Papers

Gyrochronology ties stellar rotation periods to ages. It is well studied in the young, open cluster age domain, but there are few constraints on gyrochronology in the old field star regime. In this work we use gyro-kinematic ages to explore the spin down of stars in this formerly inaccessible domain. Using forward modeling techniques which relax strict Rossby scaled assumptions, we find evidence for a departure from a standard spin down models. This departure can be explained with a mass-dependent term either in the global strength of the stellar wind or in the relationship between angular velocity and wind strength. Models with this additional mass- dependence help explain prior difficulty in fitting open cluster rotation distributions across the full mass range. Additionally, we use rotation models to identify an mass-dependent age domain over which wind driven stellar spin down can be isolated from other physical effects. For lower mass stars, this age domain is most affected by the core-envelope coupling timescale, where as higher mass stars are more subject to inertial effects late in their main sequence lifetimes. Using simple, analytic models of stellar spin down in this domain is unable to determine whether the stellar wind has a mass-dependence or if the stellar wind is strictly Skumanich-like in nature. In future studies of rotational and dynamo evolution we advocate for a forward modeling approach to gyrochronology over purely empirical approaches due to its superior ability to trace physical effects governing stellar spin down.

We introduce a general framework for quantifying the information content and representation quality of complex geophysical datasets based on the intrinsic dimension and differentiable information imbalance of data manifolds. We use it to derive and compare optimal representations of surface ocean carbon in the SOCAT database of observations and in global ocean biogeochemistry models (GOBMs) and to assess the robustness of the information we can extract from existing data. We find that within the most widely used feature set, the complexity of the data space of SOCAT observations is not fully captured by GOBMs, but the ranking and relative importance of variables learned through GOBMs are substantially correct. We observe that the learned representation of ocean carbon is less accurate in some regions, including the Southern Ocean, but doesn't appear to have evolved significantly over the last two decades. Finally, we show how the optimal representations can be used to improve the skill of distance-based machine learning models and demonstrate it for ocean carbon, and we propose two new metrics to compare models and observations that can be used to build more accurate weighted ensembles of estimates.

Signals of physics beyond the Standard Model continue to resist discovery at the LHC. Recent years have seen the proliferation of new anomaly detection techniques, promising discovery with significantly fewer model assumptions than traditional approaches. Strategies based on weak supervision have been especially successful, but so far were largely limited in scope by their reliance on a resonance manifesting a decay into a pair of jets. In this work, we demonstrate that a well-established idea from jet substructure physics - recursive soft drop - in combination with the CATHODE technique for anomaly detection can be used to simultaneously perform anomaly detection for signals with an arbitrary number of jets in the final state, greatly increasing the scope of such searches.

The D1D5 CFT exhibits a charge concentration puzzle for BPS states, similar to, but simpler than, that of $\mathcal{N}=4$ SYM. We consider the chiral algebra of 1/4-BPS operators in the D1D5 CFT arising from a supercharge cohomology, and the resulting rational correlators. Using crossing symmetry and this chiral algebra, we establish a non-perturbative proof of the existence of a family of 1/4-BPS states away from the charge concentration locus for general coupling and finite central charge. We further discuss possible implications for BPS chaos in the D1D5 CFT and compute a late-time BPS plateau at the orbifold point.

Interacting gap transients encompass several families of astrophysical phenomena where eruptive mass loss and interaction play an important role in shaping the observational properties and energetics of the events. Composed of Luminous Red Novae (LRNe), Intermediate Luminosity Red Transients (ILRTs), Luminous Blue Variable (LBV) giant eruptions, and pre-supernova precursors, interacting gap transients offer crucial insights into unstable mass transfer, extreme stellar mass loss, and binary evolution. In these proceedings, I review the observational signatures, progenitors, physical origin, and classification challenges of these heterogeneous phenomena. Finally, I highlight how ongoing and future wide-field time-domain missions will revolutionize this field by compiling complete volume-limited samples, tracking faint pre-outburst precursors, and establishing statistical links between gap transient families and their progenitor populations.

