Once a gravitational-wave signal is detected, the measurement of its source parameters is important to achieve various scientific goals. This is done through Bayesian inference, where the analysis cost increases with the model complexity and the signal duration. For typical binary black hole signals with precession and higher-order modes, one has 15 model parameters. With standard methods, such analyses require at least a few days. For strong gravitational-wave lensing, where multiple images of the same signal are produced, the joint analysis of two data streams requires 19 parameters, further increasing the complexity and run time. Moreover, for third-generation detectors, due to the lowered minimum sensitive frequency, the signal duration increases, leading to even longer analysis times. With the increased detection rate, such analyses can then become intractable. In this work, we present a fast and precise parameter estimation method relying on relative binning and capable of including higher-order modes and precession. We also extend the method to perform joint Bayesian inference for lensed gravitational-wave signals. Then, we compare its accuracy and speed to those of state-of-the-art parameter estimation routines by analyzing a set of simulated signals for the current and third generation of interferometers. Additionally, we analyze some real events known to contain higher-order modes [Phys. Rev. D 102, 043015 (2020). and Astrophys. J. Lett. 896, L44 (2020).] with relative binning. For binary black hole systems with a total mass larger than $50M_{\odot }$, our method is about 2.5 times faster than current techniques. This speedup increases for lower masses, with the analysis time being reduced by a factor of 10 on average. In all cases, the recovered posterior probability distributions for the parameters match those found with traditional techniques.

This study provides a comprehensive analytical investigation of the bound and unbound motion of magnetized particles orbiting a Schwarzschild black hole immersed in an external asymptotically uniform magnetic field, which includes all conceivable types of bounded and unbounded orbits. In particular, for planetary orbits, we perform a comparative analysis of our findings with the observed position of the S2 star carrying magnetic dipole moment around Sagittarius A*. We found maximum and minimum values for the parameter of magnetic interaction between the magnetic dipole of the star and the external magnetic field, as well as the energy and angular momentum of the S2 star. As a result, we obtain estimations of the magnetic dipole of the star in the order of ${10}^6\mathrm{G}·{\mathrm{cm}}^3$. Additionally, we explore deflecting trajectories akin to gravitational Rutherford scattering. In obtaining the solutions for the orbital equations, we articulate the elliptic integrals and Jacobi elliptic functions, and illustrative figures and simulations augment our study.

Recent measurements and analyses from the Dark Energy Spectroscopic Instrument (DESI) collaboration and supernova surveys combined with cosmic microwave background (CMB) observations, indicate that the dark energy density changes over time. Here we explore the possibility that the dark energy density is constant, but that the cosmological recombination history differs substantially from that in $\mathrm{\Lambda }\mathrm{CDM}$. When we free up the ionization history, but otherwise assume the standard cosmological model, we find the combination of CMB and DESI data prefer (i) early recombination qualitatively similar to models with small-scale clumping, (ii) a value of $H_0$ consistent with the estimate from the SH0ES collaboration at the $2\sigma$ level, and (iii) a higher CMB lensing power, which takes pressure off of otherwise tight constraints on the sum of neutrino masses. Our work provides additional motivation for finding physical models that lead to the small-scale clumping that can theoretically explain the ionization history preferred by DESI and CMB data.

We describe a new mechanism, whose ingredients are realized in string compactifications, for the formation of cosmic (super)string networks. Oscillating string loops grow when their tension $\mu$ decreases with time. If $2H+\dot{\mu }/\mu <0$, where $H$ is the Hubble parameter, loops grow faster than the scale factor and an initial population of isolated small loops (for example, produced by nucleation) can grow, percolate, and form a network. This condition is satisfied for fundamental strings in the background of a kinating volume modulus rolling toward the asymptotic large volume region of moduli space. Such long kination epochs are motivated in string cosmology by both the electroweak hierarchy problem and the need to solve the overshoot problem. The tension of such a network today is set by the final vacuum; for phenomenologically appealing large volume scenario vacua, this would lead to a fundamental string network with $G\mu \sim {10}^{-10}$.

There is limited information about the interaction strength of a scalar dark matter candidate with hadrons and leptons for a scalar particle mass exceeding ${10}^{-3}\mathrm{eV}$ while its interaction with photon is well studied. The scalar-photon coupling constant receives quantum corrections from one-loop Feynman diagrams which involve the scalar-lepton, scalar-quark, and scalar-W-boson vertices. We calculate these one-loop quantum corrections and find new limits on the scalar particle interactions with electron, muon, tau, quarks, nucleons, gluons, Higgs, and W-bosons by repurposing the results of experiments measuring the scalar-photon interaction. Limits on interactions of heavy leptons and quarks have been obtained for the first time, and limits on other interactions in certain mass intervals are 2 to 15 orders of magnitude stronger than those presented in previous publications and exclude the resolution of the muon $g-2$ anomaly with scalar particle.

