of kinetic-energy fluctuations in a Schrödinger-induction flow

Weishuo Liu

In this study, we use a constrained Schrödinger–induction system to investigate kinetic-energy fluctuations induced by a fluid singularity. Assuming the cited Navier–Stokes construction with zero initial velocity and its exact exterior profile, we construct a periodic trajectory from a constant normalized wave function and zero connection. The prescribed body force admits a smooth space–time extension across the normalized singular time $t=1$. In this construction, the probability density remains constant and the mean matter kinetic energy stays bounded, whereas the gauge-invariant kinetic-energy variance diverges. We prove a lower growth bound of order $(1-t)^{-1/2-5h}$, with $h$ fixed by the source construction, by integrating the fourth power of the complete velocity's magnitude over an exact exterior region where all oscillatory corrections vanish. After fixing a gauge with constant wave function, we identify a unique weak $L^2$ connection limit outside $L^4$ and construct its positive self-adjoint kinetic operator through the associated magnetic form. We further show that the normalized endpoint state belongs to the form domain but not the operator domain: its first kinetic spectral moment is finite, whereas its second is infinite. These results connect fluid concentration to a loss of kinetic-domain regularity and provide a dynamical benchmark for assessing the limits of mean-energy control in hydrodynamic wave formulations.
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Materials Science

Observation of Magnetic-Anisotropy Crossover and High-Temperature Skyrmions in the Dirac Magnet Fe3Ge with a Distorted Kagome Lattice

Yalei Huang, Xiaowei Lv, Bin Li et al. (+13 more)

Topological materials that simultaneously host robust high-temperature skyrmions and nontrivial electronic band structures have attracted tremendous interest owing to their distinctive advantages for both fundamental research and prospective technological applications. Here, we report the observation of robust skyrmions in the Dirac kagome magnet Fe3Ge, which exhibits a high Curie temperature of ~ 650 K. At room temperature, Fe3Ge shows a large intrinsic anomalous Hall conductivity of ~ 380 {\Omega}-1cm-1, originating from its nontrivial electronic band topology. Systematic magnetization measurements reveal a spin reorientation transition at ~ 375 K, indicating a crossover from easy-plane to easy-axis magnetic anisotropy. Below the spin reorientation temperature, a large topological Hall effect is observed, arising from microscopic noncoplanar spin structures. Lorentz transmission electron microscopy shows that mesoscopic skyrmions are stabilized in the easy-axis magnetic anisotropy regime and persist over an exceptionally wide temperature window of 375-650 K, far exceeding that of most previously reported skyrmion-hosting materials. These results establish Fe3Ge as a promising platform for exploring diverse topological properties, with strong potential for advancing future high-temperature spintronic applications, ranging from next-generation information storage to logic computing devices.
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All authors Yalei Huang, Xiaowei Lv, Bin Li, Chunqiang Xu, Dhanarajagopal Alltrin, Xiaoxuan Ma, Wanting Yang, Wei Zhou, Xiangzhuo Xing, Wen-Chin Lin, Raman Sankar, Michael Smidman, Shixun Cao, Dong Qian, Renchao Che, Xiaofeng Xu

Quantum Physics

Loss-correcting fault-tolerant quantum computing architecture for neutral atoms

Sanaa Sharma, Yutaka Hirano, Akihisa Goban et al. (+3 more)

