Papers

Quantum systems are rarely isolated from their surroundings. These hidden environments can retain information and return it later, producing correlated errors in quantum computers and complicating the interpretation of experiments. On a quantum processor, for example, one job can therefore leave an environmental trace that affects the next, even after the qubits themselves have been reset. Learning how this hidden influence persists and affects later behavior is therefore important, but the environment is often impossible to measure directly, and fully reconstructing its effects through tomography rapidly becomes impractical. Here, we introduce a response matrix that uses controlled interventions and observations of the system alone to reveal the temporal structure of environmental memory. The matrix records how future observations change across different controlled histories. Its spectrum characterizes how memory is structured and how it persists under specified system resets, while suitable linear combinations of its entries can rule out specified classical models of that memory. Because its history-future queries can be evaluated independently, numerical response matrices can be assembled in parallel. We establish the framework theoretically, characterize response spectra in an interacting spin process, and certify quantum memory in a two-qubit benchmark. This approach turns system observations into a probe of inaccessible environments and could support the diagnosis of correlated noise, tests of open system models, and memory-aware control design.

We present a homogeneous photometric, astrometric, and kinematic study of the Hyades-like open clusters NGC 2423 and NGC 2482 based on Gaia DR3 data. Cluster memberships are determined using the UPMASK algorithm in the multi-dimensional parameter space of (alpha, delta, parallax, mu_alpha cos(delta), mu_delta), with radial velocities incorporated when available. Gaussian modelling of the astrometric distributions yields mean trigonometric parallaxes of 1.060 +/- 0.035 mas and 0.735 +/- 0.061 mas, corresponding to astrometric distances of 944 +/- 31 pc and 1361 +/- 113 pc for NGC 2423 and NGC 2482, respectively. Fundamental parameters are derived through PARSEC isochrone fitting, resulting in ages of 1250 +/- 100 Myr and 445 +/- 50 Myr, observed distance moduli (m-M)_obs = 9.90 +/- 0.10 and 10.80 +/- 0.20 mag, and reddening values E(G_BP-G_RP) = 0.07 +/- 0.01 and 0.10 +/- 0.02 mag, equivalent to E(B-V) = 0.054 and 0.078. The corresponding photometric distances are 892 +/- 50 pc and 1311 +/- 146 pc. We further investigate the internal and global kinematics of both clusters using velocity-ellipsoid parameters, the convergent-point method, and action-angular-momentum diagnostics. The derived kinematic properties show that NGC 2482 closely matches the velocity-space characteristics of the Hyades stream, while NGC 2423 shares the characteristic rotational velocity and angular momentum of the Hyades-like population but is offset in its U component. Both clusters occupy the angular-momentum range associated in the literature with Hyades-like clusters and bar-related resonances, although this association is based on their present-day kinematics and action-space locations rather than a direct dynamical demonstration of resonance trapping.

We study symmetric gapped ground states of one-dimensional spin $S$ chains with a continuous exponential symmetry $U(1)\rtimes\mathbb Z_2$ with integer base $q$, where the U(1) charge has a modulated unit of charge $q^{L-j}$ decaying exponentially with site $j$. The simplest model is a quantum breakdown model that can be viewed as a $q$-deformation of the XXZ Haldane spin chain. We show that the topology of their symmetric ground states crucially depends on $S$ and $q$. For integer $S$, odd $q$ allows a nontrivial $\mathbb Z_2$ Haldane-type symmetry-protected topological (SPT) phase with protected edge modes, while even $q$ allows no nontrivial SPT phase. For half-odd integer $S$, odd $q$ prohibits any unique symmetric gapped ground state due to a Lieb-Schultz-Mattis obstruction, whereas even $q$ enforces a novel symmetric gapped phase which we name as the “half-SPT" phase. Unconventionally, the half-SPT phase only has a symmetry protected edge mode on one edge, and has half of the string orders of an SPT phase. Our results uncover a new type of symmetry-protected gapped phases beyond existing classification schemes.

