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41 results on '"Pion electroproduction"'

1. Effect of omega(782) resonance on the response functions for d(e,e’π+)nn reaction

Author

M. .. Tammam, Z. M. Mahmoud, and M. S. Koubisy

Subjects
pion electroproduction, the ω(782) resonance, invariant amplitudes, cgln amplitudes, structure functions, the impulse approximation (ia), Physics, QC1-999
Abstract

In present work we study the effect of the Omega ( ω(782) ) resonance on the response functions for the incoherent positive pion electroproduction forms the deuteron at different values for the four-momentum transfers squared (Q2 ) and the virtual photon lab energy ( klab0 ). The study is carried out in the impulse approximation (IA) i.e. the final state interactions are neglected. The elementary amplitude for pion electroproduction is taken from the MAID-2007 model. The effect seems to be very small but almost increase with increasing the virtual photon lab energy.

Published
2021
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2. Electroexcitation of the Δ+(1232) at low momentum transfer

Author

Blomberg, A, Anez, D, Sparveris, N, Sarty, AJ, Paolone, M, Gilad, S, Higinbotham, D, Ahmed, Z, Albataineh, H, Allada, K, Anderson, B, Aniol, K, Annand, J, Arrington, J, Averett, T, Baghdasaryan, H, Bai, X, Beck, A, Beck, S, Bellini, V, Benmokhtar, F, Boeglin, W, Camacho, CM, Camsonne, A, Chen, C, Chen, JP, Chirapatpimol, K, Cisbani, E, Dalton, M, Deconinck, W, Defurne, M, De Leo, R, Flay, D, Fomin, N, Friend, M, Frullani, S, Fuchey, E, Garibaldi, F, Gilman, R, Gu, C, Hamilton, D, Hanretty, C, Hansen, O, Hashemi Shabestari, M, Hen, O, Holmstrom, T, Huang, M, Iqbal, S, Kalantarians, N, Kang, H, Kelleher, A, Khandaker, M, Korover, I, Leckey, J, LeRose, J, Lindgren, R, Long, E, Mammei, J, Margaziotis, DJ, Martí Jimenez-Arguello, A, Meekins, D, Meziani, ZE, Mihovilovic, M, Muangma, N, Norum, B, Nuruzzaman, Pan, K, Phillips, S, Piasetzky, E, Polychronopoulou, A, Pomerantz, I, Posik, M, Punjabi, V, Qian, X, Rakhman, A, Reimer, PE, Riordan, S, Ron, G, Saha, A, Schulte, E, Selvy, L, Shneor, R, Sirca, S, Sjoegren, J, Subedi, R, Sulkosky, V, Tireman, W, Wang, D, Watson, J, Wojtsekhowski, B, Yan, W, Yaron, I, Ye, Z, Zhan, X, Zhang, J, Zhang, Y, Zhao, B, Zhao, Z, Zheng, X, and Zhu, P

Subjects
CMR, Pion electroproduction, Nucleon deformation, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

We report on new measurements at the resonance at the low momentum transfer region, where the mesonic cloud dynamics is predicted to be dominant and rapidly changing, offering a test bed for chiral effective field theory calculations. The new data explore the dependence of the resonant quadrupole amplitudes and for the first time indicate that the Electric and the Coulomb quadrupole amplitudes converge as. The measurements of the Coulomb quadrupole amplitude have been extended to the lowest momentum transfer ever reached, and suggest that more than half of its magnitude is attributed to the mesonic cloud in this region. The new data disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations that include pion cloud effects, chiral effective field theory and lattice calculations. The measurements indicate that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements.