Neutral-atom arrays are a leading qubit technology for large-scale, fault-tolerant quantum computing (FTQC). A dominant error source on this platform is qubit loss, which accrues with every operation and movement. The presence of loss undermines the promises of existing architectural work. Standard error correction targets stochastic Pauli errors and cannot correct loss, so most FTQC performance analyses are not directly compatible with it. Moreover, compilation and routing decisions, which strongly affect overall loss, are typically optimized against Pauli-error cost models and often remain loss-agnostic, potentially increasing exposure to the loss channel. In this work, we comprehensively model the effect of qubit loss on neutral-atom FTQC and develop a loss-tolerant transversal-gate architecture. We treat loss not as a predetermined error parameter but as a dynamic budget spent across a whole program, allowing us to control it by co-designing layout, compilation, and decoding. We target a physical implementation with no separate storage and entangling zones, eliminating the repeated SLM-AOD handoffs and long-distance shuttling that dominate loss in other layouts. We develop compiler optimizations that maximize gate parallelism while respecting the RF tone budget and AOD bandwidth constraints. Our work couples these with a loss-aware, delayed-erasure decoder and an end-to-end loss-aware magic state cultivation protocol. Overall, we improve accumulated loss per syndrome-extraction round by up to 2.15X against a zoned baseline and reduce logical error rates by over two orders of magnitude versus current architectures. Our framework also informs concrete device targets such as continuous reloading rates, AOD counts, and shuttling trajectory choices. We expect these insights to matter for system architects as neutral-atom hardware scales.
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All authors Sanaa Sharma, Yutaka Hirano, Akihisa Goban, Hayata Yamasaki, Shinichi Sunami, Prakash Murali

Quantum Physics

Why three? A two-level system with four mutually unbiased questions

Jonte R. Hance

Two sharp yes/no questions are mutually unbiased if and only if their involutions anticommute. A set of unbiased questions is therefore a Clifford algebra, whose maximal size is odd, meaning four anticommuting questions typically imply a fifth: the two-level systems of real, complex and quaternionic quantum theory allow two, three and five questions, while four is skipped. Without this operator product restriction, a two-level system with four unbiased questions exists as the four-dimensional Bloch ball, the hyperbit. The single-system postulates that pick out the Jordan state spaces allow such a model, and only energy observability rules it out. We show what it lacks, and realise it inside two qubits: its Kirkwood-Dirac imaginary parts are hidden $\mathfrak{so}(4)$ generators, its composites allow entanglement but no interaction, and its 24-cell of states stays Spekkens preparation contextual down to depolarising strength $2/3$. In fermionic terms, the four questions are the Majorana operators of two modes while the fifth is parity: the four-question system is therefore the sector removed by parity superselection.
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Earth and Planetary Astrophysics

Physics-Informed Multi-Task Surrogate Model for the Martian Nightside Thermosphere

Sergey Nikiforov

Modeling the Martian nightside thermosphere remains challenging due to sparse in situ sampling and strong coupling among transport, magnetic, and seasonal processes. Purely data-driven models can produce non-physical artifacts, such as density inversions, in poorly sampled altitude regimes. We present a multi-task physics-informed neural network that simultaneously predicts the base-10 logarithmic densities of four neutral species (O, CO$_2$, N$_2$, and Ar) using more than a decade of MAVEN/NGIMS observations (MY 32-38, 2014-2025). A shared backbone learns a common representation of the nightside thermospheric state and branches into species-specific output heads. A weak monotonicity prior is incorporated via automatic differentiation by penalizing positive vertical gradients in logarithmic density. Experiments using an orbit-disjoint train/validation/test split show that physics-informed regularization substantially reduces non-physical inversions while preserving predictive skill and slightly improving it in the best-performing configuration, as measured by RMSE, MAE, and $R^2$. The resulting model provides a computationally efficient surrogate for nightside thermospheric reconstruction with improved vertical consistency.
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Optics

Expanding RCWA capabilities with advanced S-matrix algorithms

Philippe Lalanne and Jean-Paul Hugonin

Modal methods are particularly well suited to layered photonic structures because electromagnetic propagation within each layer is described analytically. Here, we introduce a simple reformulation of the scattering-matrix (S-matrix) approach in which the S-matrix is defined as an intrinsic property of an individual layer, independently of its neighboring interfaces. This separation between layer propagation and interface coupling preserves the numerical stability of the conventional S-matrix formalism while providing a more modular description of multilayer structures. It also enables direct computation of the scattering coefficients between external plane waves and Bloch modes, as well as between Bloch modes themselves, providing generalized Fresnel coefficients for periodic interfaces. In addition, the reformulation allows the optical response to be evaluated simultaneously for many layer thicknesses or incident wavevectors, with only a modest computational overhead compared with a single calculation. Implemented in the RETICOLO freeware, these capabilities provide a practical framework for modal analysis, parameter sweeps, and the design of layered photonic structures.
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High Energy Astrophysical Phenomena

