Papers

We investigate laminar mixing of a passive dye in an infinite, two-dimensional domain filled with a Newtonian fluid by simulating a cylindrical stirrer that rotates at constant speed along a circular path, stirring an initially quiescent fluid. The fluid is marked by a passive dye in the lower half of the domain, enabling a systematic analysis of dye-interface evolution and mixing dynamics. By varying the stirring Reynolds number within the laminar regime, we identify how transitions in flow topology govern mixing and distinguish three mixing regimes spanning diffusion-dominated and advective mixing. In the diffusion-dominated regime, mixing is characterized by the formation of a well-mixed central region and the development of a spiral dye pattern that evolves in an approximately self-similar manner. Advective mixing is marked by substantial deformation of the dye interface beyond the central region. We provide a mechanistic interpretation of advective mixing by relating mixing events to specific flow features: (i) direct interaction between the stirrer and the dye interface, and (ii) vortex shedding near the stirrer and away from the central region. Enhanced mixing occurs when vortical structures are able to escape the central region and transport scalar gradients nonlocally. When vortical activity remains confined near the stirrer's path, mixing per stirrer period exhibits only weak dependence on stirring speed despite increasing stirring intensity. Significant enhancement of mixing per period occurs only when escaping vortices introduce a new transport mechanism that carries scalar gradients far beyond the stirrer's path. Overall, we present a mechanistic link between flow topology and mixing by identifying the transport mechanisms through which flow features govern scalar evolution, providing a bridge between the kinematics of mixing and the underlying fluid dynamics.

Solar flares are intense bursts of electromagnetic radiation that occur when stored magnetic energy in the Sun's atmosphere is suddenly released. They are categorized into five classes – from least to most powerful: A, B, C, M, and X – with each successive class representing a ten-fold increase in energy output. The electromagnetic radiation emitted by the stronger classes (C, M, and X) is capable of causing significant disruptions to communication systems, satellites, and power grids on Earth. Accurate prediction of solar flares is crucial for mitigating their adverse effects and ensuring the functionality of critical infrastructure. This research introduces a novel model named ResNet-Transformer, which combines a convolutional neural network (CNN), ResNet50, with a standard Transformer architecture. The hybrid model effectively processes both spatial and time-series data derived from solar images to predict the occurrence, class (C, M, and X), and probability of solar flares within 24-hour, 36-hour, and 72-hour windows. This hybrid deep learning model represents the first of its kind in the domain of image-based, multiclass solar flare prediction. We evaluated the model's performance using a comprehensive set of metrics, including weighted precision, recall, and F1 score, together with balanced accuracy, the Matthews correlation coefficient (MCC), Cohen's kappa, and the area under the receiver operating characteristic curve (ROC-AUC). Results show that ResNet-Transformer surpasses traditional machine learning methods, such as support vector machines (SVMs) and standalone CNN models, across all evaluated metrics. This study highlights the potential of integrating convolutional neural networks with Transformers to enhance predictive capabilities in solar physics, paving the way for more reliable and timely solar flare forecasting.

The ability to use single mode (SM) fibers for beam transport in optical interferometry offers practical advantages over conventional long vacuum pipes. One challenge facing fiber transport is maintaining constant differential path length in an environment where environmental thermal variations can lead to cm-level variations from day to night. We have fabricated three composite cables of length 470 m, each containing 4 copper wires and 3 SM fibers that operate at the astronomical H band (1500-1800 nm). Multiple fibers allow us to test performance of a circular core fiber (SMF28), a panda-style polarization-maintaining (PM) fiber, and a lastly a specialty dispersion-compensated PM fiber. We will present experimental results using precision electrical resistance measurements of the of a composite cable beam transport system. We find that the application of 1200 W over a 470 m cable causes the optical path difference in air to change by 75 mm (+/- 2 mm) and the resistance to change from 5.36 to 5.50 {\Omega}. Additionally, we show control of the dispersion of 470 m of fiber in a single polarization using white light interference fringes ({\lambda}c=1575 nm, {\Delta}{\lambda}=75 nm) using our method.

