On the four-quark operator matrix elements for the lifetime of ${\Lambda }_b$

Abstract

Heavy quark expansion can nicely explain the lifetime of ${\Lambda }_b$. However, there still exist sizable uncertainties from the four-quark operator matrix elements of ${\Lambda }_b$ in $1/m_b^3$ corrections, which describe the spectator effects. In this work, these four-quark operator matrix elements are investigated using full QCD sum rules for the first time. At the QCD level, contributions from up to dimension-6 four-quark operators are considered. Our method of calculating high-dimensional operator matrix elements is promising to be used to resolve the ${\Omega }_c$ lifetime puzzle.

Comments: 13 pages, 4 figures; version accepted by EPJC