Search for neutral B meson decays to two charged leptons

The decays Bd0, Bs0 → e+e−, μ+μ−, e±μ∓ are searched for in 3.5 million hadronic Z events, which constitute the full LEP I data sample collected by the L3 detector. No signals are observed, therefore upper limits at the 90% (95%) confidence levels are set on the following branching fractions: Br(B0d→e+e−) < 1.4(1.8) × 10−5; Br(B0s→e+e−) < 5.4(7.0) × 10−5; Br(B0d→μ+μ−) < 1.0(1.4) × 10−5; Br(B0s→μ+μ−) < 3.8(5.1) × 10−5; Br(B0d→e±μ−∓) < 1.6(2.0) × 10−5; Br(B0s→e±e−∓) < 4.1(5.3) × 10−5;The results for Bs0 → e+e− and Bs0 → e±μ∓ are the first limits set on these decay modes.