We use a new compilation of the hadronic $R$-ratio from available data for the process $e^{+}{e}^{-}\to \text{hadrons}$ to determine the strong coupling, ${\alpha }_s$. We make use of all data for the $R$-ratio from threshold to a center-of-mass energy of 2 GeV by employing finite-energy sum rules. Data above 2 GeV, for which at present far fewer high-precision experimental data are available, do not provide much additional constraint but are fully consistent with the values for ${\alpha }_s$ we obtain. Quoting our results at the $\tau$ mass to facilitate comparison to the results obtained from analogous analyses of hadronic $\tau$-decay data, we find ${\alpha }_s(m_{\tau }^2)=0.298\pm 0.016\pm 0.006$ in fixed-order perturbation theory, and ${\alpha }_s(m_{\tau }^2)=0.304\pm 0.018\pm 0.006$ in contour-improved perturbation theory, where the first error is statistical, and the second error reflects our estimate of various systematic effects. These values are in good agreement with a recent determination from the OPAL and ALEPH data for hadronic $\tau$ decays.

The intensity of single gluon bremsstrahlung in a QCD plasma is evaluated with a Monte Carlo which solves the transport equation for a generic interaction with the medium. In particular, the calculation is performed for a Debye screened potential and compared to the well-known Gaussian/Fokker-Planck results. The full calculation including the first and last gluons shows a qualitatively different behavior from the Baier-Dokshitzer-Mueller-Peigne-Schiff result for any finite medium length. It is shown that the emission intensity is underestimated for the Gaussian approximation, compared to the Debye screened potential. This change cannot be accounted for by a redefinition of the Gaussian parameter ($\widehat{q}$).

The probability distribution of the net baryon number is investigated within the functional renormalization group approach. We find that, because of the Roberge-Weiss periodicity which is related to the Z(3) symmetry of the gluon fields, states of the net baryon number $N_B=N\pm 1/3$ with $N\in \mathbb{Z}$ are prohibited, and only those of $N_B=N$ are possible. By employing the probability distribution of the net baryon number, we also compute the cumulants of the baryon number distribution, which are found to be quite consistent with those obtained from the generalized susceptibilities. A question about the relation between the color confinement and the probability distribution of net baryon number is put forward.

In order to obtain the equation of state and construct hybrid stars, we calculate the thermodynamic potential in the two-flavor Nambu–Jona-Lasinio model with tensor-type four-point interaction between quarks. In addition, we impose the $\beta$ equilibrium and charge neutrality conditions on the system. We show that the tensor condensate appears at large chemical potential, however, it is difficult to hold hybrid stars with two-solar mass by using the equation of state with the tensor interaction. Although we cannot obtain the stars with two-solar mass because of the absence of the repulsive interaction, the estimated magnetic moment density is very large. Therefore, we expect that the tensor interaction describes the magnetic fields of compact stars.

The first observation of the $B_s^0\to {\overline{D}}^0{K}^{+}{K}^{-}$ decay is reported, together with the most precise branching fraction measurement of the mode $B^0\to {\overline{D}}^0{K}^{+}{K}^{-}$. The results are obtained from an analysis of $pp$ collision data corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$. The data were collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The branching fraction of the $B^0\to {\overline{D}}^0{K}^{+}{K}^{-}$ decay is measured relative to that of the decay $B^0\to {\overline{D}}^0{\pi }^{+}{\pi }^{-}$ to be $\frac{\mathcal{B}(B^0\to {\overline{D}}^0{K}^{+}{K}^{-})}{\mathcal{B}(B^0\to {\overline{D}}^0{\pi }^{+}{\pi }^{-})}=(6.9\pm 0.4\pm 0.3)\%$, where the first uncertainty is statistical and the second is systematic. The measured branching fraction of the $B_s^0\to {\overline{D}}^0{K}^{+}{K}^{-}$ decay mode relative to that of the corresponding $B^0$ decay is $\frac{\mathcal{B}(B_s^0\to {\overline{D}}^0{K}^{+}{K}^{-})}{\mathcal{B}(B^0\to {\overline{D}}^0{K}^{+}{K}^{-})}=(93.0\pm 8.9\pm 6.9)\%$. Using the known branching fraction of $B^0\to {\overline{D}}^0{\pi }^{+}{\pi }^{-}$, the values of $\mathcal{B}(B^0\to {\overline{D}}^0{K}^{+}{K}^{-})=(6.1\pm 0.4\pm 0.3\pm 0.3)\times {10}^{-5}$ and $\mathcal{B}(B_s^0\to {\overline{D}}^0{K}^{+}{K}^{-})=(5.7\pm 0.5\pm 0.4\pm 0.5)\times {10}^{-5}$ are obtained, where the third uncertainties arise from the branching fraction of the decay modes $B^0\to {\overline{D}}^0{\pi }^{+}{\pi }^{-}$ and $B^0\to {\overline{D}}^0{K}^{+}{K}^{-}$, respectively.

