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

Biswas, Gargi; Modak, B.

doi:10.1142/s0217732322500833

Cited by 3 publications

(1 citation statement)

References 57 publications

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“…are a few examples of fast expanding Universe. On the other hand, the opposite situation could also arise particularly in some modified gravity theory [49][50][51][52][53] where a negative contribution in the energy density leads to slow expansion [54].…”

Section: Introductionmentioning

confidence: 99%

Reviewing the prospect of fermion triplets as dark matter and source of baryon asymmetry in non-standard cosmology

Biswas

Chakraborty

Khan

2023

J. Cosmol. Astropart. Phys.

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Indirect searches of Dark Matter (DM), in conjugation with 'missing track searches' at the collider seem to confine SU(2) L fermion triplet DM (FTDM) mass within a narrow range around 1 TeV. The canonical picture of the pure FTDM is in tension since it is under-abundant for the said mass range. Several preceding studies have reported that an extra species (ϕ), redshifts faster than the radiation (∼ a (4+n) where n > 0), leads to a faster expanding early Universe by dominating in the energy density with an enhanced Hubble parameter. This has the potential to revive the under-abundant FTDM (ℤ2 odd, lightest generation) by causing freeze-out earlier without modifying the interaction strength between DM and thermal bath. On the other hand, although the CP asymmetry produced due to the decay of ℤ2 even heavier generations of the triplet remains unaffected, its evolution is greatly affected by the non-standard cosmology. It has been observed through numerical estimations that the minimum mass of the triplet, required to produce sufficient baryon asymmetry of the Universe (BAU), can be lowered up to two orders (compared to the standard cosmology) in this fast expansion scenario. The non-standard parameters n and Tr (a reference temperature below which radiation dominance prevails), which simultaneously control DM abundance as well as the frozen value of BAU, are tightly constrained from the observed experimental values. We have found that n is strictly bounded within the interval 0.4 ≲ n ≲ 1.8 where the upper bound is imposed by the BAU constraint whereas the lower bound arises to satisfy the correct DM abundance. It has been noticed that the restriction on Tr is not so stringent as it can vary from sub GeV to a few tens of GeV.

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Section: Introductionmentioning

confidence: 99%

Reviewing the prospect of fermion triplets as dark matter and source of baryon asymmetry in non-standard cosmology

Biswas

Chakraborty

Khan

2023

J. Cosmol. Astropart. Phys.

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Wormhole inducing inflation with Einstein–Gauss–Bonnet dilaton interaction

Biswas

Dutta²,

Modak

2022

Mod. Phys. Lett. A

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A few Euclidean wormhole configurations are presented using both the analytic and numerical solutions of the field equations in four-dimensional Robertson–Walker Euclidean background with Einstein–Gauss–Bonnet dilaton interaction. In one analytic solution we present transition from a wormhole to an exponential expansion with Lorentzian time [Formula: see text] using [Formula: see text] after passing through an era of oscillating Euclidean wormhole. The numerical solutions of the scale factor [Formula: see text] 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. An inflationary cosmic scenario away from the throat of the wormhole can be obtained from the Hubble parameter and deceleration parameter obtained by curve fit of [Formula: see text] of the numerical solution invoking analytic continuation by [Formula: see text]. The potential is also observed to decay sharply.

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Euclidean Wormhole with k-essence field in the presence of Gauss–Bonnet term

Dutta,

Biswas,

Modak

2023

Mod. Phys. Lett. A

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In this paper, we present some analytical solutions of wormhole in four-dimensional Robertson–Walker Euclidean background considering Einstein–Gauss–Bonnet dilaton interaction with a [Formula: see text]-essence field for [Formula: see text]. The solutions are obtained assuming some restrictions on coupling function with a form of potential or with the ratio of kinetic to potential energy of the dilaton field. Euclidean wormhole, in one case, evolves through early transient inflationary era and after graceful exit from inflation, it asymptotically yields a radiation dominated era or a matter dominated era. In another solution, initial Euclidean wormhole is accompanied by oscillation of scale factor in Euclidean time at some late era which asymptotically yields exponential expansion. The violation of the null energy condition can be avoided asymptotically. The potential is also found to decay sharply.

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

Cited by 3 publications

References 57 publications

Reviewing the prospect of fermion triplets as dark matter and source of baryon asymmetry in non-standard cosmology

Reviewing the prospect of fermion triplets as dark matter and source of baryon asymmetry in non-standard cosmology

Wormhole inducing inflation with Einstein–Gauss–Bonnet dilaton interaction

Euclidean Wormhole with k-essence field in the presence of Gauss–Bonnet term

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