Phenomenological study on the significance of the scalar potential and Lamb shift

TL;DR

This paper investigates the impact of scalar potentials and the Lamb shift on charmonia spectra within QCD, highlighting their significance compared to QED and fitting parameters to experimental data.

Contribution

It provides a phenomenological analysis of scalar potential effects on charmonia spectra, incorporating the Lamb shift and fitting parameters to experimental data.

Findings

Scalar potential contributions are significant in QCD charmonia spectra.

Including the Lamb shift affects the spectral calculations.

Fitted parameters successfully reproduce known charmonia states.

Abstract

We indicated in our previous work that for QED the contributions of the scalar potential which appears at the loop level is much smaller than that of the vector potential and in fact negligible. But the situation may be different for QCD, one reason is that the loop effects are more significant because $\alpha_s$ is much larger than $\alpha$, and secondly the non-perturbative QCD effects may induce the scalar potential. In this work, we phenomenologically study the contribution of the scalar potential to the spectra of charmonia. Taking into account both vector and scalar potentials, by fitting the well measured charmonia spectra, we re-fix the relevant parameters and test them by calculating other states of the charmonia family. We also consider the role of the Lamb shift and present the numerical results with and without involving the Lamb shift.