2021 Impact factor 4.991
Particles and Fields
Eur. Phys. J. C 16, 555-578
DOI 10.1007/s100520000415

Measurement of the B0s lifetime and study of B0s- ${\overline{\mathrm{B^0_s}}}$oscillations using ${{\mathrm{ D_s}}\ell}$ events

The DELPHI Collaboration

P.Abreu21 - et al.

21 LIP, IST, FCUL - Av. Elias Garcia, 14-1o, 1000 Lisboa Codex, Portugal

Received: 7 February 2000 / Revised version: 23 March 2000 /
Published online: 8 June 2000 - © Springer-Verlag 2000

Lifetime and oscillations of B0s mesons have been studied in events with a large transverse momentum lepton and a Ds of opposite electric charge in the same hemisphere, selected from about 3.6 million hadronic Z0decays accumulated by DELPHI between 1992 and 1995.
The B0s lifetime and the fractional width difference between the two physical B0s states have been found to be:

\begin{displaymath}\tau_{\mathrm{B^0_s}} = (1.42^{+0.14}_{-0.13}(stat.)\pm 0.03(syst.))~ps

\begin{displaymath}\Delta \Gamma_{\rm\mathrm{B^0_s}}/\Gamma_{\rm\mathrm{B^0_s}}< 0.46 ~\mbox{at the 95\% C.L.}

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

~~~~~~~~~~\Delta m_{\mathrm{B^0_s}}> 7.4 ~ \mbox{ps}^{-1}~\mbox{at the 95\% C.L.} & \\
\end{array} \end{eqnarray*}

with a corresponding sensitivity equal to 8.1 ps-1.

Copyright Società Italiana di Fisica, Springer-Verlag 2000