Supermassive black holes at the center of each galaxy may be surrounded by dark matter. Such dark matter admits a spike structure and vanishes at a certain distance from the black hole. This dark matter will impact the spacetime near the black hole and the related ringing gravitational waves can show distinguished features of the black hole without dark matter. In the present work, we focus on the quasinormal modes of the axial gravitational perturbation who dominate the ringdown process of the perturbed black holes surrounded by dark matter spikes. The relativistic modification results in less impact on QNMs. And the relative ringing frequency difference between the black holes with and without dark matter can be as large as ${10}^{-2}$. These features can be used in future gravitational wave detection about extremal mass ratio inspiral systems to probe the existence of dark matter around supermassive black holes.

The generalized SU(2) Proca theory is a vector-tensor theory of gravity whose action is invariant under global transformations of the SU(2) group and includes second-order derivative self-interactions of the vector field beyond the massive Yang-Mills theory. We find, in particular, that the presence of two Lagrangian pieces consisting of four gauge fields minimally coupled to gravity gives rise to an exact Reissner-Nordström black hole solution endowed with two different non-Abelian effective charges that depend on the specific combination $\chi =2{\chi }_1+{\chi }_2$ of the respective coupling constants. After studying the spacetime structure of the black hole, which allows us to characterize the parameter space that preserves the weak cosmic censorship conjecture, some astrophysical implications of the black hole solutions are investigated. First, joint analysis of observations of the Event Horizon Telescope’s first images of Sagittarius ${\mathrm{A}}^{\star }$ of our Galaxy and the Keck telescope set the first serious constraint on the free parameters of the theory beyond the theoretical bounds found. Second, we investigate the accretion properties of spherical steady flows around this class of non-Abelian Reissner-Nordström black hole. Specifically, we examine the general conditions under which transonic flow is allowed. An analytical solution for critical accretion is found in terms of the coupling constant. In addition, we explore the effect of changing $\chi$ on the radial velocity and mass density numerically and show how the extremal Reissner-Nordström and the standard Schwarzschild solutions as limit cases are achieved. Finally, working in the fully relativistic regime, an analytical expression for the critical mass accretion rate of a polytropic fluid onto a black hole is derived. As a main result, we find that the critical accretion rate efficiency can be noticeably improved compared to the Schwarzschild case for a specific region of the parameter space where the non-Abelian charge becomes imaginary.

We provide the post-Newtonian (PN) waveform for binary systems in motion along generic planar orbits at 2.5PN accuracy, in terms of the dynamical variables of the effective one-body (EOB) formalism. In addition to the calculation of the higher-order terms for all the contributions to the waveform that have been already considered in previous avatars of EOB models, we also compute the EOB expression of the oscillatory memory terms. These are purely noncircular contributions, first appearing at 1.5PN order, that have been so far neglected in the EOB literature. This should foster their inclusion in EOB models and the definitive assessment of their role in shaping gravitational wave signals at infinity. To further promote the application of our results, we also derive associated noncircular factors according to the waveform factorization prescription of the noncircular EOB model TEOBResumS-DALI; the result is a set of ready-to-use noncircular factors that can be directly implemented as extra noncircular corrections in the waveform of TEOBResumS-DALI.

We study the effect of an ultralight primordial black hole (PBH) dominated phase on the gravitational wave (GW) spectrum generated by a cosmic string (CS) network formed as a result of a high-scale $U(1)$ symmetry breaking. A PBH-dominated phase leads to tilts in the spectrum via entropy dilution and generates a new GW spectrum from PBH density fluctuations, detectable at ongoing and planned near-future GW detectors. The combined spectrum has a unique shape with a plateau, a sharp tilted peak over the plateau, and a characteristic falloff, which can be distinguished from the one generated in the combination of CS and any other matter domination or new exotic physics. We discuss how ongoing and planned future experiments can probe such a unique spectrum for different values of $U(1)$ breaking scale and PBH parameters such as initial mass and energy fraction.

We explain how spin alignment of vector mesons can be induced by background fields, such as electromagnetic fields or soft gluon fields. Our study is based on the quantum kinetic theory of spinning quarks and antiquarks and incorporates the relaxation of the dynamically generated spin polarization. The spin density matrix of vector mesons is obtained by quark coalescence via the Wigner function and kinetic equation. Our approach predicts a local spin correlation that is distinct from the nonlocal expressions previously obtained in phenomenological derivations. We estimate the magnitude of such local correlations in the glasma model of the preequilibrium phase of relativistic heavy ion collisions. It is found that the resulting spin alignment could be greatly enhanced and may be comparable to the experimental measurement in order of magnitude. We further propose new phenomenological scenarios to qualitatively explain the transverse-momentum and centrality dependence of spin alignment in a self-consistent framework.