Orthogonal polarization modes of nonbirefringent origin in a geometric radio pulsar signal model

J. Dyks, L. Saha and A. Frankowski

Motion of plasma in pulsar magnetospheres essentially follows bent magnetic field lines which may result in radiation beams sweeping past the observer's sightline. We show that under certain conditions such a passing beamlet can produce two orthogonal polarization modes (OPMs) solely from averaging of radiative contributions, without involving birefringence. This requires that radiation from different stages of the passage is contributed incoherently, hence that the timescale for the coherence is much shorter than the typical sampling time. The model produces two OPMs of comparable amount, with a wide range of (single-pulse) polarized fractions, which is consistent with general observed pulsar properties. Under the specific conditions required (essentially incoherent summation of signal at appropriate time scale) the averaging effects alone can thus lead to the appearance of two orthogonal polarization tracks with OPM jumps.
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Quantum Physics

Haar-Bayesian Pure-State Prediction under Relative-Entropy Loss: Arbitrary-Effect Reduction and Global Optimality

Masahito Hayashi, Ayanava Dasgupta and Naqueeb Ahmad Warsi

We study Haar-Bayesian prediction of one unmeasured copy of an unknown finite-dimensional pure quantum state after an arbitrary collective measurement on $n$ observed copies. Performance is evaluated by quantum relative entropy. For a fixed measurement, the Bayes predictive state is the posterior mean and the optimized conditional loss is its entropy. We then optimize the measurement over all POVMs on the symmetric subspace. For every nonzero positive effect $E$, the corresponding posterior predictive state is $\mu_E=(I+n\rho_E)/(n+d)$, where $\rho_E$ is the normalized one-particle marginal of $E$. Since a pure spectrum majorizes every density-operator spectrum, this identity gives an outcome-wise entropy lower bound. Coherent rank-one effects attain the bound, and their Haar orbit yields the highest-weight covariant POVM. Hence this POVM is globally Bayes optimal over all collective measurements and, by covariance, globally minimax. Its exact risk is $h_d((n+1)/(n+d))$, where $h_d(r)=-r\log r-(1-r)\log((1-r)/(d-1))$. The same arbitrary-effect reduction shows that the highest-weight POVM also maximizes the joint overlap between the latent pure state and its posterior predictive state, equivalently the mean posterior purity, with optimum $((n+1)^2+d-1)/(n+d)^2$.
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High Energy Physics (Phenomenology)

Probing the Electromagnetic Structure of Heavy-Light Hybrid Mesons with Vector and Axial-Vector Quantum Numbers

A. Amiri, K. Azizi and P. Eslami

We investigate the electromagnetic (EM) properties of vector and axial-vector heavy-light hybrid mesons within the light cone QCD sum rules framework. These states are characterized by an explicit gluonic degree of freedom and are studied through interpolating currents corresponding to the $J^{P(C)}=1^{-(-)}$, $1^{+(-)}$, $1^{+(+)}$, and $1^{-(+)}$ hybrid configurations. By analyzing the correlation function in the presence of an external background photon and matching its hadronic and QCD representations, we derive the light cone sum rules for the magnetic dipole and electric quadrupole form factors and extract the corresponding electromagnetic moments at $Q^2=0$. The QCD side of the sum rules incorporates the perturbative photon emission contributions as well as the relevant non-perturbative effects described by photon distribution amplitudes (DAs). Numerical predictions are obtained for the charged $\bar b g u$, $b g\bar u$, $\bar c g d$, $c g\bar d$, $\bar c g s$, and $c g\bar s$ hybrid configurations. The calculated electromagnetic moments show variations among the different hybrid configurations. A more systematic pattern is observed for the electric quadrupole moments (EQMs): the results obtained from the $\mathcal J_\mu^1$ and $\mathcal J_\mu^3$ currents are generally close to each other, as are those obtained from $\mathcal J_\mu^2$ and $\mathcal J_\mu^4$, with the former pair generally yielding somewhat larger magnitudes. The magnetic dipole moments (MDMs), in contrast, do not necessarily exhibit the same systematic grouping, although they also show variations among the different currents and configurations. For the bottom-containing states...
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High Energy Physics (Phenomenology)

