We present the next-to-next-to-leading order (NNLO) quantum chromodynamics (QCD) corrections to the decay constants for both the pseudoscalar $B_c$ meson and the vector $B_c^{*}$ meson in the nonrelativistic QCD (NRQCD) effective theory. The explicit NNLO calculations prove that the $B_c$ decay constant from the pseudoscalar current is identical with the $B_c$ decay constant from the axial-vector current. The NNLO result for the vector decay constant of $B_c^{*}$ meson is novel. Combining this result with the latest extraction of the NRQCD long-distance matrix elements of $B_c$ and $B_c^{*}$ meson, we calculate and show the theoretical predictions for the branching ratios of the leptonic decays $B_c^{+}/B_c^{*+}\to l^{+}{\nu }_l$ with $l^{+}=(e^{+},{\mu }^{+},{\tau }^{+})$. In addition, the novel anomalous dimension for the flavor-changing heavy quark vector current in the NRQCD effective theory is helpful to investigate the threshold behaviors of the two different heavy quarks.

We determine the strange quark mass ($m_s$) and quark mixing element $|V_{us}|$, and their joint determination from the Cabibbo suppressed hadronic $\tau$ decays in various perturbative schemes. We improve this analysis compared to the previous analysis based on the optimal renormalization or the renormalization group summed perturbation theory (RGSPT) scheme by replacing the theoretical longitudinal contributions with phenomenological parametrization; the RGSPT coefficients are used for the dimension-4 Adler functions. The improved analysis results in the extraction of $m_s(2\mathrm{GeV})=98\pm 19\mathrm{MeV}$ and $|V_{us}|=0.2191\pm 0.0043$ from the RGSPT scheme.

We analyze the generalized quasi, Ioffe-time, and pseudodistributions of the valence quarks in the pion at the quark model scale. We use the framework of the Nambu-Jona-Lasinio model and investigate the basic question of how fast the pion has to move to effectively reach the infinite momentum limit, where the approach can provide the information on the generalized parton distribution functions. We consider both the vector distributions and the transversity distributions, related to the spin densities. With the developed analytic expressions, we conclude that to effectively approach the infinite momentum limit in the Ioffe-time distributions for values of the Ioffe-time accessible in lattice QCD, one roughly needs the pion momenta of the order of $\sim 3\mathrm{GeV}$. We explore polynomiality of the quasidistributions and study the generalized quasi form factors. The issue of separability of the transverse and longitudinal dynamics in the model is studied with the help of the generalized Ioffe-time distributions, with the conclusion that the breaking is not substantial, unless the momentum transfer $t$ is large. We also provide an estimate of the range of the Ioffe-time values needed to obtain the generalized parton distributions with a reasonable accuracy. Our model results, which are analytic or semianalytic, provide a valuable insight into the theoretical formalism and illustrate the intricate features of the investigated distributions.

We study violation of quark-hadron duality for $\overline{B}\to X_{u}l\nu$ and $D\to X_{d}l\nu$ decays in the presence of the right-handed current operator. For this case, we show that duality violation has some aspects different from the standard model due to the existence of an instanton. In particular, the fermionic zero mode of an intermediate light quark can give a nonvanishing contribution owing to its chirality structure. A duality-violating component that arises from a single instanton is then analytically extracted as a finite-distance singularity, leading to an oscillatory correction to the observable in Minkowski space. Finally, we show that the size of duality violation for the lepton energy distribution in $\overline{B}$ decays can be comparable to the chirally suppressed perturbative contribution, although the absolute size depends on the detail of the QCD vacuum.

