Search for neutral charmless B decays at LEP

Abstract

A search for rare charmless decays of B d 0 and B s 0 mesons has been performed in the exclusive channels B d(s) 0 → ηη, B d(s) 0 → ηπ 0 and B d(s) 0 → π 0 π 0. The data sample consisted of three million hadronic Z decays collected by the L3 experiment at LEP from 1991 through 1994. No candidate event has been observed and the following upper limits at 90% confidence level on the branching ratios have been set: Br( B () d → ηη) <4.1 x 10 −4, Br( B () s → ηη) < 1.5 x 10 −3, Br( B () d → ηφ ()) < 2.5 x 10 −4, Br( B () s → ηphi; ()) < 1.0 x 10 −3, Br( B () d → phi; () phi; ()) < 6.0 x 10 −5, Br( B () s → phi; () phi; ()) < 2.1 x 10 −4. These are the first experimental limits on B d 0→ηη and on the B s 0 neutral charmless modes.