Precision measurement of the B0s–$\overline{\rm B}{}^0_{\rm s}$ oscillation frequency with the decay B0s → D−sπ+

A key ingredient to searches for physics beyond the Standard Model in B0s mixing phenomena is the measurement of the B0s? 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.