Tachyon inflation in an AdS braneworld with backreaction

Abstract

We analyze the inflationary scenario based on the tachyon field coupled with the radion of the second Randall-Sundrum model (RSII). The tachyon Lagrangian is derived from the dynamics of a 3-brane moving in the five dimensional bulk. The AdS 5 geometry of the bulk is extended to include the radion. Using the Hamiltonian formalism we find four nonlinear field equations supplemented by the modified Friedmann equations of the RSII braneworld cosmology. After a suitable rescaling we reduce the parameters of our model to only one free parameter related to the brane tension and the AdS 5 curvature. We solve the equations numerically assuming a reasonably wide range of initial conditions determined by physical considerations. Varying the free parameter and initial conditions we confront our results with the Planck 2015 data.

Tachyon inflation in the holographic braneworld

“…To this end, one would need to estimate the phenomenologically acceptable range of the fundamental coupling parameter κ and solve the exact equations numerically for various potentials. Based on our experience from the previous work [20,23] we do not expect a substantial deviation from the present results.…”

Numerical calculation of hubble hierarchy parameters and observational parameters of inflation

“…The fluctuation of the interbrane distance along the extra dimension implies the existence of the radion ϕ, a massless scalar field that causes a distortion of the bulk geometry. The total action, as seen on the observers brane, is [7,16]…”

Particle creation and reheating in a braneworld inflationary scenario

“…The Hamiltonian density may be derived from the stress tensor corresponding to the Lagrangian (33) or by the Legendre transformation. Either way one finds [31] …”