Cross-Channel Constraints on Resonant Antikaon-Nucleon Scattering

• Published in: Physical review letters Vol. 130; no. 7; p. 071902
• Main Authors: Lu, Jun-Xu, Geng, Li-Sheng, Doering, Michael, Mai, Maxim
• Format: Journal Article
• Language: English
• Published: United States 17.02.2023
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.130.071902

Chiral perturbation theory and its unitarized versions have played an important role in our understanding of the low-energy strong interaction. Yet, so far, such studies typically deal exclusively with perturbative or nonperturbative channels. In this Letter, we report on the first global study of meson-baryon scattering up to one-loop order. It is shown that covariant baryon chiral perturbation theory, including its unitarization for the negative strangeness sector, can describe meson-baryon scattering data remarkably well. This provides a highly nontrivial check on the validity of this important low-energy effective field theory of QCD. We show that the K[over ¯]N related quantities can be better described in comparison with those of lower-order studies, and with reduced uncertainties due to the stringent constraints from the πN and KN phase shifts. In particular, we find that the two-pole structure of Λ(1405) persists up to one-loop order reinforcing the existence of two-pole structures in dynamically generated states.