Understanding J/ψ and ψ' production using a modified version of Non-Relativistic Quantum Chromodynamics

There is serious disagreement between the predictions of Non-Relativistic Quantum Chromodynamics (NRQCD) and the data on J/.polarisation which has persisted for almost a quarter of a century. We find that if we account for the effect of perturbative soft gluons on the intermediate charm-anticharm octet states in NRQCD then the polarisation problem can be resolved. In addition, this model, when used to fit the Run 1 data on J/psi an psi' production from the CDF experiment at Tevatron, gives good fits and yields values of (energy-independent) non-perturbative parameters. These, in turn, can be used to make parameter-free predictionsfor J/psi an psi' data from the CMS experiment at the Large Hadron Collider and the predictions are in excellent agreement with the CMS data. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.

Automated summary

There is a long-standing disagreement between the predictions of NRQCD and J/. polarization data. By accounting for the effect of soft gluons, this study proposes a solution to the polarization problem and successfully fits the experimental data from Tevatron. The non-perturbative parameters obtained can be used to make parameter-free predictions for CMS experiment at the Large Hadron Collider, which are in excellent agreement with the CMS data.