Papers

We investigate the tidal forces experienced by massive particles in radial free fall in the quantum Oppenheimer–Snyder black hole, a loop quantum gravity correction to the Schwarzschild geometry that describes the exterior of a bouncing dust ball. Using an orthonormal tetrad adapted to a freely falling observer, we show that the radial and angular components of the tidal tensor reproduce their Schwarzschild counterparts at large distances but reverse sign in the interior. The angular zero remains confined between the Cauchy and event horizons and coincides with the latter only in the extremal limit. A particle released from rest does not reach the center, it stops at a turning point inside the Cauchy horizon, where the ratio of the tidal components is independent of the parameters of the solution and is fixed by the transverse equation of state of the effective source. Solving the geodesic deviation equations for two sets of initial conditions, we find that the radial deviation vector attains its maximum at the minimum of the metric function, exactly for one set of initial conditions and asymptotically for the other, and remains finite throughout, in contrast with the Schwarzschild case, in which it diverges at the singularity. This regularity originates in the bounce rather than in a regular core, and therefore protects timelike radial infall while leaving radial null geodesics unaffected. Examining the full range of the quantum parameter, we find that its sign determines whether the tidal sector possesses any of this structure, while its magnitude determines only whether that structure is hidden: beyond the extremal value the geometry becomes horizonless, and the entire deformation history, bounce included, is exposed to distant observers.

Recent observations combining the power of ALMA and JWST have revealed large ($3-7$ kpc), massive ($3-10\times10^{10}\,\mathrm{M}_\odot$) stellar bars at $z=4-5$ when the Universe was only 1.2-1.6 Gyr old. At this early epoch, the host galaxy was baryon-dominated (typically 75% gas, 25% stars) within the observed extent of the disc ($8-15$ kpc). Using NEXUS $N$-body/hydrodynamic simulations, we show that such bars can form promptly (400$-$800 Myr), provided the disc mass fraction is high ($f_{\rm disc}\gtrsim 70\%$) and the bar is gas-dominated at the time of its formation, consistent with the observations. In this limit, gas-free bars are unstable to vertical bending modes, but a dominant gas component suppresses this instability. Unlike massive bars in the local Universe, these early bars were sites of vigorous star formation, as we show. Remarkably, for gas-rich models with $f_{\rm gas}\lesssim60\%$, the bars develop X-shaped boxy bulges; at higher gas fractions ($f_{\rm gas}> 60\%$), diffusion suppresses resonant orbit trapping and the emerging bar collapses within 1 Gyr to form a classical bulge. The bar formation time, length, mass, and $m=2$ Fourier amplitude are all inversely related to $f_{\rm gas}$. We present a simple analytic model for how stochastic forcing shifts the bar onset time, defined as the time at which the growing bar amplitude reaches a specified threshold.

Rutile RuO2 is a prominent candidate for altermagnetism, yet its magnetic ground state remains highly controversial, with experiments reporting either a nonmagnetic state or altermagnetic order. Here, we develop a generalized environment-dependent spin-lattice framework that unifies localized Heisenberg exchange, itinerant Stoner magnetism via Landau spin fluctuations, and spin-orbit-coupling-mediated spin-lattice interactions. Parameterized from a high-throughput first-principles database using machine-learning and solved by large-scale Monte Carlo simulations, the framework reveals an exceptionally flat magnetic energy landscape in RuO2, where the nonmagnetic state lies nearly degenerate with multiple altermagnetic configurations. We find that material perturbations, exemplified by intrinsic defects, select distinct magnetic ground states primarily by modifying the localized Heisenberg exchange, with perturbation-induced itinerant Stoner polarization provides an essential secondary contribution. Spin-orbit coupling controls the orientation and stability of the Néel vector, but does not determine the emergence of long-range magnetic order. These results provide a unified explanation for the conflicting experimental observations and establish a general microscopic framework for understanding how material perturbations select competing magnetic ground states in systems with nearly flat magnetic energy landscapes.

In this work, we extend the scattering quantum walk (SQW) framework to a lattice of energy-dependent point interactions. This yields, within the coined quantum walk (CQW) formalism, a coin operator that is directly related to the scattering matrix of zero-range potentials. The model thus provides a discrete-time quantum-walk (DTQW) analog of a periodic array of point interactions of the Kronig-Penney type, where the walker's wavenumber serves as a continuous, physically transparent control parameter for the coin operation. We analyze the spectra and the dynamics of position probability and entanglement, yielding distinct results for specific energies and point interactions. We relate the spectral structure to the spatial probability distribution and explicitly characterize the long-time entanglement behavior for each point interaction. The transmission modulus determines the quasienergy gap, bandwidth, and maximum group velocity, while also controlling the long-time coin-position entanglement for the initial state considered. The four families of one-dimensional point interactions ($\delta$, $\delta'$, crossed and asymmetric) realize qualitatively distinct transmission profiles and span the full range of behavior, including enhanced or strongly suppressed spreading and oscillatory entanglement.

