Refactorisation in subleading $\bar{B}\to X_s\gamma$

Abstract

We establish refactorisation conditions between the subleading $O_8$-$O_8$ contributions to the inclusive $\bar{B}\to X_s\gamma$ decay suffering from endpoint divergences and prove a factorisation theorem for these contributions to all orders in the strong coupling constant. This allows for higher-order calculations of the resolved contributions and consistent summation of large logarithms, consequently reducing the recently found large-scale dependence in these contributions. We implement the concept of refactorisation in a heavy flavour application of SCET, which includes nonperturbative functions as additional subtlety not present in collider applications.

Comments: 24 pages, 4 figures