3 CMS
IPNL - Institut de Physique Nucléaire de Lyon
Abstract : We present a measurement of the average b-hadron lifetime ${\rm \tau_b}$ at the $\mathrm{e^+e^-} \,$ collider LEP. Using hadronic Z decays collected in the period from 1991 to 1994, two independent analyses have been performed. In the first one, the b-decay position is reconstructed as a secondary vertex of hadronic b-decay particles. The second analysis is an updated measurement of ${\rm \tau_b}$ using the impact parameter of leptons with high momentum and high transverse momentum. The combined result is \begin{center} ${\rm \tau_b= [ 1549 \pm 9 \, (stat) \, \pm 15 \, (syst) ] \; fs \,}$ . \end{center} In addition, we measure the average charged b-decay multiplicity ${\rm \langle n_{\rm b}} \rangle$ and the normalized average b-energy ${\rm \langle x_E \rangle_{\rm b}}$ at LEP to be \begin{center} ${\rm \langle n_{\rm b} \rangle = 4.90 \pm 0.04 \ (stat) \pm 0.11 \, (syst)}$ , \end{center} \begin{center} ${\rm \langle x_E \rangle_{\rm b} = 0.709 \pm 0.004 \, (stat + syst).}$ \end{center}
Document type :
Journal articles

Cited literature [20 references]

http://hal.in2p3.fr/in2p3-00000012
Contributor : Sylvie Flores <>
Submitted on : Wednesday, November 4, 1998 - 3:06:00 PM
Last modification on : Friday, November 16, 2018 - 11:18:03 AM
Long-term archiving on : Wednesday, May 27, 2015 - 1:01:06 PM

### Identifiers

• HAL Id : in2p3-00000012, version 1

### Citation

M. Acciarri, O. Adriani, M. Aguilar-Benitez, S. Ahlen, J. Alcaraz, et al.. Measurement of the Average Lifetime of b-Hadrons in Z Decays. Physics Letters B, Elsevier, 1998, 416, pp.220-232. ⟨in2p3-00000012⟩

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