Gravitational waves from inflation with antisymmetric tensor field

Aashish, Sandeep; Padhy, Abhilash; Panda, Sukanta

doi:10.1088/1475-7516/2020/12/004

Cited by 8 publications

(28 citation statements)

References 58 publications

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“…Further, the primordial GW velocity was tuned to the velocity of light in vacuum using the coupling strengths [34]. This motivates us to look at the effects of the non minimal couplings in our model.…”

Section: IVmentioning

confidence: 99%

“…We adopt the analysis performed in Refs. [45] and [34]. The equations from now onwards will be expressed in the conformal time coordinate η.…”

Section: A Perturbationsmentioning

confidence: 99%

“…The predecessor antisymmetric tensor field model in Ref. [34] had the spectral index depending on both the slow roll parameters and δ. But, here we have a slight variance even at the de-Sitter level, whereas the general inflationary models predict a scale invariant power spectrum in the de-Sitter limit.…”

Section: A Perturbationsmentioning

confidence: 99%

“…This has motivated the exploration of alternative inflation models where the driving field is not a scalar. Several vector and tensor field models have been explored in the past [22][23][24][25][26][27][28][32][33][34][35]. Vector field models have been shown to suffer from generic ghost and gradient instabilities [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

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Inflation with an antisymmetric tensor field

et al. 2018

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We investigate the possibility of inflation with models of antisymmetric tensor field having minimal and nonminimal couplings to gravity. Although the minimal model does not support inflation, the nonminimal models, through the introduction of a nonminimal coupling to gravity, can give rise to stable de-Sitter solutions with a bound on the coupling parameters. The values of field and coupling parameters are sub-planckian. Slow roll analysis is performed and slow-roll parameters are defined which can give the required number of e-folds for sufficient inflation. Stability analysis has been performed for perturbations to antisymmetric field while keeping the metric unperturbed, and it is found that only the sub-horizon modes are free of ghost instability for de-Sitter space.

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Section: IVmentioning

confidence: 99%

“…We adopt the analysis performed in Refs. [45] and [34]. The equations from now onwards will be expressed in the conformal time coordinate η.…”

Section: A Perturbationsmentioning

confidence: 99%

Section: A Perturbationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Inflation with an antisymmetric tensor field

et al. 2018

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“…The de-Sitter solution is indeed a stable one and also the field values remain sub-Planckian. Moreover such non-minimal models lead to the propagating speed of the gravitational wave as unity and thus the model becomes compatible with GW170817 [124]. Here it may be mentioned that the constraints on the model parameters in order to achieve a de-Sitter solution match with that coming from the demand that the gravitational wave speed is unity.…”

Section: Cosmological Scenariomentioning

confidence: 96%

Antisymmetric Tensor Fields in Modified Gravity: A Summary

Paul

2020

Symmetry

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We provide various aspects of second rank antisymmetric Kalb–Ramond (KR) field in modified theories of gravity. The KR field energy density is found to decrease with the expansion of our universe at a faster rate in comparison to radiation and matter components. Thus as the universe evolves and cools down, the contribution of the KR field on the evolutionary process reduces significantly, and at present it almost does not affect the universe evolution. However the KR field has a significant contribution during early universe; in particular, it affects the beginning of inflation as well as increases the amount of primordial gravitational radiation and hence enlarges the value of tensor-to-scalar ratio in respect to the case when the KR field is absent. In regard to the KR field couplings, it turns out that in four dimensional higher curvature inflationary model the couplings of the KR field to other matter fields is given by 1/MPl (where MPl is known as the “reduced Planck mass” defined by MPl=18πG with G is the “Newton’s constant”) i.e., same as the usual gravity–matter coupling; however in the context of higher dimensional higher curvature model the KR couplings get an additional suppression over 1/MPl. Thus in comparison to the four dimensional model, the higher curvature braneworld scenario gives a better explanation of why the present universe carries practically no footprint of the Kalb–Ramond field. The higher curvature term in the higher dimensional gravitational action acts as a suitable stabilizing agent in the dynamical stabilization mechanism of the extra dimensional modulus field from the perspective of effective on-brane theory. Based on the evolution of KR field, one intriguing question can be—“sitting in present day universe, how do we confirm the existence of the Kalb–Ramond field which has considerably low energy density (with respect to the other components) in our present universe but has a significant impact during early universe?” We try to answer this question by the phenomena “cosmological quantum entanglement” which indeed carries the information of early universe. Finally, we briefly discuss some future perspectives of Kalb–Ramond cosmology at the end of the paper.

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Ekpyrotic bounce driven by Kalb–Ramond field

Paul

SenGupta

2023

Physics of the Dark Universe

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Gravitational waves from inflation with antisymmetric tensor field

Cited by 8 publications

References 58 publications

Inflation with an antisymmetric tensor field

Inflation with an antisymmetric tensor field

Antisymmetric Tensor Fields in Modified Gravity: A Summary

Ekpyrotic bounce driven by Kalb–Ramond field

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