Papers

Liquid scintillator detectors instrumented with distributed silicon photomultiplier (SiPM) arrays can be used in compact, topology-sensitive, and low-background experiments, but the temperature dependence of SiPMs immersed directly in the scintillation medium has not been widely characterized. We report the operation of a 125-liter linear-alkylbenzene-based liquid scintillator detector read out by 125 SiPM channels immersed in the active volume, over the range from room temperature to $-30\,^{\circ}\mathrm{C}$. The detector response was measured with cosmic-ray muons, including stopping muons followed by their Michel-electron decay. Cooling from $+15\,^{\circ}\mathrm{C}$ to $-30\,^{\circ}\mathrm{C}$ reduced the SiPM dark-count rate by a factor of 13.5, increased the single-photoelectron response by 49.1%, and increased the cosmic-ray muon light yield by 16.7%. The improved photoelectron separation and baseline stability at low temperature enabled a selection of stopping-muon events, from which the effective muon lifetime was measured to be $1959\pm132\,\mathrm{ns}$, consistent with the value expected for a hydrocarbon scintillator once $\mu^{-}$ capture on carbon is taken into account.

To improve understanding of how precipitation frequency and intensity change with warming, we combine the coupled land–atmosphere water balance with a stochastic hydrological model that retains explicit dependence on precipitation frequency and event depth. We find a linear relationship between co-variations of rainfall frequency and intensity, where the slope is a hydrological sensitivity determined by the dryness and storage indices and the intercept is a forcing term associated with changes in moisture convergence, potential evapotranspiration, and effective water-storage capacity. While a given relative change in either rainfall frequency or intensity produces an identical relative change in the mean rate, rainfall intensity additionally influences the runoff coefficient by altering terrestrial water storage relative to rainfall depth. This means frequency and intensity have different impacts on the water cycle, allowing the frequency–intensity slope to depart from -1. Analysis of long-term MOPEX records shows that the forcing term is dominated by moisture convergence and that the frequency–intensity relation becomes steeper from wet to dry regimes, consistent with the slope predicted by the theory. The framework provides a physical interpretation of the observed negative covariation between precipitation frequency and intensity and clarifies the roles of hydrological partitioning and atmospheric moisture supply in their responses to warming.

Liquid scintillator detectors instrumented with photosensors inside the scintillation volume preserve local optical information that is largely lost in conventional boundary-readout geometries. We demonstrate that this information is sufficient for charged-particle topology reconstruction using a sparse three-dimensional lattice of silicon photomultipliers. After validating the Geant4 detector response against measured photon-count distributions, a simulation-trained, time-informed convolutional neural network reconstructs the entry and exit points of through-going muons with median residuals of 1.91~cm and 2.39~cm, respectively. The reconstructed endpoints are geometrically consistent with acceptance regions defined by external trigger counters in cosmic-ray muon data. The same framework also reconstructs the production vertices of simulated positron starting-track events with a median residual of about 4.5~cm. These results establish the feasibility of topology-sensitive reconstruction using sparse in-liquid photosensor arrays in homogeneous liquid scintillator detectors.

We study the holographic description of the RN-like black hole in bumblebee gravity, which is a vector-tensor theory with spontaneous Lorentz violation. By combining the first laws of the outer and inner horizons, the thermodynamics method yields the right- and left-moving entropies, temperatures, and chemical potentials of the dual two-dimensional conformal field theory (CFT), determines the central charges from the mass-independent entropy product, and reproduces the outer and inner horizon entropies through the Cardy formula. An independent dynamical test based on the hidden conformal symmetry of a charged scalar probe confirms these results. A central outcome is the equality of the right- and left-moving central charges, $c_R=c_L$, which we trace to the spontaneous character of Lorentz breaking. Because the action of bumblebee gravity preserves diffeomorphism and local Lorentz invariance, and the symmetry is broken only by a vector vacuum expectation value, no chirally asymmetric structure arises in the dual theory, in sharp contrast to topologically massive gravity in $(2+1)$ dimensions. All CFT data depend smoothly on the Lorentz-violating parameter and reduce to the known RN results when Lorentz violation is switched off.