We propose a scenario for the onset of radiatively efficient Active Galactic Nuclei (AGN) in which circumnuclear stellar and supernova-driven winds supply mass and partially ordered magnetic flux to a compact disk reservoir around a supermassive black hole. A coherent poloidal component surviving advection to small radii strengthens inward, lowering the gas plasma beta until mean Maxwell stresses overtake MRI turbulence, compress the disk vertically, and open a magnetically dominated wedge above it. Within a quasi-force-free description of this wedge, the field self-organizes toward a critical twist at which the net radial transport changes sign, defining a magnetic saturation radius $r_c\sim10\,r_g$. The magnetic squeezing of the disk fixes the pressure balance at the interface between the disk and wedge, confining the accumulated flux at $r_c$: flux advected toward this boundary is preferentially shed, fixing $B_r\propto r^{-2}$ in the interior. From the field topology alone we then derive a normalized saturation flux $\phi \sim 50$, consistent with the MAD plateau of GRMHD simulations. The resulting compact, time-dependent saturation region is a natural candidate for the AGN X-ray corona, being collisionless, magnetized, and, at high compactness, plausibly pair-rich, with hadronic pair injection providing a conditional additional channel. Its size, variability, and spectral hardness are controlled by $r_c$, the compactness, and the magnetization. We connect these scalings to observed coronal sizes, variability, and the power partition between the corona and jet. We further propose that Little Red and Blue Dots could represent a disk-reservoir phase preceding luminous AGN activity.

Using deep XMM-Newton and Chandra observations, we compare the double-radio-relic galaxy cluster mergers MACS J1752.0+4440 and ZwCl 1856.8+6616. Both are 1:1 mass-ratio mergers with similar relic separations but differing nearly an order of magnitude in total mass. In MACS J1752.0+4440, the surface-brightness discontinuity at the northeastern relic yields Mach $M_{\rho}=1.4\pm0.2$, while the temperature jump provides a weaker constraint, corresponding to $M_{kT}\lesssim2.3$ at the $2\sigma$ level, lower than the radio-derived $M_{\rm radio}=3.1\pm0.1$. No discontinuity is detected at the southwestern relic. Thermodynamic maps and axial profiles reveal surviving relatively low-entropy cores embedded in Mpc-scale stripped-gas structures. The nearly uniform X-ray tail brightness and a southwestern plateau coincident with a third lensing mass peak favor a non-zero impact parameter and complex assembly history. In ZwCl 1856.8+6616, we do not detect a clear surface brightness discontinuity at either relic. The northern X-ray peak leads its brightest cluster galaxy (BCG) and lensing peak, while the hotter southern X-ray peak is laterally offset from its BCG and lensing peak. The asymmetric intracluster emission favors a phase near or after first apocenter, when displaced gas can develop a slingshot-like morphology. We present two TNG-Cluster analogs in which a minor merger followed by an off-axis major collision produces extended X-ray tails resembling MACS J1752.0+4440 and later leads to gas structures resembling ZwCl 1856.8+6616. X-ray morphology independently confirms the merger phases inferred from relic-based chronometry, placing MACS J1752.0+4440 before and ZwCl 1856.8+6616 after first apocenter, and demonstrating that similar relic and lensing configurations can correspond to distinct dynamical states.

Superconductivity and intrinsic topological order can intertwine in ways that go beyond simple coexistence. Here we develop a classification framework for (2+1)D gapped superconductors with condensate charge $2ne$. By focusing on the topological properties of superconducting vortices, we precisely characterize this interplay. We obtain a classification with increasing levels of intertwinement, from the well known invertible superconductors without topological order, to untwisted and twisted SC$^\ast$, and finally to SC$^{\sharp}$. Our main finding is the family SC$^{\sharp}$, in which the elementary vortex carrying $h/(2ne)$ flux cannot be factorized into an invertible superconductor vortex dressed by bulk anyons, and every elementary vortex is necessarily non-Abelian. For such phases, we also obtain no-go results: the elementary vortex sector has quantum dimension at least $\sqrt{6}$ and cannot satisfy Fibonacci fusion rules. We develop a systematic algebraic framework to obtain all these superconducting phases through anyon condensation, allowing us to construct several infinite families of examples and make connections to anyon superconductivity. Finally, we introduce primitive SC$^\sharp$ phases for which factorization of every nontrivial vortex sector is obstructed, and argue that they cannot arise by disordering the relative phases of lower-charge superconducting condensates. Our classification scheme based on vortex properties allows us to uncover new distinctions between topologically ordered superconductors and constrain how they can be realized.

