Evidence for parity nonconservation in the weak neutral current

Measurements of R^ν and R^ν¯, the ratios of neutral current to charged current ν and ν¯ cross sections, yield neutral current rates for ν and ν¯ that are consistent with a pure V-A interaction but 3 standard deviations from pure V or pure A, indicating the presence of parity nonconservation in the weak neutral current.