P-wave excited baryons from pion- and photo-induced hyperon production

TL;DR

This paper presents evidence for several P-wave excited baryon resonances from pion- and photo-induced hyperon production data, confirming some controversial states and suggesting possible new ones, with analysis constrained by established scattering amplitudes.

Contribution

It provides a comprehensive analysis confirming the existence of certain P-wave baryon resonances and clarifies previous controversies using updated scattering amplitude data.

Findings

Evidence for multiple P-wave baryon resonances.

Confirmation of controversial states like N(1710)P11.

Indications of a potential companion state at 1970 MeV.

Abstract

We report evidence for $N(1710)P_{11}$, $N(1875)P_{11}$, $N(1900)P_{13}$, $\Delta(1600)P_{33}$, $\Delta(1910)P_{31}$, and $\Delta(1920)P_{33}$, and find indications that $N(1900)P_{13}$ might have a companion state at 1970\,MeV. The controversial $\Delta(1750)P_{31}$ is not seen. The evidence is derived from a study of data on pion- and photo-induced hyperon production, but other data are included as well. Most of the resonances reported here were found in the Karlsruhe-Helsinki (KH84) and the Carnegie-Mellon (CM) analyses but were challenged recently by the Data Analysis Center at GWU. Our analysis is constrained by the energy independent $\pi N$ scattering amplitudes from either KH84 or GWU. The two $\pi N$ amplitudes from KH84 or GWU, respectively, lead to slightly different $\pi N$ branching ratios of contributing resonances but the debated resonances are required in both series of fits.