Further study of double charmonium production in e+ e- annihilation at Belle

Abstract

We report a new analysis of double charmonium production in e+ e- annihilation using a data sample collected by the Belle experiment. We confirm our previous observation of the processes e+ e- -> J/psi eta_c (chi_c0, eta_c(2S)) and perform an angular analysis for these processes. Processes of the type e+ e- -> psi(2S) (c cbar)_resonant are observed for the first time. We also observe a new charmonium state - X(3940), produced in the process e+ e- -> J/psi X(3940).

Figures (4)

• Figure 1: The mass of the system recoiling against the reconstructed $J/\psi$. The curves are described in the text.
• Figure 2: Distributions of cosines of the production (left) and $J/\psi$ helicity angles (right) for $e^+ e^- \to J/\psi\,\eta_c$ (top row), $e^+ e^- \to J/\psi\,\chi_{c0}$ (middle row) $e^+ e^- \to J/\psi\,\eta(2S)$ (bottom row). The solid lines are results of the individual fits; the dotted lines are the simultaneous fit results.
• Figure 3: The mass of the system recoiling against the reconstructed $\psi(2S)$. The curves are described in the text.
• Figure 4: The mass of the system recoiling against the reconstructed $J/\psi$. The curves are described in the text.