On the one-loop correction of "phi^4" theory in higher dimensions

We have considered phi^4 theory in higher dimensions. Using functional diagrammatic approach, we computed the one-loop correction to effective potential of the scalar field in five dimensions. It is shown that phi^4 theory can be regularised in five dimensions. Temperature dependent one-loop correction and critical temperature T_c are computed and T_c depends on the fundamental scale M of the theory. A brief discussion of symmetry restoration is also presented. The nature of phase transitions is examined and is of second orderComment: 8 pages, 5 figures. To appear in IJMP

Dvali-Gabadadze-Porrati Cosmology in Bianchi I brane

The dynamics of Dvali-Gabadadze-Porrati Cosmology (DGP) braneworld with an anisotropic brane is studied. The Friedmann equations and their solutions are obtained for two branches of anisotropic DGP model. The late time behavior in DGP cosmology is examined in the presence of anisotropy which shows that universe enters a self-accelerating phase much later compared to the isotropic case. The acceleration conditions and slow-roll conditions for inflation are obtained

Bulk scalar field in DGP braneworld cosmology

We investigated the effects of bulk scalar field in the braneworld cosmological scenario. The Friedmann equations and acceleration condition in presence of the bulk scalar field for a zero tension brane and cosmological constant are studied. In DGP model the effective Einstein equation on the brane is obtained with bulk scalar field. The rescaled bulk scalar field on the brane in the DGP model behaves as an effective four dimensional field, thus standard type cosmology is recovered. In present study of the DGP model, the late-time accelerating phase of the universe can be explained .Comment: 10 pages, to appear in JCA

Evolution of the density parameter in the anisotropic DGP cosmology

Evolution of the density parameter in the anisotropic DGP braneworld model is studied. The role of shear and cross-over scale in the evolution of $\Omega_\rho$ is examined for both the branches of solution in the DGP model. The evolution is modified significantly compared to the FRW model and further it does not depend on the value of $\gamma$ alone. Behaviour of the cosmological density parameter $\Omega_\rho$ is unaltered in the late universe. The study of decceleration parameter shows that the entry of the universe into self accelerating phase is determined by the value of shear. We also obtain an estimate of the shear parameter $\frac{\Sigma}{H_0} \sim 1.68 \times 10^{-10}$, which is in agreement with the constraints obtained in the literature using data.Comment: To apper in Int.J.Mod.Phys.D, 14 pages, 6 figure

COSMOLOGY FROM ANISOTROPIC DGP BRANEWORLD

We considered an anisotropic brane embedded in a five-dimensional bulk space–time. The Einstein equations and Friedmann equations are obtained. The corresponding Friedmann equations are modified with quadratic corrections to energy density. The anisotropic DGP model also admits a self-accelerating phase in the late universe. The acceleration conditions are obtained and they are consistent with the braneworld scenario. The acceleration condition for DGP model, in the late universe, is dependent on the crossover scale rc. </jats:p

An analytic study of hybrid inflationary model with quantum gravity corrections

We study the modified hybrid inflationary model to incorporate quantum gravity effects using an effective field theory approach. The inflationary parameters are computed, and they are modified in the presence of higher dimensional operators. We obtain a bound on the Wilsonian coefficient of higher dimensional operator and find that it depends on the vacuum energy density. Our study provides an avenue to explore the quantum gravity effects on hybrid inflationary model and can be extended to include other hybrid inflation models

PHASE TRANSITIONS IN HIGHER DIMENSIONAL COSMOLOGY

We have considered five-dimensional massive scalar field coupled to gravity and evaluated the one-loop effective potential in higher dimensions. It is demonstrated that nonminimally coupled φ4 theory can be regularized in five dimensions. Temperature dependent one-loop correction and critical temperature βc are computed. The phase transitions in the early universe depend on the space–time curvature R and scalar gravitational coupling ξ. A brief discussion of symmetry restoration is also presented and the nature of phase transitions in the early universe is found to be of second order. </jats:p