OBSERVATION OF THE TWO-PHOTON DECAY OF THE NEUTRAL-K2 MESON.

Abstract : An arrangement of spark chambers and scintillation shower detectors was used to investigate the two-photon decay mode of the neutral K2 meson. Twenty-nine candidates were found for this decay mode. However, 12 plus or minus 7 of these events can originate from the neutral-K2 to 3 neutral-pion mode and the CP-violating neutral-K to 2 neutral-pion decay. Monte Carlo simulations indicate that 5 plus or minus of the 12 events are likely to originate from the 3 neutral-pion decays, leaving 7 plus or minus events which may be ascribed to 2 neutral-pion decays. The corresponding branching ratios are: Rate (neutral-K2 to gamma) (neutral-K to all modes) = (1.3 plus or minus 0.6) x 0.0001; Rate 9neutral-K2 to 2 neutral pion)/Rate (Neutral-K2 to all modes) = (1.2 + 1.5 or -1.2) x 0.001.