Papers

We investigate stationary states of a collisionless, gravitationally stratified plasma atmosphere composed of electrons, protons, and alpha particles by extending Pannekoek–Rosseland theory to multispecies and multi-temperature plasmas. Starting from Liouville's theorem, we derive the self-consistent ambipolar electric field from kinetic equilibrium and charge neutrality. For a single-temperature atmosphere, we obtain analytical expressions for the ambipolar field, show its dependence on alpha-particle abundance, and determine the relative stratification of the three species. A first-order analytical approximation to the electrostatic potential accurately reproduces the numerical solution. We then generalize the formalism to multi-temperature plasmas generated by stochastic boundary heating, representing the stationary distribution as a superposition of Maxwellian populations. Gravitational filtering produces non-exponential density profiles and increasing temperatures with altitude, while preserving the relative species stratification, with alpha particles most strongly stratified and protons least. The ambipolar electric field contains a dominant gravitational contribution, corresponding to the generalized Pannekoek–Rosseland field, and a thermoelectric contribution arising from species-dependent temperature gradients, which accounts for its non-monotonic structure. These results provide a framework for studying the combined effects of plasma composition and stochastic heating in gravitationally stratified astrophysical plasmas.

We identify and characterize a large-scale diffuse gamma-ray structure in the Southern Galactic Hemisphere using 17 yr of Fermi-LAT data. An energy-dependent likelihood analysis, including alternative Galactic diffuse-emission models, isotropic emission, the Fermi bubbles, and resolved 4FGL sources, reveals an extended excess that persists across the tested background models and spans tens of degrees. The excess broadly follows the X-ray-defined southern eROSITA Bubble (eB) region, while also overlapping the projected southern extension of Loop I. Template fits favor a filled eB-like morphology over the adopted Wolleben Loop I shell geometry, making the structure a plausible gamma-ray counterpart of the southern eB, although Loop-I-related or other localized foreground emission cannot be excluded. Under the eB template, the southern component is fainter and softer than the northern large-scale component, with an integrated luminosity lower by a factor of about seven, broadly consistent with the eROSITA-bubble asymmetry. If interpreted as Galactic-scale outflow emission, its faint, soft spectrum may indicate aged particles and/or distributed reacceleration in the outer bubble. A hadronic interpretation is energetically demanding, whereas a leptonic inverse-Compton scenario is more economical but requires rapid transport and/or local reacceleration of high-energy electrons.

In this paper, we investigate the integrability of Lotka-Volterra (replicator) systems arising from interaction matrices generated from corresponding graph structures, continuing work started by Visomirski and Griffin [J. Phys. A., 58:015701, 2025] and Evripidou et al. [J. Phys. A., 55:325201, 2022] (among others). In particular, we define a new family of graphs, the spoked graphs, and show that all dynamics generated from this family are integrable. In reference to Evripidou et al. (2022), we define a new anti-cloning operator and show that its action on balanced tournament graphs (with odd vertex count) generates new graphs whose dynamics are integrable. Interestingly, we provide numerical evidence that this anti-cloning operation leads to chaotic behaviour when applied to other graph families (e.g., the directed cycles that generate the classically integrable Volterra lattice). This work completes a taxonomy of all integrable dynamics generated by directed graphs with up to six vertices started by Visomirski and Griffin (2025), and suggests several future directions of study on this topic.

We derive an effective scalar field theory for matter in group field theory condensate cosmology, starting from the fundamental quantum-gravity dynamics in a fully relational framework and encompassing both early- and late-universe regimes. The collective hydrodynamics of the underlying quantum geometry allows us to reconstruct both the homogeneous cosmological dynamics of matter and geometry and an inhomogeneous local field-theory description. Localization in space and time is defined relationally with respect to a material reference frame. At the homogeneous level, we obtain a modified scalar field theory on the emergent FLRW spacetime selected by the condensate. It recovers the standard dynamics of a massless scalar field in the late-time general-relativistic regime while retaining quantum-gravity corrections near the cosmological bounce. At the perturbative level, scalar inhomogeneities obey an effective wave equation that carries signatures of the underlying quantum-gravity microstructure. In the early-universe regime, this equation exhibits a modified dispersion relation with both dispersive and dissipative contributions. These corrections provide a concrete avenue for identifying phenomenological signatures of quantum gravity directly from a fundamental quantum-gravity framework.

