TY - JOUR
T1 - Completing the NLO QCD calculation of B̄ → XSγ
AU - Buras, Andrzej J.
AU - Czarnecki, Andrzej
AU - Misiak, Mikolaj
AU - Urban, Jörg
N1 - Funding Information:
We are grateful to Paolo Gambino for verifying the influence of our results for r k on the entries of Table 2 and on the final prediction for the branching ratio. J.U. would like to thank Stefan Fritsch and Michael Spranger for fruitful discussions. The work presented here was supported in part by the German Bundesministerium für Bildung und Forschung under the contract 05HT1WOA3 and the DFG Project Bu. 706/1-1, and by the Natural Sciences and Engineering Research Council of Canada. M.M. was supported by the Polish Committee for Scientific Research under grant 2 P03B 121 20.
PY - 2002/6/3
Y1 - 2002/6/3
N2 - 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]Eγ>1.6 GeV = (3.57 ± 0.30) × 10-4.
AB - 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]Eγ>1.6 GeV = (3.57 ± 0.30) × 10-4.
UR - http://www.scopus.com/inward/record.url?scp=0037013693&partnerID=8YFLogxK
U2 - 10.1016/S0550-3213(02)00261-4
DO - 10.1016/S0550-3213(02)00261-4
M3 - Article
AN - SCOPUS:0037013693
SN - 0550-3213
VL - 631
SP - 219
EP - 238
JO - Nuclear Physics, Section B
JF - Nuclear Physics, Section B
IS - 1-2
ER -