Generating nonzero $\theta_{13}$ without breaking the $2$-$3$ symmetry   of neutrino mass matrix
  The prediction of vanishing reactor angle was thought to be a signature of $2$-$3$ symmetry of neutrino mass matrix. But the present study addresses certain interesting facts related with $2$-$3$ symmetry which are not addressed so far. The investigation highlights that $\theta_{13}=0$, corresponds to a very special case in association with $2$-$3$ symmetry and to engender a non-zero $\theta_{13}$, the breakdown of $2$-$3$ symmetry is not essential. 
Subhankar Roy, N. Nimai Singh
hep-ph