The Color Octet Effect from $e^+ e^-\to{J/ψ}+X+γ$ at B Factory

Abstract

We study the initial state radiation process $e^+ e^-\to{J/ψ}+X+γ$ for $J/ψ$ production at B factory, and find the cross section is 61% larger than it's Born one for color octet part and is about half as it's Born one for color singlet part. Furthermore, the color singlet and color octet signal are very clearly separated in it's $E_γ$ spectra due to kinematics difference. We suggest to measure this $E_γ$ spectra at B factory to determine the color octet effect.

Figures (4)

• Figure 1: The typical Feynman diagrams for the $e^+ e^- \rightarrow J/\psi X$, there are 6 diagrams for the $e^+ e^- \rightarrow {J/\psi} gg$, 4 diagrams for $e^+ e^- \rightarrow {J/\psi}c\bar{c}$ and 2 diagrams for each $e^+ e^- \rightarrow {\psi[^3P^8_J]} g,~J=0,1,2$
• Figure 2: The typical Feynman diagrams for the $e^+ e^- \rightarrow J/\psi X\gamma$, there are 12 diagrams for the $e^+ e^- \rightarrow {J/\psi} gg\gamma$, 8 diagrams for $e^+ e^- \rightarrow {J/\psi}c\bar{c}\gamma$ and 4 diagrams for each $e^+ e^- \rightarrow {\psi[^3P^8_J]} g\gamma,~J=0,1,2$
• Figure 3: The differential cross section distribution vs the energy of emitted hard photon
• Figure 4: The differential cross section distribution vs the $cos(\theta)$ of the emitted hard photon and the beam