Electron-Positron Annihilation into Hadrons and Landau's Hydrodynamic Model

Abstract

The multiplicity and inclusive single-particle distribution for $e^{+}+e^{-}\to \pi +X$ are calculated for Landau's hydrodynamic model. At 3 and 5 GeV the collective motion is less important than the thermal motion. The average pion energy obtained in the Stanford linear-accelerator colliding-beam experiment is consistent with either an ultrarelativistic equation of state or one based on the observed hadron spectrum.