Measurement of the B+ and B0 lifetimes and search for CP(T) violation using reconstructed secondary vertices

OPAL Collaboration (2000) Measurement of the B+ and B0 lifetimes and search for CP(T) violation using reconstructed secondary vertices. European Physical Journal C: Particles and Fields, 12 (4). pp. 609-626. ISSN 1434-6044

Abstract

The lifetimes of the B+B+ and B0B0 mesons, and their ratio, have been measured in the OPAL experiment using 2.4 million hadronic Z0Z0 decays recorded at LEP. Z0→bb¯¯¯Z0→bb¯ 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 τB+ = 1.643 ± 0.037 ± 0.025 ps τB0 = 1.523 ± 0.057 ± 0.053 ps τB+ /τB0 = 1.079 ± 0.064 ± 0.041, where in each case the first error is statistical and the second systematic. A larger data sample of 3.1 million hadronic Z0 decays has been used to search for CP and CPT violating effects by comparison of inclusive b and b¯ hadron decays. No evidence for such effects is seen. The CP violation parameter Re(ϵB) is measured to be Re(B)=0.001 ± 0.014 ± 0.003 and the fractional difference between b and b¯ hadron lifetimes is measured to be (∆τ_τ)b≡ τ (b hadron) − τ (b hadron)__τ (average) = −0.001 ± 0.012 ± 0.008