First measurement of the differential branching fraction and CP asymmetry of the B ± → π ± μ + μ - decay

Abstract

The differential branching fraction with respect to the dimuon invariant mass squared, and the CP asymmetry of the B±→ π ±µ +µ − decay are measured for the first time. The CKM matrix elements |Vtd| and |Vts|, and the ratio |Vtd/Vts| are determined. The analysis is performed using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb−1 , collected by the LHCb experiment at centre-ofmass energies of 7 and 8 TeV. The total branching fraction and CP asymmetry of B±→ π ±µ +µ − decays are measured to be B(B ±→ π ±µ +µ −) = (1.83 ± 0.24 ± 0.05) × 10−8 and ACP (B ±→ π ±µ +µ −) = −0.11 ± 0.12 ± 0.01 , where the first uncertainties are statistical and the second are systematic. These are the most precise measurements of these observables to date, and they are compatible with the predictions of the Standard Model.