Abstract.
The lifetimes of the \(\rm B^+\) and \(\rm B^0\) mesons, and their ratio, have been measured in the OPAL experiment using 2.4 million hadronic \(\rm Z^0\) decays recorded at LEP. \(\rm Z^0 \rightarrow \rm b\overline{b}\) decays were tagged using displaced secondary vertices and high momentum electrons and muons. The lifetimes were then measured using well-reconstructed charged and neutral secondary vertices selected in this tagged data sample. The results are
\begin{eqnarray*} \tau_{B^+} & = & 1.643 \pm 0.037\pm 0.025 \rm\,ps \tau_{B^0} & = & 1.523 \pm 0.057 \pm 0.053 \rm\,ps \tau_{B^+}/ \tau_{B^0} & = & 1.079 \pm 0.064 \pm 0.041 \,, \end{eqnarray*}
where in each case the first error is statistical and the second systematic.
A larger data sample of 3.1 million hadronic \(\rm Z^0\) decays has been used to search for CP and CPT violating effects by comparison of inclusive b and \(\rm\overline{b}\) hadron decays. No evidence for such effects is seen. The CP violation parameter \(\rm Re(\epsilon_B)\) is measured to be \[ \rm Re(\epsilon_B) = 0.001 \pm 0.014 \pm 0.003 \] and the fractional difference between b and \(\rm\overline{b}\) hadron lifetimes is measured to be
\[ \left(\frac{\Delta\tau}{\tau}\right)_{\rm b} \equiv \frac{\rm\tau (b \mbox{hadron}) - \tau \mbox{(\rm\overline{b} hadron)}} {\rm\tau (average)} = -0.001\pm 0.012\pm 0.008 \,. \]
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Received: 11 December 1998 / Published online: 3 February 2000
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The OPAL Collaboration., Abbiendi et al., G. Measurement of the \(\rm B^+\) and \(\rm B^0\) lifetimes and search for CP(T) violation using reconstructed secondary vertices. Eur. Phys. J. C 12, 609–626 (2000). https://doi.org/10.1007/s100520000322
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DOI: https://doi.org/10.1007/s100520000322