N. Liyanage, B. D. Anderson, K. A. Aniol, L. Auerbach, F. T. Baker, J. Berthot, W. Bertozzi, P. -Y. Bertin, L. Bimbot, W. U. Boeglin, E. J. Brash, V. Breton, H. Breuer, E. Burtin, J. R. Calarco, L. Cardman, G. D. Cates, C. Cavata, C. C. Chang, J. -P. Chen, E. Cisbani, D. S. Dale, R. De Leo, A. Deur, B. Diederich, P. Djawotho, J. Domingo, B. Doyle, J. -E. Ducret, M. B. Epstein, L. A. Ewell, J. M. Finn, K. G. Fissum, H. Fonvieille, B. Frois, S. Frullani, J. Gao, F. Garibaldi, A. Gasparian, S. Gilad, R. Gilman, A. Glamazdin, C. Glashausser, J. Gomez, V. Gorbenko, T. Gorringe, F. W. Hersman, R. Holmes, M. Holtrop, N. d’Hose, C. Howell, G. M. Huber, C. E. Hyde-Wright, M. Iodice, C. W. de Jager, S. Jaminion, M. K. Jones, K. Joo, C. Jutier, W. Kahl, S. Kato, J. J. Kelly, S. Kerhoas, M. Khandaker, M. Khayat, K. Kino, W. Korsch, L. Kramer, K. S. Kumar, G. Kumbartzki, G. Laveissière, A. Leone, J. J. LeRose, L. Levchuk, M. Liang, R. A. Lindgren, G. J. Lolos, R. W. Lourie, R. Madey, K. Maeda, S. Malov, D. M. Manley, D. J. Margaziotis P. Markowitz, J. Martino, J. S. McCarthy, K. McCormick, J. McIntyre, R. L. J. van der Meer, Z. -E. Meziani, R. Michaels, J. Mougey, S. Nanda, D. Neyret, E. A. J. M. Offermann, Z. Papandreou, C. F. Perdrisat, R. Perrino, G. G. Petratos, S. Platchkov, R. Pomatsalyuk, D. L. Prout, V. A. Punjabi, T. Pussieux, G. Quéméner, R. D. Ransome, O. Ravel, Y. Roblin, R. Roche, D. Rowntree, G.A. Rutledge, P. M. Rutt, A. Saha, T. Saito, A. J. Sarty, A. Serdarevic-Offermann, T. P. Smith, A. Soldi, P. Sorokin, P. Souder, R. Suleiman, J. A. Templon, T. Terasawa, L. Todor, H. Tsubota, H. Ueno, P. E. Ulmer, G.M. Urciuoli, P. Vernin, S. van Verst, B. Vlahovic, H. Voskanyan, J. W. Watson, L. B. Weinstein, K. Wijesooriya, R. Wilson, B. Wojtsekhowski, D. G. Zainea, V. Zeps, J. Zhao, Z. -L. Zhou

