Zweig-forbidden radiative orthoquarkonium decays in perturbative QCD

We calculate helicity amplitudes and decay rates for Zweig-forbidden radiative decays of a ${}^3\text{S}{}_1\text{(}\text{Q}\text{Q}\text{)}$ bound state into ${}^1\text{S}{}_0\text{(}\text{q}\text{q}\text{)}\text{and}{}^3\text{P}{}_{\mathrm{J}}\text{(}\text{q}\text{q}\text{)}$ states in lowest-order QCD. We employ a new technique of scalarizing loop integrals by using covariant helicity projectors. Thereby we are able to integrate analytically all occuring loop integrals.When applied to $\text{J}\text{ψ}$ decays our results are in reasonable agreement with present experimental results. ψ′ decays will provide a further test of the model. Transitions from bottonium to charmonium are most interesting since there all dynamical assumptions are well satisfied. Unfortunately the transitions rates are very small.