Recently, the covariant formulation of the Tolman-Oppenheimer-Volkoff (TOV) equations for studying the equilibrium structure of a spherically symmetric compact star in the presence of the pressure anisotropy in the interior of a star was presented in Ref. [1]. It was suggested there that the anisotropic solution of these equations can be obtained by finding, first, the solution of the common TOV equations for the isotropic pressure, and then by solving the differential equation for the anisotropic pressure whose particular form was established on the basis of the covariant TOV equations. It turns out that the anisotropic pressure determined according to this scheme has a nonremovable singularity $\mathrm{\Pi }\sim \frac{1}{r^2}$ in the center of a star, and, hence, the corresponding anisotropic solution cannot represent a physically relevant model of an anisotropic compact star. A new scheme for constructing the anisotropic solution, based on the covariant TOV equations is suggested, which leads to the regularly behaved physical quantities in the interior of a star. A new algorithm is applied to build model anisotropic strange quark stars with the MIT bag model equation of state.

General relativity predicts mass and spin growth of an inspiralling black hole due to an energy-momentum flux flowing through the black-hole horizon. The leading-order terms of this horizon flux introduce 2.5 and 3.5 post-Newtonian corrections to inspiral motions of binary black holes. The corrections may be measurable by gravitational waves detectors. Since the proper improvements to general relativity are still a mystery, it is possible that the true modified gravity theory introduces negligible direct corrections to the geodesics of test masses, while near-horizon corrections are observable. We introduce a parametrization to describe arbitrary mass and spin growth of inspiralling black holes. Comparing signals of gravitational waves and a waveform model with parametrized horizon flux corrections, deviations from general relativity can be constrained. We simulate a set of gravitational wave signals following an astrophysical distribution with horizon flux modifications. Then, we perform a Bayesian analysis to obtain the expected constraints from the simulated response of the Advanced LIGO-Virgo detector network to the simulated signals. We show that the constraint can be improved by stacking multiple detections. The constraints of modified horizon flux can be used to test a specific class of modified gravity theories which predict dominant corrections near black-hole horizons over other types of corrections to general relativity. To support Hawking’s area theorem at 90% confidence level, over 10000 LIGO-Virgo detections are required. Within the lifetime of the LIGO and Einstein Telescope, a future ground-based gravitational wave detector, near-horizon corrections of modified gravity theories are potentially detectable if one of the modified gravity theories is true and the theory predicts a strong correction.

This paper presents an efficient numerical sensitivity-estimation method and implementation for continuous-gravitational-wave searches, extending and generalizing an earlier analytic approach by Wette [1]. This estimation framework applies to a broad class of $\mathcal{F}$-statistic-based search methods, namely (i) semi-coherent StackSlide $\mathcal{F}$-statistic (single-stage and hierarchical multistage), (ii) Hough number count on $\mathcal{F}$-statistics, as well as (iii) Bayesian upper limits on $\mathcal{F}$-statistic search results (coherent or semi-coherent). We test this estimate against results from Monte-Carlo simulations assuming Gaussian noise. We find the agreement to be within a few % at high detection (i.e., low false-alarm) thresholds, with increasing deviations at decreasing detection (i.e., higher false-alarm) thresholds, which can be understood in terms of the approximations used in the estimate. We also provide an extensive summary of sensitivity depths achieved in past continuous-gravitational-wave searches (derived from the published upper limits). For the $\mathcal{F}$-statistic-based searches where our sensitivity estimate is applicable, we find an average relative deviation to the published upper limits of less than 10%, which in most cases includes systematic uncertainty about the noise-floor estimate used in the published upper limits.

