Measurement of the CKM angle γ and Bs0-B¯s0 mixing frequency with Bs0→Ds∓h±π±π∓ decays

Abstract

The CKM angle γ is measured for the first time from mixing-induced CP violation between Bs0→Ds∓K±π±π∓ and B¯s0→Ds±K∓π∓π± decays reconstructed in proton-proton collision data corresponding to an integrated luminosity of 9 fb−1 recorded with the LHCb detector. A time-dependent amplitude analysis is performed to extract the CP-violating weak phase γ − 2βs and, subsequently, γ by taking the B0s-B¯¯¯¯0sBs0-B¯s0 mixing phase βs as an external input. The measurement yields γ = (44 ± 12)° modulo 180°, where statistical and systematic uncertainties are combined. An alternative model-independent measurement, integrating over the five-dimensional phase space of the decay, yields γ=(44−13+20)∘ modulo 180°. Moreover, the Bs0-B¯s0 oscillation frequency is measured from the flavour-specific control channel Bs0→Ds−π+π+π− to be ∆ms = (17.757 ± 0.007(stat) ± 0.008(syst)) ps−1, consistent with and more precise than the current world-average value.