Observational Signatures of F(r, T, Y) Gravity on Early Universe Evolution

The f(R, T, Y) gravity is a modified theory that involves the Ricci scalar R, the trace of the energy-momentum tensor T, and the non-minimal matter geometry coupling term Y=RabTab. In this article, we are eager to explore the imprints of f(R, T, Y) cosmology on the early universe through the observational constraints of Big Bang nucleosynthesis. To analyze the early universe scenario, we investigate the deviation of freeze-out temperature through the ratio |ΔTf/Tf| that has observation limits |ΔTf/Tf|≤4.7×10−4 and the primordial helium mass fraction Yp of the light nuclear species having observational limits Yp=0.245±0.003. For instance, we consider two models f(R,T,Y)=R+αY and f(R,T,Y)=R+αY+γT to evaluate the viability of observational limits. We analyzed these models for the radiation-dominated era (ρ=3p) in the early universe. Our findings indicate that f(R, T, Y) gravity can agree with recent observational bounds on big bang nucleosynthesis via deviations in freeze-out temperature and primordial helium abundances, leading to a viable cosmology in the early cosmic epoch.