K. Park, 2, ∗ V.D. Burkert, W. Kim, I.G. Aznauryan, 2 R. Minehart, L.C. Smith, K. Joo, 41 L. Elouadrhiri, 2 G. Adams, M.J. Amaryan, P. Ambrozewicz, M. Anghinolfi, G. Asryan, H. Avakian, 2 H. Bagdasaryan, 32 N. Baillie, J.P. Ball, N.A. Baltzell, S. Barrow, V. Batourine, M. Battaglieri, I. Bedlinskiy, M. Bektasoglu, M. Bellis, N. Benmouna, B.L. Berman, A.S. Biselli, 7, 15 L. Blaszczyk, B.E. Bonner, C. Bookwalter, S. Bouchigny, S. Boiarinov, 2 R. Bradford, D. Branford, W.J. Briscoe, W.K. Brooks, S. Bültmann, C. Butuceanu, J.R. Calarco, S.L. Careccia, D.S. Carman, 2 L. Casey, A. Cazes, S. Chen, L. Cheng, P.L. Cole, 8, 20 P. Collins, P. Coltharp, D. Cords, P. Corvisiero, D. Crabb, V. Crede, J.P. Cummings, D. Dale, N. Dashyan, R. De Masi, 23 R. De Vita, E. De Sanctis, P.V. Degtyarenko, H. Denizli, L. Dennis, A. Deur, S. Dhamija, K.V. Dharmawardane, K.S. Dhuga, R. Dickson, C. Djalali, G.E. Dodge, J. Donnelly, D. Doughty, 2 M. Dugger, S. Dytman, O.P. Dzyubak, H. Egiyan, 2, † K.S. Egiyan, L. El Fassi, P. Eugenio, 17 R. Fatemi, G. Fedotov, G. Feldman, R.J. Feuerbach, T.A. Forest, 20 A. Fradi, H. Funsten, M.Y. Gabrielyan, M. Garçon, G. Gavalian, 32 N. Gevorgyan, G.P. Gilfoyle, K.L. Giovanetti, F.X. Girod, 2 J.T. Goetz, W. Gohn, E. Golovatch, ‡ A. Gonenc, C.I.O. Gordon, R.W. Gothe, L. Graham, K.A. Griffioen, M. Guidal, M. Guillo, N. Guler, L. Guo, V. Gyurjyan, C. Hadjidakis, K. Hafidi, K. Hafnaoui, H. Hakobyan, R.S. Hakobyan, C. Hanretty, J. Hardie, 2 N. Hassall, § D. Heddle, F.W. Hersman, K. Hicks, I. Hleiqawi, M. Holtrop, C.E. Hyde-Wright, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, M.M. Ito, D. Jenkins, H.S. Jo, J.R. Johnstone, H.G. Juengst, 32 N. Kalantarians, D. Keller, J.D. Kellie, M. Khandaker, K.Y. Kim, A. Klein, F.J. Klein, 8 A.V. Klimenko, M. Klusman, M. Kossov, Z. Krahn, L.H. Kramer, 2 V. Kubarovsky, J. Kuhn, 7 S.E. Kuhn, S.V. Kuleshov, V. Kuznetsov, J. Lachniet, 32 J.M. Laget, 2 J. Langheinrich, D. Lawrence, T. Lee, Ji Li, A.C.S. Lima, K. Livingston, H.Y. Lu, K. Lukashin, M. MacCormick, N. Markov, P. Mattione, S. McAleer, B. McKinnon, J.W.C. McNabb, B.A. Mecking, S. Mehrabyan, J.J. Melone, M.D. Mestayer, C.A. Meyer, T. Mibe, K. Mikhailov, M. Mirazita, R. Miskimen, V. Mokeev, 2 L. Morand, B. Moreno, K. Moriya, S.A. Morrow, 9 M. Moteabbed, J. Mueller, E. Munevar, G.S. Mutchler, P. Nadel-Turonski, R. Nasseripour, 37 S. Niccolai, 23 G. Niculescu, 25 I. Niculescu, 2, 25 B.B. Niczyporuk, M.R. Niroula, R.A. Niyazov, 2 M. Nozar, ¶ G.V. O’Rielly, M. Osipenko, 28 A.I. Ostrovidov, S. Park, E. Pasyuk, C. Paterson, S. Anefalos Pereira, S.A. Philips, J. Pierce, N. Pivnyuk, D. Pocanic, O. Pogorelko, E. Polli, I. Popa, S. Pozdniakov, B.M. Preedom, J.W. Price, Y. Prok, 2, ∗∗ D. Protopopescu, 19 L.M. Qin, B.A. Raue, 2 G. Riccardi, G. Ricco, M. Ripani, B.G. Ritchie, F. Ronchetti, G. Rosner, P. Rossi, D. Rowntree, P.D. Rubin, F. Sabatié, 9 M.S. Saini, J. Salamanca, C. Salgado, J.P. Santoro, 8, 2 V. Sapunenko, 2 D. Schott, R.A. Schumacher, V.S. Serov, Y.G. Sharabian, D. Sharov, J. Shaw, N.V. Shvedunov, A.V. Skabelin, E.S. Smith, D.I. Sober, D. Sokhan, A. Stavinsky, S.S. Stepanyan, S. Stepanyan, B.E. Stokes, P. Stoler, I.I. Strakovsky, S. Strauch, 37 R. Suleiman, M. Taiuti, T. Takeuchi, D.J. Tedeschi, 14 A. Tkabladze, 18 S. Tkachenko, L. Todor, 36 C. Tur, M. Ungaro, 11 M.F. Vineyard, 36 A.V. Vlassov, D.P. Watts, †† L.B. Weinstein, D.P. Weygand, M. Williams, E. Wolin, M.H. Wood, ‡‡ A. Yegneswaran, J. Yun, M. Yurov, L. Zana, B. Zhang, J. Zhang, B. Zhao, and Z.W. Zhao