Hawking amplitudes provide a new way of determining the Hawking spectrum of black holes, using on-shell techniques borrowed from the literature on scattering amplitudes. In this paper, we investigate the interplay between the semi-classical and weak-field approximations previously used to compute Hawking amplitudes. We find that these limits do not necessarily commute, highlighting subtleties with the saddle point analyses governing the semi-classical limit. Resolving these issues allows us to compute semi-classical Hawking amplitudes in a range of black-hole backgrounds, including Tangherlini, Reissner-Nordström, and Hernquist metrics. Moreover, we describe the saddle-point contributions dominating Hawking amplitudes for different energies and propose a new method for determining the temperature of the resulting thermal spectrum based on Stokes lines of Hawking amplitudes.

We show that a scale-invariant $U(1)$ gauge theory can naturally realize large curvature perturbations around the end of thermal inflation, seeding the formation of primordial black holes (PBHs). The allowed nonminimal gravitational interaction $\xi$ of the Higgs field induces a Hubble-scale negative mass-squared term for positive $\xi \sim \mathcal{O}(1)$, and triggers a second order phase transition that ends thermal inflation while keeping the extra $e$-folds small. This sharp contrast to the minimally coupled case allows the gauge coupling to be much smaller than unity. It turns out that field fluctuations are dominated by thermal fluctuations around the onset of the phase transition, and sufficiently amplified to produce an appreciable amount of PBHs with a wide range of possible masses. The associated scalar-induced gravitational waves (GWs) are accompanied by cosmic-string induced GWs coming from the breaking of the $U(1)$ symmetry. As a result, the generated PBH population can have a correlated GW signature relevant to pulsar timing arrays, space-based interferometers, or ground-based detectors.

Core growth is a key process in high-mass star formation. As part of the GLASHES (Global and Local Infall in the ASHES Sample) survey, we present infall velocities and mass infall rates derived from blue-asymmetric line profiles toward cores embedded in massive 70 \textmu m-dark clumps. Robust Hill5 model fits were obtained for 70 of the 135 cores exhibiting blue-asymmetric profiles, yielding infall velocities of 0.11–1.60 km s$^{-1}$ and mass infall rates ranging from $\sim$10$^{-5}$ to $5\times10^{-3}\,M_\odot\,{\rm yr}^{-1}$. Both quantities increase systematically from prestellar candidates to warm cores and outflow-associated cores. The inferred infall velocities are close to the cores' free-fall velocities (mean $v_{\rm in}/v_{\rm ff}\sim0.75$) and $t_{\rm in}=R/v_{\rm in}$ is comparable to the free-fall time, indicating dynamical fast contraction. Hill5 infall velocity correlates moderately with the non-thermal velocity dispersion and Mach number measured from optically thin tracers, indicating that organized infall contributes to the observed line widths. The mass infall rate follows a power-law relation with core mass, $\dot{M}=1.3\times10^{-4}\,(M/M_\odot)^{0.83\pm 0.06}\,M_\odot\,{\rm yr}^{-1}$, across $0.1\,M_\odot \lesssim M \lesssim 30\,M_\odot$. The power-law index increases from $\sim$0.65 for prestellar cores to $\sim$1.10 for outflow-associated cores, likely tracing an evolution in the dominant physical process. The Hill5 infall velocities and mass infall rates for the GLASHES cores are larger than those of cores in nearby low-mass star forming regions but smaller than those of larger scale high-mass clumps. These results provide the first statistical constraints on core-scale mass accumulation during the earliest stages of high-mass star formation.

We present a comprehensive kinematic and dynamical analysis of 5,837 DA white dwarfs with SDSS DR19 spectroscopy and Gaia DR3 astrometry. Using complementary spatial distributions, kinematic properties, and orbital parameters, we show that the sample is overwhelmingly dominated by the thin disk, with only minor contributions from the thick disk and the halo. Velocity dispersions and orbital eccentricities increase systematically from the thin disk to the halo, reflecting progressively hotter Galactic populations. Total stellar ages available for 4,829 white dwarfs reveal a clear age-velocity dispersion relation with power-law indices of 0.06-0.17, confirming that white dwarfs preserve the secular dynamical heating history of the Galactic disk. We derive a thin-disk scale-height of 123-229 pc and radial scale-length of 3.2-3.5 kpc, while the thick disk has a scale height of 865 pc and contributes approximately 6-7 % of the local stellar density. Reconstructed birth radii indicate that changes in the guiding radii represent an important component of the present-day radial redistribution of nearby white dwarfs, although the relative contributions of radial migration and orbital blurring cannot be uniquely separated from these displacement measures. These results establish white dwarfs as powerful tracers of the kinematic, dynamical, and structural evolution of the Milky Way.