We examine an on-disk solar quiet region of enhanced magnetic network using Hbeta images from Daniel K. Inouye Solar Telescopes (DKISTs) Visible Broadband Imager (VBI) and line-of-sight magnetograms from DKISTs Visible Spectro-Polarimeter (ViSP). We also compare the ViSP magnetograms with co-aligned co-temporal line-of-sight magnetograms from the Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI). We find:(i) Two types of chromospheric jet-like features: Hbeta spicules, and small-scale jets. Both are rooted near edges of magnetic network lanes. Several sit close to ViSP-detected tiny islands of either minority-polarity flux or dips in majority-polarity flux. Hence, those several plausibly stem from mixed-polarity magnetic flux, and are caused by chromospheric magnetic reconnection. For He̱ta} spicules, the average width, length, lifetimes, and speeds are 420$\pm$400 km, 2600$\pm$1600 km, 4.3$\pm$0.25 min, and 12$\pm$4.7 kms. For small-scale jets, those are 385$\pm$100 km, 620$\pm$40 km, 5$\pm$3min, and 4.4$\pm$1.5 kms. (ii) H$\beta$ microflashes sit in evidently unipolar flux. Their widths, lengths, lifetimes, and speeds are 180$\pm$65 km, 365$\pm$100 km, 4.3$\pm$2.6 min, and 3.1$\pm$0.2 kms. (iii) At the base of a coronal plume, due to its higher spatial resolution than HMI, ViSP shows both some very strong (>800 G) majority-polarity flux not shown by HMI and some sub-arc-second minority-polarity-flux inclusions not shown by HMI. These sub-arcsecond chromospheric transients carry sufficient energy (10^{24}erg) to transiently heat the local chromosphere and corona and potentially contribute to solar-wind acceleration. They may represent the small-scale end of a continuum of magnetic-reconnection-driven activity, highlighting the importance of DKIST's high-resolution magnetic-field measurements for understanding small-scale chromospheric dynamics.

Bimetric theory is an extension of general relativity that perturbatively describes one massless and one massive graviton. It admits observationally viable cosmologies, passes local tests of gravity, and provides candidates for dynamical dark energy and spin-2 dark matter. Scattering amplitudes provide a complementary probe of its consistency, e.g. through analyticity, unitarity, and causality. While the tree-level $2\to2$ amplitudes of the closely related theory of massive gravity have previously been computed and analysed, the richer amplitude structure of bimetric theory has mostly been studied for selected processes and helicity sectors. We present the complete set of tree-level $2\to2$ scattering amplitudes of ghost-free bimetric theory around proportional Minkowski backgrounds. We expand the action through quartic order in the mass eigenstates and use a computer-algebra workflow to compute all of the $199$ symmetry-inequivalent helicity amplitudes. We find a clear hierarchy: amplitudes with a single massive external state vanish, those with exactly two are independent of the nonlinear bimetric parameters, and nonlinear ghost-free parameter dependence first appears with three massive external states. Taking the massive-gravity limit yields the complete set of tree-level $2\to2$ massive gravity amplitudes, which agree exactly with previous results. Finally, all amplitudes grow with energy at most as $E^6$, corresponding to the characteristic $\Lambda_3$ strong-coupling scale, and this maximal growth cannot be eliminated by any nontrivial choice of the theory parameters.

We investigate a quantum massive scalar field in the interior of a charged and spherically-symmetric (Reissner-Nordström) black hole. We examine the behaviour for varying values of the black hole charge, field mass and coupling constant when the field is in two quantum states: Hartle-Hawking (representing a black hole in thermal equilibrium) and Unruh (representing a black hole evaporating via the emission of Hawking radiation). We show that the vacuum polarization as well as the angular components of the quantum stress-energy tensor diverge on the Cauchy horizon, in stark contrast to what happens for massless fields. We also calculate the energy fluxes in Eddington-Finkelstein coordinates $\{u,v\}$. We show that these fluxes on the Cauchy horizon do not generically vanish. This implies, in particular, that in regular, Kruskal coordinates $\{U,V\}$ the ingoing flux diverges like $V^{-2}$ on the Cauchy horizon (where $V=0$). This divergence suggests that its backreaction via the semiclassical Einstein equations would yield a strong singularity, as opposed to its weaker, classical counterpart. Interestingly, there are exceptions, in which the energy fluxes in Eddington-Finkelstein coordinates vanish: (i) in the extremal limit (where the black hole is maximally charged); (ii) certain fine-tuned regions of parameter space, where the fluxes change sign.

Mass measurements of the ground and isomeric states of $^{68-70}$Co have been performed using the JYFLTRAP Penning-trap mass spectrometer at the IGISOL facility. The masses were measured, either for the first time for the isomeric states of $^{68}$Co and $^{70}$Co, or with greatly improved precision for the others, removing ambiguities in the mass surface beyond $N=40$. The ordering of the low and high-spin states in $^{68}$Co and $^{70}$Co has also been established. The results, supported by Large-Scale Shell Model and Discrete Non-Orthogonal Shell-Model calculations, show a gradual lowering of intruder states with increasing neutron number, eventually leading to an inversion in $^{70}$Co. These findings clarify previously proposed contradictory interpretations. Finally, we demonstrate the importance of including induced effective 3N forces for a consistent description of binding energies in the island of inversion near $N=40$.