The spin structure functions g, for the proton and the deuteron have been measured over a wide kinematic range in x and Q(2) using 1.6 and 5.7 GeV longitudinally polarized electrons incident upon polarized NH3 and ND3 targets at Jefferson Lab. Scattered electrons were detected in the CEBAF Large Acceptance Spectrometer, for 0.05 < Q(2) < 5 GeV2 and W < 3 GeV. The first moments of g(1) for the proton and deuteron are presented - both have a negative slope at low Q(2), as predicted by the extended Gerasimov-Drell-Hearn sum rule. The first extraction of the generalized forward spin polarizability of the proton gamma(p)(0) is also reported. This quantity shows strong Q(2) dependence at low Q(2). Our analysis of the Q(2) evolution of the first moment of g, shows agreement in leading order with Heavy Baryon Chiral Perturbation Theory. However, a significant discrepancy is observed between the gamma(p)(0) data and Chiral Perturbation calculations for gamma(p)(0), even at the lowest Q(2). (C) 2009 Elsevier B.V. All rights reserved.

This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process $e p \to e' p \pi^{+} \pi^{-} $. The data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the so-far unexplored kinematic region of photon virtuality 0.2 $<$ $Q^{2}$ $<$ 0.6 GeV$^{2}$ and invariant mass of the final hadron system $W$ from 1.3 to 1.57 GeV. For the first time, nine independent 1-fold differential cross sections were determined in each bin of $W$ and $Q^{2}$ covered by the measurements. A phenomenological analysis of the data allowed us to establish the most significant mechanisms contributing to the reaction. The non-resonant mechanisms account for a major part of cross-sections. However, we find sensitivity to s-channel excitations of low-mass nucleon resonances, especially to the $N(1440)P_{11}$ and $N(1520)D_{13}$ states in kinematical dependencies of the 1-fold differential cross-sections.

This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process ep. e -> p pi(+)pi(-). The data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the as yet unexplored kinematic region of photon virtuality 0.2 < Q(2) < 0.6 GeV2 and invariant mass of the final hadron system W from 1.3 to 1.57 GeV. For the first time, nine independent one-fold differential cross sections were determined in each bin of W and Q(2) covered by the measurements. A phenomenological analysis of the data allowed us to establish the most significant mechanisms contributing to the reaction. The nonresonant mechanisms account for a major part of cross sections. However, we find sensitivity to s-channel excitations of low-mass nucleon resonances, especially to the N(1440)P-11 and N(1520)D-13 states in kinematic dependencies of the one-fold differential cross sections.

We report measurements of the beam spin asymmetry in Deeply Virtual Compton Scattering (DVCS) at an electron beam energy of 4.8 GeV using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The DVCS beam spin asymmetry has been measured in a wide range of kinematics, 1(GeV/c)$^2$ $

We have made the first measurements of the virtual Compton scattering process via the e p -> e p gamma exclusive reaction at Q**2 = 1 GeV**2 in the nucleon resonance region. The cross section is obtained at center of mass (CM) backward angle, theta_gamma_gamma*, in a range of total (gamma* p) CM energy W from the proton mass up to W = 1.91 GeV. The data show resonant structures in the first and second resonance regions, and are well reproduced at higher W by the Bethe-Heitler+Born cross section, including t-channel pi0-exchange. At high W, our data, together with existing real photon data, show a striking Q**2 independence. Our measurement of the ratio of H(e,e'p)gamma to H(e,e'p)pi0 cross sections is presented and compared to model predictions.