Recent pulsar timing array (PTA) observations have reported evidence for a common low frequency signal consistent with a stochastic gravitational wave background. In this work, we investigate the cosmic string interpretation of this signal in a non-standard cosmological history between big bang nucleosynthesis and recombination, featuring an early matter-dominated era followed by a kination phase. Previous studies have shown that kination can significantly modify the cosmic-string-induced gravitational wave spectrum, generating characteristic features in the nanohertz range and producing a shape consistent with current PTA data. Building on this, we perform separate Bayesian analyses of the NANOGrav 15-year and EPTA DR2 New+ datasets to quantify the extent to which such a cosmological history is favored by the data. We find substantial evidence for a transient period of matter and kination domination over the standard cosmological history within a cosmic-string interpretation of the gravitational-wave signal, with a Bayes factor $3.63^{+0.22}_{-0.21}$ from the NANOGrav 15-year dataset, while leaving the inferred cosmic-string tension nearly unchanged. This cosmic-string-dominated scenario is particularly relevant if the contribution from supermassive black hole binaries (SMBHBs) is small, as hinted at by astrophysical population simulations. Compared with a scenario where gravitational waves are produced purely by SMBHBs, cosmic-string interpretations with and without an additional contribution from SMBHBs, across both expansion histories and datasets, reveal no significant preference.

We argue that the scattering amplitude of a single minus helicity gluon with arbitrarily many positive helicity gluons is topological. The amplitude is constant in chambers of kinematic space, its resonances are located at walls and its factorization is determined by wall-crossing. Yangian invariance dictates the amplitude to be determined by a 2d null Wilson loop that can be lifted into a positive and transverse 3d link. By reinterpreting wall-crossing and the Weinberg soft theorem as skein relations and Reidemeister moves of the subknots, we construct a state-counting description consisting of adding the `corners' of their HOMFLY-PT polynomials. Beyond the classical limit, we argue that this provides a conjectured but precise connection to topological field and string theory. The new formula is rigorously derived via a Lean-formalized dependency graph (DAG) as detailed in a companion paper, laying out the precise assumptions including Reidemeister III invariance. It is further tested exhaustively, including novel `star' kinematics where the amplitude and state count are shown to become Catalan numbers, in agreement with knot theory literature.

We describe the construction of a spanning set of individually pure, planar master integrals involving massless particles in four dimensions which include all maximal-weight contributions at two loops. In this basis, every independent region associated with infrared divergence is individually matched by specific masters, with all other masters being manifestly finite in four dimensions.

We study magnets composed of molecules with an arbitrary number $m$ of magnetically active atoms in a chain configuration interacting with nearest-neighbor couplings. We derive the thermodynamics of a chain of spin-$j$ $SU(2)$ magnetic atoms using a mean-field approach and determine the equilibrium states and stability conditions. The system exhibits a rich phase structure with a cascade of ferromagnetic phase transitions, their number ranging from $m$, for maximal ferromagnets, to zero, for paramagnets, depending on the relative strengths of the couplings. In the presence of impurities (modified couplings) at the ends of the chain, boundary states emerge that coexist with the paramagnetic phase or the fully ferromagnetic phase. For long chains, a continuum approximation can be taken that clarifies the structure of the phases. In the continuum description, magnetized states at temperatures lower than the critical temperature at which they appear correspond to kink solitons.

In view of potential future improvements in the branching fractions of leptonic $\tau$ decays $\tau\to\ell\nu_\tau\bar\nu_\ell$, $\ell=e,\mu$, it is timely to derive the corresponding Standard-Model predictions beyond next-to-leading order. We provide such benchmark values for the fully inclusive decay widths, profiting from higher-order corrections that have been studied in the $\overline{\text{MS}}$ scheme up to three-loop order in the case of muon decay. To obtain complete next-to-next-to-leading-order results, we perform a numerical calculation of the two-loop coefficients in the on-shell scheme, including an evaluation of the hadronic effects, and compare the leptonic results to the known $\overline{\text{MS}}$ coefficients where available. Our final results are presented in the $\overline{\text{MS}}$ scheme, to be able to also include an estimate of the three-loop contribution. In addition, we comment on radiative and rare decays, whose consideration is critical for the conversion between $\overline{\text{MS}}$ and on-shell results.