Axion fields can form exponentially growing gravitational clouds around compact objects through self-interaction-driven relaxation of ambient axion waves. As the field amplitude approaches the axion decay constant, nonlinear effects become important. We identify two distinct regimes of late-time evolution, determined by the gravitational fine-structure constant and the cloud growth rate: a Bosenova regime, characterized by collapse accompanied by explosive axion bursts, and a saturation regime, in which self-interaction-induced axion emission balances accretion. In the latter regime, the emitted axion radiation exhibits stable discrete spectral lines at odd multiples of the bound-state energy, directly probing the global structure of the axion potential beyond its quadratic minimum. We show that single-cosine potentials and QCD axion-like potentials predict distinct emission spectra, enabling probes of the underlying axion self-interaction structure and its ultraviolet completion through terrestrial detection of relativistic axion fluxes from compact objects.

We present a comprehensive recasting study of pair production of vector-like quarks. We consider decays of vector-like quarks into third generation quarks and Standard Model bosons or exotic top-philic scalars. We derive recasting bounds on all 43 combinations of decay channels. Using the efficiencies of each channel, we obtain combined limits across decay channels by adding up the contributions to each signal region. A data base of recasting results along with example codes is published, allowing for application to different models without the need for rerunning recasting tools. We demonstrate the utility of the data base by setting bounds on several sample models.

Quantum complexity has emerged as a natural probe of chaos, thermalization, and the black hole interior on timescales long after local observables have equilibrated. However, its time evolution has been studied almost exclusively in subsystems confined to a single connected region. We show, using complementary tools from holography and random quantum circuits, that noncontiguous subsystems composed of multiple disjoint regions give rise to qualitatively new physics compared to the contiguous case. First, at finite temperature, a subsystem occupying less than half of the total system can carry high complexity at late times, even as the complexity of its larger complement remains low. This inversion of the usual hierarchy is intrinsically thermal: it vanishes in the infinite-temperature limit, which is the regime modeled by random quantum circuits. Second, if a subsystem's complexity equilibrates at an early time, then fragmenting it into $m$ disjoint components can further reduce this timescale by a factor of $m$, a phenomenon we exhibit in both holography and random quantum circuits. These results not only sharpen the correspondence between geometric and computational notions of complexity, but also motivate the search for novel complexity phenomena in quantum dynamics.

Strongly-coupled light-matter exciton-polaritons constitute an on-chip solid-state platform where the macroscopic quantum phenomenon of condensation is not only achievable at elevated temperatures, but can also be optically controlled, including through their interaction with inaccessible "dark" states. A recent study has shown that polariton condensation can be established under nonlinear two-photon pumping, paving the way towards dark state-condensate coherent control and highly-efficient terahertz (THz) lasing. In this letter, we show for the first time a temporal signature of dark exciton induced bosonic stimulation by investigating one- and two-photon pumped condensation with time-resolved photoluminescence spectroscopy. Our results show a clear difference in the detuning dependence of the buildup and relaxation rates of the condensate-induced blueshifts under one- and two-photon pumping. This difference is associated with the stronger exciton-fraction dependence expected for one-photon pumped condensation, where polariton-polariton stimulation dominates, compared with two-photon pumped condensation, where a 2p-exciton-to-lower-polariton THz transition can provide another stimulation channel, together with various spin-flip, electron-hole exchange and phonon-based mechanisms. These observations indicate the presence of a new dark state originated stimulation channel that could facilitate highly-efficient THz lasing in semiconductor microcavities.

While correlated insulators are devoid of low-energy quasiparticle poles, their Green functions retain clean momentum structure through zeros. However, precisely what zeros imply is not clear. By studying the extended Hubbard model both analytically and numerically, we establish a new paradigm for strongly correlated matter: the dispersion of Green function zeros is determined by both microscopic spin-spin correlations and defect kinematics. In fact, we find that the dispersion changes discontinuously across the transition between the Mott and the checkerboard charge-density wave phases as is expected for a first-order transition. This physics is robust to the inclusion of further neighbor hopping which simply fine tunes the spin-correlation or charge-defect kinematics. We conclude that it is the dispersion of the Green-function zeros that encode the physics of ordering resultant from the strong correlations.

