Synergistic constraints on extensions of teleparallel gravity from primordial nucleosynthesis and cosmic chronometers

This study presents a dual-constraint framework to test f(T) gravity models, by combining observations from Big Bang Nucleosynthesis and cosmic chronometers. We investigate a new modified power-law model with dimensionless parameters, as well as an exponential and two logarithmic models. By incorporating recent data on the primordial helium-4 abundance—used to constrain the fractional variation in freeze-out temperature | δ T_f/T_f | —alongside measurements of the Hubble parameter H(z) , we identify parameter sets consistent with both early and late cosmic evolution. Using chi-square minimization, our approach improves upon previous BBN-only studies by providing tighter constraints that connect early-universe physics with the universe’s later expansion. These results support f(T) gravity as a promising alternative to General Relativity and establish a versatile methodology for future cosmological tests.