pNRQCD determination of E1 radiative transitions

Abstract

This contribution contains the first numerical computation of the complete set of relativistic corrections of relative order v2 for electric dipole (E1) transitions in heavy quarkonium; in particular, for the processes χbj(1P) → ϒ(1S) + γ with J = 0, 1, 2. We assume that the momentum transfer of the heavy mesons involved in the reactions lies in the weak-coupling regime of the low-energy effective field theory potential non-relativistic QCD (pNRQCD) and thus a full perturbative calculation can be performed.