We propose a new laboratory strategy to generate and detect axion-like particles via third-harmonic generation induced by two non-collinear, polarised high-intensity laser beams of peak intensity of the order of $10^{24}\,\mathrm{W/cm^2}$, where the third-harmonic signal is generated by the axion field. Starting from the axion-modified Maxwell equations, we analytically derive the axion-induced third-harmonic field, and show that by using state-of-the-art petawatt laser facilities, a detectable signal can be obtained over a broad range of axion masses and couplings. A key feature of the setup is that the axion-photon conversion rate can be resonantly enhanced by tuning the angle between the two beams through a mechanism that does not depend on the physical volume of the apparatus. The proposed configuration may therefore probe an unexplored region of axion parameter space and pave the way for next-generation high-power laser-based axion searches.

For mathematicians: In this first in a series of two papers, we give a mathematically rigorous classification of (sufficiently nice) $c=1$ vertex operator algebras (VOAs) and vertex operator superalgebras (VOSAs). We confirm the lore that any such VO(S)A is either a lattice VO(S)A $V_L$ associated to a rank-1 integral lattice $L$, or can be obtained as an orbifold thereof, i.e. a $G$-invariant subalgebra $V_L^G$ for some finite group $G$ of automorphisms. All such $G$ are known, allowing for an explicit enumeration of nice $c=1$ VO(S)As. A key ingredient in our approach is to establish a general criterion for nice VOAs, requiring knowledge only of the vacuum character, for testing when the simple modules with integer conformal dimension span a symmetric fusion subcategory which is braided tensor equivalent to $Rep(G)$. In our companion paper, we calculate the ribbon auto-equivalences of the representation categories of the nice $c=1$ VOAs, and leverage this to obtain the classification of nice bosonic and fermionic $c=1$ full conformal field theories. For physicists: We rigorously classify the chiral algebras that can arise in the holomorphic sector of a bosonic or fermionic rational $c=1$ conformal field theory (CFT) whose non-identity primaries all have positive conformal dimension. Thinking of chiral algebras as gapless boundary conditions of 3D topological quantum field theories (TQFTs), our result says that any such chiral algebra is either a holomorphic boundary of $U(1)_k$ Chern-Simons theory, or can be obtained by passing to the $G$-invariant states thereof for some finite group $G$ of symmetries. We explicitly enumerate these chiral algebras and also discuss their non-invertible symmetries. In a companion paper, we build on these results using techniques from the study of 3D TQFTs to classify full bosonic and fermionic rational $c=1$ CFTs.

The mono-photon process $e^+e^- \to \gamma+\mathrm{invisible}$ at Belle II probes both invisible new states and the electroweak couplings of neutrinos. In this work, we study the process $e^+e^- \to \gamma\nu\bar{\nu}$, finding that Belle II with the full expected dataset can determine the neutrino-sensitive effective weak mixing angle to a 3.6$\%$ relative statistical precision, competitive with existing neutrino probes at other energy scales. Polarized beams, as proposed for the Chiral Belle upgrade, separate the neutral- and charged-current contributions and provide independent access to each, giving a handle on the chiral structure of the neutrino gauge interactions. The same process is an irreducible background to dark boson searches, producing a neutrino fog once the luminosity exceeds 1 ab$^{-1}$.

We study the subleading adjacent-collinear limit of tree-level color-ordered Yang–Mills amplitudes. In general dimensions, a Lorentz null rotation transports the polarizations of collinear legs along the collinear path while preserving transversality and gauge equivalence. The finite coefficient then separates into a pole-free hard contribution, computed by a channel-deleted Berends–Giele recursion, and an explicit contribution from the adjacent factorization channel. In four dimensions, we construct the same coefficient directly from a collinear-aware Britto-Cachazo-Feng-Witten recursion whose terminal data are closed MHV and $\overline{\rm MHV}$ formulas. Both constructions apply at arbitrary momentum fraction and extend to collinear gluons with distinct polarizations; at the symmetric split, the auxiliary-vector dependence cancels for equal polarizations and for the polarization-symmetrized mixed limit. Open–closed disk relations then give a direct construction of one-graviton Einstein–Yang–Mills amplitudes and their higher-derivative string corrections from the recursively generated coefficients. A self-contained Mathematica implementation accompanies the paper.

