Eur. Phys. J. C (2016) 76: 247
https://doi.org/10.1140/epjc/s10052-016-4094-9

Regular Article - Theoretical Physics

Soliton models for thick branes

¹ Department of Physics, School of Sciences, Ferdowsi University of Mashhad, Mashhad, 91775-1436, Iran
² Physics Department, Shahid Beheshti University, Evin, Tehran, 19839, Iran
³ Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Edifício C8, Campo Grande, 1749-016, Lisbon, Portugal

^* e-mail: fslobo@fc.ul.pt

Received: 7 January 2016
Accepted: 15 April 2016
Published online: 2 May 2016

Abstract

In this work, we present new soliton solutions for thick branes in dimensions. In particular, we consider brane models based on the sine-Gordon (SG), and scalar fields, which have broken symmetry in some cases and are responsible for supporting and stabilizing the thick branes. The origin of the symmetry breaking in these models resides in the fact that the modified scalar field potential may have non-degenerate vacua. These vacua determine the cosmological constant on both sides of the brane. We also study the geodesic equations along the fifth dimension, in order to explore the particle motion in the neighborhood of the brane. Furthermore, we examine the stability of the thick branes, by determining the sign of the term in the expansion of the potential for the resulting Schrödinger-like equation, where w is the five-dimensional coordinate. It turns out that the brane is stable, while there are unstable modes for certain ranges of the model parameters in the SG and branes.