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

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 − 2β _s and, subsequently, γ by taking the Bs0‐B¯s0 mixing phase β _s 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 ∆m _s = (17.757 ± 0.007(stat) ± 0.008(syst)) ps ⁻¹, consistent with and more precise than the current world-average value. [Figure not available: see fulltext.]