2020 Impact factor 4.590
Particles and Fields
Eur. Phys. J. C 7, 553-569
DOI 10.1007/s100529901108

Search for ${\rm {\bf B}}_{\rm \bf s}^{\rm \bf 0}$ oscillations using inclusive lepton events

The ALEPH Collaboration

R. Barate - et al.

Laboratoire de Physique des Particules (LAPP), IN2P3-CNRS, F-74019 Annecy-le-Vieux Cedex, France

Received: 20 July 1998 / Published online: 19 February 1999

A search for ${\rm B}_{\rm s}^{\rm 0}$ oscillations is performed using a sample of semileptonic ${\rm b}_{\rm }^{\rm }$-hadron decays collected by the ALEPH experiment during 1991-95. Compared to previous inclusive lepton analyses, the proper time resolution and ${\rm b}_{\rm }^{\rm }$-flavour mistag rate are significantly improved. Additional sensitivity to ${\rm B}_{\rm s}^{\rm 0}$ mixing is obtained by identifying subsamples of events having a ${\rm B}_{\rm s}^{\rm 0}$ purity which is higher than the average for the whole data sample. Unbinned maximum likelihood amplitude fits are performed to derive a lower limit of ${\Delta m_{\rm s}}\gt 9.5\,{ps^{-1}}$ at the 95% confidence limit (95% CL). Combining with the ALEPH ${\rm D}_{\rm s}^{\rm -}$-based analyses yields ${\Delta m_{\rm s}}\gt 9.6\,{ps^{-1}}$ at 95% CL.

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