Binary interaction fundamentally alters the evolution of massive stars, yet the physical consequences of mass transfer remain poorly constrained. Here we present high-resolution spectroscopic observations of Plaskett's Star (HD 47129) that reveal small radial-velocity variations of its magnetic secondary, coherent with the system's 14.4 d orbital period. These measurements support an evolved, post-mass-transfer configuration in which the narrow-lined primary is a partially Roche-lobe-filling stripped star with a mass of $5.9^{+1.8}_{-1.4},M_\odot$, while the secondary is a $40.8^{+9.3}_{-6.7},M_\odot$, rapidly rotating magnetic accretor. The system provides a rare opportunity to observe the immediate aftermath of mass transfer in a massive binary and offers compelling new evidence linking binary interaction to the emergence of strong stellar magnetism. Because magnetic fields regulate angular-momentum loss and transport, their formation through mass transfer could alter the subsequent evolution of massive binaries, with consequences for stellar populations, supernova progenitors and yields, and the formation of gravitational-wave sources.

Transition states are defined by reaction pathways, yet most machine-learning methods predict them as isolated geometries. We introduce MARC-TS, a two-stage framework that learns a continuous, endpoint-conditioned path, queries it at any resolution and uses local path context to refine a transition-state candidate. We construct T1x-IRC-8K, a dataset of 8,209 reactions and 1,088,725 path-resolved geometries. On held-out reactions, the path model reduced complete-path error by 48.4% relative to endpoint interpolation, and the localizer achieved a mean aligned structural error of 0.127 Å. Quantum-chemical optimization and vibrational analysis yielded 405 frequency-confirmed first-order saddle-point candidates from 410 predictions. In a 100-reaction nudged elastic band comparison, learned-path initialization reached a joint geometry-and-force target for 66% of reactions, compared with 12% for geometric interpolation after 100 optimizer steps. By treating the path as a reusable representation rather than an auxiliary output, MARC-TS connects transition-state prediction, mechanistic interpretation and quantum-chemical refinement.

Second-order black-hole perturbation theory will be an important component of precision gravitational-wave modeling and tests of strong-field gravity with next-generation detectors. Beyond quasinormal modes (QNMs), whose quadratic interactions have been the focus of recent work in black-hole spectroscopy, a generic retarded solution consists of a continuum of real-frequency scattering states whose nonlinear interactions in Kerr remain comparatively less explored. We use numerical relativity to study the quadratic response of Kerr black holes to nearly monochromatic $(\ell,m)=(2,\pm2)$ incident gravitational waves, measuring the complex self-coupling to the outgoing $(\ell,m)=(4,4)$ daughter at twice the parent frequency for black-hole spins up to $a=0.95$. At low frequencies, the coupling is strongly suppressed and exhibits opposite spin dependence for prograde and retrograde scattering. At higher prograde frequencies, we identify a daughter-mode resonance whose frequency and width extracted from the nonlinear response track the fundamental $(\ell,m,n)=(4,4,0)$ QNM. Near the fundamental $(2,2,0)$ QNM frequency, the in-mode coupling grows with spin, in contrast to the decreasing quadratic QNM coupling, demonstrating that the nonlinear response depends on the full parent scattering state rather than on its frequency alone. A complementary semi-analytic second-order Teukolsky calculation reproduces the nonlinear response from our numerical relativity simulations. Our numerical-relativity results and their semi-analytic extension provide a basis for generic homogeneous radiative perturbations of Kerr at second order, with applications to dynamical tides, near-extremal dynamics, and second-order gravitational self-force theory.

Context: The eccentric von Zeipel-Lidov-Kozai effect, which is widely applied to diverse astrophysical settings, can drive the inner binary to extremely high eccentricities, where short-range forces such as general relativity (GR) become prominent. Aims: Poincare surfaces of section show that GR effects reshape phase-space structures, giving rise to a widespread and large-scale chaotic sea. This work aims to uncover the underlying mechanism of GR-enabled chaos. Methods: The dynamical structures are studied within an adiabatic framework, where an adiabatic invariant is constructed. Phase portraits, defined by the level curves of this invariant, establish analytical boundaries for the chaotic domains. Numerical simulations are subsequently performed to map orbital flips, maximum eccentricities, and Fast Lyapunov Indicators (FLI) across the initial eccentricity-inclination parameter space. Results: Phase portrait analysis demonstrates that GR precession introduces an uncertainty zone near polar inclinations, where trajectories crossing this zone inherently become chaotic. Leveraging this framework, the chaotic boundaries across the full parameter space are analytically derived, yielding excellent agreement with numerical maps of flipping orbits, maximum eccentricity, and FLI. Conclusions: In the presence of short-range forces, flipping orbits accompanied by extreme eccentricity excitation are fundamentally chaotic, and the underlying mechanism of large-scale chaos originates from the periodic passage of trajectories through the uncertainty zone in phase space over secular timescales.

