Speaker
Description
In this work, we perform a QCD sum rules analysis on the $\Xi_{Q}-\Xi_{Q}^{\prime}$
mixing. Contributions from up to dimension-6 four-quark operator
are considered. However, it turns out that, only dimension-4 and dimension-5 operators
contribute, which reveals the non-perturbative nature of mixing. Especially
we notice that only the diagrams with the two light quarks participating
in gluon exchange contribute to the mixing. Our results indicate that
the mixing angle $\theta_{c}=(1.2\sim2.8)^\circ$ for the $Q=c$ case and
$\theta_{b}=(0.28\sim0.34)^\circ$ for the $Q=b$ case.
Our prediction of $\theta_{c}$ is consistent with
the most recent Lattice QCD result within error. Such a small mixing
angle seems unlikely to resolve the tension between experimental
measurement and Lattice QCD calculation for the
semileptonic decay $\Xi_{c}^{0}\to\Xi^{-} e^{+}\nu_{e}$.
