Measurement of the Λ_b⁰ lifetime in the decay Λ_b⁰→J/ψ Λ⁰ with the D0 detector

Abstract

We present measurements of the Λ_b⁰ lifetime in the exclusive decay channel Λ_b⁰→J/ψ Λ⁰, with J/ψ→μ⁺μ^- and Λ⁰ →p^π-, the B⁰ lifetime in the decay B⁰→J/ψ K_S0 with J/ψ→μ⁺μ^- and K_S⁰→π⁺π^-, and the ratio of these lifetimes. The analysis is based on approximately 250 pb^-1 of data recorded with the D0 detector in pp‾ collisions at √s=1.96 TeV. The Λ_b⁰ lifetime is determined to be t(Λ_b⁰)=1.22_-0.18^+0.22 (stat)±0.04(syst) ps, theB⁰ lifetime t(B⁰)=1.40_-0.10 ^+0.11(stat) ±0.03(syst) ps, and the ratio t(Λ_b⁰) t(B⁰)=0.87_-0.14^+0.17 (stat)±0.03(syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Λ_b⁰ lifetime based on a fully reconstructed decay channel.