Metastability bounds on flavour-violating trilinear soft terms in the MSSM

TL;DR

This paper revisits metastability bounds on flavour-violating trilinear soft terms in the MSSM, emphasizing long-lived false vacua and their implications for sparticle mass constraints from collider and flavor physics.

Contribution

It introduces a numerical evaluation of vacuum transition rates considering metastability, providing more inclusive bounds that are largely independent of Yukawa couplings, except for stops.

Findings

Metastability bounds are more generous than absolute stability bounds.

Bounds remain significant even with increasing sfermion masses.

Potential to probe sparticle masses up to a few TeV via B and tau physics.

Abstract

The vacuum stability bounds on flavour-violating trilinear soft terms are revisited from the viewpoint that one should not ban a standard-model-like false vacuum as long as it is long-lived on a cosmological timescale. The vacuum transition rate is evaluated numerically by searching for the bounce configuration. Like stability, a metastability bound does not decouple even if sfermion masses grow. Apart from being more generous than stability, the new bounds are largely independent of Yukawa couplings except for the stop trilinears. With vacuum longevity imposed on otherwise arbitrary LR insertions, it is found that a super flavour factory has the potential to probe sparticle masses up to a few TeV through B and tau physics whereas the MEG experiment might cover a far wider range. In the stop sector, metastability is more restrictive than any existing experimental constraint such as from electroweak precision data. Also discussed are dependency on other parameters and reliability under radiative corrections.