In this paper, we mainly predict the rates of $M1$ radiative and spin-nonflip $\pi \pi$ transitions of the $B_c$-meson under the nonrelativistic Cornell potential model with a screening potential effect. We employ the numerical wave function to determine the $M1$ radiative transition widths of $B_c$ excited states and utilize the Kuang-Yan proposed method for the spin-nonflip $\pi \pi$ transitions among $B_c$ states. Our theoretical results are valuable for studying the $M1$ radiative and spin-nonflip $\pi \pi$ transition processes of $B_c$ states in experiments.

We study $B^{\pm }\to K^{\pm }{K}^{+}{K}^{-}$ decays using the QCD factorization model with final state interactions between $K^{+}$ and $K^{-}$ mesons taken into account. The parameters of the model are fitted to the data of the BABAR and LHCb collaborations. We describe the $K\overline{K}$ effective mass distributions and examine the $CP$-violating asymmetry effects in the full range of the Dalitz plot.

The two-particle momentum correlation functions between charm mesons (${\mathrm{D}}^{*\pm }$ and ${\mathrm{D}}^{\pm }$) and charged light-flavor mesons (${\pi }^{\pm }$ and ${\mathrm{K}}^{\pm }$) in all charge combinations are measured for the first time by the ALICE Collaboration in high-multiplicity proton–proton collisions at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$. For DK and ${\mathrm{D}}^{*}\mathrm{K}$ pairs, the experimental results are in agreement with theoretical predictions of the residual strong interaction based on quantum chromodynamics calculations on the lattice and chiral effective field theory. In the case of $\mathrm{D}\pi$ and ${\mathrm{D}}^{*}\pi$ pairs, tension between the calculations including strong interactions and the measurement is observed. For all particle pairs, the data can be adequately described by Coulomb interaction only, indicating a shallow interaction between charm and light-flavor mesons. Finally, the scattering lengths governing the residual strong interaction of the $\mathrm{D}\pi$ and ${\mathrm{D}}^{*}\pi$ systems are determined by fitting the experimental correlation functions with a model that employs a Gaussian potential. The extracted values are small and compatible with zero.

We investigate the effect of the charm quark on the chiral phase transition of light quarks at finite temperature based on the four-flavor soft-wall holographic QCD model. In the massless limit, we find that the thermal chiral phase transition is of the second order in the four-quark-flavor system. In the case with the massive charm quark and the massless light and strange quarks, the order of the phase transition changes to the first order. This is due to the quark-flavor symmetry breaking which is associated with the violation of the $U(1)$ axial symmetry. Once the light and strange quarks get massive, the explicit chiral symmetry breaking becomes eminent, and then the crossover phase transition is realized at the physical quark masses. We also map the order of the phase transition on a phase diagram in the quark-mass plane where the light- and strange-quark masses are degenerate but differ from the value of the charm-quark mass. This phase diagram is an extension of the conventional Columbia plot to the four-quark-flavor system. The critical exponents related to the chiral phase transition are also addressed.

We introduce a discrete, graph theoretical approach to conformal field theory correlators. In a certain basis, called the squid basis, the correlator of $N$ scalar operators can be expressed as the determinant of a natural, conformally covariant metric on a weighted graph, called the squid graph. We present the construction of this metric and discuss its possible role in constraining conformal data.

We introduce an algorithm to marginalize the likelihood for a gravitational wave signal from a quasicircular binary merger over its extrinsic parameters, accounting for the effects of higher harmonics and spin-induced precession. The algorithm takes as input the matched-filtering time series of individual waveform harmonics against the data in all operational detectors, and the covariances of the harmonics. The outputs are the Gaussian likelihood marginalized over extrinsic parameters describing the merger time, location and orientation, along with samples from the conditional posterior of these parameters. Our algorithm exploits the waveform’s known analytical dependence on extrinsic parameters to efficiently marginalize over them using a single waveform evaluation. Our current implementation achieves a 10% precision on the marginalized likelihood within $\approx 50\mathrm{ms}$ on a single CPU core and is publicly available through the package cogwheel. We discuss applications of this tool for (i) gravitational wave searches involving higher modes or precession, (ii) efficient and robust parameter estimation, and (iii) generation of sky localization maps in low latency for electromagnetic followup of gravitational-wave alerts. The inclusion of higher modes can improve the distance measurement, providing an advantage over existing low-latency localization methods.

