Measurement of Vub using b hadron semileptonic decay

Research output: Contribution to journalArticle

Colleges, School and Institutes


The magnitude of the CKM matrix element /V-ub/ is determined by measuring the inclusive charmless semileptonic branching fraction of beauty hadrons at OPAL based on b --> X(u)l nu event topology and kinematics. This analysis uses OPAL data collected between 1991 and 1995, which correspond to about four million hadronic Z decays. We measure Br(b --> X(u)l nu) to be (1.63 +/-0.53 (+0.15)(-0.62)) X 10(-3). The first uncertainty is the statistical error and the second is the systematic error. From this analysis,. /V-ub/ is determined to be: /Vub/ = (4.00 +/-0.65(stat)(-0.76)(+0.67) (sys) +/- 0.19(HQE)) X 10(-3). The last error represents the theoretical uncertainties related to the extraction of /V-ub/ from Br(b --> X(u)l nu) using the Heavy Quark Expansion.


Original languageEnglish
Pages (from-to)399-410
Number of pages12
JournalEuropean Physical Journal C
Issue number3
Publication statusPublished - 1 Jul 2001