Papers

We study superconductivity in representative hydrides using anharmonic phonons, electron-phonon vertex corrections, and full-bandwidth Eliashberg theory. The high-pressure binary hydrides H3S, YH6, and YH9 must be treated with both anharmonic and nonadiabatic corrections, whereas the ambient-pressure PdH/PdD/PdT series is strongly anharmonic but remains adiabatic, reproducing the inverse isotope effect without sizable vertex contributions. LaBeH8 exhibits weak anharmonicity, while vertex corrections reduce the critical temperature (Tc) by approximately 4 K, leaving the predicted Tc above experiment. To identify when treatments beyond harmonic, adiabatic Migdal-Eliashberg theory are required, we introduce the anharmonic renormalization $A_{\lambda}$ and the vertex ratio $R_{V}$ as material-specific diagnostics.

Widely used in mechanics and mathematical physics, physical components remove the inherent coordinate-dependent scaling in curvilinear coordinates, yielding components of consistent physical dimension. In orthogonal coordinates, they are constructed by normalizing the coordinate frame and coframe; in general coordinates, however, their construction requires additional, non-trivial choices. In this paper, we extract physical components of arbitrary tensors on arbitrary Riemannian manifolds by orthonormalization of the coordinate frame. We further formulate a general normalization framework distinguishing three requirements: dimensional consistency, dual frame-coframe compatibility, and unit normalization. We show that dimensional consistency alone leaves independent general linear gauge freedoms for the contravariant and covariant components. Further requiring dual compatibility locks these into a single general linear gauge; a dual-compatible frame and coframe are both of unit length if and only if they are orthonormal. Thus, the choice of orthonormal transformations emerges as the only physical-components framework that satisfies all three requirements. We apply this framework to nonlinear elasticity and inelasticity, referring broadly to constitutive responses involving internal distortions, of which we study anelasticity, viscoelasticity, and visco-anelasticity. We examine the deformation gradient, inelastic distortions, strain measures, and stress tensors. We conclude by arguing that physical components remain neither intrinsic nor unique.

Academic capital, comprising research funding ($\mathcal{F}$), accumulated titles and honours ($\mathcal{L}$), and administrative power ($\mathcal{A}$), has undergone a silent global decoupling from verifiable epistemic output since the 1990s. Here we present a parameter-unified theory of Academic Integritology that integrates 64 major parameters into a coherent chassis of twelve fundamental equations (Eqs. 0-11b). The theory introduces two computable metrics: $\Psi$ (net epistemic indispensability) and $P_{\mathrm{safe}}$ (the Markov-blanket safety boundary of systemic integrity). The $D_{zj}$ fraudulence index, defined as $\kappa[\mathrm{Cap}]/E[P]$, quantifies this decoupling. Calibrated against retraction data from 40 jurisdictions and the careers of 12 Nobel-caliber scientists, the theory derives a universal law: when $E[P]/(w_1[\mathrm{Cap}])$ falls below $\theta_c \approx 0.25$, honest research ceases to be an evolutionarily stable strategy. Three jointly necessary levers, raising $E[P]/(w_1[\mathrm{Cap}])$, auditing $R_{\mathrm{pol}}$, and constraining $\omega$, restore $P_{\mathrm{safe}}$. Three levers, pulled simultaneously, suffice. The theory transforms academic integrity from a moral aspiration into an engineerable system property.