Gravitational waves carry information on the spins of merging binary-black holes. The orientations of their spins relative to their orbits ("tilts")—while challenging to measure—differentiate the astrophysical formation mechanisms by which merging black hole binaries may form. Multiple analyses have reported tentative evidence that black hole spins are preferentially oriented in the plane of the binary orbit. We show that these results are likely extrapolated from more easily measurable "effective spin" parameters which characterize the gravitational-wave inspiral of black hole binaries but may not uniquely constrain their astrophysical formation. In particular, we reproduce a peak in the spin tilt distribution with information about the marginal effective spin distributions alone. We propose a geometric picture to compare constraints on effective spins to standard population modeling assumptions, suggesting that current inferences of a preferred spin orientation are spurious.

We demonstrate the use of proximity effect correction (PEC) in electron beam lithography (EBL) to improve the fabrication fidelity of dense photonic crystal structures. Monte Carlo simulations were employed to model electron scattering and determine the proximity function of the resist-substrate system. Based on this, a computational dose-modification scheme was implemented to compensate for nonuniform energy deposition during exposure. In addition, SEM-based image analysis was performed to quantitatively assess structural differences among uniformly exposed, manually dose-modified, and PEC-fabricated devices by comparing extracted geometries with the reference GDS design. The analysis revealed reduced dimensional deviation, improved spatial uniformity, and lower edge roughness in the PEC-corrected structures. These improvements resulted in a significantly enhanced optical quality factor in the fabricated photonic crystal cavities.

We describe Teglon, an open-source database and analysis pipeline engineered to optimize the search for electromagnetic (EM) counterparts to gravitational wave (GW) sources. Teglon constructs a 3D galaxy completeness metric from an input galaxy catalog and convolves it with the 3D localization volume of a GW event, producing an updated posterior map informed by known galaxy distributions. Using Teglon, users can ingest arbitrary instrument footprints — or download them directly from the Treasure Map — to generate dynamic observation plans that seamlessly interpolate between targeted galaxy pointing and region tiling. By focusing efforts on high-probability volumes, Teglon significantly reduces the predicted search area to find EM counterparts and increases observational efficiency, especially for small field-of-view (<= 1 deg^2) instruments like the Nancy Grace Roman Space Telescope. Furthermore, Teglon integrates with Redback to calculate pixel-level model detection efficiencies, enabling custom, event-specific observing strategies or retrospective detection efficiencies on an arbitrary grid of EM transient models. Teglon also supports custom science cases, such as prioritizing Active Galactic Nuclei searches for EM counterparts to binary black hole mergers. Having supported Gravity Collective and related programs from the LIGO-Virgo-KAGRA third observing run (O3) through O4, Teglon is being continuously developed to support O5 and beyond. We document the public repository lineage and packaging, and provide Version 2.0 as an open-source tool for the community.

The Batalin-Vilkovisky (BV) framework is a powerful technique for quantizing a wide range of gauge systems. This formalism employs fields and antifields–introducing a symplectic structure through the antibracket–to implement BRST symmetry, which captures the essence of gauge invariance. Within this context, we study the symmetry structure of a pure Yang-Mills theory with universal extra dimensions. We construct a BRST-invariant extended action for the $(4+n)$-dimensional theory depending on fields and antifields, which constitutes a proper solution to the master equation. The higher-dimensional spacetime and gauge symmetries are then hidden within their four-dimensional counterparts via canonical transformations. Gauge invariances are fixed by combining gauge-fixing procedures for both the standard and Kaluza-Klein (KK) fields. This procedure is implemented covariantly in the adjoint representation of the gauge group. While the standard gauge fields are fixed using the Background Field Method (BFM), the KK gauge excitations are fixed covariantly, as they transform as matter fields. Finally, the manifest $SU(N)$ gauge symmetry of the quantized theory is emphasized.

When independent learners are trained on data from the same disordered system, finite and noisy samples can lead them to different descriptions of the underlying physics. We quantify the reproducibility of such descriptions through consensus, the degree of agreement among independently trained models. In a teacher-student framework on the two-dimensional random-bond Ising model, an ensemble of students each infers a single uniform effective coupling from a finite set of equilibrium configurations drawn from one quenched bond realization. Aggregating the inferred couplings across students and realizations yields the consensus distribution, whose width quantifies the agreement among learners. The variance of this distribution separates exactly into a finite-sampling contribution, bounded below by inverse of Fisher information, and a quenched-disorder contribution. Sum of these two variance is minimized near critical region, so the consensus width has a minimum near the pseudocritical temperature that sharpens with increasing disorder. The two minima arise from different mechanisms: the sampling term inherits the critical peak of the Fisher information, while the disorder term is temperature-independent at leading order and acquires its critical minimum only at fourth order in the disorder strength, through the covariance between the linear and cubic responses to the bond disorder. Because the students fit a uniform coupling to a heterogeneous lattice, the inferred coupling also carries a misspecification bias that survives in the infinite-data limit. This bias displaces the minimum of the mean-squared error above the consensus minimum, so the temperature at which independent learners agree most closely is not the temperature at which their shared answer is most faithful.

