Grand unified theory constrained supersymmetry and neutrinoless double beta decay - art. no. 115007

We analyze the contributions to the neutrinoless double beta decay (0 nu be ta beta decay) coming from the grand unified theory (GUT) constrained minim al supersymmetric standard model (MSSM) with trilinear R-parity breaking. W e discuss the importance of two-nucleon and pion-exchange realizations of t he quark-level 0 nu beta beta-decay transitions. In this context, the quest ions of reliability of the calculated relevant nuclear matrix elements with in the renormalized quasiparticle random phase approximation for several me dium and heavy open-shell nuclei are addressed. The importance of gluino an d neutralino contributions to 0 nu beta beta decay is also analyzed. We rev iew the present experiments and deduce limits on the trilinear R-parity bre aking parameter lambda(111)' from the nonobservability of 0 nu beta beta de cay for different GUT constrained supersymmetry scenarios. In addition, a d etailed study of limits on the MSSM parameter space coming from the B-->X(s )gamma processes by using the recent CLEO and OPAL results is performed. So me studies in respect to the future 0 nu beta beta-decay project GENIUS are also presented. [S0556-2821(99)02819-2].