U(2) and minimal flavour violation in supersymmetry

Abstract

Rather than sticking to the full U(3)³ approximate symmetry normally invoked in Minimal Flavour Violation, we analyze the consequences on the current flavour data of a suitably broken U(2)³ symmetry acting on the first two generations of quarks and squarks. A definite correlation emerges between the ΔF=2 amplitudes $\mathcal{M}( K^{0} \to \bar{K}^{0} )$, $\mathcal{M}( B_{d} \to \bar{B}_{d} )$ and $\mathcal{M}( B_{s} \to \bar{B}_{s} )$, which can resolve the current tension between $\mathcal{M}( K^{0} \to \bar{K}^{0} )$ and $\mathcal{M}( B_{d} \to \bar{B}_{d} )$, while predicting $\mathcal{M}( B_{s}\to \bar{B}_{s} )$. In particular, the CP violating asymmetry in B _s →ψφ is predicted to be positive S _ψφ =0.12±0.05 and above its Standard Model value (S _ψφ =0.041±0.002). The preferred region for the gluino and the left-handed sbottom masses is below about 1÷1.5 TeV. An existence proof of a dynamical model realizing the U(2)³ picture is outlined.