We propose a mechanism for nonmagnetic materials to develop altermagnetic order by moiré interference with nonmagnetic substrate, which is driven by structural relaxation and spontaneous twirls in moiré domain walls of lattice-mismatched moiré square lattices. When doped with one electron per moiré domain, a correlated insulating gap is opened by electron interaction. Depending on the location of the moiré potential minima, the moiré bands can show d-wave or g-wave altermagnetic splitting. The former can be enhanced by a finite twist angle; the latter is sensitive to strains that drive a transition to d-wave.

Accurate patient-specific mean glandular dose (MGD) estimation in breast computed tomography (BCT) requires anatomically realistic models, but high-resolution patient-derived phantoms impose high computational demands on Monte Carlo (MC) dosimetry. We previously developed and validated an EGSnrc-based framework for synchrotron propagation-based phase-contrast BCT (PB-PCT) for the first-in-human study at the Australian Synchrotron. With participant imaging commencing, this study aimed to optimize phantom spatial resolution and MC efficiency while maintaining MGD accuracy, for a rapid patient-specific dosimetry. Four patient-specific heterogeneous breast phantoms with varying volume and glandularity were generated from PB-PCT images of mastectomy specimens acquired at 35 keV. The highest-resolution phantom for each specimen served as the reference. Phantoms were downsampled by increasing in-plane voxel size and slice thickness, and MGD was recalculated using EGSnrc/DOSXYZnrc. A 4.5% difference from reference MGD was adopted as the accuracy criterion. Primary photon histories were then reduced to determine the minimum required for acceptable MC precision. A common voxel size of 0.30 x 0.30 x 3.00 mm3 maintained MGD within 4.5% of reference for all four phantoms while reducing voxel number by approximately 20-31-fold. MGD was more sensitive to in-plane voxel size than slice thickness, supporting anisotropic downsampling. Reduced-resolution phantoms enabled a 15-fold reduction in photon histories to 2 x 10^8 while maintaining acceptable statistical uncertainty. Combined optimization reduced computation time from approximately 1600 to 72 min, a 22-fold acceleration. Patient-specific phantoms can be substantially downsampled while maintaining MGD accuracy and markedly reducing computational burden. This optimization provides a foundation for future real-time patient-specific BCT dosimetry.

We derive the consistency conditions governing the propagating content of linear shear-free perturbations of Friedmann-Lemaître-Robertson-Walker cosmologies in metric $f(R)$ gravity. The divergence of the shear-free constraint is shown to be the total momentum-conservation equation and therefore does not imply geodesic flow. Its projected time derivative instead supplies a nontrivial integrability condition. Scalar, vector, and tensor sectors must then be tested separately. Shear-freeness removes the independent transverse-traceless electric-magnetic Weyl pair, so no ordinary $+$ or $\times$ tensor gravitational wave survives. The scalaron is not removed algebraically, but its four-variable harmonic system must remain in the time-dependent consistent subspace generated by the shear-free constraint and all of its time derivatives. For a geodesic shear-free congruence in the spatially flat expanding de Sitter patch, this excludes every nonzero fixed comoving scalar harmonic, including the healthy $R+\alpha R^2-2\Lambda$ model with $\alpha,\Lambda>0$. Vector modes obey a curvature-dependent global eigenvalue condition whose right-hand side is negative for positive-density matter with $f'>0$ and $1+w>0$; hence no nonzero vector harmonic survives on that branch. The familiar coasting $R^3$ example evades this sign obstruction only because it lies on an $f'<0$ branch. Thus tensor radiation is absent in the imposed shear-free sector, whereas scalar radiation is not excluded kinematically but remains a model- and background-dependent constraint-closure question.

