Completing the four-body contributions to $\bar{B}\to X_s\gamma$ at NLO

Abstract

We report on the status of the ongoing calculation of multiparticle contributions to the inclusive radiative $\bar{B}\to X_s\gamma$ decay at next-to leading order. This effort amounts to the evaluation of the four-particle process $b\to s\bar{q}q\gamma$ at the one-loop level, supplemented by the corresponding five-particle tree-level cuts $b\to s\bar{q}q\gamma +g$ of the gluon bremsstrahlung. Knowledge of these pieces will formally complete the $\bar{B}\to X_s\gamma$ decay at the next-to-leading order. The different steps such as the generation of the amplitude, its renormalization, and the treatment of occurring IR-divergences are discussed. Moreover, we elaborate on the subtleties that arise when treating ${\gamma }_5$ in $D$ dimensions.

Comments: 10 pages, 4 figures. Contribution to the 14th International Symposium on Radiative Corrections (RADCOR2019), 9-13 September 2019, Palais des Papes, Avignon, France