Radiative Transitions in Charmonium

TL;DR

This paper investigates the form factors for radiative transitions in charmonium mesons using lattice QCD, extrapolates to real photon points, and compares results with experimental data, providing insights into charmonium electromagnetic properties.

Contribution

It introduces a lattice QCD approach with anisotropic lattices and domain-wall fermions to compute charmonium radiative transition form factors and compares them with experimental photocouplings.

Findings

Photocouplings are consistent with experimental values.

Form factors are successfully extrapolated to Q^2=0.

Lattice methods provide reliable predictions for radiative transitions.

Abstract

The form factors for the radiative transitions between charmonium mesons are investigated. We employ an anisotropic lattice using a Wilson gauge action, and domain-wall fermion action. We extrapolate the form factors to $Q^2 = 0$, corresponding to a real photon, using quark-model-inspired functions. Finally, comparison is made with photocouplings extracted from the measured radiative widths, where known. Our preliminary results find photocouplings commensurate with these experimentally extracted values.