Cosmic-ray muons are among the most abundant high-energy particles reaching Earth's surface, with a flux of approximately one muon per square centimeter per minute at sea level, yet they remain entirely invisible to the naked eye, posing a persistent challenge for public engagement in particle physics. We present the Muon Bulb, a self-contained cosmic ray muon detector built within the enclosure of a standard commercial LED bulb, designed to produce a vivid and immediate visible light flash upon the passage of a cosmic-ray muon. The detector integrates a plastic scintillator tile coupled to a Silicon Photomultiplier (SiPM) for efficient detection of scintillation photons produced by ionizing muons. The SiPM signal is processed by a compact analog front-end comprising an amplifier and a leading-edge discriminator, which isolates genuine muon-induced pulses from background. Validated trigger signals are passed to an ESP32/RP2350 microcontroller, which drives an internal LED, causing the bulb to flash visibly in real time. The readout additionally enables wireless data transmission for real-time monitoring of muon event rates and flux measurements. The Muon Bulb is designed to serve as a high-impact outreach instrument across science museums, planetariums, K-12 classrooms and public science festivals without requiring specialized infrastructure. Its wireless capability enables networked classroom activities where multiple Muon Bulbs can be operated simultaneously, allowing students to collaboratively measure muon flux and engage in genuine data-driven scientific inquiry. The Muon Bulb transforms a commercial house hold item into a powerful tool for particle physics, making the invisible universe visible to everyone.

Black-hole entropy and multi-horizon area-product relations represent two apparently distinct manifestations of universality, arising respectively from microscopic statistics and classical geometry. We show that these structures are unexpectedly connected. Extending a minimum-assumptions statistical discretization to multiple Killing horizons, with distinct horizon sectors treated as statistically independent, we derive a general area-product rule. In particular, while the leading Bekenstein-Hawking entropy probes the sum of the horizon areas, the logarithmic correction probes their product. Consequently, whenever the classical area product is mass independent, the logarithmic entropy automatically inherits this universality. We demonstrate this for Reissner-Nordström and, under an area-based extension to rotating horizons, Kerr-Newman black holes. However, Reissner-Nordström-de Sitter provides a crucial three-horizon counterexample, for which the area-product rule survives while mass independence is generically lost for the physical horizons. Thus, statistical area-product selection and classical universality are distinct properties. Our results uncover a structural connection between microscopic entropy counting and classical multi-horizon geometry that is invisible at the level of the leading area law, suggesting that logarithmic corrections encode distinctive information about the global horizon structure.

Growing awareness of the impact of quantum threat on classical cryptography directly translates into a growing demand for accurate network simulation tools capable of estimating the integration effects of quantum-safe cryptography in current systems. In particular, the adoption of Post-Quantum Cryptography (PQC) has a direct impact on the performance of network endpoints and transmission overhead. This also affects the scalability of widely adopted security protocols such as TLS and SSH. In this paper, we present a throughput-oriented analytical model that provides a tight upper bound on the maximum sustainable rate of post-quantum secure connection establishment in TLS and SSH. This model takes into account both endpoint and network capacity constraints, decomposing the handshake process into dominant cryptographic operation time and network transmission time. Identifying the bottleneck allows us to derive the achievable throughput in terms of handshakes per second. The experimental results provided show the accuracy of the model against the data obtained from an experimental testbed using, among others, NIST standard primitives from FIPS 203, 204, and 205, including ML-KEM and ML-DSA. Finally, we integrate our model into a network environment and demonstrate how it can be leveraged to enable efficient resource allocation among multiple endpoints, optimizing PQC traffic in multiple-unicast scenarios.

Buoyancy points straight upward, yet in the absence of external forces, a rising air bubble may trace a spiral through the water. This phenomenon was already observed by Leonardo da Vinci. We show that the gravity-free, three-dimensional two-phase incompressible Euler equations with surface tension already admit such a motion. For every nonnegative inner-to-outer density ratio and every sufficiently small positive axial Weber number, we construct smooth near-spherical bubbles and drops with compact interfaces and phasewise irrotational flow. They are stationary in a frame translating along and rotating about a fixed axis, while their centroids lie off that axis and therefore trace genuine circular helices in laboratory coordinates. These helical relative equilibria form a symmetry-breaking branch that issues from the axisymmetric family of rectilinearly translating solutions and is generated by the spherical harmonic mode of degree two and azimuthal number one. The mathematical construction exploits an overdetermined free-boundary formulation, its variational structure, and an $\mathrm{SO}(2)$-equivariant Lyapunov-Schmidt reduction. Particular difficulties in the form of resonances arise at a discrete set of density ratios, including the frequently studied vacuum case with vanishing inner density. Complementary to our existence result, in the absence of surface tension and if the inner density is not larger than the outer density we prove that the model admits neither nontrivial translating relative equilibria nor relative equilibria with helical centroid trajectories. As a byproduct, we show that every regular finite-energy stationary vortex sheet of spherical topology for the homogeneous three-dimensional Euler equations, with irrotational flow on both sides, is trivial.