We investigate how site-dependent Newtonian noise configurations affect the scientific performance of the Einstein Telescope (ET), a third-generation gravitational-wave observatory. We compare the baseline triangular and 2L detector geometries, with arm lengths of 10km and 15km, respectively, under three site-dependent noise scenarios constructed from measurements in the Euregio Meuse-Rhine region, Lausitz, and Sardinia. The differences among the adopted sensitivities are concentrated mainly below 10Hz and thus have the greatest impact on science cases that rely on the early inspiral of light objects, or on massive systems whose characteristic frequencies lie in the low-frequency band. We quantify these effects for four ET science cases: (1) detection and parameter estimation of intermediate-mass black-hole binaries; (2) post-Newtonian tests of General Relativity based on the early inspiral; (3) black-hole ringdown spectroscopy with massive remnants; and (4) early-warning and sky-localization capabilities for binary neutron-star mergers. Using Bayesian parameter estimation, we find that improved low-frequency sensitivity can significantly enhance ET's scientific performance across all four cases. Within the configurations considered here, a 2L network in which at least one of the two L-shaped interferometers attains a noise level comparable to that assumed for the Sardinian site generally provides better performance than the triangular configurations. Conversely, strong degradation of the sensitivity below 10Hz can substantially reduce, and in some regimes offset, the scientific gains expected from increasing the arm length from 10km to 15km. These results highlight the importance of site selection and low-frequency noise mitigation, alongside network geometry, for fully realizing ET's scientific potential in the largely unexplored frequency band below 10Hz.

Topologically ordered superfluids (TOSFs) support deconfined, gapped anyonic excitations while remaining gapless because of Goldstone modes. We develop a general framework for characterizing their topological data in $(2+1)$-dimensional bosonic systems with spontaneously broken charge ${\rm U}(1)_{\rm c}$ symmetry. Gauging ${\rm U}(1)_{\rm c}$ maps a TOSF to a gapped topological order enriched by a dual ${\rm U}(1)_{\rm dual}$ symmetry with vanishing Hall conductance, while gauging ${\rm U}(1)_{\rm dual}$ recovers the TOSF. This two-way mapping allows the topological data of the TOSF, including the condensate charge, deconfined anyon content, and topological properties of vortices, to be systematically encoded using the algebraic framework of symmetry-enriched topological orders. In particular, superfluid vortices share the topological properties of flux defects associated with the residual discrete symmetry in the gapped anyon sector. We develop complementary algebraic and field-theoretic formulations of this framework, with the latter also suggesting a natural transition to a gapped topologically ordered phase. Additionally, using parton constructions, we present examples of TOSFs with non-Abelian vortices in bosonic systems.

It has been argued that in quantum gravity the Hilbert space associated with any closed universe is trivially one-dimensional. To reconcile this argument with the richness of our own universe, it was suggested that a nontrivial Hilbert space will emerge once an “observer" is included. Such an “observer" has been modeled in different ways. There are three concrete classes of models: $\textbf{1)}$ The “observer" is modeled by a term in the full Hamiltonian of the system which is linear in a phase space variable; $\textbf{2)}$ The “observer" is modeled in the quantum circuit model of holography as a subsystem in the closed universe which is entangled with an external non-gravitational system; $\textbf{3)}$ The “observer" is argued to be described by the emergent Goldstone bosons when the diffeomorphisms are spontaneously broken. In fact, the third class was discovered by an attempt to physically realize the first class. In this paper, we will show that the second class can also be unified into the third class. Our result indicates that the emergence of the “observer" is a manifestation of the $\textit{Massive Islands}$ paradigm. It demonstrates that the graviton mass is a feature of the quantum state. One should think of the islands as closed universes and the Goldstone boson associated with the graviton mass as the “observer", which is exactly the case at late-times for evaporating black holes. An implication of this work is that the “observer" can “observe" global symmetries in quantum gravity.

