New insights into antikaon–nucleon scattering and the structure of the Λ(1405)

We perform a combined analysis of antikaon–nucleon scattering cross sections and the recent SIDDHARTA kaonic hydrogen data in the framework of a –πY coupled-channel Bethe–Salpeter approach at next-to-leading order in the chiral expansion of the effective potential. We find a precise description of the antikaon–proton scattering amplitudes and are able to extract accurate values of the scattering lengths, and . We also discuss the two-pole structure of the Λ(1405).