Di-electrons from $η$ meson Dalitz decay in proton-proton collisions

Abstract

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