On the universality of soft emission beyond the next-to-soft order

Martin Beneke, Maria Santana and Michel Stillger

The Low-Burnett-Kroll theorem (extended to non-abelian gauge theory) states that the tree-level emission amplitude of a soft gauge boson from an arbitrary hard process can be expressed in terms of the non-radiative amplitude including the next-to-soft term. Reformulating the soft theorem in the framework of an on-shell effective theory leads to a natural gauge-invariant split into an external and internal emission process to any order in the soft expansion. In this framework, we derive a compact expression for the all-order external emission amplitude expressed in terms of the non-radiative amplitude, and express the local emission amplitude through a single gauge-invariant operator at every order beyond the next-to-soft one. For scalar QCD, we compare the number of Lorentz- and $SU(3)$-invariant amplitudes for the radiative and non-radiative hard process with an arbitrary number of scalar quarks and antiquarks.
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Strongly Correlated Electrons

Non-equilibrium dissipative stabilization of s- and d-wave superconductivity

Aleksey Lunkin, Yury Holubeu, Denis Golež et al. (+1 more)

Stabilizing superconductivity beyond its equilibrium regime has been one of the quests of nonequilibrium state engineering. We report the presence of nonthermal pairing gap in BCS superconductors coupled to two thermal baths, where one of the baths can be at a temperature well above the equilibrium $T_c$. Superconducting state is enabled by a highly non-equilibrium steady state stabilized by weak coupling to baths that break detailed balance condition. The steady-state is well described by a generalized Gibbs ensemble parametrized with chemical potentials for associated Bogoliubov quasiparticle. A strong, non-perturbative effect is reported for both $s$-wave and $d$-wave superconductors, and its possible realization in cavity-based experiments is discussed.
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All authors Aleksey Lunkin, Yury Holubeu, Denis Golež, Zala Lenarčič

Optics

Transition of Photonic Dissipative Dynamics through the Exceptional Point

Yue Cui, Ruihen Jin, Xiong Jiang et al. (+3 more)

The decay of light in an optical structure depends not only on the intrinsic properties of the material but also on the surrounding electromagnetic environment. This principle has laid the foundation for the engineering of dissipation in photonic emitters. In the conventional wisdom, dissipation is governed by a fixed set of decay channels, each defined by the eigenstates of the structure, and energy leaks through and interacts with these channels. Here we provide experimental evidence that this paradigm fails in non-Hermitian systems. Specifically, we observe an accelerated transient decay in a pair of coupled microcavities tuned near the exceptional point, revealing that photonic dissipation can be governed not by reconfiguring existing loss channels, but rather by restructuring the underlying state space. The universality of this phenomenon is corroborated through two independent control parameters.The finding provides a new perspective on dissipative dynamics in open optical systems and offers a distinct mechanism for controlling transient decay in ultrafast photonic systems.
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All authors Yue Cui, Ruihen Jin, Xiong Jiang, Kaiyang Wang, Can Huang, Qinghai Song

Quantum Physics

Accelerating A*-Based Algorithms for Decoding Quantum Low-Density Parity-Check Codes

