SUSY GUTs with Yukawa unification: a go/no-go study using FCNC processes

Understand

We address the viability of exact Yukawa unification in the context of general SUSY GUTs with universal soft-breaking sfermion and gaugino mass terms at the GUT scale.

• We find that this possibility is challenged, unless the squark spectrum is pushed well above the limits allowed by naturalness.
• This conclusion is assessed through a global fit using electroweak observables and quark flavour-changing neutral current (FCNC) processes.
• The problem is mostly the impossibility of accommodating simultaneously the bottom mass and the BR(B --> Xs gamma), after the stringent CDF upper bound on the decay Bs --> mu^+ mu^- is taken into account, and under the basic assumption that the b --> s gamma amplitude have like sign with respect to the Standard Model one, as indicated by the B --> Xs l^+ l^- data.