Spectrum and Structure of Excited Baryons with CLAS

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 $\gamma p\to \varphi p$ 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.

11 pages, 21 figures

References in corpus (12)

• Big-Bang Nucleosynthesis
• Additional Strange Hadrons from QCD Thermodynamics and Strangeness Freeze-out in Heavy Ion Collisions
• A study of the $P_{11}(1440)$ and $D_{13}(1520)$ resonances from CLAS data on $ep\to e^{\prime }{\pi }^{+}{\pi }^{-}{p}^{\prime }$
• The melting and abundance of open charm hadrons
• Dynamical Coupled-Channels Effects on Pion Photoproduction
• A systematic study of longitudinal and transverse helicity amplidutes in the hypercentral Constituent Quark Model
• Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction $\gamma p\to \varphi p$
• Measurements of $ep\to e^{\prime }{\pi }^{+}n$ at W = 1.6 - 2.0 GeV and extraction of nucleon resonance electrocouplings at CLAS
• Empirical transverse charge densities in the nucleon-to-P11(1440) transition
• Electroproduction of the Roper resonance on the proton: the role of the three-quark core and the molecular N-sigma component
• Extracting meson-baryon contributions to the electroexcitation of the $N(1675){\frac{5}{2}}^{-}$ nucleon resonance
• Strangeness in the proton and N*(1535)

Cited by in corpus (3)

• Transition form factors and helicity amplitudes for electroexcitation of negative- and positive parity nucleon resonances in a light-front quark model
• Photon beam asymmetry $\Sigma$ in the reaction $\vec{\gamma }p\to p\omega$ for $E_{\gamma }$ = 1.152 to 1.876 GeV
• New graphical criterion for the selection of complete sets of polarization observables and its application to single-meson photoproduction as well as electroproduction