Left-handed neutrino disappearance probe of neutrino mass and character

Abstract

We explore the sensitivity to a non vanishing neutrino mass offered by dynamical observables, i.e., branching ratios and polarizations. The longitudinal polarization in the C.M. frame decreases by a 4% for $D^{+}\to {\tau }^{+}{\nu }_{\tau }$ and $m_{{\nu }_{\tau }}=24$ MeV. Taking advantage of the fact that the polarization is a Lorentz variant quantity, we study the polarization effects in a boosted frame. By means of a neutrino beam, produced by a high velocity boosted parent able to flip the neutrino helicity, we find that an enhanced left-handed neutrino deficit, induced by a Wigner rotation, appears.

Comments: 8 pages and 2 figures. Last version accepted in PRL, new references and better analysis of experimental possibilities