We explore the idea of restoring the full diffeomorphism (Diff) invariance in theories with only transverse diffeomorphisms (TDiff) by the introduction of additional fields. In particular, we consider in detail the case of a TDiff invariant scalar field and how Diff symmetry can be restored preserving locality by introducing an additional vector field. We reobtain the corresponding dynamics and energy-momentum tensor from the covariantized action and analyze the potential and kinetic domination regimes. For the former, the theory describes a cosmological constant–type behavior, while for the latter we show that the theory can describe an adiabatic perfect fluid whose equation of state and speed of sound is obtained in a straightforward way. Furthermore, the reformulation with the full symmetry allows us to analyze the gravitational properties of the theory beyond those particular regimes. In particular, we find the general expression for the effective speed of sound of the nonadiabatic perfect fluid, which provides us with physically reasonable conditions that should be satisfied by the coupling functions. Finally, we investigate the particular models leading to an adiabatic fluid.

We investigate a gedanken experiment to destroy an extremally charged black hole by dropping a test particle, provided that there are multiple $U(1)$ gauge fields coupled with each other through higher derivative interactions. It is known that the Coulomb repulsion prevents a test particle that would break the extremal condition from falling into an extremal black hole and therefore the black hole cannot be destroyed. We extend this observation to include higher derivative corrections. Although the extremal condition is modified by the higher derivative interactions, we find that the repulsive force induced by the higher derivative couplings is responsible for preventing a test particle that would break the modified extremal condition to reach the event horizon. Thus, we confirm that the weak cosmic censorship conjecture holds for extremally charged black holes even in the presence of higher derivative corrections, as long as the test particle approximation is justified.

Postadiabatic models of extreme- and intermediate-mass-ratio inspirals will require calculations of second-order gravitational self-force effects in the spacetime of a spinning, Kerr black hole. We take a step toward such calculations by implementing the recently formulated Teukolsky puncture scheme with Green-Hollands-Zimmerman metric reconstruction [Classical Quantum Gravity 39, 015019 (2022)]. This scheme eliminates the critical obstacle of gauge singularities that arise in the standard “no-string” metric reconstruction. Our first proof-of-principle implementation is limited to the simple case of circular orbits in Schwarzschild spacetime, but the method also applies to generic orbits on a Kerr background. We conclude with a discussion of various approaches to the second-order self-force problem in Kerr.

We study static and spherically symmetric black hole (BH) solutions in extended Einstein-Maxwell-scalar theories which is classified in a subclass of the $U(1)$ gauge-invariant scalar-vector-tensor theories. The scalar field is coupled to the vector field, which has electric and magnetic charges. We investigate modifications to the Reissner-Nordström solution focusing on the three types of scalar-vector interactions, including derivative couplings. We solve the field equations analytically in two asymptotic regions, which are the vicinity of the BH horizon and spatial infinity, and clarify the condition for the existence of scalar hair. To understand the behaviors of solutions in intermediate scales, the field equations are integrated numerically for concrete models with different types of couplings. We find new hairy BH solutions with scalar hair in the presence of magnetic charge and kinetic coupling. The magnetic charge plays an important role in distinguishing hairy BH solutions originated from three types of different interactions at a large coupling limit.

In this paper, we study the magnetic reconnection process of energy extraction from a rapidly rotating Kerr-Newman-modified-gravity (MOG) black hole by investigating the combined effect of black hole charge and the MOG parameter. We explore the energy efficiency of energy extraction and power by applying the new energy extraction mechanism proposed by Comisso and Asenjo. Based on an attractive gravitational charge of the MOG parameter $\alpha$ that physically manifests to strengthen black hole gravity, we show that the combined effect of the MOG parameter and black hole charge can play an increasingly important role and accordingly lead to high energy efficiency and power for the energy extraction via the magnetic reconnection. Further, we study to estimate the rate of energy extraction under the fast magnetic reconnection by comparing the power of the magnetic reconnection and Blandford-Znajek (BZ) mechanisms. We show that the rate of energy extraction increases as a consequence of the combined effect of black hole charge and MOG parameter. It suggests that magnetic reconnection is significantly more efficient than the BZ mechanism. In fact, the magnetic reconnection is fueled by magnetic field energy due to the twisting of magnetic field lines around the black hole for the plasma acceleration, and thus the MOG parameter gives rise to even more fast spin that can strongly change the magnetic field reconfiguration due to the frame dragging effect. This is how energy extraction is strongly enhanced through the magnetic reconnection, thus making the energy extraction surprisingly more efficient for the Kerr-Newman-MOG black hole than the Kerr black hole under the combined effect of black hole charge and MOG parameter.

