Vacuum stability and the MSSM Higgs mass

In the Minimal Supersymmetric Standard Model (MSSM), a Higgs boson mass of 125GeV can be obtained with moderately heavy scalar top superpartners provided they are highly mixed. The source of this mixing, a soft trilinear stop-stop-Higgs coupling, can result in the appearance of charge-and color-breaking minima in the scalar potential of the theory. If such a vacuum exists and is energetically favorable, the Standard Model-like vacuum can decay to it via quantum tunnelling. In this work we investigate the conditions under which such exotic vacua arise, and we compute the tunnelling rates to them. Our results provide new constraints on the scalar top quarks of the MSSM.