Quantum-inspired classical algorithms have dequantized several quantum machine learning routines by replacing quantum linear-algebra subroutines with classical counterparts. However, the sampler based on quantum singular value transformation (QSVT) for learning with optimized random features is not covered by existing dequantization frameworks, because the matrix to be inverted is not itself available through sampling access. In this work, we develop a classical algorithm to address this type of quantum-advantage candidate. Our method samples heavy indices, reduces the transformation to a small principal block, and outputs a sparse classical representation with operator-norm guarantees. Applying this method dequantizes the sampler for optimized random features, giving a classical sampler with prescribed accuracy and polynomially related runtime. These results show that the factorization underlying a quantum block encoding can itself provide sufficient classical structure even when sampling-and-query access to the composite matrix is unavailable.

A robust finite-volume framework is presented for the simulation of compressible multiphase flows with surface tension across a wide range of Mach numbers. The method is based on a two-pressure, six-equation diffuse interface model incorporating viscous, gravitational, and capillary effects through the continuum surface force formulation. To consistently account for capillary-induced pressure jumps, an HLLC Riemann solver is developed using generalized Riemann invariant analysis, and the instantaneous pressure relaxation procedure is modified to preserve the Laplace pressure jump during phase equilibration. To overcome the excessive numerical diffusion of conventional approximate Riemann solvers in the low-Mach regime, a robust low-Mach correction is proposed by extending our previous formulation with a modified scaling strategy that remains stable in regions of strong pressure variation. The resulting method retains accuracy from nearly incompressible flows to compressible regimes while preserving the robustness of the six-equation formulation. The numerical framework is validated using a series of benchmark problems involving surface tension, viscosity, gravity, and compressibility. The results demonstrate accurate prediction of interface dynamics, capillary pressure, and low-Mach flow features, while significantly reducing numerical dissipation without compromising stability. The proposed methodology provides an efficient and reliable approach for the simulation of complex multiphase flows spanning a broad range of flow regimes.

We realize narrow-linewidth magneto-optical traps of $^{46}$Ti, $^{48}$Ti and $^{50}$Ti atoms based on a 1040 nm-wavelength transition, cooling atoms to a minimum temperature in one dimension of $T_z=990(20)$ nK and a three-dimensional temperature of $T_\mathrm{3D}=1.28(7)$ $\mu$K. Atoms are pre-cooled in a broad-line magneto-optical trap and then transferred with about 25% efficiency to the narrow-line trap. We operate the narrow-line trap in two stages over 85 ms. First, a single cooling beam, blue-detuned from the narrow-linewidth atomic resonance, optically pumps and traps the atoms on a two-dimensional surface where the Zeeman shift from the applied spherical quadrupole magnetic field brings the light nearly to resonance. Second, four additional beams, counter-propagating in the transverse directions, cool and compress the atoms in all dimensions. The high magnetic moment of the laser cooling state makes the dynamics of the narrow-line titanium trap similar to those of other magnetic atoms. We measure the lifetime of the excited state of the transition to be $\tau=8.2(9)$ $\mu$s, indicating a transition linewidth of $\gamma/2\pi =20(2)$ kHz, and also measure isotope shifts on the narrow-line transition. We use Stern-Gerlach separation on the ultracold Ti gas to measure the $m_J$-distribution in the narrow-line magneto-optical trap, finding over 98% of the atoms in the stretched spin state.

Moiré superlattices provide a powerful platform for flat bands and correlated topological phases, yet most established examples rely on valley-contrasting Berry curvature in hexagonal lattices. Here, we propose a different route to achieve topological moiré minibands based on noncollinear spin orbit coupling in centrosymmetric type II SOC bilayers. Interlayer hybridization opens local pseudogaps and produces sharply localized Berry curvature, which twisting reconstructs into isolated topological minibands without requiring valley degrees of freedom or hexagonal symmetry. We demonstrate this mechanism in tetragonal Dresselhaus-SOC HgI2, where a Lieb-like moiré potential yields topological flat bands. To improve miniband isolation, we develop a physics-informed machine-learning surrogate that identifies stronger SOC as a key design principle and guides the replacement of Hg by Pb. The resulting PbI2 minibands are narrower and better isolated, supporting correlation-driven magnetism and tunable quantum spin Hall and Chern insulating phases, thereby providing an optimized material realization for experimental exploration.

