New insights into the nature of the $\Lambda (1380)$ and $\Lambda (1405)$ resonances away from the SU(3) limit

Abstract

Starting from the SU(3) limit, we consider the nature of the dynamically generated resonances $\Lambda (1380)$, $\Lambda (1405)$ and $\Lambda (1680)$ as the pion and kaon masses are tuned to their physical values. We show that the accidental symmetry of the two octets due to the leading order Weinberg-Tomozawa term is broken by the next-to-leading order terms. Most interestingly, we observe an interchange of the two trajectories of the $\Lambda (1380)$ and the $\Lambda (1405)$ away from the SU(3) limit at next-to-leading order. This remarkable phenomenon can be investigated using lattice QCD calculations that start from the SU(3) limit.

Comments: We have updated the notation compared to the journal version. No calculation or results are changed by this, 11 pages, 4 figures