Results

The $\bar B^0_s$ meson lifetime has been measured using the partially reconstructed semileptonic decays $\bar B^0_s \rightarrow \ell^- \bar \nu D^+_s X$ to be

$$c\tau(\bar{B}_s^0) = 414.0 \pm 16.6\ ^{+15.6}_{-13.8} \ \mu\mbox{m},$$

or

$$\tau(\bar{B}_s^0) = 1.381 \pm 0.055 \ ^{+0.052}_{-0.046} \mbox{ ps},$$

where the first uncertainties are statistical and the second are systematic. We also find the ratio of the $\bar{B}_s^0$ and $\bar{B}^0$ meson lifetimes to be

$$\tau(\bar{B}_s^0)/\tau(\bar{B}^0) = 0.938 \pm 0.044 \ ^{+0.049}_{-0.046} ,$$

where the $\bar B^0$ meson lifetime is taken from [2]. They are consistent with other recent measurements. Figures 5 and 6 show comparisons of the results from other measurements [3] and this analysis, for $\tau(\bar{B}_s^0)$ and $\tau(\bar{B}_s^0)/\tau(\bar{B}^0)$.