decay in perturbative QCD approach
CCAST (World Laboratory), P.O. Box 8730, 100080, Beijing, P.R. China
2 Institute of High Energy Physics, CAS, P.O. Box 918(4), 100049, Beijing, P.R. China
The rare decay can occur only via the penguin annihilation topology in the standard model. We calculate this channel in the perturbative QCD approach. The predicted branching ratio is very small: around 10-8. We also give the polarization fractions, which show that the transverse polarization contribution is comparable to the longitudinal one, due to a big transverse contribution from factorizable diagrams. The small branching ratio in SM makes it sensitive to any new physics contributions.
© Springer-Verlag, 2005