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The most sensitive experiment to date to search for the muon and electron lepton number violating decay K 0 L ! m 6 e 7 has detected no events consistent with this process. Based on this result, the 90% confidence level upper limit on the branching fraction is B͑K 0 L ! m 6 e 7 ͒ , 4.7 3 10 212 . [S0031-9007(98)07985-X]

We have searched for a neutral H dibaryon decaying via H → Λn and H → Σ 0 n. Our search has yielded two candidate events from which we set an upper limit on the H production cross section. Normalizing to the inclusive Λ production cross section, we find (dσ H /dΩ) / (dσ Λ /dΩ) < 6.3 × 10 −6 at 90% C.L., for an H of mass ≈ 2.15 GeV/c 2 .

We report results from Experiment 871, performed at the BNL AGS, of a measurement of the branching ratio K(0)(L)-->&mgr;(+)&mgr;(-) with respect to the CP-violating mode K(0)(L)-->pi(+)pi(-). This experiment detected over 6200 candidate &mgr;(+)&mgr;(-) events, a factor of 6 more than that seen in all previous measurements combined. The resulting branching ratio gamma(K(0)(L)-->&mgr;(+)&mgr;(-))/gamma(K(0)(L)-->pi(+)pi(-)) = (3. 474+/-0.057)x10(-6) leads to a branching fraction B(K(0)(L)-->&mgr;(+)&mgr;(-)) = (7.18+/-0.17)x10(-9), which is consistent with the current world average, and reduces the uncertainty in this decay mode by a factor of 3.

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