Aqueous foams possess multiple structural motifs across different length scales: macroscopic foam, bubbles, foam films and the air/water interface. In this study, macroscopic foams are generated by sparging gas through an aqueous dispersion of PNIPAM microgels which act as foam stabilisers due to their surface activity. The stiffness of the microgels and thus their interfacial activity are tuned by variation of the cross-linker density. The effect of the cross-linker density and the microgel concentration on the resulting foam formation properties (foamability) and the foam stability are investigated. A lower cross-linker density and a higher microgel concentration enhance the foamability, generate foams with smaller bubbles and higher liquid fractions, and increase the foam stability. These observations are correlated with the microgel behavior at the single air/water interface examined by pendant drop tensiometry and Langmuir compression experiments as well as the mobility in single free-standing foam films determined using a Thin Film Pressure Balance. Our findings highlight good agreement across all length scales: increased foamability correlates with a faster decrease in surface tension, and higher foam stability with a higher surface elastic modulus of a microgel-covered single air/water interface and decreasing mobility in foam films.

The $n$-qubit Pauli group is an essential ingredient to most quantum applications, from computing and error correction to benchmarking and simulation. Despite comprising merely a discrete set of operators, it exhibits many quintessential features of quantum theory, including contextuality, which has been identified as a key resource to quantum advantage in a variety of different flavours. Here, we extend this analysis, introducing the notion of a `noncontextual property' whose nonexistence proves the Kochen-Specker theorem, similarly to and generalising common arguments based on the nonexistence of valuations. We relate this notion formally to the existence of Boolean-valued frame functions, and characterise all such frame functions in the case of the $n$-qubit Pauli group. For two qubits, we show that the Pauli group admits noncontextual properties, despite admitting no valuations. We then establish this as the only nontrivial such case with $n\geq 2$, by proving that any Boolean-valued frame function on stabiliser states is constant for more than two qubits. We also perform a similar analysis for the symplectic theory underlying the $n$-qubit Pauli group, for which nonconstant Boolean-valued frame functions exist for all $n$, yet only in restricted form. By comparison, this shows that contextuality in the $n$-qubit Pauli group is not only a consequence of the projective nature of the Pauli group as a representation of its underlying symplectic vector space, but of the geometry of symplectic polar spaces itself. In geometric terms, our result determines all Cameron-Liebler sets of maximal totally isotropic flats in the binary affine-symplectic space.

The continuous-time quantum walk on an oriented circulant graph is determined by the Fourier eigenvalues of its Hermitian adjacency matrix. We classify perfect state transfer (PST) between distinct vertices in every nonempty oriented circulant graph. We show that each such graph is described by an odd primitive quadratic Dirichlet character of conductor $\Delta$, a set of gcd-classes, and a choice between the two orientations of each selected class. For a graph of order $n$, we derive an explicit formula for every Fourier eigenvalue without assuming that $n/\Delta$ is coprime to $\Delta$. We prove that PST occurs only for $\Delta\in\{3,4,8\}$ and give necessary and sufficient conditions on the connection set for each conductor. Equivalently, the square-free radicands of oriented circulant graphs with PST are exactly $1$, $2$, and $3$. More generally, when $\lambda_j=\sqrt{D}\eta_j$ with $\eta_j\in\mathbb{Z}$, congruences satisfied by the integers $\eta_j$ determine all PST pairs and times, the minimum period, and the largest vertex sets supporting multiple state transfer (MST). In this class, pretty good state transfer is equivalent to PST. We also determine the connected orders and enumerate the resulting graphs.