We show that scalar quantum field theory in four Euclidean dimensions with global $O(N{)}^3$ symmetry and imaginary tetrahedral coupling is asymptotically free and bounded from below in the large-$N$ limit. While the Hamiltonian is non-Hermitian, the full quantum effective action for the large-$N$ theory only depends on the square of that coupling which is real. A perturbative analysis uncovers that the renormalization group flow of the quartic couplings connects a Gaussian ultraviolet fixed point to a strongly interacting theory in the infrared. This realizes a renormalizable field theory which exhibits nontrivial dynamics, such as direct scattering, while still being analytically tractable also nonperturbatively. Our findings open up a way to address outstanding problems in strongly coupled theories from first principles.

We study the impact of stellar cooling due to light axion emission on the formation and evolution of black hole binaries, via stable mass transfer and the common envelope scenario. We find that in the presence of light axion emission, no binary black hole mergers are formed with black holes in the lower-mass gap ($M_{\mathrm{BH}}<4M_{\odot }$) via the common envelope formation channel. In some systems, this happens because axions prevent Roche lobe overflow. In others, they prevent the common envelope from being ejected. Our results apply to axions with couplings $g_{a\gamma }\gtrsim {10}^{-10}{\mathrm{GeV}}^{-1}$ (to photons) or ${\alpha }_{ae}\gtrsim {10}^{-26}$ (to electrons) and masses $m_a\ll 10\mathrm{keV}$. Light, weakly coupled particles may therefore apparently produce a mass gap $2M_{\odot }<M_{\mathrm{BH}}<4M_{\odot }$ in the LIGO/Virgo/KAGRA data, when no mass gap is present in the stellar-remnant population.

We study the time evolution of the density matrix of a high energy quark propagating in a dense QCD medium where it undergoes elastic collisions (radiation is ignored in the present study). The medium is modeled as a stochastic color field with a Gaussian correlation function. This allows us to eliminate the medium degrees of freedom and obtain a simple master equation for the evolution of the reduced density matrix of the high energy quark, making use of approximations that are familiar in the description of open quantum systems. This master equation is solved analytically, and we demonstrate that its solution can be reconstructed from a simple Langevin equation. At late times, one finds that only the color singlet component of the density matrix survives the quark’s propagation through the medium. The off-diagonal elements of the density matrix are suppressed successively in transverse position space and in momentum space, and they become independent of the details of the initial condition. This behavior is reflected in the corresponding von Neumann entropy, whose growth at late time is related to the increase of the classical phase space explored by the high energy quark in its motion through the medium. The interpretation of the Wigner transform as a classical distribution is further supported by the fact that the associated classical entropy coincides at late time with the von Neumann entropy.

We present measurements of cross sections for production of a leptonically decaying $Z$ boson in association with a large-radius jet in 13 TeV proton-proton collisions at the LHC, using $36{\mathrm{fb}}^{-1}$ of data from the ATLAS detector. Integrated and differential cross sections are measured at particle level in both a flavor inclusive and a doubly $b$-tagged fiducial phase space. The large-radius jet mass and transverse momentum, its kinematic relationship to the $Z$ boson, and the angular separation of $b$-tagged small-radius track jets within the large-radius jet are measured. This measurement constitutes an important test of perturbative quantum chromodynamics in kinematic and flavor configurations relevant to several Higgs boson and beyond-Standard-Model physics analyses. The results highlight issues with modeling of additional hadronic activity in the flavor-inclusive selection, and a distinction between flavor-number schemes in the $b$-tagged phase space.

When axionic strings carry a global charge, domain walls bounded by such strings may not be allowed to decay completely. This happens in particular in some models where a composite axionlike particle is the pseudo-Nambu-Goldstone boson of chiral symmetry breaking of an extra quark flavor. In this case, the global symmetry is the extra flavor baryonic symmetry. The corresponding axionic domain walls can carry a baryonic charge: they represent the low energy description of the baryons made by the extra quark flavor. Basic properties of these particles, such as spin, mass scale, and size are discussed. The corresponding charged axionic strings are explicitly constructed in a specific calculable model.

