Semi-leptonic form factors of $\Xi_{c}\to\Xi$ in QCD sum rules

There exists a significant deviation between the most recent Lattice QCD simulation and experimental measurement by Belle for $\Xi_{c}^{0}\to\Xi^{-}\ell^{+}\nu_{\ell}$. In this work, we investigate the $\Xi_{c}\to\Xi$ form factors in QCD sum rules. To this end, the two-point correlation functions of $\Xi_{c}$ and $\Xi$, and the three-point correlation functions of $\Xi_{c}\to\Xi$ are calculated. At the QCD level, contributions from up to dimension-6 four-quark operators are considered, and the leading order results of the Wilson coefficients are obtained. For the form factors, relatively stable Borel windows can be found. Our form factors are comparable with those of Lattice QCD, except for $f_{\perp}$. The obtained form factors are then used to predict the branching ratios of $\Xi_{c}\to\Xi \ell^{+}\nu_{\ell}$, and our predictions are consistent with the most recent data of ALICE and Belle, and those of Lattice QCD within error. Given that the branching ratios only contain limited information, we suggest the experimentalists directly measure the form factors of $\Xi_{c}\to\Xi$.