We obtain the complete theory of Newton-Cartan gravity in a curved spacetime by considering the large $c$ limit of the vielbein formulation of general relativity. Milne boosts originate from local Lorentzian transformations, and the special cases of torsionless and twistless torsional geometries are explained in the context of the larger locally Lorentzian theory. We write the action for Newton-Cartan fields in the first order Palatini formalism and the large $c$ limit of the Einstein equations. Finally, we obtain the generalized Eisenhart-Duval lift of the metric that plays an important role in nonrelativistic holography.

Proposing smooth initial conditions is one of the most important tasks in quantum cosmology. On the other hand, the low-energy effective action, appearing in the semiclassical path integral, obtains nontrivial quantum corrections near classical singularities due to specific quantum gravity proposals. In this article, we combine the well-known no-boundary proposal for the wave function of the universe with quantum modifications coming from loop quantum cosmology (LQC). Remarkably, we find that the restriction of a “slow-roll” type potential in the original Hartle-Hawking proposal is considerably relaxed due to quantum geometry regularizations. Interestingly, the same effects responsible for singularity resolution in LQC also end up expanding the allowed space of smooth initial conditions leading to an inflationary universe.

We study diffusion of charged particles in a stationary stochastic magnetic field $\mathbf{B}$ with zero mean, $⟨\mathbf{B}⟩=\mathbf{0}$. In the case when electric current is carried by electrons, the field is force-free, $\mathrm{curl}\mathbf{B}=\alpha \mathbf{B}$, where $\alpha (\mathbf{r})$ is an arbitrary scalar function. In a small region where the function $\alpha$ and the field magnitude $|\mathbf{B}|$ are approximately constant, the equations of motion of charged particles are integrated and reduced to the equation of mathematical pendulum. The transition from trapped to untrapped particles is continuously traced. Averaging over the magnetic field spectrum gives the spatial diffusion coefficient $D$ of particles as a function of the Larmor radius $r_L$ in the large-scale magnetic fields ($B_{LS}$) and a magnetic field correlation length $L_0$. The diffusion coefficient turns out to be proportional to the Larmor radius, $D\propto r_L$, for $r_L<L_0/2\pi$, and to the Larmor radius squared, $D\propto r_L^2$, for $r_L>L_0/2\pi$. We apply obtained results to the diffusion of cosmic rays in the Galaxy, which contains a large number of independent regions with parameters $L_0$ and $B_{LS}$ varying in wide range. We average over $B_{LS}$ with the Kolmogorov spectrum and over $L_0$ with the distribution function $f(L_0)\propto L_0^{-1+\sigma }$. For the practically flat spectrum $\sigma =1/15$, we have $D\propto r_m^{0.7}$, which is consistent with observations.

Supersymmetry with hadronic $R$-parity violation in which the lightest neutralino decays into three quarks is still weakly constrained. This work aims to further improve the current search for this scenario by the boosted decision tree method with additional information from jet substructure. In particular, we find a deep neural network turns out to perform well in characterizing the neutralino jet substructure. We first construct a convolutional neutral network (CNN) which is capable of tagging the neutralino jet in any signal process by using the idea of jet image. When applied to pure jet samples, such a CNN outperforms the $N$-subjettiness variable by a factor of a few in tagging efficiency. Moreover, we find the method, which combines the CNN output and jet invariant mass, can perform better and is applicable to a wider range of neutralino mass than the CNN alone. Finally, the ATLAS search for the signal of gluino pair production with subsequent decay $\tilde{g}\to qq{\tilde{\chi }}_1^0(\to qqq)$ is recast as an application. In contrast to the pure sample, the heavy contamination among jets in this complex final state renders the discriminating powers of the CNN and $N$ subjettiness similar. By analyzing the jets substructure in events which pass the ATLAS cuts with our CNN method, the exclusion limit on gluino mass can be pushed up by $\sim 200\mathrm{GeV}$ for neutralino mass $\sim 100\mathrm{GeV}$.

