γvNN^* Transition Amplitudes and Excited Baryon Structure from CLAS
Abstract
Studying excited nucleon structure through exclusive-meson electroproduction reactions is key for understanding the nature of the strong interaction in the non-perturbative regime. With its nearly complete coverage of the final-state phase space, the CLAS detector at JLab has provided the lion's share of the world's meson-electroproduction data for differential cross sections and the asymmetries arising from single- and double-polarization observables. Electrocouplings for most of the excited nucleon states (N^*) in mass range of up to 1.8 GeV have been determined from several analyses of the CLAS data for photon virtualities (Q^2) up to 5.0 GeV^2 for the ^amp;+n, ^0p, and ηp channels [1,3] as well as for the ^amp;+^amp;-p reaction for Q^2 < 1.5 GeV^2 [2,3]. Physics analyses of these N^* electrocouplings [2,3] have revealed that the structure of excited nucleon is formed of an internal core of dressed quarks with an external meson-baryon cloud. Our N^*-electrocoupling results afford access to the non-perturbative strong interaction responsible for generating the different N^* states and will also provide testing ground for the inspired by QCD quark model predictions. A dedicated experiment will run after the 12 GeV upgrade to JLab on the extraction of the N^* electrocouplings in the yet unexplored region of high photon virtualities ranging from 5.0 to 12 GeV^2. The anticipated results are of particular importance in providing a understanding of the nature of confinement and dynamical chiral symmetry breaking in baryons based upon the QCD [3].[4pt] [1] I.G. Aznauryan and V.D. Burkert, Prog. Part. Nucl. Phys. 67, 1 (2012).[0pt] [2] V.I. Mokeev et al. (CLAS Collaboration), Phys. Rev. C86, 035203 (2012).[0pt] [3] I.G. Aznauryan et al., ``Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction,'' arXiv:1212.4891[nucl-th].
- Publication:
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APS April Meeting Abstracts
- Pub Date:
- April 2013
- Bibcode:
- 2013APS..APR.X3002M