$N^*$ resonances from $K\Lambda$ amplitudes in sliced bins in energy

TL;DR

This paper analyzes $K\Lambda$ amplitudes in energy slices to identify nucleon resonance poles, comparing a multichannel Laurent+Pietarinen model with the Bonn-Gatchina approach, confirming several resonances around 1.9 GeV.

Contribution

It introduces a multichannel Laurent+Pietarinen model for extracting resonance poles from $K\Lambda$ amplitudes and compares it with existing energy-dependent fits.

Findings

Confirmed existence of multiple nucleon resonance poles near 1.9 GeV.

Identified specific quantum numbers for the resonances.

Validated the effectiveness of the L+P model in resonance analysis.

Abstract

The two reactions $\gamma p\to K^+\Lambda$ and $\pi^-p\to K^0\Lambda$ are analyzed to determine the leading photoproduction multipoles and the pion-induced partial wave amplitudes in slices of the invariant mass. The multipoles and the partial-wave amplitudes are simultaneously fitted in a multichannel Laurent+Pietarinen model (L+P model), which determines the poles in the complex energy plane on the second Riemann sheet close to the physical axes. The results from the L+P fit are compared with the results of an energy-dependent fit based on the Bonn-Gatchina (BnGa) approach. The study confirms the existence of several poles due to nucleon resonances in the region at about 1.9\,GeV with quantum numbers $J^P = 1/2^+$, $3/2^+, 1/2^-, 3/2^-, 5/2^-$.