Intermittent dynamics are ubiquitous in the Earth system and often arise from the interaction of processes evolving on different time scales. In this work, we investigate how intermittent bursts in a fast forcing system propagate to and reshape the dynamics of a slower response system that would otherwise settle onto a quasi-stationary or weakly oscillatory regime. We address this question in two coupled models of increasing complexity: a low-dimensional Lorenz-63 system and the spatially extended Kuramoto-Sivashinsky equation. Across both systems, intermittency in the forcing progressively reshapes the attractor of the slow response system and drives it into different regimes. Using the Wasserstein distance, we show that increasing the frequency of intermittent events progressively displaces the response attractor from its unperturbed counterpart, up to a limit beyond which this deviation saturates. We then show that varying the forcing intensity and the time-scale separation between the forcing and response systems drives distinct regime transitions, which we characterize through the variance of ensemble maxima, the power spectra of both systems, and extreme value statistics. Finally, we examine how the type of intermittency in the forcing system affects synchronization between the two systems through local phase locking, showing that specific transitions in the phase-locking behavior are tied to the underlying intermittency regime, and that the response delay scales exponentially with the time-scale separation.

We introduce a stretched-grid artificial intelligence (AI) weather forecasting model with 2-km resolution over the western United States and part of the Northeast Pacific and approximately 31-km resolution elsewhere globally. Forecasting over the western U.S. is challenging because complex topography and atmospheric rivers (ARs) strongly influence orographic precipitation. West-WRF AI 2-km builds on a global model pretrained with a 40-year European Centre for Medium-Range Weather Forecasts Reanalysis v5 (ERA5) dataset and is fine-tuned with the Center for Western Weather and Water Extremes (CW3E) 2-km regional reanalysis to produce autoregressive 6-hourly forecasts of precipitation and integrated vapor transport (IVT). Forecasts are evaluated over winters 2020-2023 using gridded precipitation observations, rain gauges, and AR Reconnaissance dropsondes and are benchmarked against coarser-resolution AI forecasts and regional and global numerical weather prediction (NWP) systems. West-WRF AI 2-km reproduces observed precipitation-intensity distributions, retains fine-scale spectral variability, and produces sharper narrow coastal precipitation bands and localized, terrain-sensitive extremes. Its broader-scale performance remains comparable to coarser-resolution configurations while preserving large-scale skill despite higher resolution. Dropsonde verification shows lower errors and improved categorical skill at the most extreme IVT threshold. Overall, West-WRF AI 2-km provides its greatest value for localized precipitation extremes and intense AR-related moisture transport.

Rapid intensification (RI) remains one of the most consequential and difficult aspects of tropical cyclone (TC) forecasting. Although full-physics numerical weather prediction models can represent the processes governing RI, resolving storm-environment interactions remains computationally expensive, while purely data-driven approaches often lack physical interpretability. We present FAST-ML, a hybrid framework that bridges data-driven efficiency with physical constraints. A physically informed dual-stream neural parameterization ingests 3D ERA5 fields to diagnose ventilation controls—environmental wind shear and mid-level entropy deficit. By optimizing these parameters end-to-end through a differentiable FAST intensity model, this architecture establishes a robust new paradigm for observation-driven parameter optimization, ensuring storm evolution remains strictly governed by thermodynamic principles. By better capturing the storm's continuous intensity evolution, FAST-ML improves upon its physical baseline, reducing ensemble CRPS across forecast lead times, with a reduction of approximately 31% at 60 h and nearly halving the RI false alarm ratio without sacrificing detection skill. In a 100-member ensemble configuration, FAST-ML produces intensity forecasts comparable to FNV3 for selected storms under the evaluated input configurations. Furthermore, zero-shot tests on selected Eastern Pacific storms provide encouraging evidence of cross-basin transferability. FAST-ML provides a modular intensity forecasting framework that can be coupled with externally supplied storm tracks and environmental fields. It demonstrates that observation-driven parameter learning within physically constrained dynamics simultaneously enhances accuracy, interpretability, and computational efficiency.

