Measurement ofD ⁺ _s meson production inZ decays and of theB ⁰ _s lifetime

Abstract

D ⁺ _s mesons produced inZ ⁰→bb events were separated from theZ ⁰→cc component using a lifetime tag. Using a sample of 1.5 million hadronicZ decays collected with theAleph detector theB ⁰ _s andD ⁺_s yields have been measured:$\begin{gathered} \hfill B(b \to \bar B_s^0 )B(\bar B_s^0 \to D_s^ + ) = 0.088 \pm 0.020(stat.) \\ \hfill \pm 0.020(stat.) \\ \hfill B(c \to D_s^ + ) = 0.088 \pm 0.020(stat.)_{ - 0.016}^{ + 0.019} (syst.) \\ \end{gathered}$ TheB ⁰ _s lifetime was measured in aB ⁰ _s enriched sample reconstructing the decay length from the vertex of theD ⁺ _s with a hadron from theB ⁰ _s decay. The result obtained is:$\tau _{B_s } = 1.61_{ - 0.29}^{ + 0.30} (stat.)_{ - 0.016}^{ + 0.018} (syst.)$ ps.