Probing New Physics in b → d transitions

A bstract Recent experimental data on several observables in semileptonic B -meson decays are found to be in tension with the corresponding Standard Model predictions. Most of these deviations are related to b → c and b → s flavour changing transitions. In this work, we estimate possible New Physics effects in b → dμ + μ − flavour changing neutral currents. We parametrize NP contributions in a model-independent way and determine the allowed ranges of corresponding Wilson coefficients from the data on the exclusive B ± → π ± μ + μ − decays measured recently by the LHCb collaboration. Afterwards, we investigate the impact of these results on other b → d processes such as the leptonic B 0 → μ + μ − decays and B 0 − B ¯ 0 mixing. As an example, we consider a simplified Z′ model that is found to be consistent with current b → d data in the certain regions of the NP parameter space. In addition, we estimate the correlations between the partial decay widths of B → πμ + μ − and B → K μ + μ − processes to be used for an independent determination of CKM matrix elements as well as for a combined New Physics analysis of both b → d and b → s transitions.