A rotating dilaton black hole solution for asymptotically anti-de Sitter spacetime is obtained in the small angular momentum limit with an appropriate combination of three Liouville-type dilaton potentials. The angular momentum, magnetic dipole moment, and the gyromagnetic ratio of such a black hole are determined for arbitrary values of the dilaton-electromagnetic coupling parameter.

Using unitarized chiral perturbation theory methods, we perform a detailed analysis of the $\pi \pi$ scattering poles $f_0(600)$ and $\rho (770)$ behavior when medium effects such as temperature or density drive the system towards chiral symmetry restoration. In the analysis of real poles below threshold, we show that it is crucial to extend properly the unitarized amplitudes so that they match the perturbative Adler zeros. Our results do not show threshold enhancement effects at finite temperature in the $f_0(600)$ channel, which remains as a pole of broad nature. We also implement $T=0$ finite-density effects related to chiral symmetry restoration, by varying the pole position with the pion decay constant. Although this approach takes into account only a limited class of contributions, we reproduce the expected finite-density restoration behavior, which drives the poles towards the real axis, producing threshold enhancement and $\pi \pi$ bound states. We compare our results with several model approaches and discuss the experimental consequences, both in relativistic heavy ion collisions and in $\pi \to \pi \pi$ and $\gamma \to \pi \pi$ reactions in nuclei.

The 1-loop quantum weight of the SU(N) Kraan-van Baal–Lee-Lu caloron with nontrivial holonomy is calculated. The caloron is the most general self-dual solution with unit topological charge in the 4d Yang-Mills theory with one compactified dimension (finite temperature).

Objects that are on the verge of being extremal black holes but actually are distinct in many ways are called quasi-black holes. Quasi-black holes are defined here and treated in a unified way by displaying their properties. Their main properties are as follows: (i) there are infinite redshift whole regions, (ii) the spacetimes exhibit degenerate, almost singular, features but their curvature invariants remain perfectly regular everywhere, (iii) in the limit under discussion, outer and inner regions become mutually impenetrable and disjoint, although, in contrast to the usual black holes, this separation is of a dynamical nature, rather than purely causal, and (iv) for external faraway observers the spacetime is virtually indistinguishable from that of extremal black holes. In addition, we show that quasi-black holes must be extremal. Connections with black hole and wormhole physics are also drawn.

We extend the covariant analysis of the brane cosmological evolution in order to take into account, apart from a general matter content and an induced-gravity term on the brane, a Gauss-Bonnet term in the bulk. The gravitational effect of the bulk matter on the brane evolution can be described in terms of the total bulk mass as measured by a bulk observer at the location of the brane. This mass appears in the effective Friedmann equation through a term characterized as generalized dark radiation that induces mirage effects in the evolution. We discuss the normal and self-accelerating branches of the combined system. We also derive the Raychaudhuri equation that can be used in order to determine if the cosmological evolution is accelerating.

A stiff matter-dominated universe modeled by a free massless scalar field minimally coupled to gravity in a Friedmann-Lemaître-Robertson-Walker (FLRW) geometry is quantized. Generalized complex-width Gaussian superpositions of the solutions of the Wheeler-DeWitt equation are constructed and the Bohm-de Broglie interpretation of quantum cosmology is applied. A planar dynamical system is found in which a diversity of quantum Bohmian trajectories are obtained and discussed. One class of solutions represents nonsingular inflationary models starting at infinity past from flat space-time with Planckian size spacelike hypersurfaces, which inflates without inflaton but due to a quantum cosmological effect, until it makes an analytical graceful exit from this inflationary epoch to a decelerated classical stiff matter expansion phase.

The gravitational field of supermassive black holes is able to strongly bend light rays emitted by nearby sources. When the deflection angle exceeds $\pi$, gravitational lensing can be analytically approximated by the so-called strong deflection limit. In this paper we remove the conventional assumption of sources very far from the black hole, considering the distance of the source as an additional parameter in the lensing problem to be treated exactly. We find expressions for critical curves, caustics, and all lensing observables valid for any position of the source up to the horizon. After analyzing the spherically symmetric case we focus on the Kerr black hole, for which we present an analytical 3-dimensional description of the higher order caustic tubes.

