Charge asymmetry in the processes $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}\gamma$ and $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ is measured using $232{\mathrm{fb}}^{-1}$ of data collected with the BABAR detector at $e^{+}{e}^{-}$ center-of-mass energies near 10.58 GeV. An observable is introduced and shown to be very robust against detector asymmetries while keeping a large sensitivity to the physical charge asymmetry that results from the interference between initial- and final-state radiation (FSR). The asymmetry is determined as a function of the invariant mass of the final-state tracks from production threshold to a few $\mathrm{GeV}/c^2$. It is compared to the expectation from QED for $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}\gamma$, and from theoretical models for $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$. A clear interference pattern is observed in $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$, particularly in the vicinity of the $f_2(1270)$ resonance. The inferred rate of lowest-order FSR production is consistent with the QED expectation for $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}\gamma$, and is negligibly small for $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$.

We deal with relativistic models described by a single real scalar field, searching for topological structures that behave asymmetrically, connecting minima with a distinct profile. We use such features to build a new braneworld scenario, in which the source scalar field contributes to generate asymmetric hybrid brane.

Volume-weighted statistics of large-scale peculiar velocity is preferred by peculiar velocity cosmology, since it is free of the uncertainties of galaxy density bias entangled in observed number density-weighted statistics. However, measuring the volume-weighted velocity statistics from galaxy (halo/simulation particle) velocity data is challenging. Therefore, the exploration of velocity assignment methods with well-controlled sampling artifacts is of great importance. For the first time, we apply the Kriging interpolation to obtain the volume-weighted velocity field. Kriging is a minimum variance estimator. It predicts the most likely velocity for each place based on the velocity at other places. We test the performance of Kriging quantified by the E-mode velocity power spectrum from simulations. Dependences on the variogram prior used in Kriging, the number $n_k$ of the nearby particles to interpolate, and the density $n_P$ of the observed sample are investigated. First, we find that Kriging induces 1% and 3% systematics at $k\sim 0.1h{\mathrm{Mpc}}^{-1}$ when $n_P\sim 6\times 10^{-2}(h^{-1}\mathrm{Mpc}{)}^{-3}$ and $n_P\sim 6\times 10^{-3}(h^{-1}\mathrm{Mpc}{)}^{-3}$, respectively. The deviation increases for decreasing $n_P$ and increasing $k$. When $n_P\lesssim 6\times 10^{-4}(h^{-1}\mathrm{Mpc}{)}^{-3}$, a smoothing effect dominates small scales, causing significant underestimation of the velocity power spectrum. Second, increasing $n_k$ helps to recover small-scale power. However, for $n_P\lesssim 6\times 10^{-4}(h^{-1}\mathrm{Mpc}{)}^{-3}$ cases, the recovery is limited. Finally, Kriging is more sensitive to the variogram prior for a lower sample density. The most straightforward application of Kriging on the cosmic velocity field does not show obvious advantages over the nearest-particle method [, , , , and , Phys. Rev. D 88, 103510 (2013)] and could not be directly applied to cosmology so far. However, whether potential improvements may be achieved by more delicate versions of Kriging is worth further investigation.

Statistical isotropy (SI) is one of the fundamental assumptions made in cosmological model building. This assumption is now being rigorously tested using the almost full sky measurements of the CMB anisotropies. A major hurdle in any such analysis is to handle the large biases induced due to the process of masking. We have developed a new method of analysis, using the bipolar spherical harmonic basis functions, in which we semianalytically evaluate the modifications to SI violation induced by the mask. The method developed here is generic and can be potentially used to search for any arbitrary form of SI violation. We specifically demonstrate the working of this method by recovering the Doppler boost signal from a set of simulated, masked CMB skies.