The neutron elastic magnetic form factor was extracted from quasielastic electron scattering on deuterium over the range Q(2)=1.0-4.8 GeV2 with the CLAS detector at Jefferson Lab. High precision was achieved with a ratio technique and a simultaneous in situ calibration of the neutron detection efficiency. Neutrons were detected with electromagnetic calorimeters and time-of-flight scintillators at two beam energies. The dipole parametrization gives a good description of the data.

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 pi+ 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 results. It is found that the transverse helicity amplitude A_{1/2} for the gamma* p -> N(1440)P11 transition, 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 S_{1/2}, which was previously found from CLAS ep -> eppi0,enpi+ 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 3qG hybrid state is ruled out.

A set of three out-of-plane magnetic spectrometers (OOPS) has recently been deployed and commissioned at the Bates Linear Accelerator. Measurements of the 2 H(~ e; e 0 p)n reaction have been performed using an 800 MeV polarized electron beam and the OOPS to detect protons in coincidence with an electron spectrometer in kinematics of either quasielastic (QE) at Q 2 =0.22 (GeV/c) 2 or non{quasielastic (dip) at Q 2 =0.15 (GeV/c) 2. Two and three OOPS were positioned symmetrically along the direction of momentum transfer in pq=(45,135) and (0,90,180) conngurations, respectively, for a given set of pq values. This allowed simultaneous measurements of the longitudinal-transverse responses, f LT and f 0 LT , and the transverse-transverse response f TT at various central missing momenta ranging from 145 to 265 MeV/c. Here, preliminary results are presented and compared with vigorous model calculations. The data reveal strong eeects of relativity and nal-state interactions, as well as the two-body currents, which include the meson-exchange and iso-bar currents, in the deuteron electrodisintegration. An outlook of future OOPS programs is also discussed.