The Black Hole-String Correspondence identifies the microstates of a minimal black hole with those of a highly excited string. In decompactification limits, where the light states are Kaluza–Klein modes, its proposed counterpart is the Black Hole-Tower Correspondence at the species scale. We extend it in three directions. First, we expand the free thermodynamic analysis to include towers with string-oscillators and Kaluza–Klein modes, and clarify whether the ensemble connects to a $d$-dimensional black hole or a wrapped black string. Second, we include gravitational backreaction in the pure Kaluza–Klein tower transition. With no winding-tachyon analogue, the interpolating configuration is the one-loop Kaluza–Klein gas, which reorganizes into higher-dimensional radiation and yields self-gravitating solutions whose instability points to the black string and whose thermodynamics match it at the correspondence point, $S\sim N_{\rm sp}$, where the size approaches the species length. This shows that the matching is robust under self-interactions. Third, we ask whether the two phases are continuously connected, revisiting and extending the worldsheet and topological analyses of the Black Hole-String case to include also Kaluza–Klein towers. Linear sigma model families interpolate smoothly in the heterotic string, while in type II the transition is obstructed. The cobordism classes of the two saddles agree in every structure we check, but their brane-charge lattices, given by bordism groups, differ, which is the source of the type II obstruction. This obstruction is thus perturbative, showing that the transition can only proceed through the non-perturbative, charge-violating processes of the kind predicted by the Cobordism Conjecture.

The Sun has long served as a natural dark matter detector, capturing halo particles that scatter with solar nuclei and electrons and subsequently produce indirect signals from dark matter annihilation that can be probed by either neutrino or $\gamma$-ray instruments. Previous efforts have computed cross-section constraints for dark matter scattering with electrons, as well as spin-independent and spin-dependent dark matter-proton scattering. However, the spin-dependent dark matter-neutron scattering scenario has been neglected, despite its importance in direct detection. For the first time, we compute the capture and evaporation rates for spin-dependent dark matter-neutron scattering in the Sun, including odd-neutron isotope targets in the current standard solar model. Comparing the predicted annihilation signals against current neutrino and $\gamma$-ray observations, and projecting the reach of upcoming detectors, we find that solar constraints exceed direct detection limits for several annihilation channels. For models in which the dark matter annihilates into long-lived mediators, these constraints can extend below the neutrino fog.

Observations of magnetic polluted white dwarfs indicate that most of them have higher concentrations of metals near the poles compared to lower latitudes. Maintaining such abundance gradients requires gravitational sinking times $t_\downarrow$ below the convection zone that are shorter than the horizontal spreading time $t_\leftrightarrow$ across the surface by convective eddies. We show analytically that $t_\downarrow/t_\leftrightarrow\propto T^{8/3}$, where $T$ is the temperature at the base of the convection zone, which rises by more than an order of magnitude as convection penetrates deeper into the atmosphere. Correspondingly, $t_\downarrow/t_\leftrightarrow$ jumps by several orders of magnitude, clearly delineating between hot white dwarfs with abundance variations and cold ones with homogenous surfaces. We incorporate magnetic fields self-consistently into the stellar structure and compute for the first time the sinking to spreading time-scale ratio as a function of $B$. Magnetic white dwarfs have shallower convection zones at a given $T_{\rm eff}$, and the inward penetration of convection shifts to lower $T_{\rm eff}$. Quantitatively, $B\sim 10^5\textrm{ G}$ extends the range for enhanced abundance patches from $T_{\rm eff}\gtrsim 30\,000 \textrm{ K}$ ($13\,000\textrm{ K}$) to $T_{\rm eff}\gtrsim 15\,000 \textrm{ K}$ ($6000\textrm{ K}$) for helium (hydrogen) dominated atmospheres, which is insufficient to explain the observed patchy white dwarfs, which are even colder. A possible solution is variability in the accretion rate on a time-scale of a decade, as recently detected in another white dwarf.

