\eta\ transitions between charmonia with meson loop contributions

TL;DR

This paper investigates eta transitions between specific charmonium states, incorporating meson loop effects to explain experimental decay rates, and predicts branching fractions for future experimental validation.

Contribution

The study introduces meson loop contributions within an effective Lagrangian framework to accurately estimate eta transition branching fractions between charmonia.

Findings

Branching fractions match Belle and BESIII data.

Predicted eta' transition is below current experimental limits.

Meson loop effects significantly enhance decay amplitude calculations.

Abstract

We study the $\eta$ transitions between $\psi(4040/4160)$ and $J/\psi$ by introducing charmed meson loops in an effective Lagrangian approach to enhance the decay amplitudes. The branching fractions $\mathcal{B}[\psi(4040) \to J/\psi \eta]$ and $\mathcal{B}[\psi(4160) \to J/\psi \eta]$ estimated in this paper can remarkably explain the experimental measurements of Belle and BESIII within a reasonable parameter range. The $\eta^\prime$ transition between $\psi(4160)$ and $J/\psi$ is also investigated, and the branching fraction is under the upper limit of CLEO, which can be tested by future experiments.