Grand unified theory constrained supersymmetry and neutrinoless double beta decay

Abstract

We analyze the contributions to the neutrinoless double ${\hat{I}}^2$ decay ($0\hat{I}½{\hat{I}}^2{\hat{I}}^2$-decay) coming from the Grand Unified Theory (GUT) constrained Minimal Supersymmetric Standard Model (MSSM) with trilinear R-parity breaking. We discuss the importance of two-nucleon and pion-exchange realizations of the quark-level $0\hat{I}½{\hat{I}}^2{\hat{I}}^2$-decay transitions. In this context, the questions of reliability of the calculated relevant nuclear matrix elements within the Renormalized Quasiparticle Random Phase Approximation (pn-RQRPA) for several medium and heavy open-shell nuclei are addressed. The importance of gluino and neutralino contributions to $0\hat{I}½{\hat{I}}^2{\hat{I}}^2$-decay is also analyzed. We review the present experiments and deduce limits on the trilinear R-parity breaking parameter $\hat{I}{»}_{111}^{\prime }$ from the non-observability of $0\hat{I}½{\hat{I}}^2{\hat{I}}^2$-decay for different GUT constrained SUSY scenarios. In addition, a detailed study of limits on the MSSM parameter space coming from the $B\to X_s{\hat{I}}^3$ processes by using the recent CLEO and OPAL results is performed. Some studies in respect to the future $0\hat{I}½{\hat{I}}^2{\hat{I}}^2$-decay project GENIUS are also presented.

29 pages, 8 figures