in the Standard Model
arXiv:hep-ph/9708214 · doi:10.1142/9789814503952_0014
Abstract
We give a summary about the various contributions which have to be calculated in order to obtain the next-to-leading logarithmic result for the branching ratio . Combining all these ingredients, which were obtained by different groups, a complete next-to-leading-logarithmic prediction of the inclusive decay rate was recently presented in the literature. The theoretical uncertainty in the partonic decay rate is now at the 10% level, i.e., less than half of the error in the previous leading-logarithmic result. We also mention the impact of non-perturbative corrections which scale like and discuss in some more detail the recently discovered corrections which scale like . It turns out that the - and the terms lead to corrections to the branching ratio well below the 10% level.
arXiv comment11 pages including 2 postscript figures