P. E. Bosted,35,* R. Fersch,39 G. Adams,31 M. Amarian,29 S. Anefalos,17 M. Anghinolfi,18 G. Asryan,40 H. Avakian,17,35 H. Bagdasaryan,29,40 N. Baillie,39 J. P. Ball,2 N. A. Baltzell,34 S. Barrow,13 V. Batourine,35 M. Battaglieri,18 K. Beard,21 I. Bedlinskiy,20 M. Bektasoglu,29 M. Bellis,5,31 N. Benmouna,14 A. S. Biselli,11 B. E. Bonner,32 S. Bouchigny,19,35 S. Boiarinov,20,35 R. Bradford,5 D. Branford,10 W. K. Brooks,35 S. Bültmann,29 V. D. Burkert,35 C. Butuceanu,39 J. R. Calarco,26 S. L. Careccia,29 D. S. Carman,35 B. Carnahan,6 A. Cazes,34 S. Chen,13 P. L. Cole,16,35 P. Collins,2 P. Coltharp,13 D. Cords,35,† P. Corvisiero,18 D. Crabb,38 H. Crannell,6 V. Crede,13 J. P. Cummings,31 R. De Masi,7 R. De Vita,18 E. De Sanctis,17 P. V. Degtyarenko,35 H. Denizli,30 L. Dennis,13 A. Deur,35 C. Djalali,34 G. E. Dodge,29 J. Donnelly,15 D. Doughty,8,35 P. Dragovitsch,13 M. Dugger,2 K. V. Dharmawardane,29,‡ S. Dytman,30 O. P. Dzyubak,34 H. Egiyan,35,39,§ K. S. Egiyan,40,† L. Elouadrhiri,8,35 P. Eugenio,13 R. Fatemi,38 G. Fedotov,25 R. J. Feuerbach,5 T. A. Forest,29 A. Fradi,19 H. Funsten,39 M. Garçon,7 G. Gavalian,26,29 G. P. Gilfoyle,33 K. L. Giovanetti,21 F. X. Girod,7 J. T. Goetz,3 E. Golovatch,18,‖ R. W. Gothe,34 K. A. Griffioen,39 M. Guidal,19 M. Guillo,34 N. Guler,29 L. Guo,35 V. Gyurjyan,35 C. Hadjidakis,19 K. Hafidi,1 R. S. Hakobyan,6 J. Hardie,8,35 D. Heddle,8,35 F. W. Hersman,26 K. Hicks,28 I. Hleiqawi,28 M. Holtrop,26 M. Huertas,34 C. E. Hyde-Wright,29 Y. Ilieva,14 D. G. Ireland,15 B. S. Ishkhanov,25 E. L. Isupov,25 M. M. Ito,35 D. Jenkins,37 H. S. Jo,19 K. Joo,9 H. G. Juengst,29 N. Kalantarians,29 C. Keith,35 J. D. Kellie,15 M. Khandaker,27 K. Y. Kim,30 K. Kim,22 W. Kim,22 A. Klein,29,¶ F. J. Klein,6,12 M. Klusman,31 M. Kossov,20 L. H. Kramer,12,35 V. Kubarovsky,31,35 J. Kuhn,5,31 S. E. Kuhn,29 S. V. Kuleshov,20 J. Lachniet,5,29 J. M. Laget,7,35 J. Langheinrich,34 D. Lawrence,24 Ji Li ,31 A. C. S. Lima,14 K. Livingston,15 H. Lu,34 K. Lukashin,6 M. MacCormick,19 N. Markov,9 S. McAleer,13 B. McKinnon,15 J. W. C. McNabb,5 B. A. Mecking,35 M. D. Mestayer,35 C. A. Meyer,5 T. Mibe,28 K. Mikhailov,20 R. Minehart,38 M. Mirazita,17 R. Miskimen,24 V. Mokeev,25 L. Morand,7 S. A. Morrow,7,19 M. Moteabbed,12 J. Mueller,30 G. S. Mutchler,32 P. Nadel-Turonski,14 R. Nasseripour,12,34 S. Niccolai,14,19 G. Niculescu,21 I. Niculescu,14,21 B. B. Niczyporuk,35 M. R. Niroula,29 R. A. Niyazov,29,35 M. Nozar,35 G. V. O’Rielly,14 M. Osipenko,18,25 A. I. Ostrovidov,13 K. Park,22 E. Pasyuk,2 C. Paterson,15 S. A. Philips,14 J. Pierce,38 N. Pivnyuk,20 D. Pocanic,38 O. Pogorelko,20 E. Polli,17 S. Pozdniakov,20 B. M. Preedom,34 J. W. Price,4 Y. Prok,38,** D. Protopopescu,15,26 L. M. Qin,29 B. A. Raue,12,35 G. Riccardi,13 G. Ricco,18 M. Ripani,18 G. Rosner,15 P. Rossi,17 D. Rowntree,23 P. D. Rubin,33 F. Sabatié,7,29 C. Salgado,27 J. P. Santoro,35,37,†† V. Sapunenko,18,35 R. A. Schumacher,5 V. S. Serov,20 Y. G. Sharabian,35 J. Shaw,24 N. V. Shvedunov,25 A. V. Skabelin,23 E. S. Smith,35 L. C. Smith,38 D. I. Sober,6 A. Stavinsky,20 S. S. Stepanyan,22 S. Stepanyan,8,35,40 B. E. Stokes,13 P. Stoler,31 S. Strauch,34 R. Suleiman,23 M. Taiuti,18 S. Taylor,32 D. J. Tedeschi,34 U. Thoma,35,‡‡ A. Tkabladze,14 S. Tkachenko,29 L. Todor,5 M. Ungaro,9 M. F. Vineyard,33,36 A. V. Vlassov,20 L. B. Weinstein,29 D. P. Weygand,35 M. Williams,5 E. Wolin,35 M. H. Wood,34,§§ A. Yegneswaran,35 J. Yun,29 L. Zana,26 J. Zhang,29 B. Zhao,9 and Z. Zhao34 (CLAS Collaboration) 1Argonne National Laboratory, Argonne, Illinois 60439, USA 2Arizona State University, Tempe, Arizona 85287-1504, USA 3University of California at Los Angeles, Los Angeles, California 90095-1547, USA 4California State University, Dominguez Hills, Carson, California 90747, USA 5Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA 6Catholic University of America, Washington, D.C. 20064, USA 7CEA-Saclay, Service de Physique Nucléaire, F-91191 Gif-sur-Yvette, France 8Christopher Newport University, Newport News, Virginia 23606, USA 9University of Connecticut, Storrs, Connecticut 06269, USA 10Edinburgh University, Edinburgh EH9 3JZ, United Kingdom 11Fairfield University, Fairfield, Connecticut 06824, USA 12Florida International University, Miami, Florida 33199, USA 13Florida State University, Tallahassee, Florida 32306, USA 14George Washington University, Washington, D.C. 20052, USA 15University of Glasgow, Glasgow G12 8QQ, United Kingdom 16Idaho State University, Pocatello, Idaho 83209, USA 17INFN, Laboratori Nazionali di Frascati, I-00044 Frascati, Italy 18INFN, Sezione di Genova, I-16146 Genova, Italy 19Institut de Physique Nucleaire ORSAY, Orsay, France 20Institute of Theoretical and Experimental Physics, RU-117259 Moscow, Russia 21James Madison University, Harrisonburg, Virginia 22807, USA 22Kyungpook National University, Daegu 702-701, South Korea 23Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA 24University of Massachusetts, Amherst, Massachusetts 01003, USA 25Moscow State University, General Nuclear Physics Institute, RU-119899 Moscow, Russia