Fourier-domain (FD) optical coherence tomography (OCT) depends on broadband sources to maximize axial resolution and image quality. However, these lasers significantly drive device cost or may be unavailable at desired wavelength and bandwidth ranges. A potential solution lies in integrating multiple, more affordable sources with lower individual bandwidth into a single system. However, difficulties arise if the resulting spectrum exhibits discontinuities. In this letter, we present a method that can combine OCT images from a flexible number of spectra with arbitrary, possibly non-overlapping gaps using a neural network. Compared to low-resolution input images, reconstructed B-scans are super-resolved, preserve even fine and low-contrast details and edges, and exhibit strong noise reduction that increases with the band gap. The proposed method could thereby provide a major step towards high-quality OCT imaging using spectrally disjoint, low-bandwidth sources. In broadband settings, it can be directly applied as a Fourier-domain masked autoencoder for self-supervised image quality enhancement.

Sliding ferroelectricity in parallel-stacked two-dimensional van der Waals materials enables a broad range of novel device concepts, but exploiting it requires reliable, non-destructive assignment of the underlying stacking order and polarization state. Here, we combine Kelvin-probe force microscopy (KPFM) with low-frequency Raman spectroscopy to probe the polarization domains and stacking configurations of a exfoliated trilayer 3R-MoS$_{2}$ flake on a hBN substrate. We find that ABA and BAB - both stackings with zero net polarization - are indistinguishable in KPFM, yet show drastically different low-frequency shear modes. This observation is reproduced across multiple flakes and is corroborated by low-temperature photoluminescence. Notably, the standard bond-polarizability model does not account for the difference in shear-mode activity between the ABA and BAB configurations, indicating that the interlayer Raman response of these stackings is governed by physics beyond a simple polarizability picture. Our results show that none of the here-used individual techniques alone is sufficient to assign sliding-ferroelectric stacking order and motivate a combined spectroscopic-scanning-probe approach.

The constrained equilibrium problem for the logarithmic potential was introduced by Rakhmanov (1996) as he realized that the asymptotic distribution of the zeros of discrete orthogonal polynomials in a compact interval could be described in terms of the equilibrium measure of this interval in a class of measures subject to a certain constraint. Other authors such as Dragnev and Saff (1997), and Kuijlaars and Van Assche (1999), extended this approach to more general settings. These problems have proven to be useful for describing asymptotic distributions in different settings. In the current paper, we consider constrained equilibrium problems in the Riesz setting, that is, for $s$-Riesz potentials in the hyperplane $\mathbb{R}^d,$ with $d\geq 1$ and $\max (0,d-2) < s < d$. Along with some general results, an illustrative example consisting of the solution of a constrained equilibrium problem in the unit ball is studied in detail. This is the main part of the paper. Finally, a number of numerical experiments show how the constrained equilibrium measure, the solution of the problem, may be discretized using the so-called 'constrained Leja points' introduced by Coroian and Dragnev (2001).

The evolution of giant planets depends on their formation history. While several evolutionary models self-consistently link planet formation by core accretion to long-term evolution, such models for planets formed by disk instability are lacking. We simulate the evolution of giant planets formed by disk instability and follow their evolution including the pre-collapse phase, dynamical collapse, and long-term contraction in a unified numerical framework. The evolution is simulated using the MESPA code with modifications that allow us to model gas clumps in the pre-collapse phase. We consider masses between 1 and 12 Jupiter masses and metallicities ranging from 0.5 to 2 times the protosolar value. We confirm that the pre-collapse timescale strongly depends on the planetary mass, and that after dynamical collapse the objects reach a state of long-term contraction which lasts for billions of years. We show that metallicity is a major source of uncertainty in mass estimates derived from the age-luminosity relations. For the metallicity range considered here, we find that for a given measurement of age and luminosity the difference in the inferred mass can be up to 1.5 Jupiter masses. We find that our evolution tracks predict masses that are consistent with the measured dynamical mass constraints for HR 8799 e, AF Lep b, Beta Pic b and Beta Pic c. We also show that both core accretion and disk instability can lead to very similar long-term evolutionary tracks. The agreement between our models and dynamical mass measurements suggests that disk instability remains a viable formation pathway for giant exoplanets. The luminosity evolution alone cannot distinguish between the two formation pathways. Finally, we suggest that planetary metallicity must be taken into account when inferring the masses of young giant planets from their luminosities, as it significantly affects their evolution.

