Weinberg Angle, Neutron Abundance in BBN, and Lifetime

We present state-of-the-art kinetic theory determination of the neutron abundance available for the Big-Bang nucleosynthesis (BBN). This paper is motivated by the study of the neutron lifespan measured in the laboratory and the unknown strength of weak interactions coupling constant GF at finite temperature in the primordial Universe. We draw attention to the relevant dependence of GF on the symmetry breaking Weinberg angle sW2, which is a free parameter in the standard model of particle physics. We establish how the value of sW2 by way of GF modification influences the neutron abundance available for BBN and neutron lifetime.