Texture zeros in neutrino mass matrix
  The Standard Model does not explain the hierarchy problem. Before the discovery of nonzero lepton mixing angle {\theta}13 high hopes in explanation of the shape of the lepton mixing matrix were combined with non abelian symmetries. Nowadays, assuming one Higgs doublet, it is unlikely that this is still valid. Texture zeroes, that are combined with abelian symmetries, are intensively studied. The neutrino mass matrix is a natural way to study such symmetries. 
Bartosz Dziewit, Jacek Holeczek, Monika Richter, Sebastian Zaj\k{a}c,   Marek Zra{\l}ek
hep-ph