Compatibility of big bang nucleosynthesis in some modified gravities
Abdul Malik Sultan, Abdul Jawad
Abstract
Abstract This paper is devoted to investigate the implications of Einstein-Aether and modified Hořava–Lifshitz theories of gravity to the formation of light elements in the early universe named as big bang nucleosynthesis. We choose different models from these theories for a detailed investigation of big bang nucleosynthesis epoch and compare it with the observational bounds. That is, we compare the deviation of freeze-out temperature $$T_{_f}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>T</mml:mi> <mml:msub> <mml:mrow/> <mml:mi>f</mml:mi> </mml:msub> </mml:msub> </mml:math> with the $$\Lambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi> </mml:math> CDM paradigm and use observational bounds on $$\left| \frac{\Delta T_{_f}}{T_{_f}}\right| $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mfenced> <mml:mfrac> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msub> <mml:mi>T</mml:mi> <mml:msub> <mml:mrow/> <mml:mi>f</mml:mi> </mml:msub> </mml:msub> </mml:mrow> <mml:msub> <mml:mi>T</mml:mi> <mml:msub> <mml:mrow/> <mml:mi>f</mml:mi> </mml:msub> </mml:msub> </mml:mfrac> </mml:mfenced> </mml:math> to inspect constraints on the involved free parameters of these models. We apply Chi-square test on the Hubble parameter H in each model to analyze the compatibility of model parameters with the observations and find consistent results. We find that chosen models of Einstein-Aether gravity and modified Hořava–Lifshitz gravity can satisfy big bang nucleosynthesis constraints and thus constitute a viable cosmology since they can be source for dark energy sector and late-time accelerated expansion.