Phase-curve mapping probes various atmospheric properties depending on wavelength: thermal phase curves are dominated by atmospheric emission, while visible and near-infrared phase curves include reflected light. The measured planetary phase curve offset–the longitudinal offset of the hemisphere of peak brightness from the substellar point–is therefore sensitive to differing atmospheric processes in emission-dominated vs. reflection-dominated bands. In particular, planets with partial western-dayside reflective cloud coverage show a westward reflected-light phase-curve offset relative to the thermal wavelengths. In this work, we analyze five sectors of TESS phase curve observations of the hot Jupiter WASP-43b and compare to previous published multi-band analyses to investigate dayside cloud coverage. We measure a mid-eclipse depth of 130 $\pm$ 34 ppm, indicating excess TESS planetary brightness above expectations based on observed and modeled thermal emission. Attributing this excess flux to reflection, we estimate a low geometric albedo of $A_g$ $\approx$ 0.05 - 0.10. These findings support previous conclusions that WASP-43b lacks any significant cloud coverage on its dayside. Phase-curve mapping reveals a large eastward phase curve offset of 44 $\pm$ 18 degrees, significantly eastward of offsets measured at longer wavelengths with JWST, providing evidence for a cloud-free dayside. Both the detection of excess emission in the TESS band and the large measured eastward phase-curve offset support the conclusion that WASP-43b has a hot deep atmosphere that is probed at short wavelengths.

We present GW Explorer: A Beginner's Guide, an outreach curriculum designed to introduce high school students to gravitational-wave (GW) astrophysics through interactive Python Jupyter notebooks. Most existing GW resources target beginning audiences and advanced students, leaving a gap at the pre-college level that we directly address. The curriculum integrates foundational physics with hands-on computation implemented through both self-directed and workshop-based instructional formats. In the self-directed format, students completed the curriculum independently on cloud-based platforms such as Google Colab. During the workshop format, students worked through the same activities under the guidance of University of Nevada, Las Vegas graduate student mentors. Topics span gravity, spacetime, GW sources, interferometric detection, and data analysis. An implementation in local high school classrooms informed the content and pacing, and survey results demonstrate gains in conceptual understanding and coding confidence. GW Explorer offers a scalable, open-access framework for authentic astrophysics research in the high school classroom.

We consider a class of dijet event shapes which tend to angularity in the forward limit. The factorisation formula for this class of event shapes differs from angularity only in the soft function. The NNLO soft function of an event shape in this class is therefore the only missing ingredient required for NNLL' resummation. We describe a modular approach to the calculation of the soft function for any event shape in this class, at NLO and NNLO. Much of the structure of the soft function can be written in terms of a single rapidity integral. The remainder can be computed as a three-dimensional numerical integral for which we provide a code. To demonstrate the flexibility of our approach, we compute the NNLO soft function for three new families of event shapes in this class. Potential applications include the investigation of hadronisation effects at future $e^+ e^-$ colliders, or through the re-analysis of archived data.

Much work has been done in the last two decades on the topic of quantum state transfer in a quantum spin network. One can model such a system of interacting qubits using an undirected graph, and studying vertex-to-vertex dynamics. This setup has recently been relaxed to allow for dynamics between linear combinations of two vertex states, i.e.\ from $\mathbf u = \mathbf e_a + s \mathbf e_b$ to $\mathbf \mu=\mathbf e_{\alpha} + r \mathbf e_{\beta}$, where $r=s$ is either $-1$ (which corresponds to pair state transfer) or $+1$ (which corresponds to plus state transfer), or more recently $r=s$ is taken to be any real number (which corresponds to $s$-pair state transfer). Here, we broaden the investigation of $s$-pair state transfer to \textit{perfect $(s,r)$-state transfer}, which is perfect state transfer from $\mathbf u = \mathbf e_a + s \mathbf e_b$ to $\mathbf \mu=\mathbf e_{\alpha} + r \mathbf e_{\beta}$ (up to some dilation) where $r,s\in \mathbb C$. We identify infinite families of graphs with perfect $(s,r)$-state transfer and provide characterizations of cases when $|r|= |s|$ and when $|r|\neq |s|$, showing situations when the degree of entanglement between vertex states is preserved, and when it is not preserved. The latter is particularly important as it represents perfect state transfer from an entangled pair of qubits to another one where the degree of entanglement need not be the same\mdash in fact, it can be set up so as to “boost” (increase) entanglement. We provide an algorithm that finds the vector with two nonzero entries that maximizes the fidelity of transfer for a fixed time $t$ starting from a given $s$-pair state $\mathbf u$. Finally, we provide a sensitivity analysis, with respect to readout time errors, of perfect $(s,r)$-state transfer.

