Chromomagnetic dipole-operator corrections in B¯→Xsγ at O(β0αs2)

We calculate the fermionic corrections to the photon-energy spectrum of B¯→X_sγ which arise from the self-interference of the chromomagnetic dipole operator Q₈ at next-to-next-to-leading order by applying naive non-Abelianization. The resulting O(β₀α_s²) correction to the B¯→X_sγ branching ratio amounts to a relative shift of +0.12% (+0.27%) for a photon-energy cut of 1.6 GeV (1.0 GeV). We also comment on the potential size of resummation and nonperturbative effects related to Q₈.