The propagation of narrowband wave packets is a classical problem with broad relevance across nonlinear wave physics. Within the framework of the nonlinear Schrödinger equation, solitons are known to propagate without changing shape, whereas Gaussian envelopes may undergo substantial reshaping depending on the balance between dispersion and nonlinearity. Here, we combine laboratory experiments with numerical simulations to systematically investigate the evolution of hydrodynamic Gaussian wave packets over a wide range of amplitudes and spectral bandwidths. We show that when the envelope amplitude and width match those of the stationary NLSE soliton solution, the wave packet propagates steadily in the wave flume. More generally, by varying the amplitude of the Gaussian envelope, the wave packet may undergo either dispersive broadening or nonlinear focusing, resembling the dynamics of Satsuma-Yajima breathers. These findings may facilitate the controlled generation and manipulation of localized wave packets in a variety of nonlinear dispersive systems, including optics, plasmas, and Bose-Einstein condensates.

We investigate how black hole spin and the amount of magnetic flux affect electromagnetic energy dissipation and radiation transport in supercritical accretion flows. For this purpose, we perform general relativistic radiation magnetohydrodynamic simulations of MAD and SANE accretion flows with different black hole spins. In the high-spin MAD model, we find that a fraction of the electromagnetic energy extracted by the Blandford–Znajek mechanism is dissipated near the disk surface in the vicinity of the black hole. This dissipation significantly contributes to the generation of radiative energy and enhances the luminosity. The time-averaged radiative efficiency reaches $\eta_{\rm rad}=0.60$, which is much larger than $0.088$ for the non-spinning black hole case and $0.21$ for the weak-magnetic-flux case, corresponding to the SANE state. As a result, the effective trapping radius, defined as the radius at which the outward radiative luminosity becomes equal to the inward radiative luminosity, is $r_{\rm trap}=2.5r_{\rm g}$, comparable to the ISCO radius. This value is significantly smaller than $12r_{\rm g}$ for the non-spinning case and $8.5r_{\rm g}$ for the SANE state. These results suggest that the amount of magnetic flux accumulated on the black hole can affect the radiative properties of supercritical accretion flows and should therefore be considered, in addition to black hole mass, spin, and mass accretion rate, when interpreting observed luminosities and spectra.

Being structures characterized by discrete rotational symmetry $\mathcal{C}_\nu$ of order $\nu$, photonic quasicrystals are capable to support stable propagation of linear vortex-carrying light beams and vortex solitons. However, the impact of discrete rotational symmetry $\nu$ of quasicrystals on the properties of vortex light states was not investigated so far, as only the systems constructed using the simplest Penrose tiling or corresponding optically induced Penrose lattices were considered in this context. Here we propose a broad class of quasicrystals with global topological defects – disclinations – introduced into their structure that allows to produce new quasicrystalline structures with any desired order of discrete rotational symmetry from basic Penrose structure. Such global topological deformation substantially enriches linear spectrum of quasicrystals, allowing them to support new types of linear vortex states and bifurcating from them families of stable thresholdless vortex solitons with unusual intensity and phase distributions. We found two different classes of stable vortex solitons consisting of in-phase or out-of-phase pairs of closely located bright spots, with total intensity distribution reflecting particular discrete rotational symmetry of the quasicrystal with disclination. Remarkably, even low-charge vortex solitons can be stable in quasicrystals with disclinations, while stability intervals for them broaden with decrease of the discrete rotational symmetry $\mathcal{C}_\nu$ of quasicrystal. Our results expand the theory of localization in quasicrystals to structures with global topological deformation, highlighting new prospects for robust transmission of power or information arising in these systems.

Quantum Schrödinger bridge constructions establish the existence of a conditioned process under a positivity hypothesis on the endpoint data, and three independent ones adopt it. We show that hypothesis fails on a definite locus once the conditioned object is the two-state amplitude $\phi^*\psi$ of a pre- and post-selected pair on configuration space, and that the failure is testable on recorded data. Whenever $\phi^*\psi$ has a moving zero of order $k$ across which probability flows, no diffusion of constant diffusion coefficient can both carry the conditioned density and avoid the nodal curve: the current velocity it would need grows as the inverse $2k$-th power of the distance to that curve and points toward it on one side, placing the curve at finite scale distance, so it is reached and not merely approached. Identifying the weak momentum with a bridge drift fails independently: for a free particle post-selected in position the current velocity is exactly minus the drift of the bridge to the target. The positive Doob $h$-transform and the Bernstein conditioning built on it exist wherever $\phi^*\psi$ is nodeless and fail on the nodal curve. There the osmotic part of the weak momentum diverges as the inverse distance to the zero and changes sign across it with a coefficient set by $k$, while the current part stays bounded; that boundedness rests on the signed factorization of the real-envelope class and hides the obstruction from any picture built on the current velocity alone. A measured fringe visibility fixes a single length, which puts a Lorentzian of order $10^{-3}$ into the current channel reconstructed in the two-slit trajectory experiment if the contrast is limited by an off-axis zero, and nothing there if by incoherence. The results are one-dimensional, covering the separable transverse field of a two-slit geometry, not general two-dimensional vortices.