Recent multiwavelength observations of galaxy group and cluster gas suggest stronger baryonic feedback than our best-calibrated hydrodynamical simulations produce, while modeling this feedback remains a primary source of uncertainty in Stage-IV weak-lensing (WL) analyses. We present a suite of ray-traced maps generated with BIND (Baryonic INpainting with Deep learning), a conditional flow-matching model that paints baryonic mass and gas thermodynamics onto the halos of dark-matter-only simulations, and which was developed in a companion paper. Applied to IllustrisTNG300-Dark and ray-traced, we generate convergence, optical depth, and Compton-$y$ maps at five source redshifts, each with $1000$ pseudo-independent realizations. We build lightcones across a 256-node Sobol sequence spanning the thirty-dimensional IllustrisTNG galaxy formation prior, with individual parameter variations and at the fiducial model. In validation, the maps match those built from the IllustrisTNG300 halos to within LSST-Y10-like precision for a range of WL statistics. Across the prior, the response to feedback exceeds Stage-IV statistical precision by more than an order of magnitude on small scales, and different statistics respond to different model sectors: galactic winds control the WL power spectrum and gas auto- and cross-spectra, while the stellar initial mass function slope and AGN parameters shape the morphological statistics (PDF, peaks, minima, and Minkowski functionals). Finally, we find that the response of statistics can be compressed into seven halo properties which linearly predict a range of WL and SZ statistics. We publicly release the maps, statistics, and model tables.

Baryonic feedback is a dominant source of systematic uncertainty for upcoming weak-lensing surveys, but current tools for modeling its effect rely on spherical approximations and density profiles calibrated almost entirely on two-point statistics. We introduce BIND (Baryonic INpainting with Deep learning), a conditional flow-matching model that learns a field-level mapping from dark-matter-only halos to their hydrodynamical counterparts. BIND is trained on halos from the 1024 paired hydrodynamical and dark-matter-only simulations of the CAMELS $50\,h^{-1}\,\mathrm{Mpc}$ SB35 suite and samples dark matter, gas, and stellar mass fields over redshift across the full 35-dimensional $\Lambda$CDM and IllustrisTNG galaxy formation parameter space. BIND recovers dark matter, gas, and stellar masses at the percent level, reproduces azimuthally averaged profiles to $\lesssim10\%$ at all radii, and matches halo shape distributions with high fidelity. The learned parameter dependence captures the rank correlations between the generated fields and the subgrid parameters, and the field-level response to individual parameter variations is recovered in both sign and morphology. Halo mass is never supplied as conditioning, yet the baryon fraction, stellar-to-halo mass relation, inter-component scaling relations, and the joint covariance of their residuals are all reproduced. We finally show that, applied halo-by-halo to a $(50\,h^{-1}\,\mathrm{Mpc})^3$ $N$-body volume with $512^3$ particles, BIND reproduces the projected matter power spectrum suppression to the accuracy ceiling set by pasting in the hydrodynamical halos themselves, in minutes on one GPU. We release the trained BIND models and all generated halos as open-source tools. A companion paper extends BIND to thermodynamic fields and non-Gaussian weak-lensing statistics.

Altermagnetism has recently emerged as a distinct collinear magnetic phase exhibiting momentum-dependent spin-splitting despite vanishing net magnetization, as a consequence of inequivalent non-magnetic environments. Lately, it has been proposed that strong electronic correlations may yield spontaneous altermagnetism due to orbital ordering even for equivalent non-magnetic environments. While previous studies have largely focused on the electronic structure, a unified understanding of the collective excitations associated with these two different microscopic mechanisms stabilizing altermagnetism remains absent. Here, we develop an extended Kugel'-Khomskiĭ spin-orbital model on a decorated square lattice that simultaneously incorporates inequivalent non-magnetic environments and correlation-driven orbital ordering within a common theoretical framework. Employing a self-consistent mean-field spin-wave orbital-wave formalism, we demonstrate the emergence of mutually unhybridized but interdependent magnon and orbiton excitations exhibiting characteristic chiral-splitting. We show that the splitting originates from two distinct microscopic contributions: a lattice-dependent term arising from inequivalent non-magnetic environments and an orbital-order-induced exchange-anisotropy term that survives even for equivalent non-magnetic environments. The proposed framework therefore unifies the collective excitations associated with both types of altermagnetism. We further investigate the finite-temperature evolution of the coupled spin-orbital system, revealing the breakdown of spin-wave and orbital-wave approximations through spurious 1st-order transitions, while complementary classical Monte Carlo simulations recover the expected continuous 2nd-order behaviour. Our work establishes a unified microscopic framework for understanding collective magnon and orbiton excitations in altermagnets.