Published
2016

3. Electroexcitation of the Δ+(1232) at low momentum transfer

Author

A. Blomberg, D. Anez, N. Sparveris, A.J. Sarty, M. Paolone, S. Gilad, D. Higinbotham, Z. Ahmed, H. Albataineh, K. Allada, B. Anderson, K. Aniol, J. Annand, J. Arrington, T. Averett, H. Baghdasaryan, X. Bai, A. Beck, S. Beck, V. Bellini, F. Benmokhtar, W. Boeglin, C.M. Camacho, A. Camsonne, C. Chen, J.P. Chen, K. Chirapatpimol, E. Cisbani, M. Dalton, W. Deconinck, M. Defurne, R. De Leo, D. Flay, N. Fomin, M. Friend, S. Frullani, E. Fuchey, F. Garibaldi, R. Gilman, C. Gu, D. Hamilton, C. Hanretty, O. Hansen, M. Hashemi Shabestari, O. Hen, T. Holmstrom, M. Huang, S. Iqbal, N. Kalantarians, H. Kang, A. Kelleher, M. Khandaker, I. Korover, J. Leckey, J. LeRose, R. Lindgren, E. Long, J. Mammei, D.J. Margaziotis, A. Martí Jimenez-Arguello, D. Meekins, Z.E. Meziani, M. Mihovilovic, N. Muangma, B. Norum, Nuruzzaman, K. Pan, S. Phillips, E. Piasetzky, A. Polychronopoulou, I. Pomerantz, M. Posik, V. Punjabi, X. Qian, A. Rakhman, P.E. Reimer, S. Riordan, G. Ron, A. Saha, E. Schulte, L. Selvy, R. Shneor, S. Sirca, J. Sjoegren, R. Subedi, V. Sulkosky, W. Tireman, D. Wang, J. Watson, B. Wojtsekhowski, W. Yan, I. Yaron, Z. Ye, X. Zhan, J. Zhang, Y. Zhang, B. Zhao, Z. Zhao, X. Zheng, and P. Zhu

Subjects
CMR, Pion electroproduction, Nucleon deformation, Physics, QC1-999
Abstract

We report on new p(e,e′p)π∘ measurements at the Δ+(1232) resonance at the low momentum transfer region, where the mesonic cloud dynamics is predicted to be dominant and rapidly changing, offering a test bed for chiral effective field theory calculations. The new data explore the Q2 dependence of the resonant quadrupole amplitudes and for the first time indicate that the Electric and the Coulomb quadrupole amplitudes converge as Q2→0. The measurements of the Coulomb quadrupole amplitude have been extended to the lowest momentum transfer ever reached, and suggest that more than half of its magnitude is attributed to the mesonic cloud in this region. The new data disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations that include pion cloud effects, chiral effective field theory and lattice calculations. The measurements indicate that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements.

Published
2016
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7. On wide-angle photo- and electroproduction of pions to twist-3 accuracy

Author

Passek-Kumeri��ki, K.

Subjects
High Energy Physics - Theory, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), QCD, exclusive processes, pion electroproduction, wide-angle, higher-twist, High Energy Physics::Phenomenology, Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment
Abstract

The wide-angle photo- and electroproduction of pions is investigated within the handbag mechanism in which the $\gamma^{(*)} N\to \pi N'$ amplitudes factorize into subprocess amplitudes,$\gamma^{(*)} q\to \pi q'$, and form factors representing $1/x$-moments of generalized parton distributions (GPDs). The subprocess is calculated to twist-3 accuracy taking into account both the 2- and 3-body Fock components of the pion. The cross-sections are compared to experiment and spin-effects are discussed., Comment: 4 pages, 3 figures; Contribution to the 19th International Conference on Hadron Spectroscopy and Structure in memoriam Simon Eidelman (HADRON2021)

Published
2022

8. Electroexcitation of the Δ+(1232) at low momentum transfer.

Author

Blomberg, A., Anez, D., Sparveris, N., Sarty, A.J., Paolone, M., Gilad, S., Higinbotham, D., Ahmed, Z., Albataineh, H., Allada, K., Anderson, B., Aniol, K., Annand, J., Arrington, J., Averett, T., Baghdasaryan, H., Bai, X., Beck, A., Beck, S., and Bellini, V.

Subjects
*PIONS, *MOMENTUM transfer, *PARTICLES (Nuclear physics), *DEFORMATIONS (Mechanics), *COLOSSAL magnetoresistance
Published
2016
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10. New Results on Nucleon Resonance Transition Form Factors.

Author

Burkert, Volker D. and Aznauryan, Inna

Subjects
*PARTICLES (Nuclear physics), *NUCLEAR physics, *FORM factor (Nuclear physics), *APPROXIMATION theory, *SCATTERING (Physics)
Abstract

Recent measurements with CLAS at Jefferson Lab of nucleon resonance transition form factors for several lower mass states are discussed. [ABSTRACT FROM AUTHOR]

Published
2009
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11. The EG4 Experiment at Jefferson Lab.

Author

Zheng, X.

