New Higgs Effects in B--Physics in Supersymmetry with General Flavour Mixing

Abstract

We investigate the effect of general flavour mixing among squarks on the rare decays $\bar{B}\to X_sγ$, $\bar{B}_s\toμ^+μ^-$ and $\bar{B}_s-B_s$ mixing beyond the leading order in perturbation theory. We include all large $\tanβ$--enhanced corrections whilst also taking into account the effects of general flavour mixing on the uncorrected quark mass matrix and ${\rm SU}(2)_L\times{\rm U}(1)_Y$ breaking. For $\bar{B}_s\toμ^+μ^-$ and $\bar{B}_s-B_s$ mixing we find that, in analogy to $\bar{B}\to X_sγ$, there appears a focusing effect which can reduce the contribution due to the $δ_{RR}$ (and the $δ_{LL}$) insertion by up to a factor of two at large $\tanβ$ and $μ>0$. A dependence on $δ_{LR}$ and $δ_{RL}$, that otherwise cancels to first order in the mass insertion approximation, is also reintroduced. Taking into account the current experimental bounds on $ΔM_{B_s}$ and BR($\bar{B}_s\toμ^+μ^-$), we find that the insertions $δ_{RL}$ and $δ_{RR}$ can be significantly constrained compared to bounds obtained from $\bar{B}\to X_sγ$ only.