We investigate electric dipole moments (EDMs) in a $CP$-violating minimal supersymmetric standard model with the binolike neutralino dark matter (DM) annihilating through the heavy Higgs funnel. Motivated by the current experimental results, in particular, the measured mass of the standard model-like Higgs boson, we consider a mass spectrum with stop masses of about 10 TeV. For the other sfermions, we consider masses of about 100 TeV. We show that $CP$-violating phases of the order of ten degrees in gaugino and Higgsino mass parameters are consistent with the current bound by EDMs of the electron, the neutron, and the mercury. They are within the reach of future experiments. We also show that effects of $CP$-violating phases induce a difference in DM-nucleon scattering cross section by a factor.

We first compare different approaches to estimates of the magnitude of the chiral magnetic effect in relativistic heavy ion collisions and show that their main difference lies in the assumptions on the length of persistence of the magnetic field generated by the colliding nuclei. We then analyze recent measurements of the global polarization of $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ hyperons in terms of the bounds they set on the magnitude of the late-time magnetic field.

The first observation of the $B_s^0\to {\overline{D}}^{*0}\varphi$ decay is reported, with a significance of more than seven standard deviations, from an analysis of $pp$ collision data corresponding to an integrated luminosity of $3{\mathrm{fb}}^{-1}$, collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The branching fraction is measured relative to that of the topologically similar decay $B^0\to {\overline{D}}^0{\pi }^{+}{\pi }^{-}$ and is found to be $\mathcal{B}(B_s^0\to {\overline{D}}^{*0}\varphi )=(3.7\pm 0.5\pm 0.3\pm 0.2)\times 10^{-5}$, where the first uncertainty is statistical, the second systematic, and the third from the branching fraction of the $B^0\to {\overline{D}}^0{\pi }^{+}{\pi }^{-}$ decay. The fraction of longitudinal polarization in this decay is measured to be $f_{\mathrm{L}}=(73\pm 15\pm 4)\%$. The most precise determination of the branching fraction for the $B_s^0\to {\overline{D}}^0\varphi$ decay is also obtained, $\mathcal{B}(B_s^0\to {\overline{D}}^0\varphi )=(3.0\pm 0.3\pm 0.2\pm 0.2)\times 10^{-5}$. An upper limit, $\mathcal{B}(B^0\to {\overline{D}}^0\varphi )<2.0$ $(2.3)\times 10^{-6}$ at 90% (95%) confidence level is set. A constraint on the $\omega -\varphi$ mixing angle $\delta$ is set at $|\delta |<5.2°$ (5.5°) at 90% (95%) confidence level.

In this paper, we study the entanglement entropy of a single interval on a cylinder in two-dimensional $T\overline{T}$-deformed conformal field theory (CFT). For such case, the (Rényi) entanglement entropy takes a universal form in a CFT. We compute the correction due to the deformation up to the leading order of the deformation parameter in the framework of the conformal perturbation theory. We find that the correction to the entanglement entropy is nonvanishing in the finite temperature case, while it is vanishing in the finite size case. For the deformed holographic large $c$ CFT, which is proposed to be dual to a ${\mathrm{AdS}}_3$ gravity in a finite region, we find the agreement with the holographic entanglement entropy via the Ryu-Takayanagi formula. Moreover, we compute the leading order correction to the Rényi entropy, and discuss its holographic picture as well.