Information-based diffusion schedules organize the reverse problem by prescribing how much source information remains after each forward step. For mixed-state quantum diffusion, density-level targets need not correspond to trajectories reachable from the current realization. We introduce channel-constrained information scheduling: each step optimizes over source-blind pure-state refinements reachable from the current state-resolved record through the prescribed channel. This defines a channel-constrained information clock $V_\xi$, whose inverse selects the least-corrupting step that reaches a target information level. Recursive inversion constructs a realizable equal-information schedule minimizing the worst source-information burden in Bayes reverse prediction. We establish attainment, continuity, monotonicity, convexity, finite support, and exact primal/dual formulations for $V_\xi$. We further give a sharp structural characterization: binary-qubit depolarizing trajectories attain the density-level Belavkin–Staszewski envelope, whereas every $d\ge3$ admits binary noncommuting families with a strict static–dynamic separation. Qutrit experiments show that the proposed scheduler nearly equalizes the realized multi-step burden, and learned reverse predictors recover the predicted allocation.

We study a mirror Standard Model world which contains a high scale duplicate of the Standard Model, and includes a singlet mirror scalar extension coupled to the mirror Higgs particle. Among the interactions of the mirror Higgs to the mirror singlet scalar, we include dimension-six non-renormalizable operators. We examine the electroweak phase transition of this mirror singlet extended world and we show that the phase transition is a strong first order phase transition, the bubble collision of which can be detectable by LISA, the BBO and the DECIGO gravitational wave experiments. We also provide a rough estimate of the abundance of the mirror singlet and we show that the whole dark matter in the Universe may be comprised by mirror particles and atoms.

Free-floating space manipulator systems face operational challenges due to dynamic coupling. While traditional reactionless manipulation eliminates base disturbances, enforcing the null-space projections across all rotational axes imposes excessive constraints on the system and drastically reduces the available workspace. To address this limitation, this work proposes a multi-axis selective decoupling framework that nullifies momentum transfer exclusively along mission-critical directions. By leveraging a directionally constrained sub-coupling matrix, the framework relaxes the null-space constraints. Numerical simulations confirm that this approach mathematically eliminates constrained directional disturbances along the targeted axes while preserving the remaining degrees of freedom, enabling the manipulator to execute task-space operations successfully.

Spacecraft attitude control becomes challenging when light-sensitive instruments must avoid bright objects. This work proposes a path-planning-based spacecraft attitude reorientation maneuver considering these constraints to reach the desired attitude. Constraint-compliant attitude trajectories are computed using a fuzzy enhanced potential field approach in the attitude space. Based on the path-planning output, the control input is determined by considering the dynamics and kinematics of the spacecraft to satisfy dynamic constraints in the time domain. Numerical simulation results demonstrate successful reorientation maneuvers without violating the constraints.

Can the characteristic monodromy of string scattering be derived from S-matrix consistency alone, without assuming a worldsheet? We show that finite-particle consistency fixes it to a sharply defined extent. In a massless doubly ordered identity model, two exact six-point residues generate a scalar pentagon and the odd Fay identity, forcing every analytic four-point null kernel to satisfy $q''=\kappa q$ and leaving only the linear, trigonometric, and hyperbolic branches. This converts finite-multiplicity factorization into an all-orders constraint normally associated with worldsheet geometry. For a crossing-symmetric target in the opposite KLT module, positive unsubtracted dispersion with nonzero heavy spectral weight selects the trigonometric branch, and moment determinacy fixes the Veneziano germ up to scale. A two-scale counterexample proves that module entrance is an independent input. Our result therefore identifies both a finite-to-infinite rigidity mechanism for string scattering and the precise missing principle needed for a first-principles derivation.

