Electric dipole transitions of heavy quarkonium in pNRQCD
  We propose a systematic, model-independent treatment of electric dipole transitions of heavy quarkonium. Within an effective field theory, concretely potential non-relativistic QCD, the relativistic corrections of relative order $v^2$ to the decay rate are derived. An existing formalism developed for M1 decays will be extended for our purpose. We scrutinize and complement former results from potential model calculations. 
Piotr Pietrulewicz
hep-ph