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 semileptonic B-decay spectrum. We extract the value of |V ub/Vcb| as a function of p F. We also calculate the parameter p F in the relativistic quark model using the variational method, and obtain p F=0.54 GeV which is much larger than the commonly used value, ∼0.3 GeV, in experimental analyses. When we use p 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.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)