Subjects
*PROTONS, *NEUTRONS, *RESONANCE, *PARTICLES (Nuclear physics), *ABSORPTION
Abstract

The main physics goal of the CLAS EG4 experiment at Jefferson Lab is to measure the generalized GDH sum for the proton and the neutron at very low Q2 down to Q2 = 0.015 (GeV/c)2 (inclusive channels). The same data can be used to extract asymmetries of pion electroproduction in the resonance region (exclusive channels). An overview of the experiment is presented here, as well as the analysis status of both inclusive and exclusive analyses. Some preliminary results on the single-target and the beam-target asymmetries of charged pion electroproductions are presented. [ABSTRACT FROM AUTHOR]

Published
2009
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12. Overview of Dynamic Models for γN → Δ.

Author

Drechsel, D. and Tiator, L.

Subjects
*PIONS, *NUCLEAR particle research, *NUCLEAR excitation, *MAGNETIC dipoles, *FIELD theory (Physics), *ELECTROMAGNETIC theory, *PHYSICS research
Abstract

We present an overview of dynamic and related models for pion electroproduction on the nucleon due to Δ(1232) excitation. The electromagnetic multipoles and their ratios obtained from these models and from effective field theories are compared, and the existing contradictory results for the pion cloud effects are discussed. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2007
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13. Nucleon Resonance Excitation with Virtual Photons.

Author

Tiator, L. and Kamalov, S.

Subjects
*HELICITY of nuclear particles, *NUCLEAR magnetic resonance, *PHOTONS, *HARMONIC analysis (Mathematics), *FORM factor (Nuclear physics), *PHYSICS research, PION spectra
Abstract

The unitary isobar model MAID is used for a partial wave analysis of pion photoproduction and electroproduction data on the nucleon. In particular we have taken emphasis on the region of the Δ(1232) resonance and have separated the resonance and background amplitudes with the K-matrix approach. This leads to electromagnetic properties of the dressed Δ resonance, where all multipole amplitudes become purely imaginary and all form factors and helicity amplitudes become purely real at the K-matrix pole of W = MΔ = 1232 MeV. The REM = E2/M1 and RSM = C2/M1 ratios of the quadrupole excitation are compared to recent data analysis of different groups. The REM ratio of MAID2005 agrees very well with the data and has a linear behavior over the whole experimentally explored Q2 region with a small positive slope that predicts a zero crossing around 3.5 GeV2. The recent RSM data for Q2 < 0.2 GeV2 indicate a qualitative change in the shape of the ratio which can be explained by the impact of the Siegert theorem at pseudothreshold (Q2 = -0.086GeV2) in the unphysical region. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2007
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14. Evaluation of fully integrated γ p → ππ p cross sections in the resonance region at photon virtualities 5 < Q < 12 GeV.

Author

Burkert, V., Golovatch, E., Isupov, E., Ishkhanov, B., Mokeev, V., Petrun'kin, G., Skorodumina, J., and Fedotov, G.

Abstract

Evaluation of fully integrated double pion electroproduction cross sections of protons was carried out at 1.4 < W < 2.0 GeV, 5 < Q < 12 GeV. The cross-section evaluation was obtained from an approach based on extrapolation of the double pion component of inclusive structure functions F and F from photon virtualities Q < 5 GeV towards 5 < Q < 12 GeV. Q-parameterization compatible with restrictions from the Operator Product Expansion was used to conduct the extrapolation. The results will be used to extract double pion electroproduction cross sections of protons in future experiments with the new CLAS12 detector. [ABSTRACT FROM AUTHOR]

Published
2014
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15. The Δ(1232) -resonance in chiral effective field theory

Author

Pascalutsa, Vladimir

Subjects
*PARTICLES (Nuclear physics), *NUCLEAR physics, *COLLISIONS (Nuclear physics), *CP violation
Abstract

Abstract: The problem of formulating the baryon chiral perturbation theory (BχPT) in the presence of a light resonance, such as the the lightest nucleon resonance, is discussed. It is shown how to extend the power counting of BχPT to correctly account for the resonant contributions. Recent applications of the resulting chiral effective field theory to the description of pion production reactions in the -resonance region are briefly reviewed. [Copyright &y& Elsevier]

Published
2008
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16. The exclusive reaction of pion quasi-elastic knockout from nucleon p(e, e′ π)B to various states of the final baryon-spectator B and the quark models for the pion cloud of nucleon.

