A measurement of the charge asymmetry of hadronic events in electron positron annihilation

The quark charge asymmetry, summed over flavours, has been measured at centre of mass energies of 35 GeV and 44 GeV using the JADE detector sited on the electron-positron storage ring PETRA. The asymmetry is found to be consistent with the expectations of the standard model at both energies and enables a measurement of the product of the axial-vector coupling constant of the electron with the axial-vector coupling constants of the quarks, assuming the moduli of these latter to be flavour independent. This gives, with reasonable assumptions concerning the effects of\(B^0 \overline {B^0 } \) mixing,a e a q =−1.09±0.18±0.23 where the first error is statistical and the second systematic.