We investigate several models of coupled scalar fields that present discrete Z_2, Z_2 x Z_2, Z_3 and other symmetries. These models support topological domain wall solutions of the BPS and non-BPS type. The BPS solutions are stable, but the stability of the non-BPS solutions may depend on the parameters that specify the models. The BPS and non-BPS states give rise to bags, and also to three-junctions that may allow the presence of networks of topological defects. In particular, we show that the non-BPS defects of a specific model that engenders the Z_3 symmetry give rise to a stable regular hexagonal network of domain walls.Comment: Revtex, 16 pages, 6 ps figures; Shorter version to be published in Phys. Rev.

We present a way of tiling the plane with a regular hexagonal network of defects. The network is stable and follows in consequence of the three-junctions that appear in a model of two real scalar fields that presents Z3 symmetry. The Z3 symmetry is effective in both the vacuum and defect sectors, and no supersymmetry is required to build the network.Domain walls appear in diverse branches of physics, envolving energy scales as different as the ones for instance in magnetic materials [1] and in cosmology [2]. They live in three spatial dimensions as bidimensional objects that arise in systems with at least two isolated degenerate minima. In field theory they appear in the (3, 1) dimensional space-time, and this may happen in supersymmetric theories, although supersymmetry plays no fundamental role for the presence of domain walls.Very recently, in a paper by Gibbons and Townsend [3], and also in Refs. [4,5], one investigates the presence of domain walls and their possible intersections in a WessZumino model, with a polynomial superpotential. In the supersymmetric theory, one can classify the classical solutions as BPS and non-BPS states, according to the work of Bogomol'nyi, and of Prasad and Sommerfield [6]. The BPS states are stable, and are expected to play some role in investigating duality in supersymmetric models. We recall that no BPS state can be annihilated under continuum variation of the parameters that define the supersymmetric theory.In Ref.[7] one investigates models of coupled real scalar fields in bidimensional space-time. These investigations provide a concrete way of finding BPS states and suggest other studies, in particular on the subject of defects inside defects -see Ref. [8]. Most of the models investigated in [7,8] can be seen as real bosonic portions of supersymmetric theories. In supersymmetric models the presence of discrete symmetry may produce BPS and non-BPS defects. The BPS states lie in shorter multiplets, and preserve the supersymmetry only partially [9,10]. There are BPS states that preserve 1/2 of the supersymmetry, but the possibility of BPS states preserving 1/4 supersymmetry is subtler, and is shown to appear as junctions [11,12] of domain walls in the recent papers [3][4][5].In the present work we start dealing with the bosonic portions of supersymmetric theories. We do this guided by the discrete Z 3 symmetry, with the aim of describing the presence of three-junctions and the network of defects that it can generate. We first point out that supersymmetry introduces restrictions that may lead to instability of the junction, or at least of the network that it could generate. We then examine another model, and show that all the difficulties found in the supersymmetric context are circumvented by just giving up supersymmetry.The subject of this work may be of interest to several different branches of physics, in particular in applications concerning the entrapment of networks of defects inside domain walls. This possibility can be implemented with three scalar fields, in models...

This work deals with braneworld scenarios driven by real scalar fields with standard dynamics. We show how the first-order formalism which exists in the case of four dimensional Minkowski space-time can be extended to de Sitter or anti-de Sitter geometry in the presence of several real scalar fields. We illustrate the results with some examples, and we take advantage of our findings to investigate renormalization group flow. We have found symmetric brane solutions with four-dimensional anti-de Sitter geometry whose holographically dual field theory exhibits a weakly coupled regime at high energy.

We study massless and massive graviton modes that bind on thick branes which are supergravity domain walls solutions in D-dimensional supergravity theories where only the supergravity multiplet and the scalar supermultiplet are turned on. The domain walls are bulk solutions provided by tachyon potentials. Such domain walls are regarded as BPS branes of one lower dimension that are formed due to tachyon potentials on a non-BPS D-brane.

In this paper we focus on the Hamilton-Jacobi method to determine the entropy of a self-dual black hole by using linear and quadratic GUPs(generalized uncertainty principles). We have obtained the Bekenstein-Hawking entropy of self-dual black holes and its quantum corrections that are logarithm and also of several other types. * Electronic address: anacleto, fabrito, passos@df.ufcg.edu.br arXiv:1504.06295v2 [hep-th] 30 Jul 2015

In this paper we derive acoustic black hole metrics in the (3+1) and (2+1)-dimensional Abelian Higgs model with Lorentz symmetry breaking. In this set up the sound waves lose the Lorentz boost invariance and suffer a 'birefringence' effect. We have found acoustic black holes and respective Hawking temperatures depending on the Lorentz violating parameter. Furthermore, we obtain an acoustic Kerr-like black hole metric with the Lorentz violating term affecting its rate of loss of mass. We also have shown that for suitable values of the Lorentz violating parameter a wider spectrum of particle wave function can be scattered with increased amplitude by the acoustic black hole.

In this paper we deal with defects inside defects in systems of two scalar fields in 3 + 1 dimensions. The systems we consider are defined by potentials containing two real scalar fields, and so we are going to investigate domain ribbons inside domain walls. After introducing some general comments on the possibility of finding defects that support internal structure in two specific systems, we introduce thermal effects to show how the picture for domain walls hosting domain ribbons appears at high temperature.

Within D=4 N=1 supergravity theory we obtain an effective theory of the thin wall limit for a flat domain wall configuration, interpolating between isolated supersymmetric extrema of the matter potential. We focus on the Z 2 symmetric flat wall and derive the supersymmetric effective action both in the bulk and on the wall; in the thin wall limit the scalar field, forming the wall, is frozen, and provides the delta function domain wall source, while its fermionic partner decouples due to its large mass. In addition, the interaction between the gravitational supermultiplet and the interaction of the matter multiplet decouples on the wall. While the results are explicitly demonstrated within N = 1 D = 4 supergravity, we also provide a generalization of the result to D-dimensions.