Measurement of the e+e- -> J/psi ccbar cross section at \sqrt{s} ~10.6 GeV

Understand

We present a new measurement of the e+e- -> J/psi ccbar cross section where the ccbar pair can fragment either into charmed hadrons or a charmonium state.

• In the former case the J/psi and a charmed hadron are reconstructed, while the latter process is measured using the recoil mass technique, which allows the identification of two-body final states without reconstruction of one of the charmonia.
• The measured e+e- -> J/psi ccbar cross section is (0.74 +- 0.08 + 0.09 - 0.08) pb, and the e+e- -> J/psi non-ccbar cross section is (0.43 +- 0.09 +-0.09) pb.
• We note that the measured cross sections are obtained from a data sample with the multiplicity of charged tracks in the event larger than four; corrections for the effect of this requirement are not performed as this cannot be done in a model-independent way.