Relativistic Quarkonium Model. II: Radiative E1 Transitions

Abstract

E1 transitions in the charmonium and the bb̅ system are investigated by using the instantaneous BS equation and the relativistic formulae, with recoil corrections, for the electromagnetic transitions. A scalar confining potential is assumed and the gluonic-retardation effect in pair-creation amplitudes is taken into account with a rough approximation. The predicted E1 transition rates for bb̅ system are consistent with the experimental values. It is shown that the Breit-Fermi approximation to the BS model holds well for this system except for the transitions 23Pj→13S1. The relativistic effects are large for the charmonium. The transition rate Γ(φ′→γχ0) agrees well with the experimental one. It is, however, shown that the deviations from the measured rates of the transitions φ′→γχj(j=1,2) are still large.