Condensed matter materials have shown great potential in searching for light dark matter (DM) via detecting the phonon or magnon signals induced by the scattering of DM off the materials. In this paper, we study the possibility of detecting electromagnetic form factors of fermionic DM and axionlike particles (ALPs) using superfluid ${}^4\mathrm{He}$. The phonon induced by a sub-GeV fermionic DM scattering off the superfluid can be described using the effective field theory with the interaction between DM and the bulk ${}^4\mathrm{He}$. Signals arising from the electromagnetic form factors of light DM in the presence of an external electric field are calculated. Projected constraints on the charge radius, anapole moment, and magnetic moment of the DM are derived with $1\mathrm{kg}·\mathrm{yr}$ exposure. The phonon signal induced by the scattering of ALPs off the superfluid is also calculated, which can put competitive and the first direct detection bounds on ALP-photon-dark photon couplings in the projected experiments.

We study the dynamics of spin mode by solving the axial kinetic equations under the relaxation time approximation in the presence of dissipative sources. We find transient spin modes in response to the electric field with spacetime inhomogeneity, fluid acceleration and shear. To the lowest order in spatial momentum $k$, we find the responses to electric field and acceleration can be interpreted as a retarded response to temporal variations of the magnetic field and vorticity respectively. The response to shear occurs at $O(k^2)$ and can be reduced to a retarded response to the spatial variation of vorticity. Beyond lowest order, the responses to all three sources are nonlocal with branch cut in the dispersions. We argue that the nonlocality is a consequence of the quasiparticle picture underlying the kinetic description. We also analyze the spin transport equation taking into account the spin response to temporal and spatial variations of vorticity. We find the corrections turn the original first order spin transport equation into a third order one (or a second order one in the homogeneous limit). The change in order of the transport equation is a consequence of the nonlocal nature of the responses, suggesting a possible breakdown of gradient expansion in spin hydrodynamics for microscopic theories with quasiparticles.

In our recent work [S. Noh and W. Park, Nonrelativistic quark model analysis of $T_{cc}$, Phys. Rev. D 108, 014004 (2023)], the mass and binding energy of $T_{cc}$ are found to be 3873 MeV and $-2\mathrm{MeV}$, respectively, which align with the observations reported at LHCb [R. Aaij (LHCb Collaboration), Observation of an exotic narrow doubly charmed tetraquark, Nat. Phys. 18, 751 (2022)]. Based on our latest quark model approach, we extend our search for other potentially stable configurations of doubly heavy tetraquarks using our nonrelativistic quark model described in Noh and Park, [Nonrelativistic quark model analysis of $T_{cc}$, Phys. Rev. D 108, 014004 (2023)]. Our numerical calculations indicate that the $\overline{u}\overline{s}cb$ configuration is deeply bound. However, the $\overline{u}\overline{d}cb$ configuration with the isospin symmetry in the light quark sector is relatively less bound. In this study, we emphasize a compulsory aspect for requiring a complete set of three-dimensional harmonic oscillator bases through the discussion of the $\overline{u}\overline{s}cb$ configuration and investigate the essential differences between the $\overline{u}\overline{s}cb$ and $\overline{u}\overline{d}cb$ configurations.

We revisit the dissociation of heavy quarkonia by thermal partons at the next-to-leading order (NLO, also known as inelastic parton scattering dissociation) in the quark-gluon plasma (QGP). Utilizing the chromoelectric dipole coupling from quantum chromodynamics (QCD) multipole expansion as an effective Hamiltonian, this has been conducted in the approach of second-order quantum mechanical perturbation theory, which allows us to systematically incorporate the bound state wave functions. Employing the quarkonium wave functions and binding energies obtained from an in-medium potential model, we then numerically evaluate the dissociation cross sections and rates for various charmonia and bottomonia, where the infrared and collinear divergences are regularized by the thermal masses of medium partons. We demonstrate that distinct from the leading order (LO, also known as gluo-dissociation) counterparts peaking at relatively low gluon energy and falling off thereafter, the NLO cross sections first grow and then nearly saturate as the incident parton energy increases, as a result of the outgoing parton carrying away the excess energy. The resulting NLO dissociation rates increase with temperature and take over from the LO counterparts toward high temperatures, similar to pertinent findings from previous studies. We also evaluate the in-medium second-order transition between different bound states, which may contribute to the total thermal decay widths of heavy quarkonia in the QGP.

We study the influence of magnetic field on the running coupling constant using a bottom-up holographic model. We use the boundary condition that ensures the agreement with lattice calculations of string tension between quarks at zero chemical potential. The location of the 1st order phase transitions in $(\mu ,T)$-plane does not depend on the dilaton boundary conditions. We observe that the running coupling $\alpha$ decreases with increasing magnetic field for the fixed values of chemical potential and temperature. At the 1st order phase transitions, the functions $\alpha$ undergo jumps depending on temperature, chemical potential, and magnetic field.

