Electroexcitation of the Roper Resonance for 1.7 < Q² < 4.5GeV² in ep → enπ+

Authors

CLAS Collaboration
M. J. Amaryan, Old Dominion UniversityFollow
M. Bektasoglu, Old Dominion University
S. Bültmann, Old Dominion UniversityFollow
S. L. Careccia, Old Dominion University
K. V. Dharmawardane, Old Dominion University
G. E. Dodge, Old Dominion UniversityFollow
T. A. Forest, Old Dominion University
G. Gavalian, Old Dominion University
N. Guler, Old Dominion University
C. E. Hyde, Old Dominion UniversityFollow
A. Klein, Old Dominion University
S. E. Kuhn, Old Dominion UniversityFollow
L. M. Qin, Old Dominion University
L. B. Weinstein, Old Dominion UniversityFollow
J. Yun, Old Dominion University
J. Zhang, Old Dominion University

Document Type

Article

Publication Date

2008

DOI

10.1103/PhysRevC.78.045209

Publication Title

Physical Review C

Volume

78

Issue

4

Pages

045209 (1-7)

Abstract

The helicity amplitudes of the electroexcitation of the Roper resonance are extracted for 1.7 < Q² < 4.5 GeV² from recent high precision JLab-CLAS cross section and longitudinally polarized beam asymmetry data for π⁺ electroproduction on protons at W=1.15-1.69 GeV. The analysis is made using two approaches, dispersion relations and a unitary isobar model, which give consistent Q² behavior of the helicity amplitudes for the gamma*p -> N (1440)P₁₁ transition. It is found that the transverse helicity amplitude A _1/2, which is large and negative at Q²=0, becomes large and positive at Q² similar or equal to 2 GeV², and then drops slowly with Q². The longitudinal helicity amplitude S _1/2, which was previously found from CLAS ep -> ep π⁰,en π⁺ data to be large and positive at Q² = 0.4,0.65 GeV², drops with Q². Available model predictions for gamma*p -> N(1440)P₁₁ allow us to conclude that these results provide strong evidence in favor of N (1440) P₁₁ as a first radial excitation of the 3q ground state. The results of the present paper also confirm the conclusion of our previous analysis for Q²< 1 GeV² that the presentation of N(1440)P₁₁ as a q³G hybrid state is ruled out.

Comments

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Original Publication Citation

Collaboration, C., Aznauryan, I. G., Burkert, V. D., Kim, W., Park, K., Adams, G., . . . Zhao, Z. W. (2008). Electroexcitation of the Roper resonance for 1.7 < Q² < 4.5GeV² in ep → enπ⁺. Physical Review C, 78(4), 045209. doi:10.1103/PhysRevC.78.045209

ORCID

0000-0003-1582-2376 (Dodge), 0000-0001-7282-8120 (Hyde), 0000-0003-2243-6836 (Kuhn), 0000-0001-5416-2900 (Weinstein)

Repository Citation

CLAS Collaboration; Amaryan, M. J.; Bektasoglu, M.; Bültmann, S.; Careccia, S. L.; Dharmawardane, K. V.; Dodge, G. E.; Forest, T. A.; Gavalian, G.; Guler, N.; Hyde, C. E.; Klein, A.; Kuhn, S. E.; Qin, L. M.; Weinstein, L. B.; Yun, J.; and Zhang, J., "Electroexcitation of the Roper Resonance for 1.7 < Q² < 4.5GeV² in ep → enπ+" (2008). Physics Faculty Publications. 372.
https://digitalcommons.odu.edu/physics_fac_pubs/372