Is two-pole's Λ(1405) one state or two?

To understand the nature of two poles for the A (1405) state, we revisit the interactions of (K) over barN and pi Sigma with their coupled channels, where two-pole structure is found in the second Riemann sheet. We also dynamically generate two poles in the single channel interaction of (K) over barN and pi Sigma, respectively. Moreover, we make a further study of two poles' properties by evaluating the couplings, the compositeness, the wave functions, and the radii for the interactions of four coupled channels, two coupled channels and the single channel. Our results show that the nature of two poles is unique. The higher-mass pole is a pure (K) over barN molecule, and the lower-mass one is a composite state of mainly pi Sigma with tiny component (K) over barN. From our results, one can conclude that the Lambda(1405) state may be overlapped with two different states of the same quantum numbers.

Automated summary

By studying the nature of two poles for the Λ(1405) state, it was found that one pole is a pure (K) over barN molecule, while the other is a composite state mainly composed of pi Sigma. This suggests that the Λ(1405) state may overlap with two different states of the same quantum numbers.