Quasi-Fixed Points and Charge and Colour Breaking in Low Scale Models

Abstract

We show that the current LEP2 lower bound upon the minimal supersymmetric standard model (MSSM) lightest Higgs mass rules out quasi-fixed scenarios for string scales between 10^6 and 10^{11} GeV unless the heaviest stop mass is more than 2 TeV. We consider the implications of the low string scale for charge and colour breaking (CCB) bounds in the MSSM, and demonstrate that CCB bounds from F and D-flat directions are significantly weakened. For scales less than 10^{10} GeV these bounds become merely that degenerate scalar mass squared values are positive at the string scale.

Comments: 17 pages, 4 figures. Replacement has added discussion on errors due to alpha_s(MZ) errors, as well as deviations from the quasi-fixed point. Text has been clarified