PRL: Strong evidence for nucleon resonances near 1900 MeV

Paper published in Phys. Rev. Lett. 119, 062004 – Published 11 August 2017
Accepted paper in Physical Review Letters - 10 July 2017.

https://journals.aps.org/prl/accepted/db072Yc4O111a856188a77c50a1ae4f7572e4182f

Strong evidence for nucleon resonances near 1900 MeV - A. V. Anisovich, V. Burkert, M. Hadžimehmedović, D. G. Ireland, E. Klempt, V. A. Nikonov, R. Omerović, H. Osmanović, A. V. Sarantsev, J. Stahov, A. Švarc, and U. Thoma 

Abstract:

Data on the reaction $\gamma p \to K^+\Lambda$ from the CLAS experiments are used to derive the leading multipoles, E0+, M1-, E1+, and M1+, from the production threshold to 2180\,MeV in 24 slices of the invariant mass. The four multipoles are determined without any constraints. The multipoles are fitted using a multichannel L+P model which allows us to search for singularities and to extract the positions of poles on the complex energy plane in an almost model-independent method. The multipoles are also used as additional constraints in an energy-dependent analysis of a large body of pion and photo-induced reactions within the Bonn-Gatchina (BnGa) partial wave analysis. The study confirms the existence of poles due to nucleon resonances with spin-parity J^P = 1/2^-; 1/2^+, and 3/2^+ in the region at about 1.9\,GeV.