Aubert, B (reprint author), Lab Annecy Le Vieux Phys Particules, F-74941 Annecy Le Vieux, France.
We present the first search for the decay B-0 ->(KSKSKL0)-K-0-K-0 using a data sample of 232x10(6) B (B) over bar pairs. We find no statistically significant evidence for the nonresonant component of this decay. Our central value for the branching fraction, assuming the true Dalitz distribution is uniform and excluding the phi resonance, is B(B-0 ->(KSKSKL0)-K-0-K-0)=(2.4(-2.5)(+2.7)+/- 0.6)x10(-6) where the errors are statistical and systematic, respectively. We set a single-sided Bayesian upper limit of B(B-0 ->(KSKSKL0)-K-0-K-0)< 7.4x10(-6) at 90% confidence level using a uniform prior probability for physical values. Assuming the worst-case true Dalitz distribution, where the signal is entirely in the region of lowest efficiency, the 90% confidence level upper limit is B(B-0 ->(KSKSKL0)-K-0-K-0)< 16x10(-6).