Search for a Conserved-Vector-Current Mechanism in the Emission of Protons fromμ−Stars in Emulsion

The energy spectrum of protons from 1289 single-prong ${\mu }^{-}$ stars in emulsion was studied, with special attention given to the energy region above 20 MeV. In this energy region, Bertero, Passatore, and Viano had predicted an enhanced proton emission as a result of muon interaction with pion currents in the nucleus according to the theory of conserved vector current (CVC). No evidence of the predicted 25-MeV peak in the CVC spectrum was found, nor was there any evidence of a high-energy tail to the spectrum which was predicted to extend up to 90 MeV. The results are quite consistent with Singer's earlier theory. If the CVC mechanism occurs here at all, it occurs at least a factor (2.0±1.0)×${10}^{-2\mathrm{}}$ less frequently than predicted.