We present a simple algorithm for the calculation of event weights embedding the effects of anomalous electric and magnetic dipole moments in simulation of $e^{-}{e}^{+}\to {\tau }^{-}{\tau }^{+}(n\gamma )$ events, and the subsequent decay of the $\tau$-leptons produced. The impact of these weights on the spin-correlation matrix and the total cross section is taken into account. The algorithm is prepared to work in situ the Monte Carlo kkmc program without the need for introducing any external change to the generator libraries. As an example, $e^{-}{e}^{+}\to {\tau }^{-}{\tau }^{+}(n\gamma )$, ${\tau }^{-}\to {\rho }^{-}{\nu }_{\tau }\to {\pi }^{-}{\pi }^0{\nu }_{\tau }$, ${\tau }^{+}\to {\rho }^{+}{\overline{\nu }}_{\tau }\to {\pi }^{+}{\pi }^0{\overline{\nu }}_{\tau }$ events were simulated at a center-of-mass energy of 10.58 GeV. The distributions of the acoplanarity angle between the planes spanned by the ${\pi }^{-}{\pi }^0$ and the ${\pi }^{+}{\pi }^0$ momenta of, respectively, ${\rho }^{-}$ and ${\rho }^{+}$ decays and in the rest frame of the entirely visible ${\rho }^{-}{\rho }^{+}$ system are presented for different values of the coupling constants incorporating anomalous electric and magnetic dipole moments in the ${\tau }^{-}{\tau }^{+}\gamma$ vertex.

Based on a data sample of $(448.1\pm 2.9)\times {10}^6\psi (3686)$ events collected with the BESIII detector at the BEPCII collider, the branching fraction of $\psi (3686)\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}\omega$ is measured to be $(3.30\pm 0.34(\mathrm{stat})\pm 0.29(\mathrm{syst}))\times {10}^{-5}$ for the first time. In addition, the $\mathrm{\Lambda }\omega$ (or $\overline{\mathrm{\Lambda }}\omega$) invariant mass spectra is studied and the potential presence of excited $\mathrm{\Lambda }$ states has been investigated.

In this work, we first derive the corrections to the instanton configuration of the flavored gauge field in the D4–D8 model with generic flavor numbers. Then, as the instanton configuration on the D8-branes represents equivalently baryon in this model, keeping our corrections in hand, we systemically study the spectrum of baryon, heavy-light baryon, or heavy-light meson and find it is possible to fit the experimental data with the meson data in this model. We also briefly outline how to include the interaction of glueball and heavy-light meson or baryon with our corrections, evaluate numerically the decay rate of the heavy-light meson or baryonic matter involving glueball. Since it is possible to fit all the spectra with the same choice of the parameters to the experimental data, we believe our corrections improve the framework of D4–D8 model and the corrected instanton configuration is also useful to investigate other properties of baryon in holography.

Warped anti-de Sitter (WAdS)/warped conformal field theory (WCFT) correspondence is an interesting realization of non-AdS holography. It relates three-dimensional warped anti-de Sitter (${\mathrm{WAdS}}_3$) spaces to a special class of two-dimensional quantum field theory with chiral scaling symmetry that acts only on right-moving modes. The latter are often called warped conformal field theories (${\mathrm{WCFT}}_2$), and their existence makes WAdS/WCFT particularly interesting as a tool to investigate a new type of two-dimensional conformal structure. Besides, WAdS/WCFT is interesting because it enables one to apply holographic techniques to the microstate counting problem of non-AdS, nonsupersymmetric black holes. Asymptotically ${\mathrm{WAdS}}_3$ black holes (${\mathrm{WBH}}_3$) appear as solutions of topologically massive theories, Chern-Simons theories, and many other models. Here, we explore ${\mathrm{WBH}}_3\times {\mathrm{\Sigma }}_{D-3}$ solutions of $D$-dimensional higher-curvature gravity, with ${\mathrm{\Sigma }}_{D-3}$ being different internal manifolds, typically given by products of deformations of hyperbolic spaces, although we also consider warped products with time-dependent deformations. These geometries are solutions of the second order higher-curvature theory at special (critical) points of the parameter space, where the theory exhibits a sort of degeneracy. We argue that the dual (W)CFT at those points is actually trivial. In many respects, these critical points of ${\text{WAdS}}_3\times {\mathrm{\Sigma }}_{D-3}$ vacua are the squashed/stretched analogs of the ${\mathrm{AdS}}_D$ Chern-Simons point of Lovelock gravity.