Quantum computers promise advantages for simulating strongly correlated quantum many-body systems, like atomic nuclei, that are beyond the reach of classical computers. Realizing this potential requires understanding the quantum complexity structure of the target problem. We investigate the time-evolution of two key indicators of quantum complexity, bipartite entanglement entropy and non-local magic (non-stabilizerness), in nuclear reaction dynamics. We analyze two representative dynamical processes: scattering in a one-dimensional model of strongly interacting fermions governed by the Negele potential, and a realistic simulation of $^{240}$Pu fission within time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory. In the former case, we find that interactions dynamically generate both entanglement and non-local magic, leaving persistent signatures of quantum complexity in the outgoing states. In the latter, we observe that substantial quantum complexity survives in the spatial bipartition of daughter fragments well beyond scission. The presence of significant non-local magic and entanglement in both cases strongly indicate that quantum computers would provide substantial advantages for accurately simulating nuclear reaction dynamics.

The non-extensive entropy models applied to the black-hole horizon are connected to the generalized Einstein–Hilbert action, $f(R)$, via the Wald entropy formalism. We demonstrate that quark star configurations characterized by the MIT bag model under this modified gravity approach conform to the observational lower and upper bounds established for compact objects linked to HESS J1731$-$347 and GW190814. Furthermore, we assess the effective energy conditions and corresponding speed of sound to evaluate the physical plausibility and stability of the stellar configurations. All non-extensive entropy models studied satisfied these conditions. Our findings show that the exotic compact objects offer a compelling and credible framework for exploring aspects of non-extensive entropy models, such as the Barrow, Tsallis-Cirto, and Rényi formalisms, and vice versa.

Changing-look active galactic nuclei (CLAGN) exhibit rapid spectral transitions on timescales of months to years, challenging standard AGN unification models and providing unique insight into accretion-disk variability and obscuration processes. Despite their scientific importance, systematic searches for CLAGN remain limited by the scarcity of multi-epoch spectroscopy and the difficulty of constructing large samples efficiently. We introduce CLAS+, a catalog constructed by comparing synthetic photometry derived from DESI DR1 and SDSS DR17 spectra with contemporaneous narrow-band imaging from the S-PLUS survey. Applying our pipeline to a parent sample of 98,139 quasars, we select high-confidence CLAGN candidates above a threshold of reduced chi-squared $\chi_r^2 > 15$. We identify 3,554 strong CLAGN candidates, corresponding to 3.6% of the parent sample. This selected fraction is conditional on the adopted criterion and should not be interpreted as an intrinsic CLAGN occurrence rate. Cross-matching with existing CLAGN compilations shows that CLAS+ identifies a large population of previously unreported high-priority candidates (3,481). Among the spectroscopic–photometric comparisons with reliable temporal classification, 40% are classified as photometric turn-on, 41% as intermediate, and 19% as turn-off. We also find an apparent redshift dependence in the relative fractions, with photometric turn-on candidates becoming more common at higher redshifts within the CLAS+ selected sample. Therefore, narrow-band photometry provides a powerful and efficient alternative to purely spectroscopic searches for identifying CLAGN candidates at scale. CLAS+ substantially expands the known CLAGN candidate population and provides a valuable target list for future spectroscopic follow-up and time-domain studies with facilities such as Rubin/LSST.

We introduce a diagnostic framework based on the full probability distribution of quantum coherence to probe single-particle and many-body phases at finite temperature. We first apply this approach to the localization transition in the non-interacting Aubry-André model and then extend the analysis to its interacting counterpart, whose phase diagram is substantially richer. We show that the moments of the coherence distribution provide clear signatures of quantum phase transitions and capture the emergence of many-body phases. More importantly, we find that the entropy of the coherence distribution emerges as an even more powerful indicator, retaining clear signatures of the underlying quantum phases while remaining remarkably robust against increasing thermal fluctuations.