Deep MUSE observations of SNR 0509-67.5 reveal that the coronal [Fe\,xiv] $\mathrm{\lambda}$5303 emission line appears with either one or two velocity components across the entire remnant, arising from reverse-shocked ejecta moving toward and away from the observer. A supervised dense neural network classifies each spaxel and fits Gaussian profiles plus a linear function to the observed line emission. We measure a bulk Doppler velocity of $-1000\pm60~~\mathrm{km~s^{-1}}$, interpreted as the line-of-sight component of the primary white dwarf's orbital velocity in a double-degenerate merger. The red- and blue-shifted ejecta map shows a flattened edge along the north-eastern rim, consistent with the companion's shadow, indicating a binary companion was present at explosion. Modelling this feature as a cone anchored at the explosion centre and applying Bayesian inference, we recover the cone's orientation and half-opening angle. We then use the Eggleton Roche-lobe relation to infer properties of the companion. The companion was likely a ${\sim}0.6~\mathrm{M_\odot}$ white dwarf with radius ${\sim}9800$~km and orbital velocity ${\sim}1700~\mathrm{km~s^{-1}}$ at the time of explosion. Together, these results provide a complete dynamical picture of a Type Ia supernova progenitor system whose maximum-light spectrum is independently constrained by light echo observations.

Memory is a key determinant when cultural items compete for attention and, consequently, for success, as in the case of songs on a music chart. For modeling, one adds memory to Lotka-Volterra models, the reference for Markovian competitive processes. Here we treat memory in terms of an exponential moving average, finding that it leads to an extended region of winnerless chaos characterized by log-normal popularity statistics in trailing top-k charts. Importantly, the observed log-normal behavior collapses to a power-law distribution when the feedback dynamics is fast on the scale of the charting period. This result is in agreement with the observed statistics of real-world music charts (e.g., Billboard and Spotify). In a chaotic state, the size of the largest Lyapunov exponent is a measure of how unpredictable the system is. We find that the largest Lyapunov exponent varies strongly as a function of parameters in the phase where winnerless chaos is stable. Interestingly, the sets of parameters obtained by comparing simulations with real-world cultural-item dynamics extracted from Google Books and Google Trends, movies, Reddit, Wikipedia, Twitter, and scientific publications, are located close to the points in parameter space where the largest Lyapunov exponent reaches its local maximum, namely, close to the point of maximal unpredictability. This result suggests that cultural competitive processes are maximally chaotic when memory is a key determinant.

We use a variety of analytic and numerical techniques to approximate the geometry of individual dark matter halos when modeled as collections of ultralight scalar bosons (ULDM), followed by an analysis on the future directions and implications of this work. Ultimately, we aim to understand the morphology and creation of complex structures (like spirals) in galaxies from a geometric standpoint and to investigate the connection between dark matter and baryonic matter in galaxies. We find that superpositions of gravitational eigenmodes for ULDM in a fixed background potential can yield spiral density perturbations which rotate on the order of one hundred million years and appear within ten to twenty kpc of the halo center, both features comparable to realistic galaxies, and that this model provides a natural explanation for the density waves necessary to seed baryonic spirals.

