(3+2) Neutrino Scheme From A Singular Double See-Saw Mechanism

Abstract

We obtain a 3+2 neutrino spectrum within a left-right symmetric framework by invoking a singular double see-saw mechanism. Higgs doublets are employed to break $S{U}_R(2)$ and three additional fermions, singlets under the left-right symmetric gauge group, are included. The introduction of a singularity into the singlet fermion Majorana mass matrix results in a light neutrino sector of three neutrinos containing predominantly ${\nu }_{\alpha L}$, $\alpha =e,\mu ,\tau$, separated from two neutrinos containing a small ${\nu }_{\alpha L}$ component. The resulting active-sterile mixing in the $5\times 5$ mixing matrix is specified once the mass eigenvalues and the $3\times 3$ submatrix corresponding to the MNS mixing matrix are known.

5 pages, matches published version