We calculate the exclusive cross sections for e +e - annihilation into two charmonium states through a virtual photon. Purely electromagnetic contributions are surprisingly large, changing the cross sections by as much as 21%. The predicted cross section for J/ψ+ η c is about an order of magnitude smaller than a recent measurement by the BELLE Collaboration, although part of the discrepancy can be attributed to large relativistic corrections. The cross sections for S-wave + P-wave, P-wave + P-wave, and S-wave + D-wave charmonium states are also calculated. It may be possible to discover the D-wave state η c2(1D) at the B factories through the mode J/ψ+ η c2, whose cross section is predicted to be about a factor of 10 smaller than J/ψ+ η c.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)