Next-to-Leading-Order QCD Corrections to e^ + e^- -> J/ψ+gg at the B Factories

TL;DR

It is expected that this process can serve as a very good channel to clarify the J/psi polarization puzzle by performing further experimental measurements and recent measurements from Belle agree well with the prediction for the cross section and momentum distribution.

Abstract

We calculate the next-to-leading-order (NLO) QCD corrections to $e^+e^-\to J/ψg g$ via color singlet $J/ψ(^3{-0.8mm}S_1)$ at the B factories. The result shows that the cross section is enhanced to $0.373\pb$ by a K factor (NLO/LO) of about 1.21. By considering its dependence on the charm quark mass and renormalization scale, the NLO cross section can range from 0.294 to $0.409\pb$. Further including the $ψ^\prime$ feed-down, $σ(e^+e^-\to \jpsi X(\mathrm{non} c\bar{c}))$ is enhanced by another factor of about 1.29 and reaches $0.482\pb$. In addition, the momentum distributions of $J/ψ$ production and polarization are presented. Recent measurements from Belle agree well with our prediction for the cross section and momentum distribution. It is expected that this process can serve as a very good channel to clarify the $J/ψ$ polarization puzzle by performing further experimental measurements.

Figures (4)

• Figure 1: Typical Feynman diagrams. (a): LO; (b) $e^+e^-\rightarrow {J/\psi} gq\overline{q}$; (c) $e^+e^-\rightarrow {J/\psi} g g g$; (d): One-loop. Groups $(d_1)-(d_3)$ are the counter-term diagrams, including corresponding loop diagrams.
• Figure 2: Cross sections as function of the renormalization scale $\mu$ and the center-of-mass energy of $e^+e^-$$\sqrt{s}$.
• Figure 3: Momentum distribution of ${J/\psi}$ production with $m_c=1.5$ GeV and $\mu=2m_c$.
• Figure 4: Polarization parameter $\alpha$ and angular distribution parameter $A$ of ${J/\psi}$ as functions of $p$ with $m_c=1.5$ GeV and $\mu=2m_c$.