Springer LINK: Zeitschrift für Physik C - Abstract Volume 74 Issue 3 (1997) pp 423-435

Zeitschrift für Physik C

ISSN: 0170-9739 (printed version)
ISSN: 1431-5858 (electronic version)

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Abstract Volume 74 Issue 3 (1997) pp 423-435

Measurement of the semileptonic branching fraction of inclusive b baryon decays to $\Lambda$

K. Ackerstaff et al. (8)OPAL Collaboration

(8) CERN, European Organisation for Particle Physics, CH-1211 Geneva 23, Switzerland

Received: 21 November 1996

Abstract. We present the first measurement of the ratio $R_{\Gamma\ell}$ defined as \[ R_{\Gamma\ell}={\rm BR}(\Lambda_{\rm b} \to \Lambda \ell X)/{\rm BR}(\Lambda_{\rm b} \to \Lambda X)\\ \] where $\Lambda_{\rm b}$ denotes all weakly decaying b baryons and $\ell$ represents the average of electrons and muons. Using all hadronic Z$^0$ decay events collected with the OPAL detector near the Z$^0$ resonance, we measure \[ R_{\Lambda \ell}=(7.0\pm 1.2\pm 0.7)\%. \] We also measure \[ f(\mathrm b \rightarrow \Lambda_{\rm b})\cdot {\mathrm BR}(\Lambda_{\rm b} \rightarrow \Lambda {\mathrm X})= (3.93 \pm 0.46 \pm 0.37)\%, \] \[ f(\mathrm b \rightarrow {\mathrm B})\cdot {\mathrm BR} ({\mathrm B} \rightarrow \lam {\mathrm X}) = (1.94 \pm 0.28 \pm 0.24)\%, \quad {\rm and} \] \[ {\mathrm BR} ({\mathrm b~}\rightarrow\lam {\mathrm X}) = (5.87 \pm 0.46 \pm 0.48)\%. \] In all cases, the uncertainties shown are statistical and systematic, respectively.

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