Measurement of the CKM angle gamma and Bs0-Bs0 mixing frequency with Bs0 -> Ds -/+h +/-pi +/-pi-/+ decays

The CKM angle γ is measured for the first time from mixing-induced CP violation between Bs0 → Ds∓K±π±π∓ and B0s → 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 Bs0-B0s 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+20)◦ modulo 180◦. Moreover, the B0-B0 oscillation frequency is measured from the −13 ss flavour-specific control channel Bs0 → s−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.