The axial electromagnetic (EM) perturbations of the black hole (BH) solutions in general relativity coupled to nonlinear electrodynamics (NED) were studied for both electrically and magnetically charged BHs, assuming that the EM perturbations do not alter the spacetime geometry in our preceding paper [Phys. Rev. D 97, 084058 (2018)]. Here, as a continuation of that work, the formalism for the polar EM perturbations of the BHs in general relativity coupled to the NED is presented. We show that the quasinormal modes (QNMs) spectra of polar EM perturbations of the electrically and magnetically charged BHs in the NED are not isospectral, contrary to the case of the standard Reissner-Nordström BHs in the classical linear electrodynamics. It is shown by the detailed study of QNMs properties in the eikonal approximation that the EM perturbations can be a powerful tool to confirm that in the NED light ray does not follow the null geodesics of the spacetime. By specifying the NED model and comparing axial and polar EM perturbations of the electrically and magnetically charged BHs, it is shown that QNM spectra of the axial EM perturbations of magnetically (electrically) charged BH and polar EM perturbations of the electrically (magnetically) charged BH are isospectral, i.e., ${\omega }_{\mathrm{mag}}^{\mathrm{ax}}\approx {\omega }_{\mathrm{el}}^{\mathrm{pol}}$ (${\omega }_{\mathrm{mag}}^{\mathrm{pol}}\approx {\omega }_{\mathrm{el}}^{\mathrm{ax}}$).

We investigate the influence of a brane on the vacuum expectation value (VEV) of the current density for a charged fermionic field in the background of locally AdS spacetime with an arbitrary number of toroidally compact dimensions and in the presence of a constant gauge field. Along compact dimensions, the field operator obeys quasiperiodicity conditions with arbitrary phases, and on the brane, it is constrained by the bag boundary condition. The brane is parallel to the AdS boundary, and it divides the space into two regions with different properties for the fermionic vacuum. In both these regions, the VEVs for the charge density and the components of the current density along noncompact dimensions vanish. The components along compact dimensions are decomposed into the brane-free and brane-induced contributions. The behavior of the latter in various asymptotic regions of the parameters is investigated. It particular, it is shown that the brane-induced contribution is mainly located near the brane and vanishes on the AdS boundary and on the horizon. An important feature is the finiteness of the current density on the brane. Applications are given to $Z_2$-symmetric braneworlds of the Randall-Sundrum type with compact dimensions for two classes of boundary conditions on the fermionic field. For the second one, we show that the contribution of the brane to the current does not vanish when the location of the brane tends to the AdS boundary. In odd spacetime dimensions, the fermionic fields realizing two inequivalent irreducible representations of the Clifford algebra and having equal phases in the periodicity conditions give the same contribution to the vacuum current density. Combining the contributions from these fields, the current density in odd-dimensional $C$-,$P$- and $T$-symmetric models is obtained. In the special case of three-dimensional spacetime, the corresponding results are applied for the investigation of the edge effects on the ground state current density induced in curved graphene tubes by an enclosed magnetic flux.

The Blandford-Znajek monopole is a conjectured solution of force-free electrodynamics in the vicinity of a slowly rotating Kerr black hole, supposedly defined as a perturbation in small angular momentum. It is used to argue for the extraction of energy from rotating black holes by the Blandford-Znajek process. We set up a careful analysis of the perturbative definition of the Blandford-Znajek monopole, showing in particular that the regime in which it is defined allows us to use the technique of matched asymptotic expansions. Our conclusion is that the Blandford-Znajek monopole, as it is defined, is not consistent with demanding physically reasonable boundary conditions far away from the event horizon. This puts into question the existence of the Blandford-Znajek monopole, at least in the limit of slow rotation of a Kerr black hole.

We explore the structure of a dipole-type vacuum field of a slowly rotating magnetic star near the horizon of a supermassive black hole, where the structure of field lines becomes highly distorted by effects of strong gravity. Such a situation may occur near a neutron star in the final stages of a plunging trajectory into a galactic center. We solve Maxwell’s equations in the Rindler approximation for the rotating conducting source of dipolar magnetic field arbitrarily inclined with respect to the axis of rotation. For the fixed inclination angle we calculate the field including the radiative terms while in the general case we discuss the electromagnetic field considering the near-field terms only. In the latter case we investigate the emergence of magnetic null points within the vacuum magnetosphere. Null points become highly relevant in the presence of astrophysical plasma where they are connected with processes of magnetic reconnection and mass ejection.