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

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 σ>9.1±1.0nb; assuming invariant phase-space production of pions, we calculate the detection efficiency of our detector to be (45 ±{} 11)%, yielding a cross section σ=21±5nb. The average charged hadron multiplicity is found to be n̄=4.3±0.6.