Super-resolution machine learning methods hold promise for addressing the high computational costs associated with high-dimensional features in traditional transport simulations. This paper proposes a physics-enhanced neural network coupling algorithm for discrete ordinates (SN) transport calculations. Based on high- and low-accuracy data, we develop a predictor-corrector neural network (pcNN) to predict correction factors for coarse-grid solutions. Based on transport equations, local physical features containing subgrid-scale information are selected as network inputs. Dimensionless transformation of physical quantities reduces the input space dimensionality and narrows parameter distributions, facilitating network training. Physical constraints are incorporated into the network model, and the corrected solution retains its original conservation properties. pcNN and SN transport sweeps are internally coupled, and numerical solutions are corrected online. Numerical results demonstrate that this algorithm can effectively improve coarse-grid solutions to achieve a level of accuracy comparable to that of fine-grid results. The physics-based network design enables the model to demonstrate a certain degree of reusability under different computational conditions. Compared to mesh refinement, the pcNN-SN algorithm reduces the computation time for the three-dimensional test problem by more than 60%.

For positive exponents $\alpha_1,\ldots,\alpha_4$ we evaluate the cyclic four-electron Slater integral, the topology recorded as case V in Bonham's 1965 classification, in a finite real expression of weight at most three. The general answer is an explicit sum of eighteen blocks involving only logarithms, dilogarithms and trilogarithms of rational functions of the exponents; all logarithm arguments are positive and all nonconstant polylogarithm arguments may be placed in $(-1,1)$, so no radical, generalized polylogarithm, contour prescription or unevaluated limit is required. At equal exponents the value collapses to $I(\lambda,\lambda,\lambda,\lambda)=(4\pi)^4\lambda^{-4}[\mathrm{Li}_3(1/4)/2-7\zeta(3)/24+\pi^2\log 2/12-2\log^3 2/3]$, a weight-three period over $\mathbb{Q}$ ramified only at 2 and 3. Three independently implemented numerical routes agree at four exponent tuples to at least 32 decimal places, an exact-dyadic evaluation of the classical formula gives eight 100-place certificates, and three published four-electron calibration values are reproduced to every printed digit. We also prove the small- and large-exponent limit laws with closed-form coefficients, dihedral symmetry, and a strict rearrangement law for the three inequivalent cyclic placements of four exponents. The formula applies to the four-cycle and does not evaluate the two chorded topologies.

Classical macroscopic electrodynamics allows free and bound sources to cancel as distributions while the auxiliary equations retain nonzero free-source terms. A neutralized uniformly polarized sphere has $\mathbf{E}=\mathbf{0}$ and $\mathbf{D}=\mathbf{P}$, and a compensated uniformly magnetized sphere has $\mathbf{B}=\mathbf{0}$ and $\mathbf{H}=-\mathbf{M}$. These auxiliary fields are fixed by $\mathbf{P}$ and $\mathbf{M}$ rather than forming independent degrees of freedom. Time dependence separates charge cancellation from complete four-current cancellation. Canceling the charge alone leaves a divergence-free total current whose on-shell transverse transform controls radiation. For a neutralized polarized sphere of radius $R$ maintained by a tangential free-current sheet, the exterior field equals that of a point electric dipole whose effective moment is proportional to the spherical Bessel function $j_2(kR)$, where $k=\omega/c$. Every charge multipole and the ordinary magnetic dipole vanish, yet the source radiates at generic frequencies, and the complete exterior field vanishes at nonzero roots of $j_2$. Complete four-current cancellation removes all retarded source-generated fields. Among the compactly supported separable currents that maintain the same charge, it is the only choice that never radiates. In vacuum the auxiliary fields reduce to $\mathbf{D}=\varepsilon_0\mathbf{E}$ and $\mathbf{H}=\mathbf{B}/\mu_0$, so no radiation can be carried by $\mathbf{D}$ and $\mathbf{H}$ alone.

Hamiltonian embeddings can represent dissipative nonreciprocal classical dynamics exactly on invariant manifolds of enlarged reciprocal systems. We show that canonical quantization of such an embedding need not commute with reduction to the target dynamics. For the mirror construction recently introduced for pairwise nonreciprocal interactions, the invariant manifold is Lagrangian. Exact quantum enforcement of the mirror condition therefore removes the dynamical sector rather than producing a quantum analogue of the reduced flow. If the constraint is imposed only semiclassically, contraction of the target dynamics generates inverse-transpose expansion in the conjugate mirror directions. Quantum uncertainty then gives $\ln D\ge\Xi(t)+n\ln[\pi/(\sigma\epsilon)]$, where $\Xi=-\ln|\det M|$ is the accumulated contraction and $D$ the torus Hilbert-space dimension. Exact finite-dimensional Weyl evolution of one- and two-degree-of-freedom nonreciprocal models confirms the resulting logarithmic correspondence time, including its predicted change when the initial localization scales with $\hbar$. Thus the classical embedding is exact, but its direct canonical quantization is a singular semiclassical construction.

