The internal structures of the nucleon resonances $N(1875)$ and $N(2120)$

TL;DR

This paper investigates the internal structures of the nucleon resonances $N(1875)$ and $N(2120)$, proposing a quark model explanation for the $N(2120)$ and a molecular state interpretation for the $N(1875)$ based on Bethe-Salpeter calculations.

Contribution

It offers a novel interpretation of $N(1875)$ as a $ ext{Σ}(1385)$-K molecular state and clarifies the nature of $N(2120)$ within the constituent quark model.

Findings

$N(2120)$ aligns with the third $N3/2^-$ nucleon resonance in the quark model.

$N(1875)$ is likely a molecular state from $ ext{Σ}(1385)$ and K interaction.

Bethe-Salpeter approach supports the molecular interpretation.

Abstract

A nucleon resonance with spin-parity $J^P=3/2^-$ and mass about 2.1 GeV is essential to reproduce the photoproduction cross sections for $\Lambda(1520)$ released by the LEPS and CLAS Collaborations. It can be explained as the third nucleon resonance state $[3/2^-]_3$ in the constituent quark model so that there is no position to settle the $N(1875)$ which is listed in the PDG as the third $N3/2^-$ nucleon resonance. An interpretation is proposed that the $N(1875)$ is from the interaction of a decuplet baryon $\Sigma(1385)$ and a octet meson $K$, which is favored by a calculation of binding energy and decay pattern in a Bethe-Salpeter approach.