Lamia Yous, Francisco Garcia Herrero and Mark F. Flanagan

Quantum low-density parity-check (QLDPC) codes represent a promising approach for error correction in quantum computing. The recently proposed Tesseract decoder uses the A* search algorithm that guarantees finding the most likely error pattern. However, practical implementations of Tesseract often involve an extremely large graph, and the inherently sequential nature of the search results in high computational overhead and long runtime. To improve decoding efficiency, we propose a two-stage decoding framework. First, a belief propagation (BP) decoder efficiently processes the syndrome. This step generates hard decisions (a binary error vector) and soft information (per-qubit confidence levels). In non-convergent BP cases, a gating mechanism examines the BP decoder's output to identify and filter out qubits with oscillating confidence values. In these cases, the refined output serves as input to Tesseract, which then attempts to identify and correct any residual errors. This hybrid approach leverages the high speed of BP decoding and delegates the more challenging decoding instances to Tesseract. Numerical results demonstrate a substantial reduction in overall decoding complexity while maintaining the logical error rate (LER) of the stand-alone Tesseract. Across all tested physical error rates, the proposed method achieves at least 5x reduction in the number of expanded nodes in the Tesseract, with a peak reduction of nearly 15x at a physical error rate of p = 0.05 for the [[126, 12, d < 11]] T1 code, and approximately 8.8x at p = 0.05 for the [[72, 12, 6]] bicycle bivariate (BB) code.
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Nuclear Experiment

Search for neutrinoless quadruple beta decay of $^{136}$Xe in PandaX-4T detector

PandaX Collaboration: Zhiyuan Li, Peiyuan Chen, Wei Chen et al. (+102 more)

The observation of neutrinoless quadruple beta decay (0$\nu$4$\beta$) in the absence of neutrinoless double beta decay (0$\nu$2$\beta$) has been argued to provide a strong indication that neutrinos are Dirac particles. We report a search for 0$\nu$4$\beta$ decay of $^{136}\text{Xe}$ using a total $^{136}\text{Xe}$ exposure of 148.4 kg$\cdot$yr, collected during the commissioning and the first science runs of the PandaX-4T experiment. No significant excess of events over the background is observed. A lower limit on the 0$\nu$4$\beta$ decay half-life of $^{136}\text{Xe}$ is set at 6.01 x $10^{24}$ yr at the 90% confidence level. This result establishes the most stringent constraint on this process in xenon, demonstrating the unique capability of the PandaX-4T detector in probing lepton number violation and shedding light on the fundamental nature of neutrinos.
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All authors PandaX Collaboration: Zhiyuan Li, Peiyuan Chen, Wei Chen, Xiaohua Chen, Xun Chen, Yunhua Chen, Chen Cheng, Xiangyi Cui, Yuxin Cui, Manna Deng, Roni Dey, Yingjie Fan, Deqing Fang, Xuanye Fu, Zhixing Gao, Yujie Ge, Lisheng Geng, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Ruquan Hou, Houqi Huang, Junting Huang, Yule Huang, Xiangdong Ji, Yonglin Ju, Xiaorun Lan, Chenxiang Li, Mingchuan Li, Peiyuan Li, Shuaijie Li, Tao Li, Yangdong Li, Yuan Li, Qing Lin, Jianglai Liu, Yuanchun Liu, Yunyang Luo, Yugang Ma, Yajun Mao, Yue Meng, Binyu Pang, Ningchun Qi, Xiangxiang Ren, Dong Shan, Xiyuan Shao, Manbin Shen, Xuyan Sun, Yi Tao, Yueqiang Tian, Yuxin Tian, Anqing Wang, Guanbo Wang, Hao Wang, Haoyu Wang, Jiamin Wang, Lei Wang, Meng Wang, Qiuhong Wang, Shaobo Wang, Shibo Wang, Siguang Wang, Wei Wang, Xu Wang, Zhou Wang, Yuehuan Wei, Weihao Wu, Yuan Wu, Mengjiao Xiao, Xiang Xiao, Yuhan Xie, Kaizhi Xiong, Jianqin Xu, Yifan Xu, Binbin Yan, Xiyu Yan, Yong Yang, Shunyu Yao, Peihua Ye, Chunxu Yu, Zhe Yuan, Youhui Yun, Minzhen Zhang, Peng Zhang, Shibo Zhang, Shu Zhang, Siyuan Zhang, Tao Zhang, Wei Zhang, Yang Zhang, Yingxin Zhang, Yuanyuan Zhang, Kangkang Zhao, Li Zhao, Jiaxu Zhou, Jiayi Zhou, Jifang Zhou, Ning Zhou, Xiaopeng Zhou, Zhizhen Zhou, Chenhui Zhu

