Direct Photon Production ine+e−Annihilation

Abstract

Direct photon production in hadronic events from $e^{+}{e}^{-}$ annihilation has been studied at $\sqrt{s}=29\mathrm{}$ GeV with use of the MAC detector at the PEP storage ring. A charge asymmetry $A=(-12.3\mathrm{}\pm 3.5)\%$ is observed in the final-state jets. The cross section and the charge asymmetry are in good agreement with the predictions of the fractionally charged quark-parton model. Both the charge asymmetry and total yield have been used to determine values of quark charges. Limits have been established for anomalous sources of direct photons.