Dilute solutions of linear polymer chains with tangentially active monomeric beads are simulated using a Brownian dynamics (BD) algorithm over a range of solvent quality in the thermal crossover regime between $\theta$ and athermal solvents. The conformational changes with increasing Péclet number ($Pe$) (which is proportional to the strength of activity) suggest deswelling of the chains resulting in a collapse of the radius of gyration data to a random walk (RW) statistics at a unique value of $Pe$, independent of the solvent quality. The swelling behaviour of active polymers in the crossover regime relative to their size at the $\theta$ state is found to follow the same universal characteristics as that of passive polymer chains. Furthermore, based on polymer blob theory we present a novel scaling of the thermal blob size with tangential activity of the monomeric beads which leads to the definition of a renormalized solvent quality parameter for active polymers. Altogether, this work establishes a connection between the configurational properties of active polymers and scaling laws in polymer physics, which provides a useful framework to study the dynamics of activity induced motion of polymeric molecules for various applications in biophysics and other related areas.

We present the discovery of 27 new Galactic transients made by the commensal MeerTRAP single pulse search programme at the MeerKAT telescope. We determine the location of 14 of these discoveries with arcsecond accuracy by imaging the data captured in the dedicated transient buffer. A preliminary estimate of the period was made for 8 sources using the arrival times of several pulses detected by MeerTRAP. The periods of these transients range between 0.78 s and 4 s. For the previously published MeerTRAP source MTP0040 (PSR J1357-6507), we are able to provide the position and period using new pulses detected since it was reported. We also estimate the radio fluences and discuss the burst rates derived from the commensal search detections. The accurate image-domain localizations were used to conduct follow-up observations and timing analysis. Furthermore, some follow-up observations revealed ordinary pulsar-like pulsed behavior for four of the new sources, illustrating the blurred separation between rotating radio transients and canonical pulsars. We also present coherent timing solutions for 4 sources, providing insight into their rotational properties and their place within the Galactic neutron star population.

Given a particular heat engine cycle, what is the optimal working medium that results in the highest efficiency? While one might jump to the conclusion that it must surely be the ideal gas, the situation is actually more intricate. Starting with a general Helmholtz potential that depends polynomially on molar volume and temperature we derive exact expressions for the ideal Stirling, Otto, and Brayton cycles. We find that for the thermodynamic systems described by our ansatz for the Helmholtz potential the maximal efficiency is achieved, if the working medium is described by a fundamental relation linear in temperature. This includes the ideal gas, but also classical harmonic oscillators and phenomenological models of the rubber band.

In some neutron-rich nuclei usually treated as two-neutron halos, the core can itself be resolved into a subcore-neutron-neutron subsystem, so that four valence neutrons may be involved. To describe this situation, a four-neutron halo model in the unitary limit is developed and applied to $^{22}$C, $^{19}$B, and $^{14}$Be, in which a compact nuclear core is surrounded by two weakly bound spin-singlet neutron pairs occupying different spatial shells, characterized by two independent momentum scales, with the four-neutron wave function fully antisymmetrized. The evolution of the halo structure with the ratio of the two scales is mapped from the limit of well-separated scales, where the system reduces to an effective two-neutron halo around a structured core, to the regime of comparable scales, where the four-neutron character is fully developed. At intermediate ratios, a window is identified in which the dimensionless root-mean-square distances become insensitive to the scale hierarchy and the system behaves approximately as a one-scale configuration. The calculated matter radii of $^{22}$C and $^{19}$B are consistent with the most recent experimental values and, within current uncertainties, the matter radius does not discriminate between an effective two-neutron-halo and an explicit four-neutron-halo description of $^{22}$C. Distinguishing the two pictures requires observables sensitive to the shape of the halo distribution, such as ratios of higher radial moments. For $^{14}$Be, the computed charge radius is consistent with the value derived from the measured point-proton radius.