Live-streaming platforms generate high-frequency records of collective human activity in which many loosely coordinated users react in real time to shared external stimuli and to one another. We investigate whether the temporal organization of Twitch chat messages exhibits multifractal signatures characteristic of complex dynamical systems. Selected high-activity chats were converted into time series by measuring the length of each consecutive message in words, with platform emotes treated as individual tokens. The resulting signals display heterogeneous fluctuations, bursty organization, and heavy-tailed distributions that, in several cases, are better captured by q-Weibull forms than by conventional light-tailed models. Autocorrelation analysis reveals persistent temporal dependence over broad ranges of message lags, indicating that the variability is not produced by independent message generation alone. MFDFA shows that some chats possess well-developed multifractal spectra and generalized Hurst exponents strongly dependent on moment order, whereas others exhibit weak scaling, approximately monofractal behavior, or no well-defined scaling regime. Surrogate tests indicate that temporal correlations are essential for the observed multifractality, while heavy tails enhance its apparent strength. Under particular dynamical conditions, Twitch chat may therefore form an emergent collective signal whose fragmented, reactive, associative, and multiscale organization is structurally reminiscent of stream-of-consciousness narrative. This expression is used strictly as a structural and dynamical analogy, not as a claim of a unified collective mind or of semantic, cognitive, or phenomenological equivalence with literary stream-of-consciousness writing. The results position live-stream chat dynamics within the broader physics of complex, intermittent, human-generated signals.

Scientific multimodal learning commonly assumes that paired views are comparably informative. Powder X-ray diffraction (PXRD) makes this mismatch explicit: compressing a three-dimensional crystal structure into a one-dimensional diffraction pattern loses information and makes the pattern harder to connect to the crystal structure that produced it. We introduce PXtal, a framework for learning aligned PXRD and crystal representations under this physically imposed information asymmetry. PXtal uses Unbalanced Optimal Transport (UOT) to adapt the cross-modal coupling and coupling-level generalized Kullback-Leibler (GKL) divergence to supervise the full transport plan. Across six test sets, including four zero-shot transfer sets, PXtal consistently outperforms the baseline models in PXRD-to-crystal candidate retrieval, with the largest gains when PXRD patterns have close but crystallographically distinct nonpaired neighbors, meaning similar input patterns associated with different crystals. The resulting crystal and PXRD encoders transfer more effectively to downstream materials and crystallographic tasks. These results identify information asymmetry as a general design problem in scientific multimodal learning: alignment objectives should reflect what each modality preserves.

We have presented an analytical and numerical study of efficiency fluctuations in quantum Carnot and Otto engines with pistons operating under non-quasi-static adiabatic expansion and compression processes at constant speed, along with quasi-static isothermal (for the Carnot engine) or isochoric processes (for the Otto engine). We have considered the two-point measurement scheme during the adiabatic strokes in this regard. By considering each of the pistons as a single quantum particle in a 1-D box with a non-quasi-statically movable boundary, we capture the stochastic nature of the work output resulting from the unitary evolution of the quantum mechanical state of the system during non-equilibrium processes. Furthermore, we have explicitly shown how the piston speed during quantum non-equilibrium strokes introduces additional quantum fluctuations that modify the average efficiency of both the engines.

A rigorous macroscopic analysis of classical thermodynamics reveals an overlooked contradiction at the foundations of ideal gas theory: the traditional volume dependent formula for entropy violates the fundamental axiom of thermal equilibrium during reversible isothermal processes. This paper resolves this inconsistency by establishing a strict operational distinction between strictly isothermal and quasi isothermal processes. We show that in order for the perfect gas to be strictly consistent with the laws of classical thermodynamics, the thermodynamic entropy of a perfect gas must be a function of temperature only. This independence of volume is also confirmed by a new analysis of the adiabatic free expansion of an ideal gas, which is found to be intrinsically reversible. To reconcile these results with standard thermodynamic practice, we introduce the concept of a pseudo isothermal process (a finite sequence of small adiabatic and isochoric steps) and show that the classical equations for work and heat apply rigorously to these real processes, as opposed to strictly isothermal ones. We conclude by discussing the profound implications of these findings for statistical mechanics, showing that while the corrected thermodynamic entropy is in perfect agreement with Maxwell's kinetic theory, it is essentially different from the Planck Boltzmann formula. Thus, thermodynamic entropy and statistical microstate counting are two different physical quantities, and the present analysis provides a simple way to free classical thermodynamics from the paradoxes of microscopic disorder.

