Role of Four-Quark Operators in the Inclusive ${\Lambda }_b$ Decays

Abstract

We compute by QCD sum rules the matrix elements of the relevant four-quark operators appearing in the expression of the ${\Lambda }_b$ inclusive decay rates at the order $1/m_b^3$. The results suggest that $1/m_b^3$ corrections are not responsible of the observed difference between the lifetime of ${\Lambda }_b$ and $B_d$.

Comments: LaTex, 14 pages, 3 uuencoded postscript figures