The exclusive electroproduction process $\vec{e}p \to e^\prime n \pi^+$ was measured in the range of the photon virtuality $Q^2 = 1.7 - 4.5 \rm{GeV^2}$, and the invariant mass range for the $n\pi^+$ system of $W = 1.15 - 1.7 \rm{GeV}$ using the CEBAF Large Acceptance Spectrometer. For the first time, these kinematics are probed in exclusive $\pi^+$ production from protons with nearly full coverage in the azimuthal and polar angles of the $n\pi^+$ center-of-mass system. The $n\pi^+$ channel has particular sensitivity to the isospin 1/2 excited nucleon states, and together with the $p\pi^0$ final state will serve to determine the transition form factors of a large number of resonances. The largest discrepancy between these results and present modes was seen in the $\sigma_{LT'}$ structure function. In this experiment, 31,295 cross section and 4,184 asymmetry data points were measured. Because of the large volume of data, only a reduced set of structure functions and Legendre polynomial moments can be presented that are obtained in model-independent fits to the differential cross sections.

Citation for published version: Park, K, Burkert, VD, Kim, W, Aznauryan, IG, Minehart, R, Smith, LC, Joo, K, Elouadrhiri, L, Adams, G, Amaryan, MJ, Ambrozewicz, P, Anghinolfi, M, Asryan, G, Avakian, H, Bagdasaryan, H, Baillie, N, Ball, JP, Baltzell, NA, Barrow, S, Batourine, V, Battaglieri, M, Bedlinskiy, I, Bektasoglu, M, Bellis, M, Benmouna, N, Berman, BL, Biselli, AS, Blaszczyk, L, Bonner, BE, Bookwalter, C, Bouchigny, S, Boiarinov, S, Bradford, R, Branford, D, Briscoe, J, Brooks, WK, Bultmann, S, Butuceanu, C, Calarco, JR, Careccia, SL, Carman, DS, Casey, L, Cazes, A, Chen, S, Cheng, L, Cole, PL, Collins, P, Coltharp, P, Cords, D, Watts, DP & Clas Collaboration 2008, 'Cross sections and beam asymmetries for (e)over-right-arrowp -> en pi(+) in the nucleon resonance region for 1.7 Q(2)GeV2', Physical Review C, vol. 77, no. 1, 015208, pp. -. https://doi.org/10.1103/PhysRevC.77.015208