Extracting the pole and Breit-Wigner properties of nucleon and $\Delta$ resonances from the $\gamma N\to K\Sigma$ photoproduction

TL;DR

This paper develops a covariant isobar model to analyze $K ext{Sigma}$ photoproduction, extracting nucleon and $ ext{Delta}$ resonance properties, and compares results with experimental data and Particle Data Group listings.

Contribution

The paper introduces a consistent covariant isobar model for $K ext{Sigma}$ photoproduction that accurately extracts resonance parameters from experimental data.

Findings

Resonance parameters agree well with Particle Data Group values.

The model successfully fits recent experimental data.

Different form factors' effects on the reaction were analyzed.

Abstract

We have developed a covariant isobar model to phenomenologically explain the four possible isospin channels of $K\Sigma$ photoproduction. To obtain a consistent reaction amplitude, which is free from the lower-spin background problem, we used the consistent electromagnetic and hadronic interactions described in our previous report. We used all available experimental data, including the recent MAMI A2 2018 data obtained for the $K^0\Sigma^+$ and $K^0\Sigma^0$ isospin channels. By fitting the calculated observables to these data we extract the resonance properties, including their Breit-Wigner and pole parameters. Comparison of the extracted parameters with those listed by the Particle Data Group yields a nice agreement. An extensive comparison of the calculated observables with experimental data is also presented. By using the model we investigated the effects of three different form factors used in the hadronic vertex of each diagram. A brief discussion on the form factors is given.