Author

Neudatchin, Vladimir, Obukhovsky, Igor, Sviridova, Ludmila, and Yudin, Nikolai

Abstract

The pion momentum distributions (MDs) in four channels of virtual decay p→B+π, B = N, Δ, N 1/2-(1535), N 1/2+(1440) are calculated in two models, the microscopic model of 3 P 0 scalar q−q fluctuation with the pion as a composite q−q-system and the chiral semi-microscopic model of πq interaction with the pion as a structureless Goldstone boson. The results of the above models are similar for the baryon states B = N, Δ, N 1/2-(1535) but are rather different for the Roper resonance N 1/2+(1440) which corresponds to excitation of two oscillator quanta in the nucleon. The experimental investigation of pion MDs by means of the reaction of quasi-elastic knockout of pion by an electron of a few GeV energy p(e, e′ π)B may be very suitable for Jefferson Laboratory, Virginia (JLab). [ABSTRACT FROM AUTHOR]

Published
2004
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17. Near threshold neutral pion electroproduction on deuterium in chiral perturbation theory

Author

Krebs, H., Bernard, V., and Meißner, Ulf-G.

Subjects
*DEUTERONS, *PION production, *PERTURBATION theory
Abstract

Near threshold neutral pion electroproduction on the deuteron is studied in the framework of baryon chiral perturbation theory at next-to-leading order in the chiral expansion. We develop the multipole decomposition for pion production off spin-1 particles appropriate for the threshold region. The existing data at photon virtuality k2=−0.1 GeV2 can be described satisfactorily. Furthermore, the prediction for the S-wave multipole Ed at the photon point is in good agreement with the data. [Copyright &y& Elsevier]

Published
2003
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18. Self energies of the pion and the Δ isobar from the 3He(e,e′π+)3H reaction.

Author

Kohl, M., Bartsch, P., Baumann, D., Bermuth, J., Böhm, R., Bohinc, K., Derber, S., Ding, M., Distler, M.O., Ewald, I., Friedrich, J., Friedrich, J. M., Jennewein, P., Kahrau, M., Kamalov, S. S., Kozlov, A., Krygier, K. W., Kuss, M., Liesenfeld, A., and Merkel, H.

Subjects
*PIONS, *RESONANCE
Abstract

In a kinematically complete experiment at the Mainz microtron MAMI, pion angular distributions of the 3He(e,e′π+)3H reaction have been measured in the excitation region of the Δ resonance to determine the longitudinal (L), transverse (T), and the LT interference part of the differential cross section. The data are described only after introducing self-energy modifications of the pion and Δ-isobar propagators. Using Chiral Perturbation Theory (ChPT) to extrapolate the pion self energy as inferred from the measurement on the mass shell, we deduce a reduction of the π+ mass of Δmπ+ =–1.7+1.7–2.1 MeV/c2 in the neutron-rich nuclear medium at a density of 𝜌=0.057+0.085–0.057 fm–3.Our data are consistent with the Δ self energy determined from measurements of π0 photoproduction from 4He and heavier nuclei. [Copyright &y& Elsevier]

Published
2002
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19. Electroexcitation of the Δ+(1232) at low momentum transfer