ESA's astrometric space mission Gaia is uniquely positioned for microlensing studies thanks to its all-sky coverage and simultaneous astrometric and photometric observations. In Gaia Data Release 4 (DR4), astrometric time series will be published for the first time, providing a rich dataset for isolated stellar remnant searches. In anticipation of DR4, we prepared tools for fitting photometric and 1D astrometric measurements. We tested the recovery of true event parameters and population distributions with Gaia-like observations. We created a mock survey of microlensing events mirroring Gaia DR4's design. The events were generated using dedicated Galactic simulations to provide realistic expectations on stellar and dark lens yields. For selected events, we simulated observations following Gaia's scanning law and precision, using the astromet package. Such simulations are needed to interpret forthcoming data; they also enable testing inference tools with known ground truth. We used nested sampling to infer full posterior distributions and compare them with the true lens parameters. Our simulation predicts $322 \pm 70$ microlensing events with astrometric signals above Gaia precision thresholds; $209 \pm 57$ of them have detectable photometric signals. Among those, $82 \pm 9$ and $49 \pm 7$, respectively, have remnant lenses. To assess Gaia's capabilities in constraining remnant mass distributions, we modelled $49$ events from this sample. We recovered the true Einstein times and radii for most events. Microlensing parallax measurements are consistent with true values but uncertain, limiting mass determination. We recommend focusing on events with bright sources or anomalous fits to optimize dark lens searches. We make available the mock Gaia time-series dataset, as well as a toolkit repository for working with the data format, fitting models, and visualizing results.

We study the restricted fan cut inside the dual fundamental Weyl chamber by the weights of a $27$-dimensional minuscule representation of $E_6$; the two such representations are dual and give the same arrangement. Only $11$ of the $27$ weights have kernels meeting its interior, and we prove that they determine the entire fan. It has exactly $14$ chambers and $18$ extreme rays, every chamber is a six-dimensional simplicial cone, and we determine all facets, rays, and incidence relations. The chamber count was previously obtained by Diaconescu and Entin; the simplicial structure, extreme rays, and incidence data are new. The geometry of the $27$ lines on a cubic surface then explains and organizes the resulting chamber architecture. We also enumerate all faces, compute both characteristic polynomials—the arrangement is not supersolvable—together with lattice indices and projective chamber volumes, and describe the oriented matroid. Our main result is representation-theoretic. A distinguished $14$-element visible subposet of the minuscule $\mathbf{56}$ of $E_7$, defined entirely inside $E_7$, has Hasse diagram equal to the chamber adjacency graph of the $E_6$ arrangement. Three canonical $7+7$ splittings of it, of types $A_7$, $D_7$, and $E_7$, are the visible traces of Levi-center $\mathfrak{u}(1)$-charge decompositions of the $\mathbf{56}$ and reproduce the three level-$8$ decompositions on the $E_6$ side. More strongly, the simple-root labels on its covers, transported by minimal-length coset representatives, recover chamber by chamber all six facets and, globally, the $11$ active weight hyperplanes and the boundary walls of the dual Weyl chamber. Thus the $E_7$ shadow records not merely the chamber graph but, once matched with the independent $E_6$ classification, the full local wall architecture of $I(E_6,\mathbf{27})$.

We investigate the internal structure of two galaxies from the LEWIS sample: the ultra-diffuse galaxy UDG-1 and the extended dwarf LSB-6. Both show coherent stellar rotation combined with a non-negligible fraction of random motion, with no signs of ongoing disturbance. This is the first attempt to constrain the dynamics and dark matter physics of rotation-supported UDGs through integral-field stellar kinematics. We model the galaxies as stellar spheroids with typical dwarf-like thickness embedded in spherical dark matter halos, deriving two-dimensional velocity fields that we compare with the observations in a Bayesian framework. Besides cold dark matter, we test fuzzy, self-interacting, and non-minimally coupled dark matter. The data prefer a cuspy halo in UDG-1 and a cuspless one in LSB-6. All the alternative models remain viable, although current data cannot conclusively discriminate among them. For fuzzy dark matter we obtain mutually consistent boson masses, $m_\alpha = 4.7^{+1.8}_{-1.1} \times 10^{-22}$ eV for UDG-1 and $m_\alpha = 6.3^{+0.4}_{-0.4} \times 10^{-22}$ eV for LSB-6. For self-interacting dark matter, LSB-6 yields a robust constraint on the velocity-weighted cross section, $\langle \sigma v\rangle/m = 14.3^{+2.0}_{-1.9}$ cm$^2$ km g$^{-1}$ s$^{-1}$. For non-minimally coupled dark matter we derive upper bounds on the coupling length, implying marginal deviations from $\Lambda$CDM. Regardless of the model, both galaxies exhibit a dark matter content comparable with halos of typical dwarf galaxies with similar stellar masses. Together with stellar population analyses and globular cluster information, these results support a scenario in which UDG-1 and LSB-6 originate from puffed-up dwarfs. This work is the first in a series exploiting kinematic data of extremely low-surface-brightness galaxies to test fundamental physics, from dark matter to modified theories of gravity.

