Effective lifetimes of B_s decays and their constraints on the B_s~0-B_s~0 mixing parameters

摘要

Measurements of the effective lifetimes of B _s -meson decays, which only require untagged rate analyses, allow us to probe the width difference Δ Γ _s and the CP-violating phase Φ _s of B_s~0-B_s~0 mixing. We point out that the dependence of the effective lifetime on non-linear terms in Δ Γ _s allows for a determination of Φ _s and Δ Γ _s given a pair of B _s decays into CP-even and CP-odd final states. Using recent lifetime measurements of B_s~0→K~+K~- and B_s~0→J/Ψ f_0 decays, we illustrate this method and show how it complements the constraints in the Φ _s -Δ Γ _s plane from other observables.