Precision measurement of the B⁰_s–$\overline{\rm B}{}^0_{\rm s}$ oscillation frequency with the decay B⁰_s→ D⁻_s<i>π</i>⁺

Abstract

A key ingredient to searches for physics beyond the Standard Model in B0s mixing phenomena is the measurement of the B0s-B 0 s oscillation frequency, which is equivalent to the mass difference ms of the B0s mass eigenstates. Using the world's largest B0s meson sample accumulated in a dataset, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb experiment at the CERN LHC in 2011, a measurement of ms is presented. A total of about 34 000 B0s D-s+ signal decays are reconstructed, with an average decay time resolution of 44 fs. The oscillation frequency is measured to be ms = 17.768 0.023 (stat) 0.006 (syst) ps-1, which is the most precise measurement to date.