Multi-detector programs such as Earth 2.0 (ET) require detector characterization across different technologies, operating conditions, and production batches, together with consistent procedures for operation, characterization, and device selection. Traditional laboratory workflows often distribute camera control, illumination, image analysis, and report generation across detector-specific programs and manual steps, slowing iterative development and hindering standardized characterization. We address this gap with PixelXVision, a layered software platform that combines a common camera SDK, preset-based configuration, and a runtime plugin system. Detector-specific behavior is configured through declarative presets, allowing the same host interface to operate CCD, CMOS, and infrared detectors without model-specific core changes. Characterization procedures are implemented as plugins that use a shared object manager to access camera, illumination, storage, and database services. Each run links raw frames, measured operating conditions, configuration, analysis products, and reports into a traceable archive with a queryable index. The platform supports lightweight deployment for iterative single-detector development and structured workflows for multi-detector campaigns. The platform has been applied in characterization testing across CMOS, CCD, and HgCdTe cameras, and its configurable architecture can accommodate additional camera models for subsequent CCD testing for WFST without model-specific changes to the core host software. For operational troubleshooting, the platform integrates ChatPixel, a knowledge-base assistant that provides answers with cited sources when it has relevant information.

We investigate the projective and resurgent structure of a spin hydrodynamic attractor in Bjorken expansion. We show that the nonlinear spin solution family is determined by the projective classes of the two dimensional linear solution space, with the attractor and repellor corresponding to two distinguished projective directions and the linear modes ratio generating the full one-parameter transseries tower. Using the projective transseries structure, we show analytically that the data of repellor are encoded in the Borel-Stokes structure of the attractor expansion. These results provide an explicit analytic realization of resurgence relations that are often extracted through high order expansions and numerical Borel analysis, and yield a unified description of the attractor, the repellor, and their Borel-Stokes connection in minimal causal spin hydrodynamics.

The odd- and even-parity gravitational perturbations of a Schwarzschild black hole are governed by the distinct Regge-Wheeler and Zerilli potentials, yet their quasinormal-mode (QNM) spectra are identical in vacuum. Building on our previous study of the odd-parity Regge-Wheeler spectrum [M. Ould El Hadj and S. R. Dolan, arXiv:2608.16283], we investigate the corresponding even-parity Zerilli problem and compare the two sectors under the same perturbation of amplitude $\epsilon$ at radius $r_0$. Using the Chandrasekhar-Detweiler relation, we derive an exact relation between the normalized Wronskians and show that Schwarzschild QNM isospectrality is not preserved under an identical nonzero localized defect. We find that the even- and odd-parity repelling-point branches approach the same Schwarzschild QNM frequencies at large $r_0$, with their first parity-dependent separation appearing at order $1/\mathcal R^2$, where $\mathcal R=r_{0*}/M$ is the dimensionless tortoise-coordinate location of the defect. The corresponding exceptional points (EPs) form two shifted sequences with the same asymptotic spacing in the tortoise coordinate, while their relative displacement is fixed by the phase of the asymptotic Chandrasekhar-Detweiler factor. The critical perturbation amplitudes share the same exponential decay rate in the two sectors, whereas the ratio of their asymptotic prefactors is fixed by the modulus of the same factor. We further find that the even- and odd-parity EPs connect the same neighboring QNM overtones, with nearly identical arclengths for the corresponding spectral bridges. Finally, the exceptional degeneracy is parity selective: at identical values of $(r_0,\epsilon)$, a pair of QNMs may coalesce at an EP in one parity sector while remaining distinct in the other, leading to a corresponding difference in the local pole structure of the ringdown response.

Marine lakes offer a unique opportunity to study how physical processes, such as turbulent mixing, biomixing, and tidal exchanges, regulate the vertical transport of heat, oxygen, and nutrients in relatively isolated ecosystems. The effective diffusion coefficient characterizes the overall mixing and is critical in models of marine lakes, but it is difficult to measure directly. This paper addresses the problem of inferring the depth-dependent diffusion coefficient from synthetic and real measurements of vertical temperature and salinity profiles. To do so, an inverse problem governed by a marine lake model described by the screened-Poisson equation (similar to Helmholtz) is formulated. The inverse problem is formulated as a nonlinear least-squares optimization problem, where the cost functional quantifies the misfit between the observed and recovered profiles. A Tikhonov regularization term is added to improve the conditioning of the discretized problem, with a regularization parameter chosen using the L-curve method. We solve this problem using an adjoint-based inexact Gauss-Newton method. To leverage the complementary information in these profiles, the formulation optimizes the fit across both datasets simultaneously. The accuracy of the reconstructed diffusion coefficient and the method's robustness to noise are investigated through comprehensive synthetic studies. Additionally, we contrast this framework with physics-informed neural networks, highlighting the advantages and limitations of each. When applied to real marine lake data, the adjoint method reconstructed a smaller diffusion coefficient in regions of strong density stratification, in line with physical expectations. The results indicate that the proposed approach provides a foundation for accurate modeling of marine lake dynamics.