Black-hole shadows and geometrothermodynamics (GTD) are defined in different spaces but depend on the same macroscopic black-hole parameters. We review their correspondence for Reissner–Nordström (RN), Kerr, and Kerr–AdS black holes. The three GTD metrics reveal complementary thermodynamic structures, including Davies instabilities, extremal and degenerate limits, and regular curvature zeros, which can be mapped to shadow configurations. Kerr–AdS extends this correspondence to asymmetric shadows and multidimensional equilibrium states. We formulate a local Jacobian-rank criterion for thermodynamic reconstruction from shadow observables and discuss shadow–microstructure (SM) diagrams as optical representations of GTD-classified equilibrium states. The application to Sagittarius A* illustrates the inverse problem: shadow observations constrain thermodynamic states and provide a basis for identifying additional metric-dependent observables that could distinguish among the GTD metric structures.

Translational and helical symmetries provide idealized descriptions of many flows encountered in nature and engineering. While translationally symmetric flows have been extensively studied within kinetic and continuum frameworks, the corresponding connection between microscopic dynamics and continuum behaviour for helical flows is less developed. Here, we investigate this connection for a dilute gas with time-dependent helical symmetry. Using the objective molecular dynamics framework, we derive a reduced Boltzmann equation that retains radial variations while preserving the classical collision operator under helical symmetry. Formal hydrodynamic expansions then yield the corresponding Euler and Navier-Stokes-Fourier equations. The resulting models describe how cylindrical geometry and axial deformation influence transport, including viscous transport and heat conduction, and how deformation generates unequal stresses along and across the axis in competition with collisional relaxation. Comparisons with direct simulation Monte Carlo solutions examine both spatially uniform and radially varying flows. In the cases studied, the first-order fluid corrections capture the leading stress anisotropy and improve the prediction of radial temperature variations, while larger Knudsen numbers expose limitations of the approximation.

We show that the radial sector of a Carroll-Weyl gauged null string in Poincaré $\mathrm{AdS}_D$ is locally trivial in BRST cohomology. In a quotient-adapted BFV basis, the radial coordinate, its conjugate momentum, and the associated ghosts form a contractible quartet. An explicit contracting homotopy extends this reduction to the full algebra of local spatial jets, leaving precisely the $(D-1)$-dimensional ILST BRST complex. The same quartet carries zero net Virasoro central charge, so that the anomaly condition of the parent theory, $D=27$, descends to the ILST condition $d=26$.

We introduce a flexible mixture model for the joint source-frame component-mass distribution of compact binaries, inferred simultaneously with cosmology, together with a framework that identifies structures in the reconstructed density, quantifying their posterior stability, local prominence, and cosmological relevance. Applied to GWTC-5.0, the workflow clarifies several familiar and emergent structures. The $\sim35~M_\odot$ feature is classified as a clear near-equal-mass peak despite an ambiguous interpretation in the primary-mass projection. A weaker unequal-mass concentration near $(21,12)~M_\odot$ is recovered frequently but with lower prominence. A tentative joint transition near $60~M_\odot$ appears at mildly unequal masses, with a more robust manifestation in the primary-mass projection. For cosmology, the two-dimensional mass model constraint on $H_0$ is $33\%$ narrower than a model that flexibly reconstructs only the primary mass, and only $\sim~10\%$ wider than analyses based on strongly parameterized one-dimensional spectral structure. At the feature level, we show that the $\sim10~M_\odot$ and $\sim35~M_\odot$ concentrations depend on $H_0$ mainly through a common scale which captures the entire $\sim~(1+z)$ cosmological rescaling of both masses; the intermediate unequal-mass feature instead retains residual dependence in the orthogonal mass-ratio direction. More generally, we argue that population prominence, formal inclusion in an astrophysical feature catalogue, and cosmological relevance need not coincide. These results suggest that a genuinely two-dimensional view may be required to fully exploit spectral-siren information. Our workflow provides a reproducible way to detect population structure and identify which aspects of its geometry are associated with spectral-siren constraints. The feature finder is directly applicable to other population reconstructions.

Quantum error-correcting circuits are affected by multiple physical noise mechanisms, whose contributions to logical failure must be understood to evaluate code performance and guide improvements in hardware. The individual error budget contributions for an error type $i$ can be characterized by its logical sensitivity $\nu_i = \frac{\partial p_L}{\partial p_i}$, which measures the response of the logical error rate $p_L$ to each physical noise parameter $p_i$. Normally, $\nu_i$ is measured using linear fits such as finite differences, where $p_L$ is measured at two or more values of $p_i$ to calculate partial derivatives. In this paper, we develop a differentiable estimator to obtain all components of $\nabla_{\mathbf p}p_L$ simultaneously from a single Monte Carlo data set at one noise configuration, using information about the underlying fault configurations. In surface code simulations with circuit-level noise, the estimator agrees with conventional finite differences while requiring one to two orders of magnitude fewer shots to achieve the same variance. We apply this technique to quantify error budgets, resolve sensitivities at the individual qubit level, and infer effective code distance. Finally, we incorporate the sensitivities into Newton root finding to locate and trace threshold contours in multidimensional noise models. These results provide an efficient method for extracting and applying logical sensitivity information from standard quantum error correction simulations.

