Study of $B^0_s$ oscillations and lifetime using fully reconstructed $D_s$ - decays

ALEPH Collaboration, The and Barate, R. and Betteridge, Andrew and Bowdery, Christopher and Colrain, Paul and Finch, Alexander and Foster, Frank and Hughes, Gareth and Jones, Roger and Williams, Mark (1998) Study of $B^0_s$ oscillations and lifetime using fully reconstructed $D_s$ - decays. The European Physical Journal C (EPJ C) - Particles and Fields, 4 (3). pp. 367-385. ISSN 1434-6052

Abstract

A search for B0s oscillations is performed using approximately 4 million Z→qq¯ events collected by the ALEPH experiment during 1991–1995. B0s candidates are partially reconstructed by combining tracks with fully reconstructed D−s candidates. The B0s production flavour is estimated from the sign of the opposite hemisphere charge, a fragmentation kaon in the same hemisphere, or a lepton in the opposite hemisphere. From a total sample of 1620 candidates, with a B0s purity estimated to be 22%, all values of Δms below 3.9 ps −1 and between 6.5 and 8.8 ps −1 are excluded at 95% CL. From the same sample, the B0s lifetime is measured to be τs=1.47±0.14(stat)±0.08(syst) ps. This analysis selects mainly hadronic B0s decays and is statistically independent of a previous ALEPH analysis selecting B0s→D(∗)−sℓ+ν candidates. Combining these two analyses yields Δms>7.9 ps −1 at 95% CL and τs=1.51±0.11 ps.