Speaker
Description
We report on the construction of a factorization theorem that allows to
systematically include QCD corrections to the contribution of the
electromagnetic dipole operator O7 to the $\bar B_s \to \mu^+\mu^-$
decay amplitude. We elaborate on how the occurring endpoint divergences
appearing in individual momentum regions cancel, and show how the
resulting rapidity logarithms can be isolated by suitable subtractions
applied to the corresponding bare factorization theorem. This allows to
include in a straightforward manner the QCD corrections arising from the
renormalization-group running of the hard matching coefficient, the
hard-collinear scattering kernel, and the $B_s$-meson distribution
amplitude. We estimate the effect numerically using a recently advocated
parameterization of the $B_s$-meson light-cone distribution amplitude.
