2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/14550We report on the results of a recent evaluation of all percent level corrections to weak rates of processes converting n <-> p, which are crucial for the determination of the 4He mass fraction produced during primordial nucleosynthesis.5 pages, Talk given at the Second Meeting on New Worlds in Astroparticle Physics, September 1998, Faro, PortugalAstrophysicsHigh Energy Physics - PhenomenologyA detailed analysis of the neutron to proton ratio at the onset of primordial nucleosynthesistext