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

TL;DR

This paper investigates the impact of LEP2 bounds on MSSM Higgs mass, the implications of low string scales on charge and colour breaking bounds, and how these bounds are relaxed at scales below 10^{10} GeV.

Contribution

It demonstrates that current experimental bounds exclude certain quasi-fixed MSSM scenarios unless stops are very heavy and shows that CCB bounds are significantly weakened at low string scales.

Findings

LEP2 bounds exclude quasi-fixed MSSM scenarios for certain string scales unless stops > 2 TeV.

CCB bounds are weakened for string scales below 10^{10} GeV.

Degenerate scalar masses are only required to be positive at the string scale for low scales.

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.