Two-photon decays and photoproduction on electrons of $\eta(550)$, $\eta'(958)$, $\eta(1295)$, and $\eta(1475)$ mesons

TL;DR

This paper models electromagnetic interactions of eta and eta' mesons, including their radial excitations, using an extended NJL framework, and predicts two-photon decay widths and production probabilities consistent with experimental data.

Contribution

It introduces a polynomial form factor for radial excitations within the NJL model and provides predictions for decay widths of excited eta mesons, addressing the $U_A(1)$ problem.

Findings

Two-photon decay widths of eta and eta' match experimental data.

Predicted decay widths for eta(1295) and eta(1475).

Calculated eta meson production probabilities in e+e- collisions.

Abstract

Electromagnetic interactions of the ground and first radial excited states of $\eta$ and $\eta'$ mesons in the framework of the extended $U(3)\times U(3)$ NJL model are considered. The radial excitations are described with the help of polynomial form factor of the second order over the inner quark momentum. The solution of the $U_A(1)$ problem by means of 't Hooft interaction is taken into account. For diagonalization of the free Lagrangian the $4\times4$ mixing matrix is used. Two-photon decay widths of the ground $\eta$ and $\eta'$ meson are found to be in a satisfactory agreement with the experiment. Predictions for the two-photon decay widths of $\eta(1295)$ and $\eta(1475)$ are given. The probabilities of eta meson production by two-photon mechanism in $e^+e^-$ collisions and of their photoproduction on electrons are calculated.