In this study, we investigate the role of bulk viscosity in the evolution of a spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe dominated by dust. We parameterize the bulk viscosity as p_tilde = -3[l + m(H'(t) + H^2) + nH^2]H, derive the modified Einstein field equations, and reformulate them in terms of redshift z. Using 46 Hubble parameter measurements and the Pantheon+ compilation of 1701 supernovae, we estimate the model parameters (H0, l, m, n) through chi2 minimization and refine them using Markov chain Monte Carlo (MCMC) simulations. The analysis gives a transition redshift z_t = 0.585 and a present deceleration parameter q0 = -0.705, consistent with Lambda CDM. The present age of the universe is estimated as t0 = 14.5734 Gyr. We obtain H0 = 68 km/s/Mpc from the Hubble datasets and approximately 73 km/s/Mpc from Pantheon+. These results illustrate the Hubble tension between late- and early-universe determinations of H0. We further investigate the evolution of the equation-of-state parameter omega(z), energy density rho(z), and pressure p(z). Statefinder diagnostics (r,s) demonstrate deviations from and convergence toward Lambda CDM at different epochs. The results highlight the potential role of bulk viscosity in describing the accelerated expansion of the universe and provide a useful framework for studying cosmological models.

Generalized trace dynamics (GTD) is a deterministic dynamics of aikyons (atoms of space-time-matter) whose near-equilibrium statistical mechanics yields quantum dynamics, while large anti-self-adjoint fluctuations drive spontaneous localisation and emergent classical spacetime. We separate two independent large limits: long-Connes-time coarse-graining of a finite system, which conditionally yields the quantum Ward identities, and the extensive many-aikyon/large-matrix limit required for a collective singularity. We turn the condensed-matter analogy of the E8 x omega E8 programme into a quantitative, falsifiable effective framework. Four coupled composite channels (bifermionic localisation, geometric soldering/Lorentz-Higgs, gauge-invariant electroweak, and matrix-valued flavour) define an exact susceptibility matrix and Legendre effective action, giving zero-mode and free-energy criteria for a common continuous or first-order transition. We pose the nonequilibrium problem in Schwinger-Keldysh form, define a projected fluctuation-dissipation defect and the martingale condition for Born probabilities, identify Newton's constant with the stiffness of the ordered geometric phase, and give conditions under which the Sakharov, constrained-BF, Jacobson, Padmanabhan and Verlinde descriptions of gravity are limits of one substrate. A regulated two-sector surrogate ensemble (a Myers-deformed geometric triple coupled to a matter matrix, with a Grassmann-regulated fermionic extension) shows that selected diagnostics are calculable: exact Adler-Millard charge conservation, a multi-channel first-order jump, a verified fluctuation-dissipation relation and its quench defect, and a fermionic spectral dimension d_s = 1.96 on the emergent two-sphere. The result is a calculational programme, not a completed derivation; the next step is the many-aikyon composite two-point matrix for GTD itself.

We develop a covariant Hamiltonian formalism in which evolution is measured along the proper-time flow of an observer congruence, replacing the external coordinate-time derivative with the Lie derivative. Our formalism keeps the Hamiltonian split between evolution and configuration variables and expresses it through spacetime tensors projected relative to the chosen congruence. After quantization, the resulting observer-congruent brackets lead to relativistic Heisenberg and Schrödinger equations whose evolution parameter is proper time. We then apply this framework to gravity by taking the projected spatial metric and its conjugate momentum as canonical variables, obtaining a complete model of canonical quantum gravity. Among the predictions of this theory we find a resolution to the singularity problems in cosmology, black holes and black hole thermodynamics.

