HIGHER-STATISTICS MEASUREMENT OF THE BRANCHING RATIO FOR THE DECAY KL0-]MU-MU

With a significant increase in experimental sensitivity, we have observed an additional 281 K(L)0 --> mu-mu events after a background subtraction of 19 +/- 6 events. Normalizing this sample to the simultaneous observation of the decay K(L)0 --> pi+ pi-, we obtain the branching ratio B(K(L)0 --> mu-mu) = [7.6 +/- 0.5(stat) +/- 0.4(syst)] x 10(-9). Combining these data with our previously published sample containing 87 events yields B(K(L)0 --> mu-mu) = (7.0 +/- 0.5) x 10(-9).