For a convex function $f \colon \mathbb{R}^d \to \mathbb{R}$, the problem of sampling from a distribution proportional to $e^{-f(x)}$ is called log-concave sampling. In many practical scenarios, the function $f(x)$ turns out to admit a local decomposition $f(x) = \sum_{a=1}^R \psi_a(x_{S_a})$. In this paper, we consider log-concave sampling using local queries, i.e., evaluation and gradient queries to each clause $\psi_a(\cdot)$, which can be computationally much cheaper than the queries to $f(x)$ itself. We show that if each coordinate appears in only a small number of clauses, there is a quantum algorithm for strongly log-concave sampling using $\widetilde{O}(\sqrt{\kappa}d)$ local queries, where $\kappa$ is the condition number. This improves the prior best classical result $\widetilde{O}(\kappa d)$ due to Ascolani, Lavenant, and Zanella (Ann. Probab. 2026) and the quantum result $\widetilde{O}(\sqrt{\kappa} d^2)$ implied by Childs et al. (NeurIPS 2022). Our quantum sampler applies to a broad class of locally structured models from statistical computing and machine learning, with representative examples including Gaussian Markov random fields, finite-element latent Gaussian models, and sparse generalized linear models. These results demonstrate that local structure is not merely an implementation detail, but a quantum algorithmic resource for high-dimensional sampling.

Barrow holographic dark energy connects cosmic acceleration with possible quantum-gravitational deformations of horizon entropy, encoded in the Barrow exponent $\Delta$. If such effects are scale dependent, however, there is no fundamental reason for $\Delta$ to remain constant throughout cosmic history. In this work we reconstruct $\Delta(z)$ directly from observations, without assuming any particular functional form, using the Cosmo-PINN physics-informed neural-network framework. The generalized Barrow holographic evolution equation is incorporated into the training, while PantheonPlus supernovae, DESI DR2 baryon acoustic oscillations and cosmic chronometers constrain the reconstruction. We find a mild and smooth redshift evolution, with the posterior mean favoring negative $\Delta$ and this tendency becoming stronger when the Cepheid calibration is included. Nevertheless, $\Delta=0$ and constant negative values remain compatible with current uncertainties. The reconstructed cosmology yields a viable late-time evolution, with $w_{\rm DE}$ close to $-1$ and the expected transition to accelerated expansion. Our results demonstrate that cosmological observations can directly probe the functional behavior of a quantity entering the underlying entropy law itself.

Spectrally stable cascades can undergo enormous transient growth before eventually dying out. We show that this amplification is controlled by the directed architecture of the interactions, independently of the eigenvalues that determine asymptotic stability. More remarkably, when several critical subsystems are connected sequentially, their depth becomes a new control parameter for critical fluctuations: each additional critical stage generates a new cascade-size exponent, producing an infinite hierarchy of universality classes. This result follows because the fluctuating population produced at one stage becomes the random input to the next. The mechanism persists for both finite-variance and heavy-tailed reproduction and strongly enhances the probability of rare terminal events. Applied to multitype earthquake triggering, it provides a stationary mechanism for the anomalously large abundance of foreshock-mainshock sequences. Directed architecture can therefore control both transient amplification and critical statistics in cascade processes even when it leaves spectral stability unchanged.

We study nonrotating neutron stars in energy–momentum squared gravity (EMSG). The stellar models are obtained from the modified Tolman–Oppenheimer–Volkoff equations and four original tabulated hadronic equations of state: WFF1, SLy4, APR4, and MPA1. We use the common coupling set $\alpha\in\{-20,-10,0,+5,+7.5\}\,\mathrm{km}^{2}$ and construct mass–radius and mass–central-density sequences. We compare these sequences with the $2\,M_\odot$ mass requirement, the NICER measurements of PSR J0030+0451 and PSR J0740+6620, and the region inferred from GW170817. Within the sampled coupling range, the computed pre-turning-point branches remain compatible with these four benchmarks. Negative values of $\alpha$ generally shift the high-density branches toward larger masses. Positive values produce smaller shifts in the opposite direction. The microscopic sound speed becomes superluminal at high density in the WFF1 and SLy4 tables, whereas APR4 and MPA1 remain causal over their tabulated ranges. For WFF1, the causal boundary falls within a coarse table segment. Its compatibility with the $2\,M_\odot$ requirement therefore cannot be decided at the available density resolution. At $\alpha=-20\,\mathrm{km}^{2}$, the effective-fluid sound-speed diagnostic becomes singular for WFF1, SLy4, and APR4. This singularity is absent from the explicit modified TOV system. All computed sequences remain below the standard Buchdahl reference values for compactness and surface redshift.