Relativistic jets from spinning black holes offer a possible strong-field probe of gravity through the Blandford-Znajek mechanism. We study the leading jet-power scaling in the four-dimensional power-law rotating Kalb-Ramond geometry introduced by Kumar, Ghosh, and Wang. The metric is used here as a stationary background, without assuming that it constitutes a newly established exact rotating solution. We first examine the deformation at the metric level. For $s=2$ it is absorbed completely by a mass redefinition, whereas for $s>2$ the correction decays more slowly than the usual mass term. Our main benchmark is therefore the nondegenerate $s=3/2$ case, whose correction falls faster than the Kerr mass term; $s=3$ is kept as a secondary comparison. We evaluate the BZ scaling under three magnetic assumptions: fixed total horizon flux, fixed local normal field with the proper horizon area, and a reduced radius-based flux proxy. The resulting trends differ appreciably, showing that the magnetic prescription is itself a leading systematic. For GRO J1655-40 and GRS 1915+105, the marginalized deformation posterior remains close to the horizon-conditioned effective prior for both a uniform prior and a truncated-Gaussian alternative. The jet-only profile likelihood is also nearly flat over the allowed deformation range, with the same qualitative behavior in the $s=3$ test. Thus, within the present setup, the jet-power proxies do not independently determine the Kalb-Ramond deformation. A stronger inference will require better control of the rotating background, source-dependent magnetic flux, non-Kerr spin estimates, and a larger sample.

Interactions of tetraneutrons, which are assumed to be produced in the nuclear fission process, with nuclei are studied in the framework of optical and Hauser-Feshbach statistical models. It predicts a large probability of $^{89}\mathrm{Sr}$ production for the tetraneutron-induced reaction on $^{88}\mathrm{Sr}$ compared to other isotopes. The same technique is applied to the tetraneutron-induced reaction on $^{27}\mathrm{Al}$ and the hexaneutron-induced reaction on natural zinc to revisit two historical multi-neutron experiments performed in the past.

We prove a conifold gap theorem for the topological recursion of toric mirror curves: for every local analytic family acquiring a generic one-node degeneration and every fixed genus at least two, the conifold-polarized free energy has one universal polar term, and the remainder is jointly holomorphic in the transverse and spectator parameters. The result covers separating and nonseparating nodes and allows general family deformations beyond the pure filling-fraction case.

Binary systems with circumbinary molecular and dust rings are of great interest because they provide insights into the dynamics and evolution of stellar systems and the chemistry of the surrounding material. We aim to elucidate the nature of the B[e] binary system HD 327083 and the physical properties of its circumstellar and circumbinary envelopes. We combined multi-epoch high-spectral resolution optical and near-IR observations with VLTI/MIDI observations and ASAS-3 photometry. The data were analysed to obtain the orbital parameters, study individual members of the system, and derive the properties of the atomic and molecular gas and the dusty components of the complex environment of HD 327083. We improved the orbital solution of HD 327083 and derived a period of P = 107.699 d. Most optical lines display variations in shape and intensity when folded with the orbital motion. We assigned F6 II-III and B1 spectral types respectively to the cool and hot components. A ring of molecular gas revolves around the system and varies with the orbital phase. The MIDI data show a silicate band in absorption at 9.7 micron and indicate that the dust distribution has an elliptical shape, with its inner edge varying with orbital phase between 12.5 and 44 AU. We conclude that the B[e] binary system HD 327083 comprises a B-type massive accreting star, and an F-type companion filling over 60% of its Roche lobe and evolving towards the red supergiant stage. The deformed shape of the F-type star causes a broad minimum in the light curve. The hot companion (26 000 K, log g = 3.0) is hidden by a compact disc and shows a bi-polar outflow. The entire binary system presents an O-rich environment. It is surrounded by warm CO and SiO molecular rings, which are enclosed by an elliptical dust structure. All these components were formed by the evolved donor star during its evolution towards the red supergiant phase.

