A light neutralino in hybrid models of supersymmetry breaking

Abstract

We show that in gauge mediation models where heavy messenger masses are provided by the adjoint Higgs field of an underlying SU(5) theory, a generalized gauge mediation spectrum arises with the characteristic feature of having a neutralino LSP much lighter than in the standard gauge or gravity mediation schemes. This naturally fits in a hybrid scenario where gravity mediation, while subdominant with respect to gauge mediation, provides mu and Bmu parameters of the appropriate size for electroweak symmetry breaking.

Comments: 32 pages. v2: revised discussions of the generation of Bmu and of the dark matter constraint; numerous small redactional changes; remarks and references added