Strong Interaction Dynamics and Fermi β Decay in the Nucleon and the Nucleus

Nuclear super-allowed β decay has been used to obtain tight limits on the value of CKM matrix element Vud that is important for unitarity tests and, therefore, standard model. Current requirements precision are so intense effects formerly thought too small matter now considered relevant. This article a brief review personal efforts include strong interactions Fermi decay. First, I examine role isospin violation in neutron. The size necessary correction depends upon detailed strong-interaction dynamics. violating parts nucleon wave function, at low energy decay, can be constrained by data taken much higher energies, via measurements, example, ed→e′π±+X reactions Jefferson Laboratory. next point focus nuclear short-ranged correlations, which affect needed account extracting Vud. net result previously as irrelevant relevant both neutron and