Inflation in anisotropic brane universe using tachyon field

Abstract

Cosmological solution to the gravitational field equations in the generalized Randall-Sundrum model for an anisotropic brane with Bianchi I geometry and perfect fluid as matter sources has been considered. The matter on the brane is described by a tachyonic field. The solution admits inflationary era and at a later epoch the anisotropy of the universe washes out. We obtain two classes of cosmological scenario, in the first case universe evolves from singularity and in the second case universe expands without singularity.

A Brief Study on the Prevalence of Malaria in Kolkata, West Bengal, India

“…It is usually considered that both the radial and tangential components of the tidal acceleration on the observer is not more than the acceleration due to gravity on the earth. Once, we know both the metric potentials of the wormhole, it is possible to compute the tidal accelerations using the components of the Riemann tensor as shown in Eqns ( 31)- (32). We make a reasonable approximation that the velocity with which the traveller traverses the wormhole is negligeble compared to the velocity of light, which simplifies the Lorentz factor to unity.…”

“…The standard model forces are confined to the brane, while gravity is free to propagate in the bulk. In the Randall-Sundrum (RS) single brane model [44], which is of particular interest in the cosmological context [51,52,53,54,55,56,57,58,59,60], the extra dimension is spacelike, characterized by a bulk space of Lorentzian signature. The brane tension is positive and the bulk space is Anti-deSitter (AdS 5 ), sourced by a negative cosmological constant.…”

“…Such a field is required to exist in the universe in addition to the "inflaton" scalar field responsible for the rapid accelerating expansion phase in the early universe realized through expoonential or power law type of scale factor. Inflation can also be realized via a tachyon field [19,20]. For dark matter candidates, particles which have not yet been detected experimentally and are not predicted by the standard model of particle physics have to be taken into account.…”

“…Their first model consisted of two parallel braneworlds, but in the second model [19] the brane with a negative tension was moved to infinity. The RS single brane model has a spacelike extra dimension and finds wide range of application in both cosmology [26,27,28,29,30,31,32,33,34] and astrophysics [35,36,37,38,39,40,41,42,43,44]. Soon after, a dual to the RS-II single brane model was proposed by Shtanov and Sahni (SS), with a timelike extra dimension replacing the spacelike extra dimension [1].…”

Lorentzian wormholes supported by tachyon matter

“…There is a phenomenon of rolling of the tachyon from the unstable maximum to a stable average, expected value in the vacuum. This phenomenon finds applications in cosmology [11,12,13,14]. However, our case is different as in the cosmological applications time-dependent configurations of the tachyon field find use but here we will make use of spatially dependent configurations [15,16,17].…”