Localization and mass spectrum of matters on Weyl thick branes

Abstract

In this paper, we study localization and mass spectrum of various matter fields on a family of thick brane configurations in a pure geometric Weyl integrable 5-dimensional space time, a non-Riemannian modification of 5-dimensional Kaluza-Klein (KK) theory. We present the shape of the mass-independent potential of the corresponding Schrödinger problem and obtain the KK modes and mass spectrum, where a special coupling of spinors and scalars is considered for fermions. It is shown that, for a class of brane configurations, there exists a continuum gapless spectrum of KK modes with any m 2 > 0 for scalars, vectors and ones of left chiral and right chiral fermions. All of the corresponding massless modes are found to be normalizable on the branes. However, for a special of brane configuration, the corresponding effective Schrödinger equations have modified Pöschl-Teller potentials. These potentials suggest that there exist mass gap and a series of continuous spectrum starting at positive m 2. There are one bound state for spin one vectors, which is just the normalizable vector zero mode, and two bound KK modes for scalars. The total number of bound states for spin half fermions is determined by the coupling constant η. In the case of no coupling (η = 0), there are no any localized fermion KK modes including zero modes for both left and right chiral fermions. For positive (negative) coupling constant, the number of bound states of right chiral fermions is one less (more) than that of left chiral fermions. In both cases (η > 0 and η < 0), only one of the zero modes for left chiral fermions and right chiral fermions is bound and normalizable.