Study of $\pi^{0}$ and $\eta$ decays containing dilepton

Understand

We calculate the momentum dependent form factors of $P \to \gamma^* \gamma^*$($P=\pi^{0}, \eta$) within the light-front quark model.

• Using the form factors, we examine the decays of $P \to l^+ l^-$, $P \to l^+ l^- \gamma$ and $P \to l^+ l^- l^+ l^-$($l=e$ or $\mu$) and compare our results with the experimental data and other theoretical predictions.
• In particular, for $\pi^0 \to e^+e^-$, we find that the decay branching ratio is $6.68\times 10^{-8}$, which is consistent with the recent measurement of $(7.48\pm0.29\pm0.25)\times 10^{-8}$ by E799 of KTeV/Fermilab.