Nucleon resonance electrocouplings from the CLAS data on charged double pion electroproduction
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Measurements of charged double pion (2$$\pi$$) electroproduction off protons with CLAS [1-3] provided the most extensive experimental data set of nine 1-fold differential cross sections. Phenomenological analysis of these data was carried out within the framework of model [4] in the kinematic range: 1.3 $$<$$ $$W$$ $$<$$ 1.8 GeV and 0.25 $$<$$ $$Q^{2}$$ $$<$$ 1.5 GeV$^2$. A successful description of all observables was achieved, allowing us to establish all essential contributing mechanisms, consisting of various meson-baryon isobar channels, direct 2$$\pi$$ production, and to isolate the resonant parts of the cross sections. For the first time electrocouplings of the $$P_{11}(1440)$$ and $$D_{13}(1520)$$ states were obtained in studies of 2$$\pi$$ electroproduction. Good agreement with the previous results [5] obtained from studies of $$\pi^{+}n$$ and $$\pi^{0}p$$ electroproduction channels show that these electrocouplings can be evaluated reliably. The CLAS 2$$\pi$$ data allowed us to determine electrocouplings for several high lying $$N^{*}$$ states (M $$>$$ 1.65 GeV), that have major hadronic decays with 2$$\pi$$ emission. The information on amplitudes of contributing non-resonant mechanisms will be used in future $N^*$$ studies in a global multi-channel analysis under development at EBAC [6]. [1] M.~Ripani et al., Phys. Rev. Lett. {\bf 91}, 022002 (2003). [2] G.~V. Fedotov et al., (CLAS Collaboration), arXiv:0809.1562 [nucl-ex] accepted by Phys. Rev. C. [3] http://clasweb.jlab.org/physicsdb/ (CLAS Physics Data Base). [4] V.~I. Mokeev et al., arXiv: 0809.4158[hep-ph]. [5] I.G.Aznauryan, et. al., Phys. Rev.,C71, 015201 (2005). [6] A.Matsuyama, et. al., Phys.Rep., 439, 193 (2007)$$;$$ B.Julia-Diaz, et.al., Phys. Rev., C76, 065201 (2007).
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1999667
- Report Number(s):
- JLAB-PHY-09-1020; DOE/OR/23177-0806
- Resource Relation:
- Conference: 2009 APS April Meeting, May 2–5, 2009; Denver, Colorado
- Country of Publication:
- United States
- Language:
- English
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