NNLO QCD counterterm contributions to $B$ \to $X_s γ$ for the physical value of $m_c$

One of the most important O($α_s^2$) corrections to the $B \to X_s γ$ branching ratio originates from interference of contributions from the current-current and photonic dipole operators. Its value has been estimated using an interpolation in the charm quark mass between the known results at $m_c=0$ and for $m_c \ll m_b/2$. An explicit calculation for the physical value of $m_c$ is necessary to remove the associated uncertainty. In the present work, we evaluate all the ultraviolet counterterm contributions that are relevant for this purpose.