RADIATIVE SIGMA+/- DECAYS AND SEARCH FOR NEUTRAL CURRENTS

The decay modes Σ±→nπ±γ, Σ+→pγ, Σ+→pe+e}- were studied in the 81 cm Saclay hydrogen bubble chamber. In the radiative decay Σ±→nπ±γ only low momentum pions which stop in the chamber were accepted. We obtain the following branching ratios: {Mathematical expression} {Mathematical expression} {Mathematical expression} {Mathematical expression} The radiative branching ratios (1) and (2) agree well with theoretical calculations and confirm very strongly the assignment S wave to Σ-→nπ- and P wave to Σ+→nπ+ decay. The branching ratio (4) is based on 3 events with very low invariant masses of the electron-positron pair, being most probably radiative decays with internal conversion of the γ-ray. Combining (3) and (4) we obtain for the conversion coefficient ρ:[Figure not available: see fulltext.] in agreement with predictions from electrodynamics. © 1969 Springer-Verlag.