Exchange alone gives the electron gas a local field factor with a sharp peak just below 2kF. Quantum Monte Carlo finds none. Both spin channels are computed here from their lowest diagrams with a dynamically screened interaction and no fitting. Parallel spin correlation is the negative image of exchange and removes about half the peak; the calculated spin-resolved factors account for the QMC data at rs = 1 and 2, and at q = 0 for the compressibility and spin susceptibility obtained from the ground-state energy. The two classes of diagrams are the two terms of the kernel of Hedin's vertex equation, of which the second is routinely dropped.

The effective radii of young star clusters correlate with cluster mass, but the large scatter about that relation is not well understood. Theory predicts that a cluster's initial radius depends on the gas surface density of its natal environment, so the star formation environment should leave a measurable imprint on cluster structure. In a companion analysis of 5,105 clusters across 31 LEGUS galaxies, we found that galaxy-wide specific star formation rate (sSFR) carries no predictive power for cluster radius. Here we test whether that null result reflects the spatial scale on which the environment was measured. We cross-match the LEGUS cluster catalog of Brown & Gnedin with H-alpha maps from the PHANGS-MUSE survey in the four galaxies common to both surveys, and measure the local star formation rate surface density, Sigma_SFR, at the position of every cluster by aperture photometry. For the 325 clusters younger than 10 Myr with reliable radius and mass measurements, local Sigma_SFR significantly predicts effective radius (beta = 0.079, p = 2 x 10^-4) in a model containing mass and age, while the host galaxy's sSFR does not (beta = 0.042, p = 0.40) for those same clusters. The local model generalizes nearly three times better under cross-validation (CV R^2 = 0.061 versus 0.022). The effect operates among clusters within a single galaxy: it survives galaxy fixed effects (beta = 0.068, p = 0.001) and appears independently in each of the two galaxies large enough to fit alone. Including local Sigma_SFR also reduces the mass coefficient by 26%. The birth environment measurably shapes cluster structure, but only when it is measured on the scale on which clusters actually form.

This paper is an English translation of a contribution to the latest German edition (2017) of Hermann Weyl's classic text "Symmetry", edited and annotated by Erhard Scholz, Klaus Volkert, and myself. In this contribution I discuss various physical aspects of the notion of symmetry and place them in context from the perspective of theoretical physics. In particular, a distinction is drawn between symmetries of individual configurations (solutions of equilibrium equations or equations of motion) and symmetries of the laws themselves. Likewise, a distinction is made between those operations that alter physical states and so-called gauge symmetries, which leave physical states unchanged and merely represent a redundancy in the mathematical description. Besides gauge symmetries, I comment on the connection to conservation laws, symmetry breaking, and the philosophy of space.

We investigate polarized synchrotron emission from an optically thin accretion flow around a rotating braneworld black hole, focusing on how higher-dimensional gravity modifies photon propagation and polarization transport. We integrate the null-geodesic and parallel-transport equations for the polarization four-vector and, within a common emissivity and magnetic-field prescription, examine the effects of tidal charge, black-hole spin, observer inclination, and prograde or retrograde orbital motion. We analyze the linearly polarized intensity, electric-vector position angle (EVPA), Stokes parameters, the joint $Q$–$U$ polarization-state space, and the cumulative net linear polarization degree, and compare representative braneworld configurations with Kerr and Kerr–Newman spacetimes. Within the parameter range considered, tidal charge and spin do not generate a qualitatively new large-scale polarization morphology. Instead, they primarily reorganize the polarized intensity, orientation, and polarization-state distribution in the strong-field region near the shadow boundary and photon ring. Viewing inclination controls the dominant projected morphology, while high inclinations enhance projection and Doppler asymmetries and make the distinction between prograde and retrograde flows more pronounced. The Stokes components and their joint state space expose local bending, stretching, and trajectory concentration that are less apparent in intensity images. The cumulative net linear polarization degree decreases with increasing cumulative radius, and larger tidal charge or spin lowers its amplitude for the representative models considered. Together, these complementary polarization observables provide a potential route for separating spacetime, viewing-geometry, and accretion-flow effects and for constraining braneworld tidal charge with horizon-scale polarimetry.

