Compatibility of big bang nucleosynthesis in some modified gravities

This paper is devoted to investigate the implications of Einstein-Aether and modified Horava-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 with the Lambda CDM paradigm and use observational bounds on vertical bar Delta T-f/T-f vertical bar 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 Horava-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.