Testing a Dilaton Gravity Model Using Nucleosynthesis

Abstract

Big Bang Nucleosynthesis (BBN) offers one of the most strict evidences for the Λ-CDM cosmology at present, as well as the Cosmic Microwave Background (CMB) radiation. In this work, our main aim is to present the outcomes of our calculations related to primordial abundances of light elements, in the context of higher dimensional steady-state universe model in the dilaton gravity. Our results show that abundances of light elements (primordial D, 3 He, 4 He, T, 7 Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model and Λ-CDM in the light of the astrophysical observations.

Primordial Big Bang Nucleosynthesis and Generalized Uncertainty Principle

“…It is well-known that the η 10 parameter which successfully fits the abundances of 4 He, D and other light elements is somehow inconsistent with observations of 7 Li. In fact, the ratio of the predicted value of 7 Li abundance to the observed one lies in the interval [2.4, 4.3] according to the standard cosmological theory [62,68]. Quite unexpectedly, neither BBN nor any alternative model are able to fit this so low abundance ratio.…”

“…In this regard, we observe that in the ordinary Cosmology based on General Relativity, one simply has Z = 1. Deviations of Z from unity may arise due to either modified descriptions of gravity or the presence of additional light particles such as neutrinos, in which case one has [62]…”

Effects of quantum fluctuations of metric on the universe

“…Here we are interested in the modifications coming for the quantum fluctuations of metric and take N ν = 3. As well know, the big bang nucleosynthesis (BBN) provides very stringent constraints on the evolution of the early universe [28][29][30][31][32][33][34][35] and has been used to test cosmological models (for example, see references [36][37][38][39][40][41][42][43][44][45][46]). From equations (25) and (39) and taking 0.85 < s < 1.15 [32], we find the parameter α is constrained as −0.141 < α < 0.09 or 1.000025 < α < 1.000046.…”

Effects of quantum fluctuations of metric on the universe

“…As well know, the big bang nucleosynthesis (BBN) provides very stringent constraints on the evolution of the early universe [28][29][30][31][32][33][34][35] and has been used to test cosmological models (for example, see references [36][37][38][39][40][41][42][43][44][45][46]). From equations (25) and (39) and taking 0.85 < s < 1.15 [32], we find the parameter α is constrained as −0.141 < α < 0.09 or 1.000025 < α < 1.000046.…”