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

TL;DR

This paper presents a detailed analysis of double charmonium production in electron-positron annihilation at Belle, confirming previous results, performing angular analysis, and discovering a new charmonium state X(3940).

Contribution

It reports the first observation of e+ e- -> psi(2S) (c cbar)_resonant processes and identifies a new charmonium state X(3940).

Findings

Confirmed previous double charmonium production observations.

Performed angular analysis of the processes.

Discovered a new charmonium state X(3940).

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).