The Blandford–McKee (BM) solution describes the ultra-relativistic self-similar flow behind a strong spherical blast wave propagating into an external density profile $\propto r^{-k}$, where $k<4$ and $r$ is the distance from the center, but it applies only to the hot shell adjacent to the shock, sufficiently deep behind it, the fluid leaves the BM regime. Since the similarity profiles are determined solely by the shock conditions, with no conditions imposed at the inner end, the validity of the solution near the shock depends on whether the flow beyond the BM regime can imprint on this hot shell. For shallow density profiles, $k<k_g\simeq 2.062$, the characteristic structure of the BM solution already prevents forward-going acoustic information from the non-BM interior from reaching the shock during the ultra-relativistic stage. For steeper profiles, $k_g<k<4$, the hot equation of state fails while the flow is still relativistic and shock-connected. There, we derive a new self-similar solution for the cooling relativistic flow, which has its own similarity scale, equations, and characteristic structure. It overlaps with the hot BM solution toward the shock, and reaches a sonic point beyond this overlap. This critical point separates the shock-connected BM-plus-cooling composite from the deeper downstream region, so acoustic signals generated beyond it cannot propagate toward the shock. The mechanism is explicit at $k=7/2$, for which the cooling solution is obtained analytically. This causal structure is therefore what enables the BM solution, which remains self-consistent near the shock even though it does not globally describe the full downstream flow.

Supermassive black holes/active galactic nuclei (SMBHs/AGN), forming only a few hundred million years after the Big Bang as observed with the James Webb Space Telescope (JWST), challenge theoretical understanding. How could they grow so massive $(M_{\rm BH} > 10^6 {\rm \,M}_\odot)$ so quickly after initial seeding? Is this rapid growth related to the numerous and enigmatic Little Red Dots (LRDs), compact sources with AGN-like characteristics, discovered by JWST? To address these mysteries, we consider the first-order constraint on SMBH growth: enough baryonic material has to reach the vicinity of the SMBH seed, located near the bottom of the gravitational potential well of the host dark matter halo. We specifically examine cold-mode accretion, where gas from the cosmic environment flows into the virialized halo in cold streams without being shock-heated, efficiently reaching the center on a free-fall timescale. We find that cold mode accretion is necessary to supply material for the SMBHs to reach the observed masses, whereas for shock-heated gas inflow the required amount could only be supplied by implausibly rare halos. Moreover, cold-mode inflow in rare $(\sim1$ Gpc$^{-3}$) halos matches the mass and number of the massive quasars, and halos able to support super-Eddington accretion for massive SMBHs ($\sim10^7$ M$_\odot$) match LRD number densities. The decreasing LRD abundance at lower redshifts may then reflect the termination of cold-mode accretion in the growing host halos. The populations of massive SMBHs and LRDs at early times may thus arise naturally from cosmological structure formation, based on the abundance of halos capable of supplying sufficient material through cold accretion.

Recent Gaia-based measurements of the Milky Way rotation curve and stellar-stream modeling give significantly different estimates of the Galactic dynamical mass beyond Galactocentric radii of 15 kpc. The stream-based model predicts an outer halo five times more massive than that predicted by the Gaia rotation curve. We aim to test the impact of analytic assumptions used in stream modeling and to assess whether the currently available stream constraints can distinguish between low- and high-mass Galactic potentials. We first compared globular-cluster disruption in analytic and N-body Milky Way potentials. We then modeled Palomar~5 and ATLAS–Aliqa Uma, which are unique in probing the outer region beyond $R_{GC}$=15 kpc and are the most relevant to understanding the mass discrepancy. Both streams have usable constraints on sky position, proper motion, line-of-sight velocity, and RR~Lyrae distance. They were modeled for both a rotation-curve-based and a stream-based Galactic potential. In the N-body simulations, tidal shocks have a stronger effect on the closer orbit than on the more distant orbit, and therefore do not naturally explain the outer-Galaxy mass discrepancy. For the streams Palomar 5 and ATLAS–Aliqa Uma, simulations performed for both low- and high-mass Galactic potentials provide comparably good fits of their morphologies and kinematics. Neither potential provides a uniformly better match to all observables, and their differences are comparable to the present observational and modeling uncertainties. Current stream data do not discriminate between the low- and high-mass Milky Way models over the radial range probed by Palomar~5 and ATLAS–Aliqa Uma. This resolves the apparent tension between the rotation-curve- and stream-based constraints over this radial range.

