Inflationary scenario from higher curvature warped spacetime

We consider a five dimensional AdS spacetime, in presence of higher curvature term like $F(R) = R + \alpha R^2$ in the bulk, in the context of Randall-Sundrum two-brane model. Our universe is identified with the TeV scale brane and emerges as a four dimensional effective theory. From the perspective of this effective theory, we examine the possibility of "inflationary scenario" by considering the on-brane metric ansatz as an FRW one. Our results reveal that the higher curvature term in the five dimensional bulk spacetime generates a potential term for the radion field. Due to the presence of radion potential, the very early universe undergoes a stage of accelerated expansion and moreover the accelerating period of the universe terminates in a finite time. We also find the spectral index of curvature perturbation ($n_s$) and tensor to scalar ratio ($r$) in the present context, which match with the observational results based on the observations of $Planck$ $2015$.Comment: 10 pages, 5 figures. arXiv admin note: text overlap with arXiv:1701.0157

A parametric reconstruction of the cosmological jerk from diverse observational data sets

A parametric reconstruction of the jerk parameter, the third order derivative of the scale factor expressed in a dimensionless way, has been discussed. Observational constraints on the model parameters have been obtained by Maximum Likelihood Analysis of the models using Supernova Distance Modulus data (SNe), Observational Hubble Data (OHD), Baryon Acoustic Oscillation (BAO) data and CMB shift parameter data (CMBShift). The present value of the jerk parameter has been kept open to start with, but the plots of various cosmological parameter like deceleration parameter $q(z)$, jerk parameter $j(z)$, dark energy equation of state parameter $w_{DE}(z)$ indicate that the reconstructed models are very close to a $\Lambda$CDM model with a slight inclination towards a non-phantom behaviour of the evolution.Comment: 12 pages, 44 figures; Accepted for publication in Phys. Rev.

An Exact Interior Kerr Solution

We present a simple exact solution for the interior of a rotating star. The interpretation of the stress energy tensor as that of a fluid requires the existence of a high viscosity, which is quite expected for a rotating fluid. In spite of the negative stresses, energy conditions are in fact all satisfied.Comment: Two columns; 3 printed page