The sensitivity of all-sky searches for gravitational-wave pulsars is primarily limited by the finite availability of computing resources. Semicoherent searches are a widely used method of maximizing sensitivity to gravitational-wave pulsars at fixed computing cost: the data from a gravitational-wave detector are partitioned into a number of segments, each segment is coherently analyzed, and the analysis results from each segment are summed together. The generation of template banks for the coherent analysis of each segment, and for the summation, requires knowledge of the metrics associated with the coherent and semicoherent parameter spaces respectively. We present a useful approximation to the semicoherent parameter-space metric, analogous to that presented in Wette and Prix [Phys. Rev. D 88, 123005 (2013)] for the coherent metric. The new semicoherent metric is compared to previous work in Pletsch [Phys. Rev. D 82, 042002 (2010)], and Brady and Creighton [Phys. Rev. D 61, 082001 (2000)]. We find that semicoherent all-sky searches require orders of magnitude more templates than previously predicted.

We study the chiral dynamics of vector mesons in two-flavor QCD in vacuum by utilizing a functional renormalization group approach. This allows us to capture the dynamical transition from the quark-gluon phase at high energies to the hadronic phase at low energies without the necessity of model parameter tuning. We use this to analyze the scaling of vector meson masses towards the chiral symmetry breaking scale, the decoupling of the mesons at high energies, and the validity of vector meson dominance.

We study the neutralinos and sleptons in multilepton final states at the LHC in light of $(g-2{)}_{\mu }$ anomaly. We scan the minimal supersymmetric standard model parameters relevant to $(g-2{)}_{\mu }$ and focus on three distinct cases with different neutralino compositions. The explanation of $(g-2{)}_{\mu }$ excess at $2\sigma$ range requires the smuon (${\tilde{\mu }}_1$) to be lighter than $\sim 500(1000)\mathrm{GeV}$ for $\tan \beta =10(50)$. Correspondingly the two lightest neutralinos, ${\tilde{\chi }}_1^0$, ${\tilde{\chi }}_2^0$, have to be lighter than $\sim 300(650)\mathrm{GeV}$ and 900 (1500) GeV, respectively. We explore the prospects of searching these light neutralinos and smuons at the LHC. The upcoming run of the LHC will be able to set 95% CL exclusion limit on $M_{{\tilde{\chi }}_2^0}$ ($\sim 650-1300\mathrm{GeV}$) and $m_{\tilde{l}}$ ($\sim 670-775\mathrm{GeV}$) with $M_{{\tilde{\chi }}_1^0}\sim 100-250\mathrm{GeV}$ at $3000{\mathrm{fb}}^{-1}$ integrated luminosity in $\text{multilepton}+{\cancel{E}}_T$ channel.

We analyze high-multiplicity proton-proton ($pp$) collision data in the framework of the string percolation model that has been successful in describing several phenomena of multiparticle production, including the signatures of recent discovery of strongly interacting partonic matter, the quark-gluon plasma, in relativistic heavy-ion collisions. Our study in terms of the ratio of shear viscosity and entropy density ($\eta /s$) and the [Lattice Quantum Chromodinamics (LQCD)] predicted signature of QCD change of phase, in terms of the effective number of degrees of freedom ($\epsilon /T^4$), reiterates the possibility of a strongly interacting collective medium in these events.

We construct self-gravitating axially symmetric sphaleron solutions of the $3+1$-dimensional Skyrme model coupled to Einstein gravity. The solutions are static and asymptotically flat; they are characterized by two integers $n$ and $m$, where $\pm n$ are the winding numbers of the constituents and the second integer $m$ defines the type of the solution. These configurations correspond to the chains of charge $n$ Skyrmions and charge $-n$ anti-Skyrmions placed along the axis of symmetry in alternating order. We investigate the dependency of the masses of the gravitating sphalerons on the gravitational coupling. We find new chains of self-gravitating $|n|=1$ Skyrmions-anti-Skyrmions that emerge at some critical nonzero value of the gravitational coupling and do not have flat space limit. In contrast, the branches of self-gravitating $|n|\ge 2$ Skyrmion-anti-Skyrmion chains emerge from the corresponding flat space configurations. In both cases these branches merge at some maximal value of the effective gravitational coupling the branches of different type. The branch of the gravitating Skyrmion-anti-Skyrmion pair extends all the way back to the limit of vanishing coupling constant where solutions approach the corresponding generalized Bartnik-McKinnon solutions. The upper branch of gravitating Skyrmion-anti-Skyrmion-Skyrmion chain exists up to some critical value of the gravitational coupling at which the chain becomes broken. We further find that for small values of the coupling constant on the upper branches, the solutions correspond to composite systems, consisting of a scaled inner Einstein-Yang-Mills solution and outer Skyrmions that are separating from the inner configuration.

