QCD corrections to $\bm{e^+ e^- \to J/\psi g g}$ at B Factories

TL;DR

This paper calculates next-to-leading-order QCD corrections to $e^+ e^- o J/ + g g$ at B factories, showing these corrections significantly improve theoretical predictions of quarkonium production rates.

Contribution

It provides the first NLO QCD correction calculation for $e^+ e^- o J/ + g g$ within NRQCD, addressing discrepancies with experimental data.

Findings

NLO corrections increase the cross section by about 20%.

Improved fit to the ratio $R_{c ar c}$ with NLO results.

Analysis of leading logarithm resummation effects on $J/$ momentum distribution.

Abstract

In heavy quarkonium production, the measured ratio $R_{c \bar c}=\sigma[J/\psi+ c\bar c + X]/\sigma[J/\psi +X]$ at B factories is much larger than existing theoretical predictions. To clarify this discrepancy, in nonrelativistic QCD (NRQCD) we find the next-to-leading-order (NLO) QCD correction to $e^+ e^- \to J/\psi +gg$ can enhance the cross section by about 20%. Together with the calculated NLO result for $e^+ e^- \to J/\psi +c\bar c$, we show that the NLO corrections can significantly improve the fit to the ratio $R_{c \bar c}$. The effects of leading logarithm resummation near the end point on the $J/\psi$ momentum distribution and total cross section are also considered. Comparison of the calculated cross section for $e^+ e^- \to J/\psi +gg$ with observed cross section for $e^+ e^- \to J/\psi +non(c\bar c)$ is expected to provide unique information on the issue of color-octet contributions.