Di-electrons from $\eta$ meson Dalitz decay in proton-proton collisions

Abstract

The reaction $pp\to pp\eta \to pp\gamma e^{+}{e}^{-}$ is discussed within a covariant effective meson-nucleon theory. The model is adjusted to data of the subreaction $pp\to pp\eta$. Our focus is on di-electrons from Dalitz decays of $\eta$ mesons, $\eta \to \gamma {\gamma }^{\ast }\to \gamma e^{+}{e}^{-}$, and the role of the corresponding transition form factor $F_{\eta \gamma {\gamma }^{\ast }}$. Numerical results are presented for the intermediate energy kinematics of HADES experiments.