BBN constraints on f(Q,T) gravity

Abstract

[Formula: see text] gravity is a novel extension of the symmetric teleparallel gravity where the Lagrangian [Formula: see text] is represented through an arbitrary function of the nonmetricity [Formula: see text] and the trace of the energy–momentum tensor [Formula: see text].23 In this work, we have constrained a widely used [Formula: see text] gravity model of the form [Formula: see text] from the primordial abundances of the light elements to understand its viability in cosmology. We report that the [Formula: see text] gravity model can elegantly explain the observed abundances of Helium and Deuterium while the Lithium problem persists. From the constraint on the expansion factor in the range [Formula: see text], we report strict constraints on the parameters [Formula: see text] and [Formula: see text] in the range [Formula: see text] and [Formula: see text], respectively.