Complete one-loop MSSM predictions for B0 → l+ l- at the Tevatron and LHC

During the last few years the Tevatron has dramatically improved the bounds on rare B-meson decays into two leptons. In the case of B-s(0) -> mu(+) mu(-), the current bound is only 10 times greater than the standard model expectation. Sensitivity to this decay is one of the benchmark goals for LHCb performance and physics. The Higgs penguin dominates this rate in the region of large tan beta of the minimal supersymmetric standard model. This is not necessarily the case in the region of low tan beta, since box and Z-penguin diagrams may contribute at a comparable rate. In this article, we compute the complete one-loop minimal supersymmetric standard model contribution to B-s,d(0) -> l(+) l(-) for l, l(') = e, mu. We study the predictions for general values of tan beta with arbitrary flavor mixing parameters. We discuss the possibility of both enhancing and suppressing the branching ratios relative to their standard model expectations. In particular, we find that there are cancellation regions'' in parameter space where the branching ratio is suppressed well below the standard model expectation, making it effectively invisible to the LHC.