Recent JWST observations have revealed a large population of compact red sources at $z \gtrsim 4$, known as Little Red Dots (LRDs), many of which show signatures of accreting massive black holes (BHs). The physical nature of these sources and their connection to host galaxies are under debate. We propose an independent avenue for constraining their nature through transient phenomena, such as tidal disruption events (TDEs) and quasi-periodic eruptions (QPEs), arising from interactions between a star and the gas envelope surrounding the BH. These event rates depend sensitively on BH mass and provide a way to "weigh" LRDs. We calculate the expected TDE and QPE rates in LRDs under three distinct scenarios: (1) LRDs are truly overmassive BHs, (2) LRDs have BH masses following the classical local scaling relations (and the reported BH masses in observations are overestimated), and (3) the currently observed LRDs are only the tip of the iceberg of a larger population of low-mass BHs. We find that the predicted TDE and QPE rates differ dramatically across scenarios, especially in the presence of steep stellar cusps. The expected TDE rates per degree-square, assuming a Hernquist stellar distribution with a Bahcall-Wolf cusp embedded, are $2.78 \times 10^{-3}$, $1.96 \times 10^{-3}$, and $3.37 \times 10^{-2} \, {\rm yr}^{-1} \, {\rm deg}^{-2}$ for the three scenarios, respectively, while the QPE rates are $1.64 \times 10^{-2}$, $4.72 \times 10^{-2}$, and $4.96 \times 10^{-1} \, {\rm yr}^{-1} \, {\rm deg}^{-2}$. Upcoming wide-field surveys with Euclid, Roman, and LSST may be capable of detecting these high-redshift transient events and obtaining light curves, which encode additional information about the BH mass and the gas structure of LRDs. Stellar transient events will provide valuable insight into the early assembly of massive BHs.

We present the Skyfire program, a 21-hour Cycle 3 JWST/NIRSpec survey with the G395M medium-resolution grating covering five pointings in the Extended Groth Strip. The survey is designed to carry out a systematic census of faint, broad-line AGN candidates with a range of rest-optical colors identified at z > 3 by the Cosmic Evolution Early Release Science (CEERS) Survey. Our primary targets include photometrically-selected Little Red Dots (LRDs), blue extreme emission line galaxies (EELGs), and X-ray-detected AGN. We present spectroscopic redshifts for 178 sources observed by Skyfire, as well as a catalog of 34 sources with broad emission lines in the redshift range 2.7 < z < 6.5. Our broad-line sample includes 18 LRDs, which brings the spectroscopic completeness of LRDs with $\beta_{\rm opt}>-0.02$ in the CEERS field to 73%. We explore the prevalence of broad emission lines in photometrically-selected LRDs as a function of their rest-frame continuum slope and observed color distributions. We find the broad-line detection fraction in LRDs remains high at relatively blue rest-optical colors and extends smoothly into the bluer regime occupied by Little Blue Dots (LBDs). We discuss the implications of this finding for LRD-LBD unification scenarios. We also find that only 18% (3/17) of EELGs selected primarily for their high-equivalent-width emission lines and compact morphologies exhibit broad emission lines, suggesting these criteria alone are poor predictors of broad-line activity. We present a revised set of LRD selection criteria that captures bluer sources by extending down to $\beta_{\rm opt}=-0.52$. Using this new threshold, we find that $80.9^{+4.6}_{-7.5}\%$ of photometrically-selected LRDs brighter than 26.5 in F444W show broad emission lines and that LRDs make up 54% of the overall broad-line population identified in the CEERS field.

