Scalar and Spinor Particles in the Spacetime of a Domain Wall in String Theory

TL;DR

This paper investigates how scalar and spinor particles behave in the spacetime of a domain wall within string theory, deriving the metric and analyzing particle spectra and currents influenced by scalar-tensor gravity parameters.

Contribution

It derives the metric of a domain wall in scalar-tensor theories and solves the Klein-Gordon and Dirac equations to analyze particle spectra and currents in this spacetime.

Findings

Energy spectrum depends on scalar-tensor parameters for massive particles.

Current density is influenced by the domain wall's properties.

Massless spinor energy spectrum is unaffected by scalar-tensor parameters.

Abstract

We consider scalar and spinor particles in the spacetime of a domain wall in the context of low energy effective string theories, such as the generalized scalar-tensor gravity theories. This class of theories allows for an arbitrary coupling of the wall and the (gravitational) scalar field. First, we derive the metric of a wall in the weak-field approximation and we show that it depends on the wall's surface energy density and on two post-Newtonian parameters. Then, we solve the Klein-Gordon and the Dirac equations in this spacetime. We obtain the spectrum of energy eigenvalues and the current density in the scalar and spinor cases, respectively. We show that these quantities, except in the case of the energy spectrum for a massless spinor particle, depend on the parameters that characterize the scalar-tensor domain wall.