$\chi_{cJ}\rightarrow e^{+}e^{-}$ decays revisited

Understand

We present a calculation of the width for $\chi_{cJ}\rightarrow e^{+}e^{-}$ decay.

• The amplitude of the process is computed within the NRQCD framework.
• The leading-order contribution is described by two terms associated with the two different integration domains in the electromagnetic loop describing two-photon annihilation of the heavy quark-antiquark pair.
• The corresponding operators are defined in the framework of NRQCD.