New analytical model predicts how fluid flows around a cylinder at high speeds, capturing wake patterns, turbulence, and shock waves with less computation than full simulations.

The radial acceleration relation (RAR) is a tight correlation between the distribution of baryonic matter in galaxies and their observed dynamics, even in systems where dark matter dominates. This suggests a universal acceleration scale exists in galaxies, which appears to challenge the $\Lambda$CDM standard cosmological model and favor Modified Newtonian dynamics (MOND). However, MOND also deviates from the RAR, so these deviations are not fully explained by the $\Lambda$CDM model or MOND. A theory that explains gravity and the dark sector geometrically, and treats dark matter as a spin-1 particle, is required, such as Modified General Relativity (MGR). It is the only metric-compatible theory of gravity that describes local gravitational energy-momentum by the connection-independent symmetric tensor $\varPhi_{\alpha\beta}$, which completes the total energy-momentum tensor of the Einstein equation. Dark energy is explained by the energy-related component $\varPhi_{00}$, and dark matter by the stress components $\varPhi_{ij}$. Dark matter is extremely difficult to observe because it is fundamentally related to the Lorentzian metric of spacetime itself. The physical origin of the RAR follows directly from the equilibrium between the dark energy and Newtonian forces in the outer part of the rotation curve of galaxies or galaxy clusters, and that between the dark sector forces in the inner part of the rotation curve. It is shown that MGR subsumes MOND, accounts for the gravitational anomaly observed in wide binaries, and exhibits the observed Newtonian behavior of gravity at large scales.

Hawking radiation away from stationarity is governed, at the ray tracing level, by the retarded time evolution of the null mapping. We consider an extracted massless conformal channel whose outgoing directions are labelled on a fixed reference horizon slice. Balanced uniformisation, after fixing a nondegenerate balanced branch, defines an induced antipodal involution on this slice. We prove that creation and erasure of centred antipodal odd structure in the channel labelled peeling field enforce a lower bound on the time integrated spatial norm of the conformal channel defect. The forcing scale depends only on the largest intermediate mismatch and the intrinsic Jacobian distortion of the induced antipode, while greybody filtering, angular and frequency mixing, mass effects, spin dependence, and residual propagation or extraction corrections enter through a remainder whose integrated norm must be controlled independently. Round sphere odd scalar harmonics provide analytic calibrations, with the compact dipole pulse saturating the geometric and temporal estimates. A time-averaged form identifies a transient conformal channel scale proportional to the antipodal peeling amplitude divided by the episode duration.

Simulating real-time dynamics in lattice gauge theories (LGTs) is severely constrained by the circuit depth overhead of standard fermion-to-qubit mappings, which scale linearly or quadratically with system size. To overcome this depth-scaling bottleneck, we introduce the Hardware-Aware Lattice Optimization (HALO) compiler, an architecture executing global time-evolution in an immutable $\mathcal{O}(1)$ circuit depth per Trotter step. By natively mapping composite gauge links to hardware topologies, HALO achieves a $91.36\%$ reduction in entangling gate overhead compared to unoptimized Jordan-Wigner baselines, compressing a 16-qubit global step to 56 CNOTs and bypassing extensive $\mathcal{O}(N)$ scaling limits. We validate this compiler on IBM superconducting transmon processors by simulating the mesoscopic Quantum Link Model (QLM) truncation of the Schwinger model. Coupling $\mathcal{O}(1)$ compilation with Zero-Noise Extrapolation (ZNE), we track localized string rupture, extracting the dynamical crossover of pair creation at $t \approx 0.790$ with an $18.3 \pm 2.2\%$ rupture probability. Furthermore, we map the dynamical phase diagram, identifying the confinement phase boundary at $g_c = 1.0$. Finally, we introduce a scalable 2D unit-cell blueprint, paving a direct pathway toward the fault-tolerant simulation of two-dimensional Quantum Chromodynamics (QCD).

