$K^+\Lambda$ and $K^+\Sigma^0$ photoproduction with fine center-of-mass energy resolution

TL;DR

This paper presents high-resolution measurements of $K^+$ photoproduction cross-sections using a novel identification method, significantly impacting nucleon excitation spectrum studies and challenging quark-diquark models.

Contribution

Introduces a new $K^+$ identification technique with fine energy resolution, improving partial wave analyses of nucleon excitations.

Findings

Data disfavor strong quark-diquark dynamics in the nucleon.

Enhanced energy resolution benefits partial wave analysis.

Method applicable to other facilities for meson identification.

Abstract

Measurements of $\gamma p \rightarrow K^{+} \Lambda$ and $\gamma p \rightarrow K^{+} \Sigma^0$ cross-sections have been obtained with the photon tagging facility and the Crystal Ball calorimeter at MAMI-C. The measurement uses a novel $K^+$ meson identification technique in which the weak decay products are characterized using the energy and timing characteristics of the energy deposit in the calorimeter, a method that has the potential to be applied at many other facilities. The fine center-of-mass energy ($W$) resolution and statistical accuracy of the new data results in a significant impact on partial wave analyses aiming to better establish the excitation spectrum of the nucleon. The new analyses disfavor a strong role for quark-diquark dynamics in the nucleon.