Hadron Production by Electron - Positron Annihilation at 5 GeV Center - of Mass Energy

Abstract

We have measured the cross section σ for electron - positron annihilation into three or more hadrons, with at least two charged particles in the final state, at 5 GeV center-of-mass energy. We find a model-independent lower limit of $\sigma >9.1\mathrm{}\pm 1.0$nb; assuming invariant phase-space production of pions, we calculate the detection efficiency of our detector to be (45 ± 11)%, yielding a cross section $\sigma =21\mathrm{}\pm 5$nb. The average charged hadron multiplicity is found to be $\overline{n}=4.3\mathrm{}\pm 0.6$.