In some instances of study of quantum evolution of classical backgrounds it is considered inevitable to resort to nonperturbative methods at the price of treating the system semiclassically. We show that a fully quantum perturbative treatment, in which the background is resolved as a multiparticle state, recovers the semiclassical nonperturbative results and allows going beyond. We reproduce particle creation by a classical field in a theory of two scalars as well as in scalar QED in terms of scattering processes of high multiplicity. The multiparticle treatment also gives a transparent picture of why a single-process transition from a classical to a quantum state, which we call quantumization, is exponentially suppressed, whereas the opposite process, classicalization, can take place swiftly if the microstate degeneracy of the classical state is high. An example is provided by the $N$-graviton portrait of a black hole: a black hole can form efficiently via a $2\to N$ classicalization process in the collision of high-energy particles, but its quantumization via a decay $N\to 2$ is exponentially suppressed.

We construct the covariantly defined multipole moments on the common horizon of an equal-mass, nonspinning, quasicircular binary-black-hole system. We see a strong correlation between these multipole moments and the gravitational waveform. We find that the multipole moments are well described by the fundamental quasinormal modes at sufficiently late times. For each nonzero multipole moment with $\ell \le 6$, at least two fundamental quasinormal modes of different $\ell$ are detectable in the best model. These models provide faithful estimates of the true mass and spin of the remnant black hole. We also show that by including overtones, the $\ell =m=2$ mass multipole moment admits an excellent quasinormal-mode description at all times after the merger. This demonstrates the perhaps surprising power of perturbation theory near the merger.

We investigate gravitational waves (GWs) generated in a two-field inflationary model with a noncanonical kinetic term, in which the gravitational Chern-Simons term is coupled to a heavy dynamical field. In such a model, primordial GWs experience a period of resonant amplification for some modes. In addition, isocurvature perturbations suffer from a temporary tachyonic instability due to an effective negative mass, which source curvature perturbations, resulting in large induced GWs. These two stochastic gravitational wave backgrounds correspond to different frequency bands, which are expected to be detected by future GW detectors such as SKA, LISA, and Taiji.

We present a formulation of Einstein-Maxwell vacuum fields due to plane fronted electromagnetic waves sharing their wave fronts with gravitational waves. This is based on a recent geometrical reconstruction of plane fronted wave fields by the authors that clearly identifies the cases in which the wave fronts collide or do not collide. In the former case our construction suggests an explicit example of a searchlight beam, accompanied by gravitational radiation, which sweeps across the sky. This gravitoelectromagnetic searchlight and its properties are described in detail.

Recent population studies have searched for a subpopulation of primordial black holes (PBHs) in the gravitational-wave (GW) events so far detected by LIGO/Virgo/KAGRA (LVK), in most cases adopting a phenomenological PBH mass distribution. When deriving such a population from first principles in the standard scenario, however, the equation of state of the Universe at the time of PBH formation may strongly affect the PBH abundance and mass distribution, which ultimately depend on the power spectrum of cosmological perturbations. Here we improve on previous population studies on several aspects: (i) we adopt state-of-the-art PBH formation models describing the collapse of cosmological perturbations across the QCD epoch; (ii) we perform the first Bayesian multipopulation inference on GW data including PBHs and directly using power spectrum parameters instead of phenomenological distributions; (iii) we critically confront the PBH scenario with LVK phenomenological models describing the GWTC-3 catalog both in the neutron-star and in the BH mass ranges, also considering PBHs as a subpopulation of the total events. Our results confirm that LVK observations prevent the majority of the dark matter to be in the form of stellar mass PBHs. We find that the best-fit PBH model can comprise a small fraction of the total events, in particular it can naturally explain events in the mass gaps. If the lower mass-gap event GW190814 is interpreted as a PBH binary, we predict that LVK should detect up to a few subsolar mergers and one to $\approx 30$ lower mass-gap events during the upcoming O4 and O5 runs. Finally, mapping back the best-fit power spectrum into an ultra-slow-roll inflationary scenario, we show that the latter predicts detectable PBH mergers in the LVK band, a stochastic GW background detectable by current and future instruments, and may include the entirety of dark matter in asteroid-mass PBHs.

