Neutrino mass and lepton mixing hierarchies and future oscillation experiments

Abstract

Future experiments searching for neutrino oscillations are discussed on the assumption of the existence of a hierarchy in the neutrino masses. Different scenarios for the hierarchy of coupling among lepton families are considered. Relations and inequalities among transition probabilities are derived. The inequalities follow the pattern in the hierarchy of coupling among lepton generations. Simpson's 17 keV neutrino is discussed. It is shown that if such a heavy neutrino exist, the probability of the transition v e→ v τ will not exceed approximately 2×10 −2 independently of the nature (Dirac or Marjorana) and the number of the neutrino mass eigenstates.