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

Heavy quark expansion can nicely explain the lifetime of Λ${}_b$. However, there still exist sizable uncertainties from the four-quark operator matrix elements of Λ${}_b$ 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 for calculating high-dimensional operator matrix elements holds promise for use in resolving the Ω${}_c$ lifetime puzzle.