QCD corrections to double J/ψproduction in e+e- annihilation at \sqrt{s}=10.6 GeV

TL;DR

Next-to-leading-order (NLO) QCD corrections to double J/psi production in e+e- annihilation at sqrt[s]=10.6 GeV are calculated and it is found that they greatly decrease the cross section, with a K factor ranging from -0.31 to 0.25 depending on the renormalization scale.

Abstract

Next-to-Leading-Order(NLO) QCD corrections to double J/psi production in e^+e^- annihilation at sqrt{s}=10.6 GeV are calculated. We find that they greatly decrease the cross section, with a K factor (NLO/LO) ranging from -0.31 to 0.25 depending on the renormalization scale. Although the renormalization scale dependence indicates a large uncertainty, when combined with the NLO QCD corrections to J/psi + eta_c production, it can explain why the double J/psi$ production could not be found at B factories while the J/psi + eta_c production could, despite the fact that cross section of the former is larger than that of the latter at LO by a factor of 1.8.

Figures (4)

• Figure 1: Feynman diagrams for LO.
• Figure 2: All Feynman diagrams at NLO in six groups. The counter-term diagrams of photon-quark vertex are included in (a) and (c) where only the corresponding loop diagrams are shown. More diagrams can be obtained by reversing the arrows of quark lines and/or interchanging the places of $p_3$ and $p_4$ and/or interchanging the places of $e^+$ and $e^-$.
• Figure 3: Differential cross section as function of $|x|$ where $x=\cos(\theta)$. $\theta$ is the angle between the ${J/\psi}$ and the beam, and $K=\frac{\mathrm{d}\sigma^{\rm NLO}}{\mathrm{d}|x|} / \frac{\mathrm{d}\sigma^{\rm LO}}{\mathrm{d}|x|}$ is the ratio of differential cross section of NLO to LO. $m_c$ is set as $1.5$ GeV and $\mu=\sqrt{s}$ is taken.
• Figure 4: Cross section as function of the CM energy $\sqrt{s}$ with $m_c=1.5$ GeV and $\mu=\sqrt{s}/2$.