Flavour issues for string-motivated heavy scalar spectra with a low gluino mass: the G2-MSSM case

In recent years it has been learned that scalar superpartner masses and trilinear couplings should both generically be larger than about 20 TeV at the short-distance string scale if our world is described by a compactified string or M-theory with supersymmetry breaking and stabilized moduli (Acharya et al.). Here we study implications of this, somewhat generally and also in detail for a particular realization (compactification of M-theory on a G2 manifold) where there is significant knowledge of the superpotential and gauge kinetic function, and a light gluino. In a certain sense this yields an ultraviolet completion of minimal flavour violation. Flavour violation stems from off-diagonal and non-universal diagonal elements of scalar mass matrices and trilinear couplings, and from renormalization group running. We also examine stability bounds on the scalar potential. While heavy scalars alone do not guarantee the absence of flavour problems, our studies show that models with heavy scalars and light gluinos can be free from such problems. (orig.)