We carry out two searches for periodic gravitational waves using the most sensitive few hours of data from the second LIGO science run. Both searches exploit fully coherent matched filtering and cover wide areas of parameter space, an innovation over previous analyses which requires considerable algorithm development and computational power. The first search is targeted at isolated, previously unknown neutron stars, covers the entire sky in the frequency band 160–728.8 Hz, and assumes a frequency derivative of less than $4\times {10}^{-10}\mathrm{Hz}/\mathrm{s}$. The second search targets the accreting neutron star in the low-mass x-ray binary Scorpius X-1 and covers the frequency bands 464–484 Hz and 604–624 Hz as well as the two relevant binary orbit parameters. Because of the high computational cost of these searches we limit the analyses to the most sensitive 10 hours and 6 hours of data, respectively. Given the limited sensitivity and duration of the analyzed data set, we do not attempt deep follow-up studies. Rather we concentrate on demonstrating the data analysis method on a real data set and present our results as upper limits over large volumes of the parameter space. In order to achieve this, we look for coincidences in parameter space between the Livingston and Hanford 4-km interferometers. For isolated neutron stars our 95% confidence level upper limits on the gravitational wave strain amplitude range from $6.6\times {10}^{-23}$ to $1\times {10}^{-21}$ across the frequency band; for Scorpius X-1 they range from $1.7\times {10}^{-22}$ to $1.3\times {10}^{-21}$ across the two 20-Hz frequency bands. The upper limits presented in this paper are the first broadband wide parameter space upper limits on periodic gravitational waves from coherent search techniques. The methods developed here lay the foundations for upcoming hierarchical searches of more sensitive data which may detect astrophysical signals.

We study the effect of unparticle stuff on $B_s-{\overline{B}}_s$ mixing and consider possible implications of it for the decay modes $B_s\to J/\psi \varphi$ and $\varphi \varphi$. We find that due to the new contributions from the unparticles the $B_s-{\overline{B}}_s$ mixing phase could be observable at the CERN LHC along with the possible sizable $CP$ asymmetry parameters $S_{\psi \varphi (\varphi \varphi )}$ in $B_s\to J/\psi \varphi (\varphi \varphi )$ decay modes.

The axial charge $g_A$ is calculated in the $ϵ$ regime of heavy-baryon chiral perturbation theory to order ${ϵ}^3$. To perform this calculation, we develop a technique to compute baryon properties in the $ϵ$ regime of chiral perturbation theory. This technique includes contributions from pion zero momentum modes and can be used at arbitrary order, diagram by diagram, in the $ϵ$ regime to calculate any matrix element. Also, a calculation of $g_A$ in the ${ϵ}^{\prime }$ regime to order ${ϵ}^{\prime 3}$ is performed. A discussion of the domain of applicability for both the $ϵ$ and ${ϵ}^{\prime }$ regimes is also included.

We present new sets of fragmentation functions for protons and inclusive charged hadrons obtained in combined next-to-leading order QCD analyses of single-inclusive hadron production in electron-positron annihilation, proton-proton collisions, and deep-inelastic lepton-proton scattering. These analyses complement previous results for pion and kaon fragmentation functions with charge and flavor discrimination. The Lagrange multiplier technique is used to assess the uncertainties in the extraction of the new sets of fragmentation functions.

We have searched for prompt production of ${\chi }_{c1}$, ${\chi }_{c2}$ and $X(3872)$ in continuum $e^{+}{e}^{-}$ annihilations using a $386{\mathrm{fb}}^{-1}$ data sample collected around $\sqrt{s}=10.6\mathrm{GeV}$ with the BABAR detector using the $\gamma J/\psi$ decay mode. After accounting for the feed-down from $\psi (2S)\to \gamma {\chi }_{c1,2}$, no significant signal for prompt ${\chi }_{c1,2}$ production is observed. We present improved upper limits at 90% confidence level on the production cross sections of 77 fb for ${\chi }_{c1}$ and 79 fb for ${\chi }_{c2}$, for events where the ${\chi }_c$ momentum exceeds 2.0 GeV and there are at least three additional charged tracks. These limits are consistent with NRQCD predictions. We also set an upper limit on the prompt production of $X(3872)$ through the decay $X(3872)\to \gamma J/\psi$.

The concept of black hole entropy is one of the most important enigmas of theoretical physics. It relates thermodynamics to gravity and allows substantial hints toward a quantum theory of gravitation. Although Bekenstein conjecture—assuming the black hole entropy to be a measure of the number of precollapse configurations—has proved to be extremely fruitful, a direct and conclusive proof is still missing. This paper computes accurately the entropy evaporated by black holes in $(4+n)$ dimensions taking into account the exact greybody factors. This is a key process to constrain and understand the entropy of black holes as the final state is unambiguously defined. Those results allow us to generalize Zurek’s important argument, in favor of the Bekenstein conjecture, to multidimensional scenarios.

