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Four-Loop Anomalous Dimensions for Radiative Flavour-Changing Decays

Michal Czakon·Ulrich Haisch·Mikolaj Misiak
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Abstract

We evaluate the complete four-loop anomalous dimension matrix that is necessary for determining the effective flavour-changing neutral current couplings qbar-q'-gamma and qbar-q'-g at the next-to-next-to-leading order in QCD. The resulting O(alpha_s^2(mu_b)) correction to the B -> X_s gamma branching ratio amounts to around -2.9% for mu_b = 5 GeV, and -4.4% for mu_b = 2.5 GeV

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Michal Czakon, Ulrich Haisch, Mikolaj Misiak. 2006-12-27. Four-Loop Anomalous Dimensions for Radiative Flavour-Changing Decays. https://doi.org/10.1088/1126-6708%2F2007%2F03%2F008

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