Simple model fore+e−annihilation predicts rapid rise of hadron multiplicity observed at PETRA

The simple model for $e^{+}{e}^{-}$ annihilation developed in an article previously published in this journal [Phys. Rev. D 20, 1093 (1979)] is extended to the PETRA energy range (10 to 40 GeV in the c.m.). The calculated values of the average charged-hadron multiplicity are in reasonable agreement with experiment.