The SVZ sum rules and the heavy quark limit for ${\Lambda }_Q$

Abstract

In this work, we evaluate the accuracy of the leading order results in Shifman-Vainshtein-Zakharov (SVZ) sum rules and the leading power results in the heavy quark limit for the mass of ${\Lambda }_Q$. Up to dim-5 condensate contributions are considered. By comparing with the experimental results, we find that the leading order results in SVZ sum rules can reach about 5\% accuracy both for ${\Lambda }_b$ and ${\Lambda }_c$, and it seems that better results can be obtained from the sum rules of the heavy quark limit both for ${\Lambda }_b$ and ${\Lambda }_c$. We re-check that the SVZ sum rules in the heavy quark limit coincide with the HQET sum rules. As a byproduct, we also have an exploratory discussion on the $ud$ diquark in ${\Lambda }_Q$.

Comments: 10 pages, 3 figures