A standard Bell observable is a scalar correlation associated with a selected pair of local measurement directions. We formulate it as a projection of a complete two-particle correlation tensor and distinguish two angular sectors. The central result is a reversal of the sign multiplying the cosine law: for coincident calibrated settings, the Bell observable is positive for photons and negative for a fermionic singlet. This distinction provides an operational criterion for experimental identification. For photons, the positive sign follows from averaging two projection amplitudes over the complete non-inertial phase interval; the fermionic sign follows from the negative exchange holonomy of the phase–momentum sector. Mapping phase directions to linear-polarizer axes produces the corresponding double-angle dependence. The photon Stokes tensor has positive linear-polarization components and a negative circular-polarization component, whereas the fermionic singlet has an isotropic negative tensor. We introduce a motion-dependent extended tensor and a frequency-dependent non-inertial susceptibility. A phase-synchronous two-arm experiment combines optical modulation, rotation, and seeded multiaxial piezoelectric vibration. Independent motion measurements separate common and differential components and allow controlled variation from correlated to independent and oppositely driven motion; a single rigid platform is the simpler common-frame limit. Bell-setting and state-correlation vectors express the sign reversal as a scalar projection. The construction yields binary joint probabilities and recovers the Tsirelson bound with oppositely signed optimal CHSH combinations.

For two hundred years - ever since Faraday's first conception of the field lines - hearts and minds of students have been pervaded by erroneous and unsubstantiated claims about these well defined mathematical objects. The most prominent misconceptions include: (1) a notion of the field lines as of 'lines of force'; (2) a notion that the field lines coincide with particle trajectories; (3) a notion that a field line density measures a magnitude of a vector field; (4) a notion that the field lines of a divergence-free field always form closed loops. Even the modern day literature systematically perpetuates some of these claims. We compile here the trivial counterexamples to these claims, providing physics instructors with an efficient and effective way of dispelling these misconceptions.

For electrons with nonzero initial velocity $u_0\ne0$ in vacuum, the space-charge-limited current density (SCLCD) is given by $J_{Jaff\acute{e}}$. For current densities $J>J_{Jaff\acute{e}}$, electron reflections occur along with virtual cathode (VC) oscillations. Past studies have exhibited hysteresis by sustaining these oscillations until $J=J_{hys}$, often claiming $J_{hys}\approx J_{LD}<J_{Jaff\acute{e}}$, where $J_{LD}$, also called the bifurcation solution, represents the steady-state current density where the electron velocity is zero at the VC. In this study, we demonstrate that $J_{LD}$ is not a valid steady-state solution since it represents a higher charge density than $J_{Jaff\acute{e}}$, the true SCLCD. We further demonstrate that $J_{Jaff\acute{e}}$ also corresponds to the true, mathematical bifurcation solution. Using particle-in-cell simulations across various gap distances and voltages, we demonstrate that $J_{hys}$ consistently differs from $J_{LD}$ and can be represented by a simple semi-empirical relationship as a function of $J_{Jaff\acute{e}}/J_{CL}$, where $J_{CL}$ is the SCLCD in vacuum for $u_0=0$.

The treatment of the stellar surface in binary neutron star simulations is crucial for the accuracy of the numerical evolution and the physical reliability of the predicted observables. Numerical artifacts associated with the treatment of steep gradients near the stellar surface can produce spurious heating during the inspiral, leading to an artificial increase of the internal energy and an unphysical expansion of the neutron star. In this work, we investigate the effectiveness of the entropy-based flux-limiting (EFL) scheme in mitigating these numerical effects within the finite-difference code BAM. We perform simulations of both isolated neutron stars and binary neutron star inspirals employing a representative set of hybrid equations of state. We show that the EFL scheme significantly reduces artificial surface heating. This reduction is observed consistently across all stellar models and binary configurations considered, demonstrating that the reduction of numerical heating is a robust feature of the EFL method.

