Phys. Rev. C
78,
045209
(2008)
[7 pages]
Electroexcitation of the Roper resonance for 1.7<Q2<4.5 GeV2 in e⃗p→enπ+
I. G. Aznauryan et al. CLAS Collaboration
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I. G. Aznauryan1,2, V. D. Burkert1, W. Kim4, K. Park3,4, G. Adams36, M. J. Amaryan34, P. Ambrozewicz18, M. Anghinolfi24, G. Asryan2, H. Avakian1, H. Bagdasaryan2,34, N. Baillie43, J. P. Ball6, N. A. Baltzell3, S. Barrow19, V. Batourine4, M. Battaglieri24, I. Bedlinskiy26, M. Bektasoglu34, M. Bellis9, N. Benmouna20, B. L. Berman20, A. S. Biselli9,17,36, L. Blaszczyk19, B. E. Bonner37, C. Bookwalter19, S. Bouchigny25, S. Boiarinov1,26, R. Bradford9, D. Branford15, W. J. Briscoe20, W. K. Brooks1,14, S. Bültmann34, C. Butuceanu43, J. R. Calarco31, S. L. Careccia34, D. S. Carman1, L. Casey10, A. Cazes3, S. Chen19, L. Cheng10, P. L. Cole1,10,22, P. Collins6, P. Coltharp19, D. Cords1,*, P. Corvisiero24, D. Crabb42, V. Crede19, J. P. Cummings36, D. Dale22, N. Dashyan2, R. De Masi11,25, R. De Vita24, E. De Sanctis23, P. V. Degtyarenko1, H. Denizli35, L. Dennis19, A. Deur1, S. Dhamija18, K. V. Dharmawardane34, K. S. Dhuga20, R. Dickson9, C. Djalali3, G. E. Dodge34, J. Donnelly21, D. Doughty1,12, M. Dugger6, S. Dytman35, O. P. Dzyubak3, H. Egiyan1,31, K. S. Egiyan2,*, L. El Fassi5, L. Elouadrhiri1, P. Eugenio9,19, R. Fatemi42, G. Fedotov30, G. Feldman20, R. J. Feuerbach9, T. A. Forest22,34, A. Fradi25, H. Funsten43,*, M. Y. Gabrielyan18, M. Garçon11, G. Gavalian31,34, N. Gevorgyan2, G. P. Gilfoyle38, K. L. Giovanetti27, F. X. Girod1,11, J. T. Goetz7, W. Gohn13, E. Golovatch24,30, A. Gonenc18, C. I. O. Gordon21, R. W. Gothe3, L. Graham3, K. A. Griffioen43, M. Guidal25, M. Guillo3, N. Guler34, L. Guo1, V. Gyurjyan1, C. Hadjidakis25, K. Hafidi5, K. Hafnaoui5, H. Hakobyan2, R. S. Hakobyan10, C. Hanretty19, J. Hardie1,12, N. Hassall21, D. Heddle1, F. W. Hersman31, K. Hicks33, I. Hleiqawi33, M. Holtrop31, C. E. Hyde34, Y. Ilieva3,20, D. G. Ireland21, B. S. Ishkhanov30, E. L. Isupov30, M. M. Ito1, D. Jenkins41, H. S. Jo25, J. R. Johnstone21, K. Joo13,42, H. G. Juengst20,34, N. Kalantarians34, D. Keller33, J. D. Kellie21, M. Khandaker32, K. Y. Kim35, A. Klein34, F. J. Klein10,18, A. V. Klimenko34, M. Kossov26, Z. Krahn9, L. H. Kramer1,18, V. Kubarovsky1,36, J. Kuhn9,36, S. E. Kuhn34, S. V. Kuleshov26, V. Kuznetsov4, J. Lachniet9,34, J. M. Laget1,11, J. Langheinrich3, D. Lawrence29, T. Lee31, Ji Li36, A. C. S. Lima20, K. Livingston21, H. Y. Lu3, K. Lukashin10, M. MacCormick25, N. Markov13, P. Mattione37, S. McAleer19, B. McKinnon21, J. W. C. McNabb9, B. A. Mecking1, S. Mehrabyan35, J. J. Melone21, M. D. Mestayer1, C. A. Meyer9, T. Mibe33, K. Mikhailov26, R. Minehart42, M. Mirazita23, R. Miskimen29, V. Mokeev1,30, L. Morand11, B. Moreno25, K. Moriya9, S. A. Morrow11,25, M. Moteabbed18, J. Mueller35, E. Munevar20, G. S. Mutchler37, P. Nadel-Turonski20, R. Nasseripour3,20, S. Niccolai20,25, G. Niculescu27,33, I. Niculescu1,20,27, B. B. Niczyporuk1, M. R. Niroula34, R. A. Niyazov1,34, M. Nozar1,39, G. V. O'Rielly20, M. Osipenko24, A. I. Ostrovidov19, S. Park19, E. Pasyuk6, C. Paterson21, S. Anefalos Pereira23, S. A. Philips20, J. Pierce42, N. Pivnyuk26, D. Pocanic42, O. Pogorelko26, E. Polli23, I. Popa20, S. Pozdniakov26, B. M. Preedom3, J. W. Price8, Y. Prok1,12,28, D. Protopopescu21,31, L. M. Qin34, B. A. Raue1,18, G. Riccardi19, G. Ricco24, M. Ripani24, B. G. Ritchie6, G. Rosner21, P. Rossi23, D. Rowntree28, P. D. Rubin38, F. Sabatié11,34, M. S. Saini19, J. Salamanca22, C. Salgado32, J. P. Santoro1,10, V. Sapunenko1,24, D. Schott18, R. A. Schumacher9, V. S. Serov26, Y. G. Sharabian1, D. Sharov30, J. Shaw29, N. V. Shvedunov30, A. V. Skabelin28, E. S. Smith1, L. C. Smith42, D. I. Sober10, D. Sokhan15, A. Stavinsky26, S. S. Stepanyan4, S. Stepanyan1, B. E. Stokes19, P. Stoler36, I. I. Strakovsky20, S. Strauch3, R. Suleiman28, M. Taiuti24, T. Takeuchi19, D. J. Tedeschi3,16, A. Tkabladze20,33, S. Tkachenko34, L. Todor9,38, C. Tur3, M. Ungaro13,36, M. F. Vineyard38,40, A. V. Vlassov26, D. P. Watts15,21, L. B. Weinstein34, D. P. Weygand1, M. Williams9, E. Wolin1, M. H. Wood3,29, A. Yegneswaran1, J. Yun34, M. Yurov4, L. Zana31, B. Zhang28, J. Zhang34, B. Zhao13, and Z. W. Zhao3 (CLAS Collaboration)
1Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
2Yerevan Physics Institute, 375036 Yerevan, Armenia
3University of South Carolina, Columbia, South Carolina 29208, USA
4Kyungpook National University, Daegu 702-701, Republic of Korea
5Argonne National Laboratory, Argonne, Illinois 60439, USA
6Arizona State University, Tempe, Arizona 85287-1504, USA
7University of California at Los Angeles, Los Angeles, California 90095-1547, USA
8California State University, Dominguez Hills, Carson, California 90747, USA
9Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
10Catholic University of America, Washington, D.C. 20064, USA
11CEA-Saclay, Service de Physique Nucléaire, F-91191 Gif-sur-Yvette, France
12Christopher Newport University, Newport News, Virginia 23606, USA
13University of Connecticut, Storrs, Connecticut 06269, USA
14Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso, Chile
15Edinburgh University, Edinburgh EH9 3JZ, United Kingdom
16Emmy-Noether Foundation, Germany
17Fairfield University, Fairfield, Connecticut 06824, USA
18Florida International University, Miami, Florida 33199, USA
19Florida State University, Tallahassee, Florida 32306, USA
20The George Washington University, Washington, D.C. 20052, USA
21University of Glasgow, Glasgow G12 8QQ, United Kingdom
22Idaho State University, Pocatello, Idaho 83209, USA
23INFN, Laboratori Nazionali di Frascati, I-00044 Frascati, Italy
24INFN, Sezione di Genova, I-16146 Genova, Italy
25Institut de Physique Nucleaire ORSAY, Orsay, France
26Institute of Theoretical and Experimental Physics, Moscow, RU-117259, Russia
27James Madison University, Harrisonburg, Virginia 22807, USA
28Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
29University of Massachusetts, Amherst, Massachusetts 01003, USA
30Moscow State University, General Nuclear Physics Institute, RU-119899 Moscow, Russia
31University of New Hampshire, Durham, New Hampshire 03824-3568, USA
32Norfolk State University, Norfolk, Virginia 23504, USA
33Ohio University, Athens, Ohio 45701, USA
34Old Dominion University, Norfolk, Virginia 23529, USA
35University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
36Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA
37Rice University, Houston, Texas 77005-1892, USA
38University of Richmond, Richmond, Virginia 23173, USA
39TRIUMF, 4004, Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
40Union College, Schenectady, New York 12308, USA
41Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0435, USA
42University of Virginia, Charlottesville, Virginia 22901, USA
43College of William and Mary, Williamsburg, Virginia 23187-8795, USA
Received 3 April 2008; revised 15 August 2008; published 27 October 2008
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 γ*p→N(1440)P11 transition. It is found that the transverse helicity amplitude A1/2, which is large and negative at Q2=0, becomes large and positive at Q2≃2 GeV2, and then drops slowly with Q2. The longitudinal helicity amplitude S1/2, which was previously found from CLAS e⃗p→epπ0,enπ+ data to be large and positive at Q2=0.4,0.65 GeV2, drops with Q2. Available model predictions for γ*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.
© 2008 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevC.78.045209
DOI:
10.1103/PhysRevC.78.045209
PACS:
13.60.Le, 11.55.Fv, 13.40.Gp, 14.20.Gk
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