We formulate a perturbation expansion for the effective action in a new approach to the functional renormalization group method based on the concept of composite fields for regulator functions being their most essential ingredients. We demonstrate explicitly the principal difference between the properties of effective actions in these two approaches existing already on the one-loop level in a simple gauge model.

We define a procedure by which observers can measure a type of special-relativistic linear and angular momentum $(P^a,J^{ab})$ at a point in a curved spacetime using only the spacetime geometry in a neighborhood of that point. The method is chosen to yield the conventional results in stationary spacetimes near future null infinity. We also explore the extent to which spatially separated observers can compare the values of angular momentum that they measure and find consistent results. We define a generalization of parallel transport along curves which gives a prescription for transporting values of angular momentum along curves that yields the correct result in special relativity. If observers use this prescription, then they will find that the angular momenta they measure are observer dependent, because of the effects of spacetime curvature. The observer dependence can be quantified by a kind of generalized holonomy. We show that bursts of gravitational waves with memory generically give rise to a nontrivial generalized holonomy: there is, in this context, a close relation between the observer dependence of angular momentum and the gravitational-wave memory effect.

The scattering cross sections of the unpolarized electromagnetic and gravitational waves are shown to be equal for the extreme Reissner-Nordström black hole using $N=2$ supergravity. The conversion cross sections between the unpolarized electromagnetic and gravitational waves are also shown to coincide. The gravitational and electromagnetic scattering cross sections are computed numerically for Reissner-Nordström black holes for several charge-to-mass ratios and the coincidence between the two scattering cross sections for the extremal case is confirmed.

In the framework of the Einstein-Maxwell-aether theory, we present two new classes of exact charged black hole solutions, which are asymptotically flat and possess the universal as well as Killing horizons. We also construct the Smarr formulas and calculate the temperatures of the horizons, using the Smarr mass-area relation. We find that, in contrast to the neutral case, a temperature obtained this way is not proportional to its surface gravity at either of the two types of horizons. Einstein-Maxwell-aether black holes with the cosmological constant and their topological cousins are also presented.

We study the one-photon scalar pair production QED process on the expanding de Sitter spacetime. Using perturbation theory, we obtain the transition probability and study its properties as a function of the expansion parameter $\omega$. On flat space the process is forbidden by energy-momentum conservation. It is expected that for a dynamical background there is an energy exchange correlate to the strength of the gravitational field. We use momentum space plots and compute the mean production angle to illustrate this. We show that the mean angle grows with $\omega$, but also find that in the flat limit the fall-off is unexpectedly slow. To investigate this further we obtain the probability around different angular configuration, at leading order in $m/\omega$, and find that the $\omega$ dependence at small angles is very weak. We comment on the possible astrophysical implications.

We describe the Hamilton geometry of the phase space of particles whose motion is characterized by general dispersion relations. In this framework spacetime and momentum space are naturally curved and intertwined, allowing for a simultaneous description of both spacetime curvature and nontrivial momentum space geometry. We consider as explicit examples two models for Planck-scale modified dispersion relations, inspired from the $q$–de Sitter and $\kappa$-Poincaré quantum groups. In the first case we find the expressions for the momentum and position dependent curvature of spacetime and momentum space, while for the second case the manifold is flat and only the momentum space possesses a nonzero, momentum dependent curvature. In contrast, for a dispersion relation that is induced by a spacetime metric, as in general relativity, the Hamilton geometry yields a flat momentum space and the usual curved spacetime geometry with only position dependent geometric objects.