The standard moving mirror model in (1+1)-dimensional spacetime is known to reproduce several quantum aspects of black hole evaporation. A perfectly reflecting, accelerating mirror can emit radiation whose frequency spectrum resembles that of Hawking radiation, although this correspondence holds only under certain approximations. Moreover, the standard in-out formulation does not provide a natural notion of the partner modes associated with the Hawking radiation. In this paper, we reformulate the moving mirror model in terms of Rindler/Milne modes. This formulation not only attributes the origin of the required approximations to mode squeezing effects but also naturally incorporates the notion of partner modes. Furthermore, as a consequence of these mode squeezing effects, the radiation received by an inertial observer at future null infinity exhibits additional nontrivial quantum correlations, even though its frequency spectrum approximately follows a Bose–Einstein or Fermi–Dirac distribution.

Perovskite oxides and their heterostructures exhibit a wide range of functional properties. Among these materials, BaSnO$_3$/LaInO$_3$ heterostructures form high-mobility two-dimensional electron gases (2DEGs) at their interfaces. In particular, room-temperature electron mobilities exceeding 100~cm$^2$/Vs were enabled by recent advances in thin-film growth. This work presents a combined experimental and theoretical study of the electronic structure of BaSnO$_3$, LaInO$_3$, and BaSnO$_3$/LaInO$_3$ heterostructures with varying LaInO$_3$ overlayer thicknesses. Soft and hard X-ray photoelectron spectroscopy (SXPS and HAXPES) measurements are combined with densities of states (DOS) derived from hybrid density functional theory (DFT) calculations. The analysis of core, semi-core, and valence states allows to arrive at a comprehensive understanding of the chemical bonding and electronic structure in the parent oxides as well as the formed heterostructures. For the BaSnO$_3$/LaInO$_3$ heterostructure, the band offset and population of 2DEG states at the interface is directly probed using HAXPES.

Building on earlier work by Gang, Kim, and Lee, we extend the known class of 3-dimensional non-unitary topological quantum field theories (TQFTs) and 2-dimensional non-unitary rational conformal field theories (RCFTs). The TQFTs are obtained by applying topological twist to generalized S-fold superconformal field theories (SCFTs). They are related to the RCFTs through the bulk-boundary correspondence. For certain families, we propose simple lines in the TQFTs, together with expressions for the characters and modular $S$ matrices of their associated boundary RCFTs. For broader family, we propose modular $S$ and $T$ matrices for the TQFTs. For particular members of this family, the resulting modular matrices are identified with the generalized Haagerup-Izumi modular matrices up to Galois conjugation.

Massive particles reach timelike rather than null infinity, leaving their Carrollian boundary description unresolved. We construct a Carrollian dictionary for massive one-particle states on $\mathscr I^\pm$ without requiring their worldlines to reach null infinity. The dictionary encodes the bulk momentum through its projections onto the null frame associated with each celestial point. The Poincaré intertwining equations require the complete Carrollian representation to describe massive states. We apply the dictionary to the Källén–Lehmann representation and to soft photon and graviton theorems. The Källén–Lehmann application fixes the coefficient function of the non-contact two-point function in terms of the bulk spectral density. Soft theorems show that global modes reproduce the ordinary $U(1)$ and Poincaré actions, whereas local actions remain integrals over celestial directions.

Low-dimensional multiferroics hold great promise for integrated magnetoelectric devices. Spin spiral state has recently been shown to induce ferroelectricity in single-layer van der Waals (vdW) material NiI2. However, how this state evolves and can be tuned towards the two-dimensional limit remain unclear. Here, we combine spin-polarized scanning tunneling microscopy, layer-by-layer film growth, and multi-scale theoretical modeling to investigate the spin spirals in NiI2 thin films. As the film thickness increases from 1 to 7 monolayers, we observed a continuous increase of spin-spiral wavelength and a rotation of wavevector from near [110] to [1-10] direction, which evidences a dimensional crossover primarily driven by enhanced interlayer exchange energy. Moreover, we find that the film wrinkles can cause deflection of the spin spiral wavevector, which is caused by local curvature induced modification of exchange interactions. Our findings establish thickness and local strain as two tuning methods for engineering non-collinear helical magnetism and accompanied electric polarization in vdW multiferroics.