The good-bad-ugly-F model is a system of semilinear wave equations that mimics the asymptotic form of the Einstein field equations in generalized harmonic gauge with specific constraint damping and suitable gauge source functions. These constraint additions and gauge source functions eliminate logarithmic divergences appearing at the leading order in the asymptotic expansion of the metric components. In this work, as a step towards using compactified hyperboloidal slices in numerical relativity, we evolve this model numerically in spherical symmetry, axisymmetry, and full 3D on such hyperboloidal slices. Promising numerical results are found in all cases. Our results show that nonlinear systems of wave equations with the asymptotics of the Einstein field equations in the above form can be reliably captured within hyperboloidal numerical evolution without assuming symmetry.

In this paper, we construct exact rotating wormholes using the Ehlers solution-generating technique. This is based on the Ernst description of four-dimensional, stationary, and axially symmetric solutions of the Einstein-Maxwell theory. We adopt the static Barceló-Visser wormhole derived from the Einstein-Maxwell-conformal-scalar theory as a seed and demonstrate, through the Ernst approach, how to construct two novel geometries of rotating wormholes. These geometries correspond to the Barceló-Visser wormhole embedded within a rotating and a magnetic background. In the first case, the rotation is a result of a dragging force (due to the rotating background) acting on the initial static wormhole, while in the second case, it is caused by the electromagnetic interaction between the electric charge of the static wormhole and the external magnetic field. We conduct a comprehensive analysis of the geometric properties of these configurations and examine the new features introduced by rotation, such as the emergence of ergoregions. Recent evidence suggests that incorporating slow rotation can stabilize wormholes, rendering these exact, fully rotating solutions particularly appealing.

We apply the Simpson-Visser phenomenological regularization method to a cylindrically symmetric solution of the Einstein-Maxwell equations known as an inverted black hole. In addition to analyzing some properties of thus regularized space-time, including the Carter-Penrose diagrams, we show that this solution can be obtained from the Einstein equations with a source combining a phantom scalar field with a nonzero self-interaction potential and a nonlinear magnetic field. A similar kind of source is obtained for the cylindrical black bounce solution proposed by Lima et al. as a regularized version of Lemos’s black string solution. Such sources are shown to be possible for a certain class of cylindrically, planarly, and toroidally symmetric metrics that includes the regularized solutions under consideration.

Black holes in general relativity are famously characterized by two “hairs” only, the mass and the spin of the Kerr spacetime. Theories extending general relativity, however, allow in principle for additional black hole charges, which will generally modify the multipole structure of the Kerr solution. Here, we show that gravitational wave observations of the postmerger ringdown signal from black hole binaries may permit measuring these additional hairs. We do so by considering spacetime geometries differing from the Kerr one at the level of the quadrupole moment, and computing the differences of their quasinormal mode frequencies from the Kerr ones in the eikonal limit. We then perform a Bayesian analysis with current and future gravitational wave data and compute posterior constraints for the quadrupole deviation away from Kerr. We find that the inclusion of higher modes, which are potentially observable by future detectors, will allow for constraining deviations from the Kerr quadrupole at percent level.

Recently, nonzero rotation angle $\beta =0.30°\pm 0.11°$ (68% C.L.) [Phys. Rev. Lett. 128, 091302 (2022)] has been reported for linear polarization of cosmic microwave background (CMB) radiation, which is known as cosmic birefringence (CB). We used this birefringence angle of CMB to study and distinguish different candidates of dark matter (DM), e.g., dipolar and sterile neutrino DM. We calculated CMB forward scattering by those probable candidates of DM to generate $\beta$ in the presence of primordial scalar fluctuations’ background. We explicitly plotted bounds on the mass and electromagnetic coupling for different sectors of DM, sterile neutrino, and dipolar DM, and compared them with other experimental bounds. Regarding dipolar DM, our calculations put a bound on the Majorana magnetic dipole moment about $\mathcal{M}\le 1.4\times {10}^{-14}\frac{\beta }{0.30°}\sqrt{\frac{m_{\mathrm{DM}}}{1\mathrm{GeV}}}e.\mathrm{cm}$. In the case of sterile neutrino DM, the bound on the mass and mixing angle was estimated at ${\theta }^2\le 3.3(\mathrm{rad}{)}^2\frac{\beta }{0.30°}\frac{m_{\mathrm{DM}}}{\mathrm{KeV}}$, which can be a new constraint for sterile neutrino DM whose production mechanism is motivated by models with a hidden sector coupled to the sterile neutrino. Based on our results, if the constraint on the mass and the electromagnetic coupling for DM must be within the allowed region, none of the considered candidates can compensate for all the observed CB angle. We also discussed the maximum contribution of the CB angle via CMB forward scattering by different sectors of the dark matter.