Counting the global optima of a classical optimization problem is a #P-hard task. We develop the canonical thermal pure quantum (CTPQ) state-based degeneracy counting (CTPQsd#) algorithm that determines the number of global optima of a classical optimization problem P by measuring only a small probe S, without finding individual minima. The method exploits a perturbative relation between the decoherence measure of S and the degeneracy of P when S and P are together in a CTPQ state. We provide the first numerical demonstration that this relation can be used to count the global minima, applying it to problems encoded by diagonal random-energy Hamiltonians as a maximally unstructured testbed for classical binary optimization problems. Classical simulations of up to 20 problem qubits quantify the algorithm's sensitivity to variations in the temperature of the CTPQ state, the Hamiltonian energy range, the problem size, and degeneracy. We establish the temperature threshold for determining the exact degeneracy and identify a second, lower threshold that provides a temperature window to count near-degenerate minima within a user-defined energy tolerance. By confining measurement to S, the protocol replaces tomography over the exponentially large problem Hilbert space with tomography over a small probe represented by only four qubits.

The Sun's motion through the interstellar medium creates a flow of interstellar neutral (ISN) atoms through the heliosphere. ISN He, due to its high universal abundance and relatively low ionization rate, is the most abundant of the interstellar species near 1 au and ideal for flow parameter determination. The Interstellar Boundary Explorer (IBEX) measurements of ISN He flow parameters (speed, temperature, and direction) yielded a tube in 4D parameter space – narrow in cross-section but highly extended along one parameter axis (e.g., ecliptic longitude direction). This “4D parameter tube” results in large systematic uncertainties, a direct consequence of IBEX-Lo's fixed viewing orientation on the spacecraft. On the Interstellar Mapping and Acceleration Probe (IMAP), the articulation of the IMAP-Lo boresight using its pivot platform enables multiple viewing orientations of the ISN flow for significant systematic uncertainty reduction. We provide first results that definitively intersect ISN parameter tubes for elongation angles $79^\circ$, 94$^\circ$, and 109$^\circ$, resulting in precise interstellar parameters: speed $26.37 \pm 0.82$ km s$^{-1}$, ecliptic longitude direction $74.85^\circ \pm 0.96^\circ$, ecliptic latitude direction $-5.212^\circ \pm 0.035^\circ$, and temperature $7740^{+770}_{-730}$ K. The inferred flow of the Very Local Interstellar Medium is not consistent with either the Local Interstellar Cloud or the G-Cloud, but rather an intermediate state. IMAP is now positioned to study the detailed physics of this complex, nearby interstellar region. By resolving and understanding its physics, we determine how the heliosphere responds to the local interstellar flow, and how it may evolve in time

Galactic high-mass X-ray binaries (HMXBs) are important systems for studying accretion mechanisms onto compact objects and for investigating the complex stellar winds of massive stars. In particular, HMXBs hosting a neutron star allow us to reveal the structure of the accreted material in X-ray pulsars and consequently to investigate how matter behaves under extreme conditions of pressure and density. These are major scientific goals for XRISM and NewAthena. Here we report on the first out-of-eclipse XMM-Newton observation of the HMXB 4U 1538-52, complemented by NuSTAR coverage. Our campaign aimed to investigate stellar-wind variability and continuum changes with high-resolution spectroscopy at a critical orbital phase: when the neutron star is in inferior conjunction. Thanks to simultaneous observations covering both soft and hard X-rays, we obtain the most detailed X-ray view of the accreted material in 4U 1538-52 to date. In particular, we perform time-resolved spectroscopy down to the pulse period of the neutron star to highlight wind clumping properties and accretion structures. In this dataset, we observe a bright flare reaching $\sim$10$^{37}\,\rm{erg\,s^{-1}}$ probably induced by the accretion of a $10^{20}\,\rm{g}$ clump, followed by a luminosity dip forming a heartbeat-like episode. This event is followed by three local absorption peaks with local variability of the order of the pulse period, and a gradual hardening of the underlying spectrum throughout the observation. This could indicate the presence of both small-scale and large-scale overdense structures in the vicinity of the neutron star, which can be attributed to clumps and filamentary structures embedded in the accretion wake. These observational evidences are further supported and reproduced by 3D hydrodynamic simulations.

