Quark model calculation of $\eta \to l^{+}{l}^{-}$ to all orders in the bound state relative momentum

B. Margolis, J. Ng, M. Phipps +1

The electromagnetic box diagram for the leptonic decays of pseudoscalar mesons in the quark model is evaluated to all orders in $\mathbf{p}/m_q$, where $\mathbf{p}$ is the relative thr…