Reanalysis of the four-quark operators relevant to theΛblifetime from the QCD sum rule

The ${\Lambda }_b$ matrix element of the four-quark operator relevant to its lifetime is reanalyzed by the QCD sum rule method. The new ingredients introduced are that (1) more vacuum condensates are considered, (2) a different quark-hadron duality is adopted, and (3) the possible deviation from the vacuum saturation assumption for the four quark condensates is considered. With ${\kappa }_1=4\mathrm{}$ the related hadronic parameter r is calculated to be $(3.6\mathrm{}\pm 0.9),$ and the lifetime ratio $\tau \left({\Lambda }_b\right)/\tau {(B}^0)=(0.83\mathrm{}\pm 0.04),$ which is consistent with experimental data.