Two-photon transitions of charmonia on the light front

TL;DR

This paper studies two-photon transitions of charmonium states using light-front dynamics, deriving wave functions from an effective Hamiltonian, and successfully predicts form factors and decay widths consistent with experimental data.

Contribution

It introduces a novel calculation of charmonium two-photon transitions using light-front holography and basis light-front quantization without free parameters.

Findings

Predicted two-photon decay widths agree with BaBar and Belle measurements.

Calculated form factors match experimental data, confirming the model's validity.

Highlights the relativistic effects in charmonium transitions.

Abstract

We investigate the two-photon transitions $H_{c\bar c} \to \gamma^*\gamma$ of the charmonium system in light-front dynamics. The light-front wave functions were obtained from solving the effective Hamiltonian based on light-front holography and one-gluon exchange interaction within the basis light-front quantization approach. We compute the two-photon transition form factors as well as the two-photon decay widths for S- and P-wave charmonia, $\eta_c$ and $\chi_{cJ}$ and their excitations. Without introducing any free parameters, our predictions are in good agreement with the recent experimental measurements by BaBar and Belle, shedding light on the relativistic nature of charmonium.