Completing the NLO QCD calculation of B -> Xs gamma
High Energy Physics - Phenomenology
2009-11-07 v1
Abstract
We evaluate two-loop b -> s gamma matrix elements of all the four-quark operators containing no derivatives. Contrary to previous calculations, no expansion in the mass ratio mc/mb is performed, and all the possible Dirac and flavor structures are included. Consequently, we are able to provide the last item in the NLO analysis of B -> Xs gamma that has been missing so far, namely the two-loop matrix elements of the QCD-penguin operators. Due to smallness of the Wilson coefficients of those operators in the Standard Model, their effect on the branching ratio is small: a reduction by roughly 1%. We find BR[ B -> Xs gamma]_{E_gamma > 1.6 GeV} = (3.57 +_ 0.30)*10^{-4}.
Cite
@article{arxiv.hep-ph/0203135,
title = {Completing the NLO QCD calculation of B -> Xs gamma},
author = {Andrzej J. Buras and Andrzej Czarnecki and Mikolaj Misiak and Joerg Urban},
journal= {arXiv preprint arXiv:hep-ph/0203135},
year = {2009}
}
Comments
18 pages, 2 figures, uses graphicx