Hyperon resonances coupled to pseudoscalar- and vector-baryon channels

TL;DR

This paper models hyperon resonances by solving coupled channel equations including pseudoscalar and vector baryon interactions, fitting experimental data to identify resonance properties, notably reproducing the Lambda(1405) and discovering a Sigma state around 1400 MeV.

Contribution

It introduces a coupled channel scattering approach incorporating both pseudoscalar and vector baryon channels, providing new insights into hyperon resonance structures.

Findings

Successfully reproduces properties of Lambda(1405)

Identifies a Sigma resonance near 1400 MeV

Cross section predictions align with experimental data

Abstract

We study hyperon resonances by solving coupled channel scattering equations. The coupled systems include pseudoscalar- and vector-baryon channels. The parameters of the model are restricted by making a $\chi^2$-fit to the cross section data on processes: $K^- p \to K^- p$, $K^- p \to \bar K^0 n$, $K^- p \to \eta \Lambda$, $K^- p \to \pi^0 \Lambda$, $K^- p \to \pi^0 \Sigma^0$, $K^- p \to \pi^\pm \Sigma^\mp$. Data on the energy level shift and width of the $1s$ state of the kaonic hydrogen, as well as some cross-section ratios near the threshold are also considered in the fit. Two types of fits are found as a result. In both cases, the properties of $\Lambda(1405)$ are well reproduced. In addition to this, a $\Sigma$ state is also found with mass around 1400 MeV. Cross sections, obtained with one of the two fits, are found to stay close to the data at energies away from the thresholds too, and as a result resonances with higher masses have also been studied.