Very Constrained Minimal Supersymmetric Standard Models

Abstract

We consider very constrained versions of the minimal supersymmetric extension of the Standard Model (VCMSSMs) which, in addition to constraining the scalar masses m_0 and gaugino masses m_{1/2} to be universal at some input scale, impose relations between the trilinear and bilinear soft supersymmetry breaking parameters A_0 and B_0. These relations may be linear, as in simple minimal supergravity models, or nonlinear, as in the Giudice-Masiero mechanism for generating the Higgs-mixing mu term. We discuss the application of the electroweak vacuum conditions in VCMSSMs, which may be used to make a prediction for tan beta as a function of m_0 and m_{1/2} that is usually unique. We baseline the discussion of the parameter spaces allowed in VCMSSMs by updating the parameter space allowed in the CMSSM for fixed values of tan beta with no relation between A_0 and B_0 assumed {\it a priori}, displaying contours of B_0 for a fixed input value of A_0, incorporating the latest CDF/D0 measurement of m_t and the latest BNL measurement of g_mu - 2. We emphasize that phenomenological studies of the CMSSM are frequently not applicable to specific VCMSSMs, notably those based on minimal supergravity, which require m_0 = m_{3/2} as well as A_0 = B_0 + m_0. We then display (m_{1/2}, m_0) planes for selected VCMSSMs, treating in a unified way the parameter regions where either a neutralino or the gravitino is the LSP. In particular, we examine in detail the allowed parameter space for the Giudice-Masiero model.