Measurement of the Bs0-B¯s0 oscillation frequency Δms in Bs0→Ds−(3)π decays

The Bs0-B¯s0 oscillation frequency Δms is measured with 36 pb−1 of data collected in pp collisions at s=7TeV by the LHCb experiment at the Large Hadron Collider. A total of 1381 Bs0→Ds−π+ and Bs0→Ds−π+π−π+ signal decays are reconstructed, with average decay time resolutions of 44 fs and 36 fs, respectively. An oscillation signal with a statistical significance of 4.6σ is observed. The measured oscillation frequency is Δms=17.63±0.11(stat)±0.02(syst)ps−1.