Beta -decay end point and heavy neutrino searches.

Abstract

We carefully consider the relation between the $\ensuremath{\beta}$-decay end point and heavy neutrino mixing relative to the least ${\ensuremath{\chi}}^{2}$ fitting procedure. We examine the 1991 experimental results of Hime and Jelley by considering variations due to end-point energy, radiative corrections, and spectrum pileup. We show that their result can be made consistent with the null hypothesis within 3 standard deviations. From consideration of end-point effects we conclude that the spectral region very near to the end point is questionable at best and should be ignored in the analysis of the data. These findings apply to any search for heavy neutrino mixing near the end point of $\ensuremath{\beta}$ decay.