We consider the problem of finding critical domains $\Omega\subset{\mathbb R}^3$ for the energy functional $$ \mathcal E (\Omega) = {\rm Per}\,(\Omega) + \frac 12 \iint_{\Omega\times \Omega } \frac{dx\,dy}{|x-y|} $$ under the volume constraint $|\Omega|=V$. We look for smooth, embedded, compact surfaces $\partial\Omega$ that solve this problem. We construct an axially symmetric, non-minimizing solution that, for a sufficiently small $V>0$, resembles the union of two balls with volume $V/2$ connected by a tiny, approximately catenoidal neck with a width of the order $V^{\frac 43}$.

Agentic systems now address tasks across theoretical, phenomenological, and experimental high energy physics (HEP), but their scientific capabilities remain difficult to reuse across different large language models, providers, and harnesses. We argue that stable parts of these workflows should be promoted into versioned scientific operations and exposed through common protocols. Existing general-purpose harnesses can then be specialized for HEP through task-specific sets of tools and skills, while community-maintained registries would make these capabilities discoverable and citable. We identify mismatches in conventions, assumptions, and domains of validity among independently developed operations as a potential obstacle to their composition, and discuss machine-readable scientific contracts as one possible solution. These design principles and evaluation guidelines provide a near-term path toward a portable and community-maintained agentic harness for HEP.

Corrosion accounts for approximately 4% of global GDP, and reliable prediction is essential for timely mitigation. Machine learning effectively predicts corrosion rates from composition, microstructure, and environmental variables, but cannot explain the underlying mechanisms. A reliable approach in safety-critical materials engineering requires not only accurate retrieval but also mechanistically defensible reasoning, a capability that existing factuality metrics cannot assess. This work presents a domain-adapted retrieval-augmented generation framework for corrosion knowledge synthesis, demonstrated on magnesium alloy corrosion. Three open-weight language models (Llama-3.1-8B, Qwen-2.5-7B, Mistral-7B) are fine-tuned on 3,309 expert-verified question-answer pairs from 840 peer-reviewed papers and integrated with a hybrid dense-lexical retrieval pipeline. Retrieval augmentation produces Token F1 gains of 143-194%, with system faithfulness of 0.964 and context recall of 0.988. Blind external validation on newly published literature and in-house electrochemical data confirms trend-level generalisation. Reason Map, a proposition-graph framework, is further introduced; it independently constructs directed evidence graphs from generated answers and retrieved literature, enabling systematic detection of causal direction inversions and unsupported inferential leaps that flat factuality metrics cannot expose. The modular architecture can be applied across domains, offering a generalizable blueprint for trustworthy AI-assisted knowledge synthesis to circumvent corrosion, which can also be applied to other engineering domains.

It was suggested by 't Hooft that to avoid the divergence of the free energy or entropy of the probe fields, one has to introduce an infrared (IR) cutoff. This introduction of the IR cutoff, namely, the brick wall model, has been studied for the Schwarzschild black hole and has been shown by 't Hooft that to have the entropy of the order of Bekenstein-Hawking entropy, the cutoff must be of the order of Planck length. In this study, we investigated the brick wall model in the context of a Reissner-Nordstróm, quantum corrected Schwarzschild and quantum corrected Reissner-Nordström black holes. In particular, we have shown that the brick wall model can give logarithmic correction to the black hole entropy in the subleading order. The important aspect of our analysis is that we have not considered the near horizon approximation of the lapse function and get more accurate correction to the entropy. This corrected entropy has an important feature that it is larger than the usual Bekenstein-Hawking entropy which aligns with the result of Barrow entropy.

A two-stage methodological proof of concept for screening simplified post-merger gravitational-wave damping anomalies in real LIGO Livingston noise is presented. The injected signal is a controlled damped-sinusoid proxy rather than a physically complete binary-neutron-star post-merger waveform; it is used to test statistical detectability and damping-time scoring under real-noise calibration. Stage 1 constructs a local time-frequency graph from Constant-Q representations of whitened candidate windows and uses the leading eigenvalue as a detectability statistic, with its null distribution calibrated empirically on real detector noise. Stage 2 estimates an effective damping-time score for Stage-1-passing candidates using nonlinear least squares and an interpretable ridge/energy-decay estimator, with thresholds fixed before final held-out evaluation. The matched-filter SNR convention is checked with synthetic Gaussian noise, while the graph statistic is assessed through power-comparison and tile-shuffling tests. On a held-out real-noise test block, the nonlinear least-squares Stage-2 score gives AUC = 0.943 and TPR = 0.879 at FPR = 0.012, outperforming a calibrated power-only baseline.

