Spectrum and Structure of Excited Baryons with CLAS

TL;DR

This paper reviews recent light quark baryon spectroscopy results from CLAS data, highlighting new baryon states discovered via open strangeness channels and discussing the sensitivity of meson electroproduction to underlying resonance structures.

Contribution

It presents new baryon states discovered through kaon-hyperon channels and analyzes the distance-scale dependence of resonance transitions using meson electroproduction data.

Findings

Discovery of new baryon states via $ o K^+ \Lambda$ and $ o K^+ \\Sigma^0$ channels

Demonstration of meson electroproduction sensitivity to resonance structure

Identification of quark core and meson-baryon contributions in excited states

Abstract

In this contribution we discuss recent results in light quark baryon spectroscopy involving CLAS data and higher level analysis results from the partial wave analysis by the Bonn-Gatchina group. New baryon states were discovered largely based on the open strangeness production channels $\gamma p \to K^+ \Lambda$ and $\gamma p \to K^+ \Sigma^0$. The data illustrate the great potential of the kaon-hyperon channel in the discovery of higher mass baryon resonances in s-channel production. Other channels with discovery potential, such as $\gamma p \to p \omega$ and $\gamma p \to \phi p$ are also discussed. In the second part I will demonstrate on data the sensitivity of meson electroproduction to expose the active degrees of freedom underlying resonance transitions as a function of the probed distance scale. For several of the prominent excited states in the lower mass range the short distance behavior is described by a core of three dressed-quarks with running quark mass, and meson-baryon contributions make up significant parts of the excitation strength at large distances. Finally, an outlook is given of baryon resonance physics at the 12 GeV CEBAF electron accelerator.