We show how consistency relations can be used to robustly extract the amplitude of local primordial non-Gaussianity ($f_{\mathrm{NL}}$) from the squeezed limit of the matter bispectrum, well into the nonlinear regime. First, we derive a nonperturbative relation between primordial non-Gaussianity and the leading term in the squeezed bispectrum, revising some results present in the literature. This relation is then used to successfully measure $f_{\mathrm{NL}}$ from $N$-body simulations. We discuss the dependence of our results on different scale cuts and redshifts. Specifically, the analysis is strongly dependent on the choice of the smallest soft momentum, $q_{\min }$, which is the most sensitive to primordial bispectrum contributions, but is largely independent of the choice of the largest hard momentum, $k_{\max }$, due to the non-Gaussian nature of the covariance. We also show how the constraints on $f_{\mathrm{NL}}$ improve at higher redshift, due to a reduced off-diagonal covariance. In particular, for a simulation with $f_{\mathrm{NL}}=100$ and a volume of $(2.4\mathrm{Gpc}/h{)}^3$, we measure $f_{\mathrm{NL}}=98\pm 12$ at redshift $z=0$ and $f_{\mathrm{NL}}=97\pm 8$ at $z=0.97$. Finally, we compare our results with a Fisher forecast, showing that the current version of the analysis is satisfactorily close to the Fisher error. We regard this as a first step towards the realistic application of consistency relations to constrain primordial non-Gaussianity using observations.

We propose a novel method to examine whether Galactic double neutron star binaries are formed in the Laser Interferometer Space Antenna (LISA) band. In our method, we assign an effective time fraction $\tau$ to each double neutron star binary detected by LISA. This fraction is given as a function of the observed orbital period and eccentricity and should be uniformly distributed in the absence of in-band binary formation. Applying statistical techniques such as the Kolmogorov-Smirnov test to the actual list of $\tau$, we can inspect the signature of the in-band binary formation. We discuss the prospects of this method, paying close attention to the available sample number of Galactic double neutron star binaries around 1 mHz.

The existence of eV-mass sterile neutrinos is not ruled out because of persistent experimental anomalies. Upcoming multimessenger detections of neutron-star merger remnants could provide indirect constraints on the existence of these particles. We explore the active-sterile flavor conversion phenomenology in a two-flavor scenario (one active plus one sterile species) as a function of the sterile neutrino mixing parameters, the neutrino emission angle from the accretion torus, and the temporal evolution of the merger remnant. The torus geometry and the neutron richness of the remnant are responsible for the occurrence of multiple resonant active-sterile conversions. The number of resonances strongly depends on the neutrino emission direction above or inside the remnant torus and leads to a large production of sterile neutrinos (and no antineutrinos) in the proximity of the polar axis, as well as more sterile antineutrinos than neutrinos in the equatorial region. As the black-hole torus evolves in time, the shallower baryon density is responsible for more adiabatic flavor conversion, leading to larger regions of the mass-mixing parameter space being affected by flavor mixing. Our findings imply that the production of sterile states could have indirect implications on the disk cooling rate, its outflows, and related electromagnetic observables which remain to be assessed.

The Tibet $\mathrm{AS}\gamma$ collaboration has reported a diffuse $\gamma$-ray emission signal from the Galactic Plane. We consider the possibility that the diffuse emission from the outer Galactic Plane at the highest energies is produced by cosmic rays spreading from a single supernova-type source either in the Local or Perseus arm of the Milky Way. We show that anisotropic diffusion of multi-PeV cosmic rays along the Galactic magnetic field can produce an extended source spanning ten(s) of degrees on the sky, with a flux-per-unit-solid-angle consistent with Tibet $\mathrm{AS}\gamma$ measurements. Observations of this new type of very extended sources, and measurements of their morphologies, can be used to characterize the anisotropic diffusion of PeV cosmic rays in the Galactic magnetic field, and to constrain the locations and properties of past PeVatrons.

The quantum phase-space approach allows one to define relativistic spatial distributions inside a target with arbitrary spin and arbitrary average momentum. We apply this quasiprobabilistic formalism to the whole electromagnetic four-current operator in the case of spin-0 and spin-$\frac{1}{2}$ targets, study in detail the frame dependence of the corresponding spatial distributions, and compare our results with those from the light-front formalism. While former works focused on the charge distributions, we extend here the investigations to the current distributions. We clarify the role played by the Wigner rotation and argue that electromagnetic properties are most naturally understood in terms of Sachs form factors, contrary to what the light-front formalism previously suggested. Finally, we illustrate our results using the pion and nucleon electromagnetic form factors extracted from experimental data.