Was the Electroweak Phase Transition Preceded by a Color-Broken Phase?

TL;DR

The paper investigates whether a color-broken phase can precede the electroweak phase transition in the MSSM, concluding that tunneling rates are too small for this to occur without additional physics.

Contribution

It provides a detailed analysis showing that in the MSSM, the tunneling rate from a color-broken vacuum to the electroweak vacuum is negligible, constraining models with light stops.

Findings

Tunneling rate is many orders of magnitude too small in MSSM.

Color-breaking phase unlikely to precede EWPT without new physics.

Constraints on stop mass and mixing parameters.

Abstract

It has been suggested, in connection with electroweak baryogenesis in the Minimal Supersymmetric Standard Model (MSSM), that the right-handed top squark has a negative mass squared parameter, such that its field could condense prior to the electroweak phase transition (EWPT). Thus color and electric charge could have been broken just before the EWPT. Here we investigate whether the tunneling rate from the color-broken vacuum can ever be large enough for the EWPT to occur in this case. We find that, even when all parameters are adjusted to their most favorable values, the nucleation rate is many orders of magnitude too small. We conclude that, without additional physics beyond the MSSM, the answer to our title question is ``no.'' This gives constraints in the plane of the light stop mass versus parameters related to stop mixing. However it may be possible to get color breaking in extended models, such as those with R-parity violation.