Charged Hadron Production ine+e−Annihilation at 29 GeV

The inclusive production cross sections and mean multiplicities of ${\pi }^{\pm }$, $K^{\pm }$, $p$, and $\overline{p}$ in $e^{+}{e}^{-}$ annihilation at a c.m. energy of 29 GeV have been measured with the time-projection chamber at PEP, using ionization energy loss to separate particle types. On average, 10.7±0.6 ${\pi }^{\pm }$, 1.35±0.13 $K^{\pm }$, and 0.60±0.08 $p$,$\overline{p}$ are contained in an annihilation event. The fraction of pions among final-state particles decreases from over 95% at 0.3 GeV/c momentum to about 60% at high momentum; the kaon and proton fractions rise correspondingly.