We present a model to explain the Standard Model flavor hierarchy. Our model is based on explicit smooth confinement (namely confinement without chiral symmetry breaking in a supersymmetric gauge theory) at an intermediate energy scale, before the electroweak symmetry breaking by the Higgs condensation at lower energy. In our context, the smooth confinement preserves the SU(3) and the chiral ${\mathrm{SU}(2)}_L\times {\mathrm{U}(1)}_Y$ symmetry in a supersymmetric Standard Model, while this internal symmetry becomes dynamically gauged in the end. In contrast to Razamat-Tong’s symmetric mass generation model also preserving the $G_{\mathrm{SM}}\equiv {\mathrm{SU}(3)}_C\times {\mathrm{SU}(2)}_L\times {\mathrm{U}(1)}_Y$ internal symmetry, our model introduces different matter contents with a different kind of superpotential deformation irrelevant at UV, which further induces Yukawa-Higgs terms marginal at IR, breaking the $G_{\mathrm{SM}}$ down to ${\mathrm{SU}(3)}_C$ and the electromagnetic ${\mathrm{U}(1)}_{\mathrm{EM}}$ only when Higgs condenses. In our model, the IR fermions in the first and second families are composite of UV fields, while the third-family elementary fermions match between UV and IR. The smallness of the first- and second-family fermion masses is explained by the exponential hierarchy between the cutoff scale and the smooth confinement scale via dimensional transmutation. As a result, our UV Lagrangian only contains the natural parameters close to the order one.

To avoid the impact from the background events directly from $e^{+}{e}^{-}$ annihilations or $J/\psi$ decays, we propose a novel approach to investigate $\eta$ decays, in particular for its rare or forbidden decays, by using ${\eta }^{\prime }\to \pi \pi \eta$ produced in $J/\psi$ decays at the $\tau$-charm factories. Based on the Monte Carlo studies of a few typical decays, $\eta \to \pi \pi$, $\gamma l^{+}{l}^{-}(l=e,\mu )$, $l^{+}{l}^{-}$, as well as $l^{+}{l}^{-}{\pi }^0$, the sensitivities could be obviously improved by taking advantage of the extra constraint of ${\eta }^{\prime }$. Using $1\times {10}^{12}J/\psi$ events accumulated at the super $\tau$-charm facility, the precision on the investigation of $\eta$ decays could be improved significantly and the observation of the rare decay $\eta \to e^{+}{e}^{-}$ is even accessible.

We consider multishell configurations in the Skyrme model within the rational map ansatz. We show that equations for the Skyrme field are linearized in the limit of a large number of shells, thus allowing for a simple analytic solution. Although this solution is approximate, it provides an accurate description of multishell configurations in the Skyrme model in the region where the Skyrme field is large, $F\gg 1$. We use this solution to calculate the mass and the root mean square radius of multishell skyrmion configurations. In particular, for solutions with one unit of baryon charge per shell (the “hedgehog” solution) the mass scales as $M\propto B^2$, and its rms radius scales as $B^{1/2}$ with the baryon charge $B$. This scaling for the mass can be reduced to $M\propto B^{4/3}$ in the model with many units of baryon charge per shell. Although this solution is unstable against decays into single-shell or single-skyrmion configurations, it may be useful for modeling skyrmion stars or compact composite objects in some models of dark matter if the decay of such configurations is prevented by some mechanism.

We use a variational method to calculate the spectrum and the parton distribution function of ground-state hadrons of various gauge theories in $1+1$ dimensions. The template functions in our method minimize a free-energy functional defined as a combination of free-valence partons’ kinetic energy on the light cone and the Renyi entanglement entropy of biparton subsystems. Our results show that hadrons in these theories minimize the proposed free energy. The success of this technique motivates applying it to confining gauge theories in higher dimensions.

We study the decay $J/\psi \to {\pi }^{+}{\pi }^{-}{\pi }^0$ within the framework of the Khuri-Treiman equations. We find that the BESIII experimental dipion mass distribution in the $\rho (770)$-region is well reproduced with a once-subtracted $P$-wave amplitude. Furthermore, we show that $F$-wave contributions to the amplitude improve the description of the data in the $\pi \pi$ mass region around 1.5 GeV. We also present predictions for the $J/\psi \to {\pi }^0{\gamma }^{*}$ transition form factor.