Quantum state tomography provides a foundation for characterizing state preparation and predicting measurement outcomes. We characterize the minimax expected trace norm risk of quantum state tomography over classes with polynomial spectral decay under randomized nonadaptive single copy measurements. Under an explicit sufficient block size condition for the two layer periodic Clifford ensemble, we establish statewise expected trace norm oracle inequalities for operator norm minimum distance and measurement weighted projected least squares, with bounds that depend on each state's actual spectral tail, while the estimators require no prior knowledge of the state's structural characteristics, including its rank, eigenbasis, or spectral structure. Over these polynomial spectral decay classes, both estimators attain the minimax expected trace norm rates up to constants. As a direct consequence, the same estimators attain the minimax rate over every fixed rank constrained class, while remaining adaptive to the unknown structural characteristics of the state. For admissible logarithmic block sizes, the periodic Clifford measurements attain these guarantees with logarithmic elementary gate depth. The main technical ingredient is a uniform bound on the fourth moment of projectors for the periodic Clifford ensemble. The bound is sharp in dimension and holds for arbitrary test states, including those entangled across blocks. Covariance concentration and positivity yield adaptive oracle bounds, while a shared rotation information argument on spectral tail packings establishes matching lower bounds. We also provide polynomial time reconstruction algorithms, numerical comparisons, and Lean formalizations of all labeled theoretical results.

Thermal-laser epitaxy (TLE) extends the accessible pressure, temperature, and growth-rate regimes of conventional molecular-beam epitaxy, enabling in situ laser annealing, high-purity buffer-layer growth, and efficient evaporation of refractory elements. These capabilities make TLE a promising platform for engineering low-loss superconducting resonators and Josephson-junction heterostructures. Here, we study the TLE growth of TiN on sapphire and observe improved transport properties with increasing growth temperature up to 1150 C. Unfortunately, we observe that the high ammonia pressure and elevated substrate temperatures required for optimal TiN properties promote reactions at the sapphire surface, resulting in voids at the TiN-substrate interface. These defects increase interfacial surface area, introduce dangling bonds, and could compromise tunnel-barrier heterostructures. We mitigate this degradation using an initial TiN seed layer grown at 850 C. With the seed layer, we achieve a superconducting transition temperature of 5.8 K, a residual resistivity ratio of 12.2, and a resistivity of 1.19 micro-ohm cm at 10 K, which, to our knowledge, is the lowest reported for TiN grown on sapphire.

We propose that instructional effectiveness may depend on an interaction between two design dimensions: dosage—the total duration of student-centered active learning allocated to a topic—and precision—the degree to which an intervention targets a specific, documented cognitive bottleneck with a mechanism-matched representational tool. This paper formalizes the framework, anchors it in cognitive load theory, derives its falsifiable predictions, and clarifies its incremental contribution relative to existing instructional-design literature. The central theoretical move is to decompose precision into three components—targeting ($P_t$), representational match ($P_r$), and scope restriction ($P_s$)—and to argue that only representational match acts directly on extraneous load. This decomposition yields a compact model in which the effective dosage is $D_{\mathrm{eff}}=D P_s$, the germane processing is $G=D P_s\eta(P_r)$ with $\eta$ the representational efficiency, and learning is $E=g(G)$ with $g$ increasing and concave \rev{(here $E$ is the cumulative learning outcome on the target construct, not a rate)}. The framework's core proposition (P3)—that precision can compensate for dosage—then becomes a quantifiable substitutability claim, $\mathrm{d}D/\mathrm{d}P_r=-\eta/\eta'$, rather than a mere existence statement; its scope is bounded by a precision ceiling and a minimum dosage threshold. We distinguish the framework from Carroll's classic time-needed model by the directional character of precision and by the estimability of the substitution rate, and from the ICAP framework by distinguishing “matching of participation content to the bottleneck” from “mode of participation.” As an illustrative case (not a test of the framework),

