arXiv subjects

B Modak

Publications and source records attributed to B Modak.

3 recordsLinked to original sources

arXiv2021

Wormhole inducing inflation with Einstein Gauss Bonnet dilaton interaction

We present a few Euclidean wormhole configurations using both the analytic and numerical solutions of the field equations considering Einstein Gauss-Bonnet dilaton interaction in 4-dimensional Robertson Walker Euclidean background. In one analytic solution we present transition from a wormhole to an exponential expansion with Lorentzian time $t$ using $\tau=it$ after passing through an era of oscillating Euclidean wormhole. The numerical solutions of the scale factor $a(\tau)$ show multiple local maxima and minima about a global minimum for inverse power law potentials, while for exponential potential the wormholes have a single minimum. The Hubble parameter and deceleration parameter obtained by curve fit of $a(\tau)$ of the numerical solution show an inflation away from the throat of the wormhole invoking analytic continuation by $\tau=it$. A sharp decay of the potential is also observed.

gr-qc↗

arXiv2021

Cosmic scenario of early Universe in context of Euclidean wormhole in dilatonic Einstein Gauss Bonnet gravity

We present some wormhole configurations using analytic and numerical solutions of the Euclidean field equations considering Einstein Gauss Bonnet dilaton coupled interaction in the Robertson Walker metric. Analytic solutions invoking slow-roll type approximation for some potentials yield identical wormholes in the early era. Eventually, in a later era, the universe enters to an expanding era much faster than usual inflation accompanied by oscillations with analytic continuation \tau=it. The numerical solutions of wormholes in terms of the scale factor a(\tau) are almost identical for some standard potentials of the dilaton field, except for the evolution of potentials. The Hubble parameter and deceleration parameter obtained by curve fit of a(\tau) of the numerical solution of wormhole yield an inflationary era away from the throat of the wormhole using \tau=it. A sharp decay of the potential is also observed.

gr-qc↗

arXiv2021

Wormhole inducing exponential expansion in $R^2$ gravity

Wormholes are considered both from the Wheeler deWitt equation, as well as from the field equations in the Euclidean background of Roberson Walker mini-superspace in $R^2$ gravity. Quantum wormhole satisfies Hawking Page wormhole boundary condition in the Euclidean background of mini-superspace, however, in the Lorentzian background wave functional turns to the usual oscillatory function. The Euclidean field equations for $\kappa=0, \pm1$ lead to the wormhole configuration; as well as oscillating universe in Euclidean time $\tau$. The oscillating universe is equivalent to expanding universe under analytic continuation $\tau=it$ and asymptotically leads to exponential solution. An Euclidean wormhole in the very early era evolves to an oscillating universe in $\tau$, thereafter crossing deSitter radius transition to an inflationary era is evident at later epoch only for $\kappa=1$.

gr-qc↗