Turbulent fluxes between the surface and the atmosphere are typically parameterized using empirically fit relationships. Here we test machine learning techniques for fitting the relationship for the offshore environment. To do that, data from three offshore sites are used: the Martha's Vineyard Coastal Observatory (MVCO) air-sea interaction tower, the FINO1 research platform, and the CASPER-West FLIP research vessel deployed off the coast of California. Two machine learning methods were employed: Neural Networks (NN) and Random Forests (RF). Because the observational sites had towers with measurements at different levels, the vertical differences were input as gradients. Models were built for both momentum flux and heat flux. ML models trained at the individual sites were competitive with and in some cases, better than the physically-based COARE-3 model tailored to offshore fluxes. The heat flux ML models generally outperformed the physics-based parameterizations for most metrics, but the results were mixed for momentum flux, with only the site with the most training data (MVCO) producing results better than COARE-3. When the ML models from that site were applied to the other sites, results were degraded from using data from the site being tested. ML models built from data combined from the three sites generally showed improvements for the sites with less available training data. When assessing which variables were most important, the wind speed was most important for momentum flux and temperature gradient for heat flux.

Updated reference data and an analytic parameterisation of elastic electron and X-ray scattering are presented for all 118 neutral atoms. The reference electron densities for the multi-electron elements $Z=2$–$118$ are computed with the relativistic B-spline Dirac–Fock code atomx, while hydrogen is constructed from the exact relativistic one-electron Dirac $1s$ solution; the electron scattering factor $f_e(g)$, X-ray scattering factor $f_x(g)$ and radial moments are derived from these densities. The reported parameterisation extends the fixed-size Lobato–Van Dyck hydrogenic expansion while retaining closed-form expressions for $f_x(g)$, $\rho(r)$, the electrostatic potential $V(r)$ and the projected potential $V(R)$. These extensions are an element-adaptive basis size $n_t(Z)$, a simultaneous real- and reciprocal-space fit, an exact $\langle r^4\rangle$ constraint in place of the non-relativistic Kato cusp, and a charge-carrying Dirac–Padé basis term that adds a polynomial-times-exponential shape channel without replacing the hydrogenic basis by a tabulated Dirac radial function or assigning the term to a physical shell. For the same total parameter count, the Dirac–Padé-enriched basis improves on the parameter-matched non-relativistic basis for 111 of the 118 elements, lowering the mean total cost by 39%. Relative to a controlled fixed five-term refit on the same reference grid and objective, the element-adaptive bases improve the median reciprocal-space deviations by about three to four orders of magnitude and resolve shell structure in $4\pi r^2\rho(r)$ that the fixed five-term basis cannot. The largest changes occur near the nucleus and in the reciprocal-space tail beyond the legacy 12 inverse angstroms range, which is directly relevant to quantitative high-angle scattering and electron-diffraction measurements.

The Bode-Fano bound sets a fundamental trade-off between bandwidth and reflection in passive, linear, time-invariant matching networks. We show that an aperiodically time-modulated reactive element can emulate the non-Foster response required to match a prescribed pulse, achieving reflectionless, nearly distortionless energy transfer beyond the Bode-Fano limit. The approach introduces a new constraint: a minimum dc bias that scales with pulse bandwidth, derived from the requirement that the modulated capacitance remain positive at all times. This modulation-bias bound replaces the classical bandwidth-reflection trade-off with a bandwidth-energy trade-off. A realistic circuit simulation confirms broadband matching with preserved waveform fidelity, demonstrating that the scheme is physically realizable and not merely a mathematical circumvention.