In this article we revisit Aristarchus' ancient experiment to determine the ratios between the Earth-Moon and Earth-Sun distances. We present here the construction of a simple instrument, basically a tube that, by projecting its shadow, that allows one to estimate the Sun-Earth-Moon angle at the moment of first (or last) quarter. The simplicity of its construction and the accuracy of the measurements obtained may come as a surprise. We discuss the complexities involved in determining the exact moment of first quarter, based on the shape of the elliptical shadow projected on the Moon. Finally, we analyze and implement a strategy that allows us to approximate the measurement of this angle and estimate its value using observations that can be performed twice a month, and more accurately a couple of times during the year. We place Aristarchus' problem in its historical context and detail the physical and mathematical topics that can be developed and motivated through this experiment, in addition to carrying out a very thorough analysis of the errors associated with this measurement.

We introduce a bi-oriented interlaced matrix product on $2\times 2$ matrices over a unital, possibly non-associative algebra, extending a matrix mnemonic for Cayley–Dickson doubling. The opposite orientations $X_R$ and $X_L$ coincide precisely when the underlying algebra is commutative. For the canonical position and momentum operators $Q,P$ on $L^2(\mathbb{R})$, a matrix $D$ and its companion $\widetilde{D}$ satisfy, on the common Schwartz domain, $\widetilde{D} X_R D =\widetilde{D} X_L D =2H Id_2$, where $H=(P^2+Q^2)/2$. We study the associated interlaced eigenvalue equations for operator-valued columns. The combinations $\Phi=A+iB$ and $\Psi=A-iB$ decouple the equations into two-sided Sylvester equations. We construct explicit rank-one generalized eigenoperators from position and momentum eigenstates. Their distributional kernels belong to the doubled rigged Hilbert space $S(\mathbb{R}^2)\subset L^2(\mathbb{R}^2) \subset S'(\mathbb{R}^2)$; the corresponding position and momentum operators act on different tensor factors and therefore commute. The rank-one families do not exhaust the distributional solutions: higher-order generalized solutions are also exhibited. We distinguish the algebraic identities on the Schwartz core from questions concerning closed-operator realizations.

We review the conceptual and theoretical status of twin-universe models, from Sakharov's early ideas on baryogenesis, CPT symmetry, and reversed arrows of time to recent quantum-cosmological scenarios involving pair-created entangled universes. Particular attention is given to the distinction between Sakharov-type cosmological symmetry, modern bimetric theories of gravity, and speculative models involving negative mass sectors. We summarize the main consistency conditions faced by bimetric gravity, including the Boulware-Deser ghost, Higuchi-type bounds, covariant conservation laws, and no-go results for positive- and negative-mass sectors. We then examine the Janus cosmological model and related black-hole replacement proposals, emphasizing the difference between heuristic twin-universe narratives and fully specified relativistic field theories. We argue that while twin-universe ideas remain a fertile framework for questions about the arrow of time, matter-antimatter asymmetry, and the quantum origin of the universe, models combining bimetric gravity, negative mass, dark-sector phenomenology, and alternatives to Kerr black holes face a substantial burden of mathematical and observational proof.

The topological classes of coherent structures in magnetohydrodynamic turbulence are studied using the irreducible representations of the SO(3) and SO(2) rotation groups. We probe the coherent structures around axisymmetric magnetic fields in the universe. Such axisymmetric fields can be found around filamentary structures as well as cosmic strings. We have considered a Gaussian and a non Gaussian magnetic field. We find that the field distribution leads to different coherent structures for the two cases. Our results show that the scattering of particles from the Gaussian structure depends predominantly on two lengthscales. In the case of the non Gaussian distribution, we can define a third intermediate lengthscale, similar to the Taylor lengthscale. In both the cases, we find that there is a dominance of the polarization anisotropy which indicates that the field gradients are forced into rigid spatial configurations. In the early universe, this will change the mean free path of the baryons and leptons in the coherent structures. Trapping of charged particle as well as their acceleration will be more frequent in the case of a magnetic field with a heavy tailed distribution. The lengthscale of density inhomogeneities close to these structures will thus be determined by the magnetic field distribution of the fields.

