(1/2)+→(1/2)+ beta decay with neutrino mass effects in the elementary particle treatment of weak interactions

We compute the effect of a nonvanishing neutrino mass on the electron spectrum of tritium beta decay using the elementary particle treatment of weak interactions. Coulomb corrections are taken into account in this formalism, as are the effects of weak magnetism and nuclear recoil. The effect of a mixture of excited atomic final states is also discussed. These corrections combine to make small changes in the shape of the end point, which could be important in determinations of the neutrino mass