Since the recent derivation of a well-defined $D\to 4$ limit for regularized 4D Einstein-Gauss-Bonnet (4DEGB) gravity, there has been considerable interest in testing it as an alternative to Einstein’s general theory of relativity. In this paper we construct slowly rotating black hole solutions for 4DEGB gravity in asymptotically flat, de Sitter, and anti–de Sitter spacetimes. At leading order in the rotation parameter, exact solutions of the metric functions are derived and studied for all three of these cases. We compare how physical properties (innermost stable circular orbits, photon rings, black hole shadow, etc.) of the solutions are modified by varying coupling strength of the 4DEGB theory relative to standard Einstein gravity results. We find that a vanishing or negative cosmological constant in 4DEGB gravity enforces a minimum mass on the black hole solutions, whereas a positive cosmological constant enforces both a minimum and maximum mass with a horizon root structure directly analogous to the Reissner-Nordström–de Sitter spacetime. Besides this, many of the physical properties are qualitatively similar to general relativity, with the greatest deviations typically being found in the low (near-minimal) mass regime.

The multipole moments of black holes in general relativity obey certain consistency relations known as the no hair theorems. The details of this multipolar structure are imprinted into the gravitational waves emitted by binary black holes, particularly if the binary is precessing. If black holes do not obey the vacuum field equations of general relativity, then the no hair theorems may be broken, and the observed gravitational waves will be modified, thus providing an important test of the no hair theorems. Recently, analytic solutions to the precession dynamics and inspiral waveforms were computed within the context of binaries possessing nonaxisymmetric mass quadrupole moments, which are parametrized by a modulus $q_{\mathcal{m}}$ and phase $a_{\mathcal{m}}$ with $\mathcal{m}=1$, 2 the azimuthal spherical harmonic number. Here, we use a Fisher analysis to study plausible constraints one may obtain on generic, nonaxisymmetry quadrupole configurations using current and future ground-based detectors. For nonprecessing binaries, we generically find that no meaningful constraints can be placed with current detectors on the nonaxisymmetry parameters $(q_{\mathcal{m}},a_{\mathcal{m}})$ due to the presence of strong degeneracies with other waveform parameters, while with next generation detectors, only weak constraints are possible. For precessing configurations, the exact value of the uncertainty is strongly dependent on the sky location, system orientation relative to the line of sight, and initial inclination angle of the orbital angular momentum. After averaging over these parameters, we find that with GWTC-3-like events, one should be able to plausibly constraint nonaxisymmetric mass quadrupole deviations to $\mathrm{\Delta }{q}_{\mathcal{m}}\sim {10}^{-2}$ for LIGO at design sensitivity, and $\mathrm{\Delta }{q}_{\mathcal{m}}\sim {10}^{-4}$ for the same sources with Einstein Telescope and Cosmic Explorer.

Hořava-Lifshitz gravity has been proposed as a renormalizable and ghost-free quantum gravity model candidate with an anisotropic UV-scaling between space and time. We present here a cosmological background analysis of two different formulations of the theory, with particular focus on the running of the parameter $\lambda$. Using a large dataset consisting of cosmic microwave background data from Planck, $\text{Pantheon}+\text{supernovae}$ catalog, SH0ES Cepheid variable stars, baryon acoustic oscillations (BAO), cosmic chronometers, and gamma-ray bursts (GRB), we arrive at new bounds on the cosmological parameters, in particular $\lambda$, which runs logarithmically with energy and describes deviation from general relativity, which corresponds to $\lambda =1$ For the detailed balance scenario we arrive at the bound $\lambda =1.0406\pm 0.0023$, and for beyond detailed balance the limit reads $\lambda =1.0064\pm 0.0002$. We also study the influence of different datasets and priors, and we find that removing low-redshift data generally moves $\lambda$ closer toward UV values, while simultaneously widening the error bars. In the detailed balance scenario, this effect is more noticeable, and without prior $\lambda \ge 1$ it takes on values that are significantly below unity.

Pulsar-timing collaborations have recently reported evidence for the detection of an isotropic stochastic gravitational-wave background (SGWB) consistent with one sourced by a population of inspiraling supermassive black hole binaries. However, a certain degree of anisotropy and polarization may be present. Thus, the characterization of the energy density and polarization of the background at different angular scales is important. In this paper, we describe the signatures of linear polarization in the stochastic gravitational-wave background on the timing residuals obtained with pulsar-timing arrays. We expand the linear polarization map in terms of spin-weighted spherical harmonics and recast it into the $E$-mode (parity even) and $B$-mode (parity odd) basis. We provide expressions for the minimum-variance estimators for the coefficients of that expansion and evaluate the smallest detectable signal as a function of the signal-to-noise ratio with which the isotropic GW signal is detected and the number of pulsars in the survey. We evaluate the covariance between the estimators for the spherical-harmonic coefficients of the linear polarization $E$ modes and those for the intensity anisotropy. We also show that there is no covariance between the spherical-harmonic coefficients for the $B$ modes of the linear polarization and those for the circular polarization, even though both have the same parity. Under the simplifying assumptions of our harmonic analysis, we show that detection of the lowest-order linear-polarization anisotropies is only possible if the isotropic intensity contribution is measured with a signal-to-noise ratio $\ge 300$, with a pulsar-timing network comprised of more than $\sim 100$ pulsars. We also show that, in this limit, the lowest order anisotropies in the $E$ mode have a negligible covariance with corresponding anisotropies in the SGWB intensity. Our approach results in simple, elegant, and easily evaluated expressions for the overlap reduction functions for linear polarization.