With the attempt to find the holographic description of the usual acoustic black holes in fluid, we construct an acoustic black hole formed in the $d$-dimensional fluid located at the timelike cutoff surface of a neutral black brane in asymptotically ${\mathrm{AdS}}_{d+1}$ spacetime; the bulk gravitational dual of the acoustic black hole is presented at the first order of the hydrodynamic fluctuation. Moreover, the Hawking-like temperature of the acoustic black hole horizon is showed to be connected to the Hawking temperature of the real anti–de Sitter (AdS) black brane in the bulk, and the duality between the phonon scattering in the acoustic black hole and the sound channel quasinormal mode propagating in the bulk perturbed AdS black brane is extracted. We thus point out that the acoustic black hole appearing in fluid, which was originally proposed as an analogous model to simulate Hawking radiation of the real black hole, is not merely an analogy, it can indeed be used to describe specific properties of the real AdS black holes, in the spirit of the fluid/gravity duality.

In this paper we investigate the limits imposed by thermodynamics on a dark energy fluid. We obtain the heat capacities and the compressibilities for a dark energy fluid. The thermal and mechanical stabilities require these quantities to be positive. We show that dark energy fluids must satisfy the stability conditions and that such a requirement puts difficulties on the cosmic fluid models with negative constant equation-of-state (EoS) parameters. We also show that the observational constraints imposed by type Ia supernova, BAO and $H(z)$ data on a general dark energy fluid with a time-dependent EoS parameter are in conflict with the constraints imposed by thermodynamics. This result indicates that dark energy fluid models are unphysical.

Among various strong-curvature extensions of general relativity, Einstein-dilaton-Gauss-Bonnet gravity stands out as the only nontrivial theory containing quadratic curvature corrections while being free from the Ostrogradsky instability to any order in the coupling parameter. We derive an approximate stationary and axisymmetric black hole solution of this gravitational theory in closed form, which is of fifth order in the black hole spin and of seventh order in the coupling parameter of the theory. This extends previous work that obtained the corrections to the metric only to second order in the spin and at the leading order in the coupling parameter, and allows us to consider values of the coupling parameter close to the maximum permitted by theoretical constraints. We compute some quantities which characterize this solution, such as the dilaton charge, the moment of inertia, and the quadrupole moment, and its geodesic structure, including the innermost stable circular orbit and the epicyclic frequencies for massive particles. The latter provides a valuable tool to test general relativity against strong-curvature corrections through observations of the electromagnetic spectrum of accreting black holes.

Tidal disruption has a dramatic impact on the outcome of neutron star–black hole mergers. The phenomenology of these systems can be divided in three classes: nondisruptive, mildly disruptive, and disruptive. The cutoff frequency of the gravitational radiation produced during the merger (which is potentially measurable by interferometric detectors) is very different in each regime, and when the merger is disruptive it carries information on the neutron star equation of state. Here we use semianalytical tools to derive a formula for the critical binary mass ratio $Q=M_{\mathrm{BH}}/M_{\mathrm{NS}}$ below which mergers are disruptive as a function of the stellar compactness $\mathcal{C}=M_{\mathrm{NS}}/R_{\mathrm{NS}}$ and the dimensionless black hole spin $\chi$. We then employ a new gravitational waveform amplitude model, calibrated to 134 general relativistic numerical simulations of binaries with black hole spin (anti-)aligned with the orbital angular momentum, to obtain a fit to the gravitational-wave cutoff frequency in the disruptive regime as a function of $\mathcal{C}$, $Q$, and $\chi$. Our findings are important to build gravitational-wave template banks, to determine whether neutron star–black hole mergers can emit electromagnetic radiation (thus helping multimessenger searches), and to improve event rate calculations for these systems.