The Quasi-Fixed MSSM

TL;DR

This paper analyzes the infrared fixed points of the MSSM parameters, showing how the quasi-fixed point regime enhances the model's predictability by focusing parameters towards their true fixed points at the weak scale.

Contribution

It provides an analytical and numerical study of the quasi-fixed points in the MSSM, especially for the top-Yukawa and trilinear couplings, improving understanding of parameter focusing.

Findings

Top-quark trilinear couplings approach -0.59 m_g at the fixed point.

Remaining parameters are significantly focused towards their fixed points.

The quasi-fixed point regime increases MSSM's predictivity.

Abstract

The infra-red fixed points are determined for all the parameters of the MSSM. They dominate the renormalisation group running when the top-Yukawa is in the quasi-fixed point regime (i.e. large at the GUT scale). We examine this behaviour analytically, by solving the full set of one-loop renormalisation group equations in the approximation that the electroweak contributions are negligible, and also numerically. We find the quasi-fixed points for the top-quark trilinear couplings; A_{U_{\alpha 3}} = A_{U_{3\alpha}}=-0.59 m_g independently of the input parameters at the unification scale. All the remaining parameters are significantly focused towards their true fixed points at the weak scale. We examine how this increases the predictivity of the MSSM in this regime.