Extracting the pole and Breit-Wigner properties of nucleon and Δ resonances from the γN→KΣ photoproduction

S Clymton,T Mart

doi:10.1103/physrevd.104.056015

S Clymton, T Mart

Open Access

https://doi.org/10.1103/physrevd.104.056015

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Abstract

We have developed a covariant isobar model to phenomenologically explain the four possible isospin channels of $K\mathrm{\ensuremath{\Sigma}}$ 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 ${K}^{0}{\mathrm{\ensuremath{\Sigma}}}^{+}$ and ${K}^{0}{\mathrm{\ensuremath{\Sigma}}}^{0}$ 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.

Highlights

For more than 50 years kaon photoproduction off a nucleon has gained a special interest in the hadronic physics community
It has been soon realized that an accurate theoretical model describing this elementary process is useful in many branches of hadronic and nuclear physics
In hadronic physics the model is indispensable in the investigation of the missing resonances that have considerably large branching ratio to the strangeness channel [4], the narrow resonance which is predicted to have a large branching ratio to the KΛ channel [5], and the resonance hadronic coupling constant that measures the strength of the interaction between kaon-hyperon final state and the resonance

Summary

INTRODUCTION

For more than 50 years kaon photoproduction off a nucleon has gained a special interest in the hadronic physics community. An accurate elementary model, describing the photoproduction and electroproduction of kaon on the nucleon target is timely and urgently required. Our previous model used to this end was Kaon-Maid [10], which includes kaon photoproduction and electroproduction off the nucleon in six isospin channels. The model fits nearly 9000 experimental data points and employs the consistent hadronic and electromagnetic interactions that eliminate contributions of high-spin resonance background [12,13]. The latter is widely known as an intrinsic problem that plagues the formalism of highspin propagators used to describe the contribution of nucleon and delta resonances.

FORMALISM

Resonance properties

General results

SUMMARY AND CONCLUSION