Left-handed neutrino disappearance probe of neutrino mass and character
  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 $D^+ \rightarrow \tau^+ \nu_\tau$ 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. 
G. Barenboim (1,2), J. Bernabeu (1), O. Vives (1,2), ((1) Dep. Fisica   Teorica, U. de Valencia, (2) IFIC, Centre mixte U. d...