Nucleon Resonances Near 2 GeV

TL;DR

This paper investigates nucleon resonances near 2 GeV using photoproduction data and a Regge-plus-resonance model, identifying key resonances and their nature, and challenging existing classifications.

Contribution

It introduces a combined analysis of experimental data with a Regge-plus-resonance approach, clarifying the nature of certain nucleon resonances and their placement in quark models.

Findings

The $ ext{N}(2120)$ is essential for data reproduction and is a third $N3/2^-$ resonance.

The $ ext{N}(1875)$ likely originates from $ ext{Sigma}(1385)K$ interactions, not a three-quark state.

The $ ext{Delta}(2000)$ is identified as a second $[ ext{Delta} 5/2^+]$ resonance.

Abstract

The nucleon resonances near 2 GeV are investigated through the $\Sigma$(1385) and $\Lambda(1520)$ photoproductions within a Regge-plus-resonance approach based on the new experimental data released by the CLAS Collaboration. The $\Delta(2000)$ and the $N(2120)$ are found essential to reproduce the experimental data and should be assigned as second $[\Delta 5/2^+]$ and third $[N3/2^-]$ in the constituent quark model, respectively. A calculation of the binding energy and decay pattern supports that the $N(1875)$, which is listed in the PDG as the third $N3/2^-$ nucleon resonance instead of the $N(2120)$, is from the $\Sigma(1385)K$ interaction rather than a three quark state.