Search for neutral charmless B decays at LEP

Abstract

A search for rare charmless decays of B⁰_d and B⁰_s mesons has been performed in the exclusive channels B⁰_d(s) →ηη⁰, B⁰_d(s) →ηπ⁰ and B⁰_d(s) →π⁰π⁰. 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(B⁰_d→ηη) <4.1 x 10⁻⁴, Br(B⁰_s →ηη) < 1.5 x 10⁻³, Br(B⁰_d→ηπ⁰) < 2.5 x 10⁻⁴, Br(B⁰_s→ηπ⁰) < 1.0 x 10⁻³, Br(B⁰_d→π⁰π⁰) < 6.0 x 10⁻⁵, Br(B⁰_s→π⁰π⁰) < 2.1 x 10⁻⁴. These are the first experimental limits on Bd0→ηη and on the Bs0 neutral charmless modes.