The existence of three fermion generations remains one of the unexplained structural features of the Standard Model. This article reviews an algebraic framework in which an intrinsic $S_3$ family symmetry relates three gauge-equivalent fermion sectors. The framework is motivated by division- and Clifford-algebra constructions in which the complex octonions and $\mathbb{C}\ell(6)$ organise the colour and electromagnetic quantum numbers of one generation. Continuing the Cayley–Dickson sequence, the sedenions provide an intrinsic $S_3$ automorphism structure, while their complexified left-multiplication operators generate an associative algebra isomorphic to $\mathbb{C}\ell(8)$. In the $\mathbb{C}\ell(8)$ formulation, the order-three family action generates three linearly independent fermion sectors while leaving a single $\mathfrak{su}(3)_C\oplus\mathfrak{u}(1)_{\mathrm{em}}$ gauge algebra. Extension to $\mathbb{C}\ell(10)$ incorporates a single $\mathfrak{su}(3)_C\oplus\mathfrak{su}(2)_L\oplus\mathfrak{u}(1)_Y$ gauge algebra, with each generation including a right-handed neutrino sterile under the SM gauge interactions. We place the construction in context by comparing it with representative algebraic and family-symmetry approaches to three generations, including triality-based proposals, and clarify why the family symmetry used here is distinct from standard $\operatorname{Spin}(8)$ triality despite the common appearance of $\mathbb{C}\ell(8)$ and $S_3$. The framework remains algebraic and representation theoretic rather than a complete dynamical theory; family-symmetry breaking, realistic fermion masses and mixing, and a dynamical account of the gauge and matter sectors remain open problems.

Dark matter is theorized to be gravitationally captured within the Earth and to subsequently annihilate into dark photons. The dark photons kinetically mix with the Standard Model photons which would allow the decay of the dark photon to pairs of observable fermions near Earth's surface. We examine the feasibility and sensitivity of an LHC-class general-purpose detector to observe muons originating from these dark matter models. We calculate the expected signal rates at a hypothetical general-purpose detector and examine the effect of significant backgrounds on sensitivity. We also consider experimental efficiencies of such a detector to determine expected limits for the proposed analysis. We find these expected limits constitute a significant improvement over existing ones, strongly motivating a search for upward-going muons stemming from dark matter bound within the Earth.

We construct an evolving wormhole cosmological model from a Morris–Thorne metric with a separable, time-dependent shape function in a spatially flat Friedmann–Lemaitre–Robertson–Walker background, deriving the corrected wormhole energy-momentum tensor and a volume-averaging procedure that yields a modified Friedmann equation with a redshift-dependent wormhole correction term. We show that the shape-function index and throat-evolution exponent combine into a single macroscopic exponent $\beta$, and we demonstrate that the resulting wormhole equation of state is consistent with this geometric averaging. All traversability conditions are verified. Confronting the model with cosmic chronometer, DESI Data Release~2 BAO, and standard BAO data across seven dataset combinations, our findings show that all combinations are mutually consistent, with the joint fit giving a present-day expansion rate intermediate between local and CMB-inferred values, a deceleration-to-acceleration transition consistent with independent determinations, and an effective dark-energy equation of state close to, but distinguishable from, a pure cosmological constant. The evolving throat radius offers a novel, geometry-specific observable for discriminating wormhole spacetimes from phenomenological dark-energy parametrisations.

We formalize the gauge structure of the Navier–Stokes equation for incompressible fluids, interpreting $\nabla\cdot\mathbf{v}=0$ as a gauge fixing analogous to the Coulomb gauge in electromagnetism. We construct the Martin–Siggia–Rose action and its full BRST symmetry, introducing BRST doublets for the Gribov parameter $\gamma$ and the monodromy phase $\theta$. Through a Higgs mechanism, $\gamma$ acquires a vacuum expectation value $\gamma_{0}$, generating a mass scale for the vorticity and the ghosts; we compute the one-loop effective potential and analyze vacuum stability. Intermittency — measured by the exponents $\zeta_{n}$ — is described by fluctuations of the Higgs field $\sigma$ around the condensate, via a Gribov-inspired log-Poisson hierarchy that satisfies exactly $\zeta_{3}=1$ (Kolmogorov's four-fifths law). Fits to DNS data favor filamentary vorticity structures, with $D_{f}\approx1$ (one parameter) or $D_{f}\approx2.1$, $\Delta\approx0.44$ (two parameters). The one-loop anomalous dimension in $d=3$, $\Delta_{\sigma}\approx0.50$, supports the identification $D_{f}=2\Delta_{\sigma}$. The formalism unifies classical hydrodynamics with gauge theory and spontaneous symmetry breaking, opening the study of turbulence and intermittency to quantum field theory methods.