Toward a NNLO calculation of the B-->X_s+gamma decay rate with a cut on photon energy: II. Two-loop result for the jet function

Thomas Becher; Matthias Neubert

Paper

Toward a NNLO calculation of the B-->X_s+gamma decay rate with a cut on photon energy: II. Two-loop result for the jet function

Abstract

The complete two-loop expression for the jet function J(p^2,mu) of soft-collinear effective theory is presented, including non-logarithmic terms. Combined with our previous calculation of the soft function S(omega,mu), this result provides the basis for a calculation of the effect of a photon-energy cut in the measurement of the B-->X_s+gamma decay rate at next-to-next-to-leading order in renormalization-group improved perturbation theory. The jet function is also relevant to the resummation of Sudakov logarithms in other hard QCD processes.