We describe the staged modernization of a local multilayer TRIM.SP implementation, denoted TRIM.SP-NL. The work included behavior-preserving refactoring, correction of localized bookkeeping and initialization defects, support for more than five elements per layer, reproducible build modes, and a runtime-selectable random-number-generator (RNG) interface. The RANLUX RNG remains the default reference backend, while PCG32 and xoshiro256** provide faster alternatives without changing the input-deck format. The code validation combined exact regression testing with statistical comparisons over 13 representative target multilayer configurations, comprising 143 energy-configuration points per backend and 429 simulations in total. Across the test suite, PCG32 and xoshiro256** reduced runtime by factors of 1.98 and 2.01, respectively. The implanted, backscattered, and transmitted fractions, as well as the mean implantation depths, range straggling, and representative depth profiles showed no systematic RNG dependence. Together with a Node.js-based graphical interface for setup, scans, and result collection, the Fortran engine forms the open-source TRIM.SP-NL Workbench.

The gravitational influence of dark matter (DM) halos on the strong-field regime around supermassive black holes (SMBHs) remains largely unexplored. In the present work, we try to make a framework of the halo-modified space times for four well-known DM profiles including the Navarro Frenk-White (NFW), Moore, Burkert, and Dehnen-(1,4,3/4) profiles, respectively. We derive the corresponding photon spheres, shadow radii, and innermost stable circular orbits (ISCO) for the Sgr A* and M87*. We then constrain the DM halo parameters by comparing the theoretical values with the observed Event Horizon Telescope (EHT) data, and the robustness was checked by comparing the obtained virial mass of the Milky Way and M87 from the parameters with the values already present in the literature. In addition to this we extend the geodesic analysis by formulating the perturbed orbital dynamics using a Painlevé-Gullstrand Hamiltonian framework, and as a result we compute orbital trajectories, Poincaré sections, and finite-time Lyapunov ex ponents. These chaotic dynamics leave distinct imprints on gravitational waveforms, including phase irregularities and amplitude modulations.

Superconductivity in graphite intercalation compounds requires occupancy of a carbon-derived interlayer band filled by charge from an electropositive intercalant. Bis-hexahapto (eta6-eta6) coordination binds transition metals covalently to two graphene sheets with little charge transfer: the mechanism defining this chemistry removes the donation that superconductivity rests on. We ask, for group-6 Cr, Mo and W in bilayer graphene, whether Fermi-level states retain the interstitial, carbon-p character of ionic references, with bulk CaC6 and same-cell C12Ca/C12Li controls. Electron-phonon coupling is not computed. At one metal per gallery (C12M), the ionic controls retain 68 and 45 per cent of gallery spectral weight in atom-masked interstitial regions at EF; the group-6 systems retain 15, 22 and 23 per cent. The contrast is compositional: group-6 galleries carry more absolute interstitial weight than C12Li, but projected density of states within +/-0.15 eV of EF is carbon dominated in the ionic references and metal dominated (~73 per cent, of which 89-98 per cent is d) in all three group-6 bilayers. Every system studied is metallic; they differ in what carries the Fermi surface. Zone-centre phonons are clean for all three ordered bilayers; the pristine AA bilayer is not, its unstable mode being the AA-to-AB shear. Geometrically, eta6-eta6 coordination requires AA stacking and reverses the intrinsic Bernal preference by 400-600 meV wherever metal is present. Ordered phases are metastable against bulk metal (+2.9-5.0 eV per atom) but bound against isolated atoms (-1.6-4.1 eV); instability ordering (Cr least, W most) matches Cr > Mo > W reactivity. C12Cr is metallic; tungsten alone carries 0.65 muB. Bis-hexahapto intercalation delivers strong interlayer bonding and a definite AA registry, but not the interlayer-band character of superconducting graphite intercalation compounds.