R-parity Conserving Supersymmetry, Neutrino Mass and Neutrinoless Double Beta Decay

Abstract

We consider contributions of R-parity conserving softly broken supersymmetry (SUSY) to neutrinoless double beta ($\text{znbb}$) decay via the (B-L)-violating sneutrino mass term. The latter is a generic ingredient of any weak-scale SUSY model with a Majorana neutrino mass. The new R-parity conserving SUSY contributions to $\text{znbb}$ are realized at the level of box diagrams. We derive the effective Lagrangian describing the SUSY-box mechanism of $\text{znbb}$-decay and the corresponding nuclear matrix elements. The 1-loop sneutrino contribution to the Majorana neutrino mass is also derived. Given the data on the $\text{znbb}$-decay half-life of ${}^{76}$Ge and the neutrino mass we obtain constraints on the (B-L)-violating sneutrino mass. These constraints leave room for accelerator searches for certain manifestations of the 2nd and 3rd generation (B-L)-violating sneutrino mass term, but are most probably too tight for first generation (B-L)-violating sneutrino masses to be searched for directly.

Comments: LATEX, 29 pages + 4 (uuencoded) figures appended