Measurement of the \({\mathrm{B^0_s}}\) lifetime and study of \({\mathrm{B^0_s}}\) - \({\overline{\mathrm{B^0_s}}}\) oscillations using \({{\mathrm{ D_s}}\ell}\) events

Abstract

Abstract.

Lifetime and oscillations of \({\rm B^0_s}\) mesons have been studied in events with a large transverse momentum lepton and a \({\rm D_s}\) of opposite electric charge in the same hemisphere, selected from about 3.6 million hadronic \({\rm Z^0}\) decays accumulated by DELPHI between 1992 and 1995. The \({\rm B^0_s}\) lifetime and the fractional width difference between the two physical \({\rm B^0_s}\) states have been found to be:

In the latter result it has been assumed that \(\tau_{{\rm B^0_s}}=\tau_{\rm B_d^}\). Using the same sample, a limit on the mass difference between the physical \(\mbox{B}^0_{\mathrm s}\) states has been set:

with a corresponding sensitivity equal to \(8.1 ps^{-1}\).