Nucleon Resonance Electrocouplings from the CLAS Meson Electroproduction Data

Abstract

Transition helicity amplitudes ${\gamma }_{v}N{N}^{\ast }$ (electrocouplings) were determined for prominent excited proton states with masses below 1.8 GeV in independent analyses of major meson electroproduction channels: ${\pi }^{+}n$, ${\pi }^{0}p$ and ${\pi }^{+}{\pi }^{-}p$. Consistent results on resonance electrocouplings obtained from analyses of these exclusive reactions with different non-resonant contributions demonstrate reliable extraction of these fundamental quantities for states that have significant decays for either $N\pi$ or $N\pi \pi$ channels. Preliminary results on electrocouplings of $N^{\ast }$ states with masses above 1.6 GeV have become available from the CLAS data on ${\pi }^{+}{\pi }^{-}p$ electroproduction off protons for the first time. Comparison with quark models and coupled-channel approaches strongly suggest that $N^{\ast }$ structure is determined by contributions from an internal core of three constituent quarks and an external meson-baryon cloud at the distances covered in these measurements with the CLAS detector.

6 pages, 3 figures

Cited by in corpus (8)

• Explanation and Prediction of Observables using Continuum Strong QCD
• Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction
• Completing the picture of the Roper resonance
• New Results from the Studies of the $N(1440)1/2^{+}$, $N(1520)3/2^{-}$, and $\Delta (1620)1/2^{-}$ Resonances in Exclusive $ep\to e^{\prime }{p}^{\prime }{\pi }^{+}{\pi }^{-}$ Electroproduction with the CLAS Detector
• Revealing dressed-quarks via the proton's charge distribution
• Looking into the matter of light-quark hadrons
• Nucleon Resonance Electrocouplings from the CLAS Data on Exclusive Meson Electroproduction off Protons
• Hadron physics and dynamical chiral symmetry breaking