A de Sitter tachyonic braneworld revisited

TL;DR

This paper revisits a tachyonic braneworld model, demonstrating a simplified solution with a zero 5D cosmological constant that retains key features like a stable de Sitter brane, localized gravity, and field confinement, enhancing cosmological model realism.

Contribution

It provides a less parameter-dependent, stable, zero cosmological constant solution in a tachyonic braneworld, preserving essential physical properties for realistic cosmological applications.

Findings

Stable de Sitter brane with localized gravity.

Graviton spectrum with a mass gap, ensuring 4D gravity dominance.

Localization of gauge, scalar, and fermion fields.

Abstract

Within the framework of braneworlds, several interesting physical effects can be described in a wide range of energy scales, starting from high-energy physics to cosmology and low-energy physics. An usual way to generate a thick braneworld model relies in coupling a bulk scalar field to higher dimensional warped gravity. Quite recently, a novel braneworld was generated with the aid of a tachyonic bulk scalar field, having several remarkable properties. It comprises a regular and stable solution that contains a relevant 3--brane with de Sitter induced metric, arising as an exact solution to the 5D field equations, describing the inflationary eras of our Universe. Besides, it is {\it asymptotically flat}, despite of the presence of a negative 5D cosmological constant, which is an interesting feature that contrasts with most of the known, asymptotically either dS or AdS models. Moreover, it encompasses a graviton spectrum with a single massless bound state, accounting for 4D gravity localized on the brane, separated from the continuum of Kaluza-Klein massive graviton modes by a mass gap that makes the 5D corrections to Newton's law to decay exponentially. Finally, gauge, scalar and fermion fields are also shown to be localized on this braneworld. In this work, we show that this tachyonic braneworld allows for a nontrivial solution with a vanishing 5D cosmological constant that preserves all the above mentioned remarkable properties with a less amount of parameters, constituting an important contribution to the construction of a realistic cosmological braneworld model.