Quantum Gases

A machine-learned dynamical phase diagram of the one-dimensional nonlinear Schrödinger equation with quasiperiodic disorder and a static field

Marcos Pérez

We map the transport regimes of a wave packet evolving under the one-dimensional discrete nonlinear Schrödinger (Gross-Pitaevskii) equation with a quasiperiodic Aubry-André potential and a static (Stark) field, as a function of self-interaction $g$, field $F$, and quasiperiodic strength $\lambda$, for two initial states (delta and Gaussian). Instead of one expensive long-time simulation per grid point, we run 3600 short simulations, reduce each to eight dynamical features, and cluster parameter space with a Gaussian mixture model. Clustering finds the boundaries between regimes unsupervised; each cluster's name is then assigned by a hand-calibrated rule, and an ablation shows clustering measurably smooths those boundaries rather than merely relabeling them. The five resulting regimes (ballistic, localized, oscillatory-localized, subdiffusive, and self-trapped) are validated against 100 long runs on a lattice eight times larger than the short sweep, so the validation window is longer than the training window even for the fastest-spreading regime. The short-time clusters predict the long-time asymptotic spreading exponent ($\alpha_\infty = 2.01\pm0.07$ ballistic, $0.28\pm0.16$ subdiffusive, consistent with the weak-chaos prediction $\alpha=1/3$) and, independently, a long-time retention $\Pi_0=0.72\pm0.32$ for the self-trapped cluster, whose exponent alone is not diagnostic. The initial-state contrast is striking: the delta state develops a broad self-trapping wedge (onset at $g=3.907\pm0.017$ at $\lambda=0$) that invades the ballistic and localized regions as $g$ grows, while the Gaussian state shows no self-trapping, instead opening a subdiffusive corridor along the Aubry-André critical line that widens with $g$. The scheme yields a full $15\times15$ phase map in minutes per slice, where direct asymptotic simulation ($t\gtrsim10^6$ per point) is prohibitive.
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Quantum Physics

Quantum computational resources and validation protocols for a three-mode non-Gaussian trilinear Hamiltonian

Niccolò Laurora, Matteo Bina, Giulia Ferrini et al. (+1 more)

Non-Gaussian interactions are a key ingredient for achieving universality in continuous-variable quantum computation, yet their experimental characterization and the validation of their correct implementation remain challenging tasks. In this work, we focus on a three-mode non-Gaussian trilinear Hamiltonian that has recently been realized in superconducting microwave platforms, and present a comprehensive theoretical analysis of the computational resources it generates, together with experimentally accessible protocols to validate their presence. We systematically investigate its ability to generate two key resources for quantum computation: multipartite entanglement and Wigner negativity. In particular, using displaced-parity Bell tests, we demonstrate the generation of nonlocal states and thereby provide an operational certification of multipartite entanglement in the non-Gaussian states produced by the dynamics. We further quantify the Wigner logarithmic negativity and benchmark it against that of established non-Gaussian resource states. Building on this resource-based characterization, we introduce a measurement-efficient protocol for the experimental validation of the Hamiltonian implementation without requiring full reconstruction of the Wigner function. The protocol combines the measurement of zero-variance observables (nullifiers and stabilizers) with a limited number of targeted phase-space measurements, leading to a drastic reduction of the experimental overhead.
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All authors Niccolò Laurora, Matteo Bina, Giulia Ferrini, Alessandro Ferraro

