Transition magnetic moment of $\Lambda$ $\to$ $\Sigma^0$ in QCD sum rules

Abstract

The $\Lambda$ $\to$ $\Sigma^0$ transition magnetic moment is computed in the QCD sum rules approach. Three independent tensor structures are derived in the external field method using generalized interpolating fields. They are analyzed together with the $\Lambda$ and $\Sigma^0$ mass sum rules using a Monte-Carlo-based analysis, with attention to OPE convergence, ground-state dominance, and the role of the transitions in the intermediate states. Relations between sum rules for magnetic moments of $\Lambda$ and $\Sigma^0$ and sum rules for transition magnetic moment of $\Lambda$ $\to$ $\Sigma^0$ are also examined. Our best prediction for the transition magnetic moment is $\mu_{\Sigma^0\Lambda}= 1.60\pm 0.07\; \mu_N$. A comparison is made with other calculations in the literature.