On the two-loop penguin contributions to the Anomalous Dimensions of four-quark operators

Abstract

We revisit the Next-to-Leading Order (two-loop) contributions to the Anomalous Dimensions of ∆F = 1 four-quark operators in QCD. We devise a test for anomalous dimensions, that we regard as of general interest, and by means of which we detect a problem in the results available in the literature. Deconstructing the steps leading to the available result, we identify the source of the problem, which is related to the operator known as Q11. We show how to fix the problem and provide the corrected anomalous dimensions. With the insight of our findings, we propose an alternative approach to the one used in the literature which does not suffer from the identified disease, and which confirms our corrected results. We assess the numerical impact of our corrections, which happens to be in the ballpark of 5% in certain entries of the evolution matrix. Our results are important for the correct resummation of Next-to-Leading Logarithms in analyses of physics beyond the Standard Model in ∆F = 1 processes, such as the decays of Kaons and B-mesons.