The majority of massive stars are born in close binary systems. As stars expand when they age, mass transfer or even a merger with their companion is inevitable. However, most binary interaction products appear as single stars, such that the main evidence of their exciting past is lost. In a comprehensive grid of detailed massive binary evolution models we find systematic trends in chemical surface abundances that allow identifying the past mass gainers. We develop an analytic framework which is independent of specific evolutionary models, to constrain the amount and composition of the accreted material from their observed surface abundances. This yields tight constraints on the uncertain mass transfer physics in massive binary stars and allows us to reconstruct the past evolutionary history of the progenitor binary system. This method, which is shown to also constrain binary mergers (for example, SN 1987A), is applied to some of the best-studied OB stars so far. For {\gamma} Columbae, suggested to be an envelope-stripped star, we show that it is a mass gainer instead, whose companion star likely formed a stripped-envelope supernova. Our results highlight surface abundance measurements as a powerful tool to improve our understanding of massive binary systems evolving towards supernovae and compact object binaries.

Vortex electrons carry a quantized orbital angular momentum (OAM) degree of freedom, but whether this internal structure can survive repeated transport through an accelerator lattice remains unclear. Here we formulate a density-matrix theory for periodic round lattices and show that the symmetry-protected quantity is a Lewis-Floquet OAM invariant, rather than the instantaneous kinetic OAM. The classical transfer map lifts to unitary state evolution, while stochastic field errors generate a Lindblad channel. This framework exposes a sharp separation between visibility and state survival. Dipole jitter displaces the wavepacket, rapidly smearing a vortex signature measured about a fixed origin without altering its recentered internal OAM distribution. Quadrupole fluctuations instead drive genuine $\Delta\ell=\pm2$ leakage. For a matched $n=0$, $|\ell|=1$ mode, white-noise estimates based on representative IOTA and PETRA III parameters give fixed-frame smearing scales of $4.9\times10^2$ and $3.3$ turns, but intrinsic-leakage scales of $2.1\times10^5$ and $2.2\times10^6$ turns, respectively. Thus loss of an unrecentered vortex image need not signal destruction of the vortex state: its internal OAM structure can persist hundreds to hundreds of thousands of times longer. Centroid tracking and quadrupole stability are therefore distinct experimental requirements for observability and state survival, respectively.

The 2024 Noto Peninsula Earthquake caused widespread power outages, communication failures, and road disruptions, and a tsunami warning was issued immediately after the earthquake, highlighting the importance of reliable disaster information transmission. The Noto Peninsula is surrounded by the sea on three sides and has limited transportation networks, making community isolation and securing reliable information transmission critical challenges. This study defines "Disaster Information Reachability" as the capacity to deliver necessary information to those who need it when they need it, and examines the role of medium-wave AM broadcasting from this perspective. In September 2024, the author conducted a mobile reception survey from Kanazawa to Suzu City and a fixed-point reception survey in Suzu City using commercially available radio receivers and passive radio receivers, including HOOPRA. Medium-wave stations in Niigata, Toyama, Akita, and Tokyo were clearly received, although the local NHK Kanazawa stations were affected by noise. The nationwide high-power NHK Radio 2 network, which was still operational at the time, was confirmed to provide a wide-area, multidirectional reception pathway through maritime propagation, demonstrating its critical significance as a redundant disaster information infrastructure. The fact that FM relay station damage was documented in subsequent policy materials, while medium-wave AM broadcasting received no explicit attention, suggests that its disaster information reachability remains insufficiently recognized. Medium-wave AM broadcasting, with its wide-area simultaneous broadcast capability, high-power coverage, and maritime propagation characteristics, functions effectively as a disaster information infrastructure in peninsular regions and warrants reassessment in preparation for large-scale disasters such as a Nankai Trough megaquake.