We constrain oscillatory features in the primordial power spectrum using the public DESI DR1 galaxy and quasar clustering data. Our analysis is based on a custom pipeline for the redshift-space power spectrum and bispectrum of the six main DESI DR1 tracers, modeled with the Lagrangian effective field theory,which provides a principled resummation of the non-linear damping of the features. We consider oscillations that are linear and logarithmic in wavenumber, and, for the first time, consistently include the galaxy bispectrum in the search. We also study the dependence of the results on the background cosmology, which is important given the tension between the DESI BAO and Planck data within the baseline cosmological model. Marginalizing over $\Lambda$CDM parameters, we bound the amplitude of linear and logarithmic oscillations to $A_{\rm lin}<0.033$ and $A_{\rm log}<0.035$ respectively (at 95$\%~$CL) across the frequency ranges $\omega_{\rm lin}^{\rm phys}\in(20,800)~{\rm Mpc}$ and $\omega_{\rm log}\in(2.5,80)$. The constraints reach percent-level precision away from the frequencies degenerate with the baryon acoustic oscillations (BAO). Fixing to the Planck 2018 cosmology, the bounds tighten to $A_{\rm lin}<0.024$ and $A_{\rm log}<0.031$, but in this case we also find a $\simeq 3\sigma$ global preference for a logarithmic feature with $\omega_{\rm log}\simeq 15$, dominated by the LRG2 sample, whose local wavelength matches the apparent BAO scale at wavenumbers best constrained by DESI. Since the preference for this feature disappears once the cosmological parameters are varied, we expect that it is a manifestation of the known distance-scale tension between the DESI and Planck data rather than a primordial signal. Our analysis thus emphasizes the importance of cosmology marginalization in searches for primordial features.

We establish a charge-regular formulation of separated Kerr–Newman perturbations and an explicit map from master solutions to physical radiative fields. We derive regular angular and radial first-order systems and their second-order reductions, with finite-charge deformations of the spin $\pm1$ and $\pm2$ Teukolsky equations. The field and boundary normalizations recover the standard Kerr conventions while accounting for the nonuniform zero-charge limit at infinity. For physical Einstein–Maxwell perturbations with the usual peeling behavior, we obtain explicit outgoing gravitational and electromagnetic amplitudes and energy fluxes at nonzero real frequency. The resulting finite-charge radiation-composition ratios depend only on the regular angular functions, independently of the radial excitation.

In this work we study phenomenological Landau theories of non-relativistic magnetic systems, generalizing work on the collinear case to coplanar and non-coplanar orders. Focusing on zero-wavevector ($\boldsymbol{k}=0$) magnetic orders described by a single irreducible representation of the crystallographic point group, we construct the symmetry-allowed free energies to quartic order for all possible multi-dimensional irreducible ordering channels. We find distinct Landau theories for tetragonal, trigonal/hexagonal, and cubic symmetry. Similar to the case of spin-nematic fluids, we find two natural outcomes: a collapse to a lower-symmetry collinear phase or a genuinely coplanar or non-coplanar order where the order parameters form a mutually orthogonal set in spin space – reminiscent of the $A$ and $B$ phases in ${}^3$He. We show in general that this symmetry-broken phase realizes the spin space group associated with the spatial representation of the order parameter sharing the same parent space group as the paramagnetic phase. This provides a direct link between the Landau and spin space group approaches. We calculate key observables using this Landau approach, including net magnetization, spin conductivity, multipolar moments, and piezomagnetism, connecting our results to constraints from the underlying spin space group. Examples of coplanar and non-coplanar magnetic orders for each case are worked out in detail. Finally, we discuss the relationship of the lower-symmetry collinear phases to the usual collinear spin groups, as well as connections to atomic altermagnetism, superfluid ${}^3$He and electronic nematic phases.