Charge-coupled devices (CCDs) are a leading technology in direct searches for dark matter because of their eV-scale energy threshold and micrometer-scale spatial resolution. Recent studies have also highlighted the potential for using CCDs to detect coherent elastic neutrino-nucleus scattering. The sensitivity of future CCD experiments could be enhanced by distinguishing nuclear recoil signals from electronic recoil backgrounds in the CCD silicon target. We present a technique for event-by-event identification of nuclear recoils based on the spatial correlation between the primary ionization event and the defect cluster left behind by the recoiling atom, later identified as a localized excess of leakage current under thermal stimulation. By irradiating a CCD with an ${}^{241}\mathrm{Am}{}^9\mathrm{Be}$ neutron source, we demonstrate $>93\%$ identification efficiency for nuclear recoils with energies $>150\mathrm{keV}$, where the coincident ionization events were confirmed to be nuclear recoils due to their topology. The technique remains fully efficient down to 90 keV, decreasing to 50% at 8 keV and reaching $(6\pm 2)\%$ between 1.5 and 3.5 keV. Irradiation with a ${}^{24}\mathrm{Na}$ gamma-ray source does not result in any detectable defect clusters, with the fraction of electronic recoils with energies $<85\mathrm{keV}$ that are spatially correlated with defects $<0.1\%$.

We study ${\nu }_{\mu }\text{−}{\nu }_s$ and ${\overline{\nu }}_{\mu }\text{−}{\overline{\nu }}_s$ mixing in the protoneutron star (PNS) created in a core-collapse supernova (CCSN). We point out the importance of the feedback on the general composition of the PNS in addition to the obvious feedback on the ${\nu }_{\mu }$ lepton number. We show that for our adopted mixing parameters $\delta m^2\sim {10}^2{\mathrm{keV}}^2$ and ${\sin }^{2}2\theta$ consistent with the current constraints, sterile neutrino production is dominated by the Mikheyev–Smirnov–Wolfenstein conversion of ${\overline{\nu }}_{\mu }$ into ${\overline{\nu }}_s$ and that the subsequent escape of ${\overline{\nu }}_s$ increases the ${\nu }_{\mu }$ lepton number, which in turn enhances muonization of the PNS primarily through ${\nu }_{\mu }+n\to p+{\mu }^{-}$. While these results are qualitatively robust, their quantitative effects on the dynamics and active neutrino emission of core-collapse supernovae should be evaluated by including ${\nu }_{\mu }\text{−}{\nu }_s$ and ${\overline{\nu }}_{\mu }\text{−}{\overline{\nu }}_s$ mixing in the simulations.

Sunlike stars can transmute into comparable mass black holes by steadily accumulating heavy nonannihilating dark matter particles over the course of their lives. If such stars form in binary systems, they could give rise to quasi-monochromatic, persistent gravitational waves, commonly known as continuous gravitational waves, as they inspiral toward one another. We demonstrate that next-generation space-based detectors, e.g., Laser Interferometer Space Antenna (LISA) and Big Bang Observer (BBO), can provide novel constraints on dark matter parameters (dark matter mass and its interaction cross-section with the nucleons) by probing gravitational waves from transmuted sunlike stars that are in close binaries. Our projected constraints depend on several astrophysical uncertainties and nevertheless are competitive with the existing constraints obtained from cosmological measurements as well as terrestrial direct searches, demonstrating a notable science case for these space-based gravitational wave detectors as probes of particle dark matter.

We propose the Optomechanical Dark-matter Instrument (ODIN), based on a new method for the direct detection of low-mass dark matter. We consider dark matter interacting with superfluid helium in an optomechanical cavity. Using an effective field theory, we calculate the rate at which dark matter scatters off phonons in a highly populated, driven acoustic mode of the cavity. This scattering process deposits a phonon into a second acoustic mode in its ground state. The deposited phonon ($\mathrm{\mu }\mathrm{eV}$ range) is then converted to a photon (eV range) via an optomechanical interaction with a pump laser. This photon can be efficiently detected, providing a means to sensitively probe keV scale dark matter. We provide realistic estimates of the backgrounds and discuss the technical challenges associated with such an experiment. We calculate projected limits on dark matter–nucleon interactions for dark matter masses ranging from 0.5 to 300 keV and estimate that a future device could probe cross sections as low as $\mathcal{O}({10}^{-32}){\mathrm{cm}}^2$.