Using both the in-out formalism and the monodromy method, we study the emission of charges from near-extremal charged Nariai black holes with the black hole event and cosmological horizons close to each other, whose near-horizon geometry is ${\mathrm{dS}}_2\times {\mathrm{S}}^2$. The emission becomes catastrophic for a charge with energy greater than its chemical potential, whose leading exponential factor increases inversely proportional to the separation of two horizons. This effect may prevent near-extremal Nariai black holes with large charges that evaporate dominantly through the charge emission from evolving to black holes with a naked singularity, in analog to near-extremal RN-dS black holes that have the Breitenlohner-Friedman bound, below which they become stable against Hawking radiation and Schwinger effect of charge emission. The near-extremal Nariai black holes with small charges, which are close to near-extremal Schwarzschild-de Sitter black holes, emit dominantly charge-neutral particles and evolve to black holes with increasing charge to mass ratio. We illuminate the origin of the catastrophic emission in the phase-integral formulation and monodromy method by comparing near-extremal charged Nariai black holes with near-extremal Reissner-Nordtröm-dS black holes.

In this study, we employ eth-operators and spin-weighted spherical harmonics to express the ADM mass of a static spacetime in terms of the mean values of its components over a radius-$r$ sphere. While initially derived for standard spherical coordinates, we demonstrate its versatility by applying it to express a quasilocal mass, specifically the Bartnik mass, for surfaces $\mathrm{\Sigma }$ representing linear perturbations of the 2D-sphere in the 3D-Euclidean manifold. Additionally, leveraging this formulation, we propose a neural network approach for numerically constructing static metrics with an inner boundary $\mathrm{\Sigma }$, viewed as general perturbations of the 2D sphere with a specified Bartnik mass.

We study wave metrics in the context of Cotton gravity and conformal Killing gravity. First, we consider $pp$-wave metrics with flat and nonflat wave surfaces and show that they are exact solutions to the field equations of these theories. More explicitly, the field equations reduce to inhomogeneous Laplace and Helmholtz differential equations, depending on the curvature of the two-dimensional geometry of the wave surfaces. An interesting point here is that the ones with nonflat wave surfaces are not present in classical GR, which manifests a crucial distinction between these theories and GR. Moreover, we investigate Kerr-Schild-Kundt metrics in the context of these theories and show that, from among these metrics, only the AdS wave metrics solve the field equations of these theories. However, AdS spherical and dS hyperbolic wave metrics do not solve the field equations of these theories, which is in contrast to the classical GR. In the case of AdS wave metrics, the field equations of these theories reduce to an inhomogeneous Klein-Gordon equation. We give all the necessary and sufficient conditions for the metric function $V$ to solve these field equations.

We calculate the interferometric signatures of black hole photon rings beyond the universal regime by perturbatively including the effects of finite ring width. Our approach first slices a thick ring into a series of thin rings, each of which falls within the universal regime. We thus calculate the visibility of the thick ring by aggregating the contributions from each thin ring and then perturbatively expand the result into polynomials of the baseline length $u$. We show that the visibility amplitude of a thick ring depends on its “center-of-light” diameter; it also includes additional higher-order corrections due to the width of the ring, with the leading correction terms proportional to $u^2$ for the envelope and $u^3$ for the phase. We apply our method to images ray traced from general-relativistic magnetohydrodynamic simulations and demonstrate that incorporating the higher-order corrections is crucial for accurately modeling the visibility of the first photon ring around M87*.

Ionization produced by low-energy nuclear recoils is among the primary direct signatures of dark matter interactions. Despite the urgency of dark matter detection and the recent measurements of coherent elastic neutrino-nucleus scattering, detector response to nuclear recoils is not well characterized in the ${\mathrm{keV}}_{\mathrm{nr}}$ and $\mathrm{sub}\text{−}{\mathrm{keV}}_{\mathrm{nr}}$ regime across a variety of materials. We have reperformed a measurement of the ionization produced by monoenergetic $254{\mathrm{eV}}_{\mathrm{nr}}$ nuclear recoils in Ge with improved digital electronics and additional systematic studies. Our results indicate an ionization yield of $64\pm 8{\mathrm{eV}}_{\mathrm{ee}}$ corresponding to a quenching factor of $25\%\pm 3\%$, greater than the 14% predicted by the Lindhard model. This ionization enhancement could greatly improve the sensitivity of high-purity Ge detectors in dark matter detection and measurement of neutrinos via coherent scattering.