In the framework of a holographic QCD approach we study the influence of matter on the deconfinement temperature $T_c$. We first consider the quark flavor number ($N_f$) dependence of $T_c$. We observe that $T_c$ decreases with $N_f$, which is consistent with a lattice QCD result. We also delve into how the quark number density ${\rho }_q$ affects the value of $T_c$. We find that $T_c$ drops with increasing ${\rho }_q$. In both cases, we confirm that the contributions from quarks are suppressed by $1/N_c$, as it should be, compared to the ones from a gravitational action (pure Yang-Mills theory).

A new kind of $Q$-balls is found: $Q$-balls in a nonlinear sigma model. Their main properties are presented together with those of their self-gravitating generalization, sigma model $Q$-stars. A simple special limit of solutions which are bound by gravity alone (“sigma stars”) is also discussed briefly. The analysis is based on calculating the mass, global $U(1)$ charge and binding energy for families of solutions parametrized by the central value of the scalar field. Two kinds (differing by the potential term) of the new sigma model $Q$-balls and $Q$-stars are analyzed. They are found to share some characteristics while differing in other respects like their properties for weak central scalar fields which depend strongly on the form of the potential term. They are also compared with their ordinary counterparts and although similar in some respects, significant differences are found like the existence of an upper bound on the central scalar field. A special subset of the sigma model $Q$-stars contains those which do not possess a flat space limit. Their relation with sigma star solutions is discussed.

We introduce a new spinfoam vertex to be used in models of 4d quantum gravity based on SU(2) and SO(4) BF theory plus constraints. It can be seen as the conventional vertex of SU(2) BF theory, the $15j$ symbol, in a particular basis constructed using SU(2) coherent states. This basis makes the geometric interpretation of the variables transparent: they are the vectors normal to the triangles within each tetrahedron. We study the condition under which these states can be considered semiclassical, and we show that the semiclassical ones dominate the evaluation of quantum correlations. Finally, we describe how the constraints reducing BF to gravity can be directly written in terms of the new variables, and how the semiclassicality of the states might improve understanding the correct way to implement the constraints.

Quasinormal ringing of acoustic black holes in Laval nozzles is discussed. The equation for sounds in a transonic flow is written into a Schrödinger-type equation with a potential barrier, and the quasinormal frequencies are calculated semianalytically. From the results of numerical simulations, it is shown that the quasinormal modes are actually excited when the transonic flow is formed or slightly perturbed, as well as in the real black hole case. In an actual experiment, however, the purely-outgoing boundary condition will not be satisfied at late times due to the wave reflection at the end of the apparatus, and a late-time ringing will be expressed as a superposition of boxed quasinormal modes. It is shown that the late-time ringing damps more slowly than the ordinary quasinormal ringing, while its central frequency is not greatly different from that of the ordinary one. Using this fact, an efficient way for experimentally detecting the quasinormal ringing of an acoustic black hole is discussed.

We investigate here spherically symmetric gravitational collapse in a space-time with an arbitrary number of dimensions and with a general type I matter field, which is a broad class that includes most of the physically reasonable matter forms. We show that given the initial data for matter in terms of the initial density and pressure profiles at an initial surface $t=t_i$ from which the collapse evolves, there exist the rest of the initial data functions and classes of solutions of Einstein equations which we construct here, such that the space-time evolution goes to a final state which is either a black hole or a naked singularity, depending on the nature of initial data and evolutions chosen, and subject to validity of the weak energy condition. The results are discussed and analyzed in the light of the cosmic censorship hypothesis in black hole physics. The formalism here combines the earlier results on gravitational collapse in four dimensions in a unified treatment. Also the earlier work is generalized to higher-dimensional space-times to allow a study of the effect of the number of dimensions on the possible final outcome of the collapse in terms of either a black hole or naked singularity. No restriction is adopted on the number of dimensions, and other limiting assumptions such as self-similarity of space-time are avoided, in order to keep the treatment general. Our methodology allows us to consider to an extent the genericity and stability aspects related to the occurrence of naked singularities in gravitational collapse.

We derive the equations of motion in metric-affine gravity by making use of the conservation laws obtained from Noether’s theorem. The results are given in the form of propagation equations for the multipole decomposition of the matter sources in metric-affine gravity, i.e., the canonical energy-momentum current and the hypermomentum current. In particular, the propagation equations allow for a derivation of the equations of motion of test particles in this generalized gravity theory, and allow for direct identification of the couplings between the matter currents and the gauge gravitational field strengths of the theory, namely, the curvature, the torsion, and the nonmetricity. We demonstrate that the possible non-Riemannian spacetime geometry can only be detected with the help of the test bodies that are formed of matter with microstructure. Ordinary gravitating matter, i.e., matter without microscopic internal degrees of freedom, can probe only the Riemannian spacetime geometry. Thereby, we generalize previous results of general relativity and Poincaré gauge theory.