Complete (O_7,O_8) contribution to B -> X_s gamma at order alpha_s^2

TL;DR

This paper computes specific second-order QCD corrections to the B -> X_s gamma decay, refining the theoretical prediction of its branching ratio within the Standard Model.

Contribution

It provides the complete O(alpha_s^2) corrections from O_7 and O_8 operators, advancing the precision of theoretical calculations for B -> X_s gamma decay.

Findings

Corrections do not alter the central value of the branching ratio by more than 1%.

Enhances the accuracy of Standard Model predictions for B -> X_s gamma.

Supports future experimental and theoretical studies in flavor physics.

Abstract

We calculate the set of O(alpha_s^2) corrections to the branching ratio and to the photon energy spectrum of the decay process B -> X_s gamma originating from the interference of diagrams involving the electromagnetic dipole operator O_7 with diagrams involving the chromomagnetic dipole operator O_8. The corrections evaluated here are one of the elements needed to complete the calculations of the B -> X_s gamma branching ratio at next-to-next-to-leading order in QCD. We conclude that this set of corrections does not change the central value of the Standard Model prediction for Br(B -> X_s gamma) by more than 1 %.