Instrumentation and Methods for Astrophysics

Modelling Fourier filtering wavefront sensors for PSD-based methods: the AOPERA tool

Romain Fétick, Vincent Chambouleyron, Lisa-Marie Mazzolo et al. (+6 more)

Compensation of the atmospheric turbulence thanks to adaptive optics (AO) has now become commonly used for VLT or ELT class telescopes in order to retrieve a resolution close to their diffraction limit. Following the increasing trend of AO system, there is also a stronger necessity for simulations in order to understand and predict their performance facing different observing conditions, that are the evolution of the atmospheric turbulence or the diversity of AO guide source. The so-called PSD based methods are well adapted to the demand thanks to their simplicity and speed. Moreover, they provide a comprehensive breakdown error budget and impact on focal plane, that is of high interest especially in the case of extreme adaptive optics. Their drawback is the challenge to describe non-linear wavefront sensors (WFS) such as the pyramid WFS or the Zernike WFS. There is a necessity to develop fast yet accurate methods to describe the behaviour of AO systems including sensitive WFS. We thus develop a method to compute the AO system response (electromagnetic phase power spectral density, and point spread function) including the non-linear behaviour of the wavefront sensor within PSD-based numerical tools. Mathematical formalism to describe the FF-WFS sensitivity combined to non-linearity management greatly improve the accuracy of description of AO systems through numerical simulations. After a mathematical description of the method, its numerical implementation is compared with end-to-end simulations using the OOPAO tool. Indeed end-to-end simulations are reproducing the response of AO systems with high fidelity, especially regarding WFS sensitivity and non-linearity. Similarity of results for the fitting error, temporal error and noise error proves the validity of our method in managing Fourier filtering WFS sensitivity and non-linearity.
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All authors Romain Fétick, Vincent Chambouleyron, Lisa-Marie Mazzolo, Christophe Vérinaud, Arnaud Striffling, Cédric Héritier-Salama, Benoit Neichel, Jean-Francois Sauvage, Thierry Fusco

High Energy Astrophysical Phenomena

Evidence of a Low-Energy Cutoff in the Injected Spectrum of a Pulsar Wind Nebula

Zhihong Shi, C.-Y. Ng, Niccol`o Bucciantini et al. (+5 more)

Bow-shock pulsar wind nebulae (PWNe) are synchrotron sources formed when the outflow of supersonic pulsars is confined by the surrounding interstellar medium. These sources are dominated by freshly injected particles, thus providing a unique laboratory for studying particle acceleration in relativistic outflows. The Mouse is a prototypical bow-shock PWN and is bright in the radio and X-ray bands, enabling detailed multi-wavelength spectral modeling. With data from 17 telescopes, the Mouse is detected from 118 MHz to 353 GHz, covering over 3 decades in frequency, and in X-rays from 0.5 to 30 keV. A clear spectral break is identified at 3.7 GHz. The radio spectrum exhibits a rising trend at low frequency, peaks at the break, and then declines. We find a change in spectral index $\Delta\alpha=0.65\pm0.05$ across the break. We attribute this to an intrinsic cutoff or steepening in the injected particle distribution. This could indicate the characteristic energy of leptons leaving the pulsar magnetosphere, or energy dissipation after the particles cross the termination shock.
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All authors Zhihong Shi, C.-Y. Ng, Niccol`o Bucciantini, B. M. Gaensler, Zhen Yan, David J. Wilner, Douglas C.-J. Bock, Hua-bai Li

