Homogeneous Black Strings in Einstein-Gauss-Bonnet with Horndeski hair and beyond

In this paper we construct new exact solutions in Einstein-Gauss-Bonnet and Lovelock gravity, describing asymptotically flat black strings. The solutions exist also under the inclusion of a cosmological term in the action, and are supported by scalar fields with finite energy density, which are linear along the extended direction and have kinetic terms constructed out from Lovelock tensors. The divergenceless nature of the Lovelock tensors in the kinetic terms ensures that the whole theory is second order. For spherically, hyperbolic and planar symmetric spacetimes on the string, we obtain an effective Wheeler's polynomial which determines the lapse function up to an algebraic equation. For the sake of concreteness, we explicitly show the existence of a family of asymptotically flat black strings in six dimensions, as well as asymptotically AdS$_{5}\times R$ black string solutions and compute the temperature, mass density and entropy density. We compute the latter by Wald's formula and show that it receives a contribution from the non-minimal kinetic coupling of the matter part, shifting the one-quarter factor coming from the Einstein term, on top of the usual non areal contribution arising from the quadratic Gauss-Bonnet term. Finally, for a special value of the couplings of the theory in six dimensions, we construct strings that contain asymptotically AdS wormholes as well as rotating solutions on the transverse section. By including more scalars the strings can be extended to $p$-branes, in arbitrary dimensions.Comment: 20 pages, 2 figures. V2: 20 pages, 2 figures. Explicit construction of the asymptotically flat black strings in 6D EGB, included. To appear in EJP

D=10 dyonic black holes in string inspired models

We consider string-inspired models in D=10 spacetime dimensions, which include couplings with 1- and 3-form fields as well as R4 higher-curvature corrections to the gravitational action. For such models, we explicitly construct a family of black hole solutions with both electric and magnetic charges, and with different horizon topologies. The solutions exhibit some features similar to those of self-gravitating monopoles in Einstein-Yang-Mills theory, which we discuss. When higher-curvature corrections are switched off, our solutions reduce to charged p-brane solutions previously studied in the literature. Novel qualitative features appear due to the R4 terms, though. Such is the case for the emergence of branch singularities for charged solutions that, nonetheless, can be shielded by the event horizon.Fil: Giribet, Gaston Enrique. University of New York; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Lagos, Marcela. Universidad de Concepción; ChileFil: Oliva, Julio. Universidad de Concepción; ChileFil: Vera, Aldo. Universidad de Concepción; Chil

Crystals of superconducting Baryonic tubes in the low energy limit of QCD at finite density

The low energy limit of QCD admits (crystals of) superconducting Baryonic tubes at finite density. We begin with the Maxwell-gauged Skyrme model in (3+1)-dimensions (which is the low energy limit of QCD in the leading order of the large N expansion). We construct an ansatz able to reduce the seven coupled field equations in a sector of high Baryonic charge to just one linear Schrodinger-like equation with an effective potential (which can be computed explicitly) periodic in the two spatial directions orthogonal to the axis of the tubes. The solutions represent ordered arrays of Baryonic superconducting tubes as (most of) the Baryonic charge and total energy is concentrated in the tube-shaped regions. They carry a persistent current (which vanishes outside the tubes) even in the limit of vanishing U(1) gauge field: such a current cannot be deformed continuously to zero as it is tied to the topological charge. Then, we discuss the subleading corrections in the 't Hooft expansion to the Skyrme model (called usually \mathcal{L}_{6}$,$\mathcal{L}_{8}$ and so on). Remarkably, the very same ansatz allows to construct analytically these crystals of superconducting Baryonic tubes at any order in the 't Hooft expansion. Thus, no matter how many subleading terms are included, these ordered arrays of gauged solitons are described by the same ansatz and keep their main properties manifesting a universal character. On the other hand, the subleading terms can affect the stability properties of the configurations setting lower bounds on the allowed Baryon density.Comment: 30 pages, 19 figures. Accepted for publication in European Physical Journal

Panorama migratorio Colombia - Canadá 2009-2011

Se pretende demostrar que el movimiento migratorio no se basa en su aporte a la fuerza de trabajo en general, sino en su calificación educacional y en las ciertas opciones ocupacionales que brinda el país receptor, es así como Canadá tiene una política excluyente de migración la cual favorece la migración de profesionales altamente calificados, que pueden cumplir los requisitos para migrar de manera legal.Pregrad

Exact solutions for a ferromagnet with Dzyaloshinskii-Moriya interaction

On the two-dimensional non-linear $\Sigma$-model describing a ferromagnet with Dzyaloshinskii-Moriya interaction, we build three families of exact static solutions depending on a single Cartesian variable. One of them describes a clockwise helix configuration, that characterizes the ground state of the system. A second one corresponds to a counterclockwise helix, representing an excited state. These two families of solutions are parameterized by a continuous parameter that depends on the magnetic field and the Dzyaloshinskii-Moriya coupling. Finally, the third family exists only for isolated values of the same parameter, corresponding to a discrete family of Viviani curves on the target sphere. The degeneracy of the resulting spectrum suggests that an approximate symmetry may emerge at specific values of the magnetic field, at which additional solutions could then exist.Comment: 16 pages, 6 figures. Replaced by published versio

In and out-of-equilibrium features of hadronic layers in the low-energy limit of quantum chromodynamics

The entanglement entropy dynamics of baryonic layers in $3+1$ dimensions in the low-energy limit of quantum chromodynamics is computed. The evolution after quantum quenches can be described explicitly. In particular, it is shown analytically that the von Neumann and R\'{e}nyi entropies may display undamped oscillations in time, whose frequencies can be calculated in terms of the baryonic distribution of the hadronic matter in the cavity. Moreover, the Loschmidt amplitude and the fidelity and work distribution can be derived as well. These results, which are entirely unexpected in non-integrable theories such as the Skyrme model, are achieved thanks to a remarkable mapping from any $(3+1)$-dimensional hadronic distribution of matter in a cavity close to its boundary to the sine-Gordon theory in $1+1$ dimensions. In the attractive regime, such results are valid for low-enough energy scales.Comment: 18 pages, 5 figure