We derive a Lipatov type effective action for the Reggeized gravitons. In place of the order by order construction of the effective currents from diffeomorphism invariance, we propose a current which is a single ordered exponential $W_{ij}$ along the light cone, generated by the optical tidal matrix integrated once. The nested ordering of it reproduces the known perturbative answer with some new terms added. These new terms are non-local along the light cone and have a structure which the diffeomorphism construction cannot produce, the form of the third order contribution to the current is also calculated. The effective action, the current to Reggeon vertex and the current to current interaction are obtained in closed form, in three equivalent writings, one of them covariant. Generally defined $W_{ij}$ reduces to four parameters of the ray bundle, its density, its shear, the orientation of the shear and a rotation of the image. The effective current uses three of them, being the second light cone derivative of a single scalar, it is not sensitive to the orientation. Comparing with the standard eikonal gravitational Wilson line, which is the phase, $W_{ij}$ is the Hessian of the same eikonal: it carries the shear and the focusing that the Abelian phase does not, and it is inverse to the Jacobi propagator of the congruence at first order in the field. A generalization of the proposed ordered operator is discussed as well as applications of the gravitational effective action.

We investigate the sampling efficiency in a segment-based continuous-time hybridization-expansion quantum Monte Carlo solver within dynamical mean-field theory for the doped SU(3) Fermi-Hubbard model. Focusing on the low-temperature and strong-coupling regime, where a ferromagnetic state appears upon hole doping away from one-third filling, we compare several update schemes. Adding the double-flip update to the basic local update yields the smallest integrated autocorrelation time of the majority-flavor occupation in the ferromagnetic regime, whereas adding the flavor-permutation update is the most effective in the paramagnetic regime. We further clarify the origin of this difference by analyzing the characteristic occupation changes caused by accepted updates.

Topological edge states offer a robust route to photonic devices and systems that remain functional despite structural imperfections. Topological waveguide arrays have been shown to deliver robust coupling, but only for full power transfer between the two edge waveguides—a robust route to an arbitrary intermediate ratio has remained unknown. Here we show that the topological edge states of a finite Su-Schrieffer-Heeger chain, realized with only four identical waveguides, form an arbitrary-ratio power splitter whose ratio is robust to both the device length and fabrication errors. Two near-degenerate edge supermodes beat to produce a step-like power transfer with a flat, length-insensitive plateau, in contrast to the sinusoidal transfer of a conventional directional coupler. The splitting ratio at this plateau is governed by the difference between the two waveguide gaps, making it immune to correlated fabrication offsets. We derive this behavior analytically and confirm it numerically and experimentally on a conventional silicon-on-insulator platform. Beyond this device, our analysis can be applied to general topological waveguide arrays, while the robust splitter offers a practical building block for fabrication-tolerant photonic circuits.

Interstellar Objects (ISOs) may provide direct evidence of planetesimals ejected from early-stage solar systems. Studying these objects and predicting their detection through various surveys is vital for enhancing our understanding of planetary formation. We show how ISO size distribution (SFD), f_D~D^-q, controls expected detections in current and future surveys. We focus on TESS and the Vera Rubin Observatory LSST while analyzing Pan-STARRS and ATLAS. TESS is expected to detect ~1 ISO from shallow SFDs (q<2.5). On the other hand, LSST is likely to detect ~0.2-100 ISO yr^-1 over its lifetime. ATLAS is likely to detect one non-cometary object for populations with q<3. We further estimate ~0-8 detections of cometary like-3I/ATLAS objects by LSST in 10 years and ~1 cometary object detected by TESS over its mission time, independent of the nucleus size distribution. By considering both 1I/'Oumuamua and 3I/ATLAS from the same SFD, our results suggest that more asteroid-like objects are produced rather than comets during the early stages of planetary formation. Imminent detections of ISOs by LSST will help constrain the slopes of the SFDs for asteroid-like and cometary ISOs better, and, if applicable, differentiate between them.