We report the detection of hard X-ray pulsations from the M31 accreting non-ULX X-ray pulsar 3X J0042 (3XMM J004232.1+411314) using archival NuSTAR observations. The source has a spin period of ~3 s and an orbital period of ~4.15 hr, with coherent pulsations previously detected only in XMM-Newton observations. We reanalyse all five publicly available NuSTAR observations by correcting the photon arrival times for binary motion and optimizing the orbital epoch and projected semi-major axis. Coherent pulsations are detected in all five observations. The broad-band pulse profiles show similar morphology across the five observations spanning ~2.3 yr, with no significant long-term evolution. The pulse profile also shows energy dependence, with structured, non-sinusoidal profiles below ~20 keV and a less structured profile at higher energies. The pulse periods show an overall decrease over the ~2.3 yr NuSTAR baseline, continuing the long-term spin-up trend observed in the ~16 yr of XMM-Newton observations, but with a faster average spin-up rate of ~-1.1e-10 s/s compared to the earlier reported ~-6e-11 s/s. The short orbital period and inferred low-mass companion star shows it to be a low-mass X-ray binary containing a magnetized neutron star, with systems such as Her X-1, 3A 1822-371, and XMM J174457-2850.3 providing closer Galactic comparisons. This work represents the first detection of hard X-ray pulsations from a non-ULX extragalactic accreting pulsar.

Fault tolerance is essential for scalable quantum technologies and is enabled by quantum error-correction codes. Bell-state measurements (BSMs) are a fundamental building block for modern quantum technologies such as measurement-based quantum computation and fusion-based quantum computation, as well as quantum networks. Therefore, performing BSMs on error-corrected qubits is a necessary step for achieving fault tolerance in these applications. In this work, we realise a logical BSM using linear optics, based on a two-qubit repetition code, an instance of a quantum parity code that allows detection of bit-flip errors, and experimentally achieve a mean success probability of (70.8 +/- 0.4)%. While standard linear-optical BSMs are fundamentally limited to a maximum success probability of 50%, this increased success probability enables higher secure key rates in quantum communication and facilitates the generation of large graph states for quantum computation. Since fault-tolerant schemes require error-correction codes regardless, this improvement comes at no additional resource overhead. Our results demonstrate that error-correction codes can be used to surpass the linear-optics limit of BSMs, which is an important step towards practical, fault-tolerant, and scalable photonic quantum technologies.

In the context of the QGEM (Quantum Gravity-induced Entanglement of Masses) experiment, we consider two adjacent matter-wave interferometers in linear and parallel configurations that interact solely via gravity. If gravity were quantum, then the two matter-wave interferometers would become entangled via the virtual excitation of the massless graviton. In this paper, we consider witnessing this entanglement by considering a generic experimental scenario where the two interferometers are subject to different global phases and different decoherence rates. In this context, we show that the individual global phases do not affect the witness, discuss common and differential decoherence modes, and perform the parameter search optimal for different masses. We provide a mathematical framework for these asymmetric decoherence rates and then search for parameters that determine the entanglement witness. We have kept the inter-separation distance between the two closest superpositions of the interferometers' masses fixed while varying the experimental time from $\tau=0.1$ s to $\tau=1$ s. Finishing the experiment at $ \tau=0.1$ s has many advantages from the point of view of protecting the experiment from random acceleration noise. However, witnessing the entanglement also suffers from $\langle W\rangle \sim -{\cal O}(10^{-2})$ for $m=10^{-14}$~kg, for decoherence rate in the ranges of ${\cal O}(10^{-1}-1)$~Hz for $\tau=0.1$ s experiment. However, as we show, increasing the mass of the matter-wave interferometer may improve the witness considerably.

The growth of primordial black holes through the absorption of the surrounding plasma has recently been shown to exhibit a critical behavior during radiation domination. We extend this analysis to the reheating era and derive analytical solutions for general reheating histories. We show that reheating modifies the critical condition for runaway absorption, making it dependent on both the reheating dynamics and the black-hole formation time. We identify two distinct regimes: runaway growth occurring during reheating, or being triggered after the onset of radiation domination by the mass accumulated during reheating. More generally, we derive a simple composition law describing how independent mass- growth mechanisms combine across successive cosmological eras. Applying it to radiation absorption and inflaton accretion, we obtain analytical results in excellent agreement with the full numerical evolution.