Mathematical Physics · Cross-listed from math.PR

A central limit theorem for Bessel and Dunkl processes with drift

Michael Voit

For some discrete parameters, multivariate (Dunkl-)Bessel processes on Weyl chambers $C$ are projections of Brownian motions on Euclidean spaces $V$; the most prominent examples are Dyson Brownian motions. More generally, the projections of Brownian motions on $V$ with drift are Bessel processes with drifts on $C$, where again the associated transition densities can be described in terms of multivariate Bessel functions. Moreover, Dunkl processes with drift can be defined in an analogous way. In this paper we prove central limit theorems for these Bessel and Dunkl processes with drift for regular drift vectors, and arbitrary root systems and multiplicities. These results improve recent results of the author.
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Quantum Physics

Semi-device-independent quantum randomness certification in semiconductor spin-noise measurements

Hamid Tebyanian, Marius Cizauskas, Manfred Bayer et al. (+2 more)

Complex solid-state systems are promising platforms for scalable, high-bandwidth quantum random-number generation, yet certifying the quantum origin of their fluctuations remains difficult because the underlying microscopic dynamics are hard to model and validate. Here we demonstrate semi-device-independent quantum randomness certification from semiconductor spin noise, to our knowledge the first such certificate on any spin-noise source, without relying on a microscopic model of the spin system. The untrusted optical source is constrained by an experimentally tested mean-photon-number bound together with a declared analogue-range and per-sample clipping ceiling, while the trusted receiver is described as a calibrated, noisy, coarse-grained homodyne measurement. Using a semidefinite programme with rigorously controlled Fock-space truncation, we certify randomness that remains private against an adversary holding arbitrary quantum side information. Offline analysis yields certified entropy rates of $3.2$–$3.4$\,Gbit/s from a singly charged (In,Ga)As quantum-dot ensemble and $33$\,Mbit/s from $n$-GaAs in a spin-noise-matched detection mode. This exceeds the certified entropy rate of earlier spin-noise generators by more than two orders of magnitude, and the certificate tolerates a resolved per-symbol energy contribution from the solid-state emitter itself rather than requiring a near-vacuum input.
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All authors Hamid Tebyanian, Marius Cizauskas, Manfred Bayer, Marc Assmann, Alex Greilich

Earth and Planetary Astrophysics

Magnetically Driven Obliquity in Circumplanetary Disks and Twisted Bipolar-jet Formation

Raúl O. Chametla, Martin E. Pessah, F. Javier Sánchez-Salcedo et al. (+4 more)

Circumplanetary disks (CPDs) regulate gas accretion onto forming giant planets and provide the environment in which their satellites may form. We use high-resolution, global three-dimensional simulations to investigate the early formation, orientation, and outflows of a CPD around a Jupiter-mass planet embedded in a turbulent magnetized protoplanetary disk. Within a locally isothermal, ideal-MHD framework, we evolve disks threaded by net vertical magnetic fields, corresponding to initial plasma parameters $875\leq\beta\leq3500$, until magnetorotational-instability-driven turbulence is established before inserting the planet. We also perform a hydrodynamic control simulation. In the most strongly magnetized model, with $\beta=875$, the CPD forms already highly inclined and reaches a maximum tilt of approximately $87^\circ$. By contrast, the hydrodynamic CPD and the MHD models with $\beta\gtrsim1000$ remain nearly coplanar. A control simulation in which the planet is inserted before global MRI turbulence develops also remains coplanar, despite producing local turbulence and bipolar outflows. The large tilt is therefore associated with the pre-existing global turbulent state and its evolved velocity and toroidal magnetic-field structure, although our current diagnostics do not distinguish between a direct magnetic torque and the accretion of misaligned angular momentum. All MHD models launch bipolar outflows; in the highly tilted case, these develop a curved, helical morphology that persists until the end of our short-term simulations. These results identify pre-existing global magnetized turbulence as a viable route to generating strongly inclined CPDs and twisted planetary outflows.
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All authors Raúl O. Chametla, Martin E. Pessah, F. Javier Sánchez-Salcedo, David Vokrouhlický, Mauricio Reyes-Ruiz, Ondrej Chrenko, Alessandro Morbidelli