Positron-Neutrino Correlation in the 0[sup +][r arrow]0[sup +] Decay of [sup 32]Ar

The positron-neutrino correlation in the 0[sup +][r arrow]0[sup +] [beta] decay of [sup 32]Ar was measured at ISOLDE by analyzing the effect of lepton recoil on the shape of the narrow proton group following the superallowed decay. Our result is consistent with the standard model prediction. For vanishing Fierz interference we find a=0.9989[plus minus]0.0052[plus minus]0.0039 , which yields improved constraints on scalar weak interactions. [copyright] [ital 1999] [ital The American Physical Society]