Magnetic reconnection between emerging magnetic flux and the ambient coronal field fundamentally drives solar jets. We use three-dimensional resistive-MHD simulations of eruptive flux emergence to investigate how the large-scale current sheet formed at the interface fragments during recurrent jet activity. The simulations show that jet formation and current-sheet disruption are coupled elements of a single multiscale process. The current structures developing along open field lines and within the jet are relatively weak, exhibiting a predominantly filamentary morphology. In contrast, the larger structures linked to the closed-field topology are noticeably stronger, and the eruptive development of the emerging flux further increases both their number and strength. The parallel-current distributions within the closed magnetic field lines region exhibit Gaussian central cores with pronounced non-Gaussian tails, implying a small subset of strong, intermittent structures. Magnetic spectra follow a power law with a Kolmogorov-like slope in the large-scale range, becoming much steeper in the small-scale range—consistent with reconnection-mediated magnetic structuring. Box-counting analysis shows that the strongest current structures have a fractal dimension $D_{\mathrm{f}} \simeq 2$, indicating a fragmented population of sheet-like coherent structures. Cluster analysis further reveals broad, power-law distributions of cluster volumes and their Ohmic dissipation energies, with individual events reaching $\sim 10^{20}$–$10^{25}$ erg over their estimated lifetimes. These results demonstrate that eruptive flux emergence can self-consistently transform a global reconnecting current sheet into a localized, intermittent, sheet-dominated dissipative network, providing a natural environment for impulsive coronal heating and motivating future particle-acceleration studies.

We show how genuine three-body phase information can enter the invariant mass of a relativistic three-particle Dirac system in $(1+1)$ dimensions. As a solvable reference system, we consider the Sakamoto–Munakata–Ino model with pairwise contact interactions $g_{ij}(1-\alpha_i\alpha_j)\delta(x_i-x_j)$. These singular interactions can be transferred into sector-dependent phases and matching conditions by a discontinuous unitary transformation. Although the explicit contact terms are thereby removed, the nonzero constituent-mass operator is rotated and retains nontrivial spectral information. We introduce a genuine three-body holonomy generated by $Q_3=\alpha_1\alpha_2\alpha_3$. The kinetic and pair-interaction parts commute with $Q_3$, while the constituent-mass operator anticommutes with it. Consequently, the massless system separates into the $Q_3=\pm1$ sectors, which acquire opposite holonomy phases $e^{\pm i\theta_3}$, whereas nonzero constituent masses mix the two sectors. This phase-sector-mixing mechanism makes the relative three-body phase dynamically accessible to the bound-state spectrum and establishes an operator-level mechanism through which the three-body holonomy generates a $\theta_3$ dependence of the physical three-body invariant mass. We further emphasize that the topological three-body holonomy is not automatically equivalent to a bare triple-contact potential; such an equivalence requires a regulated self-adjoint realization and a compatible interaction-dependent boost satisfying the Poincaré algebra. The resulting framework therefore connects genuine three-body phase information to the mass spectrum of a relativistic composite system while clearly separating the controlled holonomy construction from the unresolved short-distance triple-contact realization.

Inspired by black hole thermodynamics and other results suggesting that general relativity has some intrinsic connection with thermodynamics, this work aims to establish a quasi-local thermodynamic formalism in general spacetimes. With this purpose, we generalize the Bondi-Sachs formalism to past light cones associated with an arbitrary worldline. From this generalization, we demonstrate the emission of Hawking radiation in a quasi-local context through a few examples, suggesting that it may occur under mild conditions. In addition, we argue that an "irreversible inequality" is satisfied in typical gravitational systems, indicating that an analogue of the second law may be established. Together with a definition of internal energy derived from the Landau-Lifshitz pseudotensor, these results are used to construct a postulational framework that generalizes classical thermodynamics in order to include the dynamics of spacetime. As a consequence, it is possible to define the rest-mass density from thermodynamic variables, decoupling it from the dynamics of constituent numbers.

A recent article explores some respective contributions of the initial velocity and effective mass of a striking implement to the ultimately induced, post-collision velocity of a stationary strike target, in a combat sports context. Therein, it was found that multiplicative increases in the effective mass associated with a punch to the human body can have a greater quantitative effect on target velocity than that of its initial, pre-collision speed. Given that fold-increases in effective mass may be limited to low-integer multiples of a modest, literature-supported value that spans martial arts styles – and the fact that increases in the strike velocity are likely bounded by a factor of two, even for trained fighters – translating the aforementioned findings into incremental changes in either variable may be of more benefit to coaches who intend to apply the theoretical physics of fighting to develop practical training programs. Here, we build on previous work, studying the effects of marginal increases in effective mass on target velocity, and relating them to equivalent, single-unit changes in strike speed.