Multiquark picture for Sigma(1620)

Abstract

In this work we report on a new QCD sum rule analysis to predict masses of the excited baryon states (e.g. Sigma(1620) and Lambda(1405)) by using multiquark interpolating fields ($(q\bar{q})(qqq)$). For the Sigma(1620) we consider the $\bar{K}N$, $\pi\Sigma$, and $\pi\Lambda$ (I=1) multiquark interpolating fields. The calculated mass from those multiquark states is about 1.592 GeV. For the Lambda(1405) we first show the result using the $\pi^+\Sigma^- + \pi^0\Sigma^0 + \pi^-\Sigma^+$ (I=0) multiquark interpolating field, and compare the calculated mass to that of our previous result using the $\pi^0\Sigma^0$ multiquark state. We then show that the mass 1.405 GeV is well reproduced when using the $\bar{K}N$ (I=0) multiquark state. The uncertainties in our sum rules are also discussed.