Radioactive decays from ${}^{42}\mathrm{Ar}$ and its progeny ${}^{42}\mathrm{K}$ are potential background sources in large-scale liquid-argon-based neutrino and dark matter experiments. In the atmosphere, ${}^{42}\mathrm{Ar}$ is produced primarily by cosmogenic activation on ${}^{40}\mathrm{Ar}$. The use of low radioactivity argon from cosmogenically shielded underground sources can expand the reach and sensitivity of liquid-argon-based rare event searches. We estimate ${}^{42}\mathrm{Ar}$ production underground by nuclear reactions induced by natural radioactivity and cosmic-ray muon-induced interactions. At 3000 mwe, ${}^{42}\mathrm{Ar}$ production rate is $1.8\times {10}^{-3}$ atoms per ton of crust per year, seven orders of magnitude smaller than the ${}^{39}\mathrm{Ar}$ production rate at a similar depth in the crust. By comparing the calculated production rate of ${}^{42}\mathrm{Ar}$ to that of ${}^{39}\mathrm{Ar}$ for which the concentration has been measured in an underground gas sample, we estimate the activity of ${}^{42}\mathrm{Ar}$ in gas extracted from 3000 mwe depth to be less than two decays per ton of argon per year.

We study the possibility of testing a dark matter (DM) scenario embedded in a global lepton number symmetry $U(1{)}_L$ via gravitational waves (GWs) and cosmic microwave background (CMB) observations. The spontaneous breaking of $U(1{)}_L$ symmetry generates the seesaw scale as well as DM mass dynamically. The (pseudo-)Nambu-Goldstone boson, known as a Majoron, acquires nonzero mass due to soft symmetry-breaking terms of quadratic type in the scalar potential, which eventually breaks $U(1{)}_L$ to its $Z_2$ subgroup. The spontaneous symmetry breaking, which effectively breaks $Z_2$, leads to the formation of domain walls (DWs), posing a threat to successful cosmology, if allowed to dominate. As gravity does not respect any global symmetries, we consider higher-dimensional operators suppressed by the scale of quantum gravity (QG), namely, ${\mathrm{\Lambda }}_{\mathrm{QG}}$, which introduces the required bias leading to DW annihilation and emission of stochastic GWs observable at near future experiments. The same operators also lead to decay of DM bringing interesting indirect detection aspects. While DM is produced nonthermally via scalar portal interactions, light Majorons can give rise to additional $\mathrm{\Delta }{N}_{\mathrm{eff}}$ within reach of future CMB experiments.

Hierarchical decays of $N$ matter species to radiation may balance against Hubble expansion to yield stasis, a new phase of cosmological evolution with constant matter and radiation abundances. We analyze stasis with various machine learning techniques on the full $2N$-dimensional space of decay rates and abundances, which serve as inputs to the system of Boltzmann equations that governs the dynamics. We construct a differentiable Boltzmann solver to maximize the number of stasis $e$-folds $\mathcal{N}$. High-stasis configurations obtained by gradient ascent motivate log-uniform distributions on rates and abundances to accompany power-law distributions of previous works. We demonstrate that random configurations drawn from these families of distributions regularly exhibit many $e$-folds of stasis. We additionally use them as priors in a Bayesian analysis conditioned on stasis, using stochastic variational inference with normalizing flows to model the posterior. All three numerical analyses demonstrate the generality of stasis and point to a new model in which the rates and abundances are exponential in the species index. We show that the exponential model solves the exact stasis equations, is an attractor, and satisfies $\mathcal{N}\propto N$, exhibiting inflation-level $e$-folding with a relatively low number of species. This is contrasted with the $\mathcal{N}\propto \log (N)$ scaling of power-law models. Finally, we discuss implications for the emergent string conjecture and string axiverse.

We compute the renormalized Dirac spectral density in $N_f=2+1$ QCD at physical quark masses, temperature $T=230\mathrm{MeV}$, and system size $L_s=3.4\mathrm{fm}$. To that end, we perform a pointwise continuum limit of the staggered density in lattice QCD with staggered quarks. We find, for the first time, that a clear infrared structure (IR peak) emerges in the density of the Dirac operator describing dynamical quarks. We also provide numerical evidence that a component of this peak, which becomes dominant in the thermodynamic limit, is due to a nontrivial accumulation of near-zero modes. Features of this structure are consistent with those previously attributed to the recently proposed IR phase of thermal QCD. Our results (i) provide the only complete first-principles evidence that these IR features exist and are physical, (ii) improve the upper bound for IR phase transition temperature $T_{\mathrm{IR}}$ so that the new window is $200<T_{\mathrm{IR}}<230\mathrm{MeV}$, and (iii) are consistent with the nonrestoration of anomalous ${\mathrm{U}}_{\mathrm{A}}(1)$ symmetry (chiral limit) below $T=230\mathrm{MeV}$.