Hadron Production by Electron-Positron Annihilation at 4-GeV Center-of-Mass Energy

Abstract

We have measured the total cross section for electron-positron annihilation into three or more hadrons, with at least two charged particles in the final state. The measurement was made at a center-of-mass energy of 4 GeV with a $2\ensuremath{\pi}\ensuremath{-}\mathrm{s}\mathrm{r}$ nonmagnetic detector. With 88 events detected, we obtain a model-independent lower limit on the hadron production cross section of 9.6 \ifmmode\pm\else\textpm\fi{} 1.4 nb; a calculation of detection efficiency based on invariant phase-space production of pions leads to a total cross section of 26 \ifmmode\pm\else\textpm\fi{} 6 nb. This cross section is 4.7 \ifmmode\pm\else\textpm\fi{} 1.1 times the theoretical total cross section for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$. The average charged multiplicity is $\overline{n}=4.2\ifmmode\pm\else\textpm\fi{}0.6$.