Completing the NLO QCD calculation of B̄ → XSγ

Andrzej J. Buras, Andrzej Czarnecki, Mikolaj Misiak, Jörg Urban

Research output: Contribution to journalArticlepeer-review

160 Scopus citations

Abstract

We evaluate two-loop b → sγ 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 B̄ → Xsγ 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[B̄ → Xsγ]>1.6 GeV = (3.57 ± 0.30) × 10-4.

Original languageEnglish
Pages (from-to)219-238
Number of pages20
JournalNuclear Physics, Section B
Volume631
Issue number1-2
DOIs
StatePublished - 3 Jun 2002

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