An analysis of the gargamelle freon data concerning pion production by the weak neutral current

Semi-inclusive pion production of all three charge states by the weak neutral current has been analysed in the Gargamelle Freon neutrino and antineutrino experiments. Using the complete neutral current sample a κ² fit of the measured charge ratios to the hypothesis of a purely isoscalar current has a confidence level of less than 10^?4. Using a restricted pion sample, corresponding to current fragment pions, a κ² fit of the π⁺/π^- ratios in νv and $\text{ν}$ to the predictions of an isovector current has confidence level 0.017. The sign of the isovector-isoscalar interference term is found to be consistent with that predicted by the Weinberg-Salam model.