Abstract
The exclusive electroproduction process \(ep \rightarrow e'p'\pi ^{0}\) was measured in the range of the photon virtualities \(Q^{2} = 0.4\)–1.0 GeV\(^{2}\), and the invariant mass range of the \(p\pi ^{0}\) system \(W = 1.1\)–1.8 GeV. For the first time these kinematics are covered in exclusive \(\pi ^{0}\) electroproduction off the proton with the nearly complete angular coverage in the \(p\pi ^{0}\) center of mass system with high statistics. The cross section was measured and the structure functions \(\sigma _T+\epsilon \sigma _L\), \(\sigma _{TT}\) and \(\sigma _{LT}\) were extracted via fitting the \(\phi ^{*}_{\pi ^{0}}\) dependance. Analysis of these results has revealed the data sensitivity to the contribution from the nucleon resonances \(N(1650)1/2^-\), \(N(1685)5/2^{+}\), and \(\varDelta (1700)3/2^{-}\). Combined studies of \(\pi ^{+}n\) and \(\pi ^{0}p\) electroproduction off proton data from CLAS at \(W>1.6\) GeV will provide the first results on the high lying \(N^{*}\) and \(\varDelta \) electrocouplings at \(Q^{2}\) < 1.0 GeV\(^{2}\) for all excited nucleons with substantial decays to the \(N\pi \) final states. These new experimental data will extend the insight into the complex interplay between the inner quark core and outer meson–baryon cloud in the structure of nucleon resonances with masses above 1.6 GeV.
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References
K.A. Olive et al., (Particle data group), Chin. Phys. C 38, 090001 (2014)
G. Laveissiere, Phys. Rev. C 69, 045203 (2004)
J.J. Kelly et al., Phys. Rev. C 95, 102001 (2007)
J.J. Kelly et al., Phys. Rev. C 75, 025201 (2007)
L.C. Smith et al., in Proceedings of the Workshop “Shape of Hadrons”, (Athens, 2006), p. 222
K. Joo, L.C. Smith et al., Phys. Rev. Lett. 88, 122001 (2002)
M. Ungaro, P. Stoler, I. Aznauryan, V.D. Burkert, K. Joo, L.C. Smith, Phys. Rev. Lett. 97, 112003 (2006)
V.V. Frolov et al., Phys. Rev. Lett. 82, 45–48 (1999)
I. Aznauryan et al., Phys. Rev. C 80, 055203 (2009)
V. Burkert, C. Roberts. arXiv:1710.02549 [nucl-ex]
S. Capstick, B.D. Keister, Phys. Rev. D 51, 3598 (1995)
I.G. Aznauryan, Phys. Rev. C 76, 025212 (2007)
V. Mokeev, Phys. Rev. C 86, 035203 (2012)
K. Park, I. Aznauryan, Phys. Rev. C 91, 045203 (2015)
I. Aznauruan, V.D. Burkert, Progr. Part. Nucl. Phys. 67, 1 (2012)
R.G. Moorhouse, Phys. Rev. Lett. 16, 772 (1966)
M. Ronniger, B. Metsch, Eur. Phys. J. A 49, 8 (2013)
E. Santopinto, M. Giannini, Phys. Rev. C 86, 065202 (2012)
B. Julia-Diaz, T.-S.H. Lee, A. Matsuyama, Phys. Rev. C 77, 045205, 12 (2008)
https://www.jlab.org/Hall-B/document/gsim/node1.html. Accessed 13 Aug 2018
D. Drechsel, S.S. Kamalov, L. Tiator, Eur. Phys. J. A 34, 69–97 (2007)
A. Afanasev, I. Akushevich, V. Burkert, K. Joo, Phys. Rev. D 66, 074004 (2002)
I.G. Aznauryan, Phys. Rev. C 67, 015209 (2003)
Nucleon Resonance Photo-/Electrocouplings Determined from Analyses of Experimental Data on Exclusive Meson Electroproduction off Protons. https://userweb.jlab.org/~mokeev/resonanceelectrocouplings/
V.I. Mokeev, in The 11th International Workshop on the Physics of Excited Nucleons—N*2017, (2017) (See these proceedings)
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This article belongs to the Topical Collection “NSTAR 2017 – The International Workshop on the Physics of Excited Nucleons”.
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Markov, N., Joo, K., Ungaro, M. et al. Exclusive \(\pi ^{0}\) Electroproduction in the Resonance Region. Few-Body Syst 59, 134 (2018). https://doi.org/10.1007/s00601-018-1448-x
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DOI: https://doi.org/10.1007/s00601-018-1448-x