Dependence of |V ub/Vcb| on Fermi momentump F in ACCMM model

Abstract

The Gaussian width of Fermi momentum,p F, is the most important parameter of the ACCMM model, and its value is essential in the determination of |V ub/Vcb| because the experimental analysis is allowed only at the end-point region of inclusive semileptonicB-decay spectrum. We extract the value of |V ub/Vcb| as a function ofp F. We also calculate the parameterp F in the relativistic quark model using the variational method, and obtainp F=0.54 GeV which is much larger than the commonly used value, ∼0.3 GeV, in experimental analyses. When we usep F=0.5 GeV instead of 0.3 GeV, the value of |V ub/Vcb| from ACCMM model is increased by a factor 1.81, and can give a good agreement with Isgur et al. model.