Author

V. Bellini, C.M. Camacho, E. Schulte, H. Albataineh, J. W. Watson, M. Huang, M. Hashemi Shabestari, J. Sjoegren, C. Gu, Simon Širca, F. Garibaldi, I. Yaron, L. Selvy, M. Khandaker, V. A. Punjabi, T. Holmstrom, E. Fuchey, B. D. Anderson, M. Defurne, W. Tireman, D. J. Margaziotis, R. A. Lindgren, Or Hen, J. P. Chen, I. Korover, E. Piasetzky, Z. E. Meziani, A. Blomberg, H. Baghdasaryan, Olfred Hansen, K. Chirapatpimol, J. R. M. Annand, Juliette Mammei, A. Polychronopoulou, Salvatore Frullani, M. Posik, N. Muangma, X. Zhan, S. K. Phillips, John Arrington, X. Bai, J. Leckey, D. Flay, Nikos Sparveris, Ping Zhu, B. Zhao, Guy Ron, David Hamilton, W. B. Yan, A. Kelleher, X. Zheng, N. Kalantarians, R. Shneor, S. Riordan, Abdurahim Rakhman, A. Saha, Kalyan Allada, Vincent Sulkosky, Z. W. Zhao, Z. Ye, E. Long, Xin Qian, R. Subedi, D. G. Meekins, Bogdan Wojtsekhowski, B. E. Norum, J. LeRose, R. De Leo, M. Mihovilovič, A. Martí Jiménez-Argüello, E. Cisbani, S. Iqbal, M. M. Dalton, W. U. Boeglin, Chunhui Chen, H. Kang, A. Camsonne, Nuruzzaman, Michael Paolone, C. Hanretty, D. Anez, N. Fomin, Shalev Gilad, K. A. Aniol, T. Averett, Wouter Deconinck, Ishay Pomerantz, Z. Ahmed, A. J. Sarty, Fatiha Benmokhtar, D. Wang, S. Beck, Ronald Gilman, Douglas Higinbotham, K. Pan, Yiyang Zhang, A. Beck, Jie Zhang, M. Friend, P. E. Reimer, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Ecole Centrale Paris, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Angular momentum, Nuclear and High Energy Physics, High Energy Physics::Lattice, Nuclear Theory, Constituent quark, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nucleon deformation, 01 natural sciences, 7. Clean energy, Atomic, Nuclear physics, Pion, Particle and Plasma Physics, 0103 physical sciences, Coulomb, Effective field theory, Nuclear, CMR, 010306 general physics, Nuclear Experiment, Mathematical Physics, Physics, 010308 nuclear & particles physics, Momentum transfer, Pion electroproduction, Molecular, Nuclear & Particles Physics, lcsh:QC1-999, Quantum electrodynamics, Quadrupole, Nucleon, Astronomical and Space Sciences, lcsh:Physics
Abstract

International audience; We report on new p(e,e′p)π∘p(e,e′p)π∘ measurements at the Δ+(1232)Δ+(1232) resonance at the low momentum transfer region, where the mesonic cloud dynamics is predicted to be dominant and rapidly changing, offering a test bed for chiral effective field theory calculations. The new data explore the Q2Q2 dependence of the resonant quadrupole amplitudes and for the first time indicate that the Electric and the Coulomb quadrupole amplitudes converge as Q2→0Q2→0. The measurements of the Coulomb quadrupole amplitude have been extended to the lowest momentum transfer ever reached, and suggest that more than half of its magnitude is attributed to the mesonic cloud in this region. The new data disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations that include pion cloud effects, chiral effective field theory and lattice calculations. The measurements indicate that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements.

Published
2016

20. Effect of Omega(782) resonance on the response functions for d(e,e’π+)nn reaction

Author

Tammam, M., Mahmoud, Z. M. M., Koubisy, M. S. I., Tammam, M., Mahmoud, Z. M. M., and Koubisy, M. S. I.

Abstract

In the present work we study the effect of the Omega ( ω(782) ) resonance on the response functions for the incoherent positive pion electroproduction on the deuteron at different values of the squaredfour-momentum transfers (Q 2) and the virtual photon lab energy ( klab0). The study is carried out in the impulse approximation (IA), i.e. the final state interactions are neglected. The elementary amplitude for pion electroproduction is taken from the MAID-2007 model. The effect seems to be very small and slightly increases with increasing virtual photon lab energy. © 2018. All Rights Reserved.

Published
2018

21. Effect of Omega(782) resonance on the response functions for d(e,e’π+)nn reaction

Author

Mahmoud Tammam, Mohamed S. I. Koubisy, and Zakaria M. M. Mahmoud

Subjects
Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), Materials Science (miscellaneous), Nuclear Theory, Omega, the impulse approximation (IA), Nuclear magnetic resonance, the ω(782) resonance, THE Ω(782) RESONANCE, INVARIANT AMPLITUDES, Nuclear Experiment, PION ELECTROPRODUCTION, Physics, Radiation, Resonance, THE IMPULSE APPROXIMATION (IA), CGLN AMPLITUDES, General Medicine, Condensed Matter Physics, lcsh:QC1-999, pion electroproduction, invariant amplitudes, structure functions, STRUCTURE FUNCTIONS, lcsh:Physics, CGLN amplitudes
Abstract

In the present work we study the effect of the Omega ( ω(782) ) resonance on the response functions for the incoherent positive pion electroproduction on the deuteron at different values of the squaredfour-momentum transfers (Q 2) and the virtual photon lab energy ( klab0). The study is carried out in the impulse approximation (IA), i.e. the final state interactions are neglected. The elementary amplitude for pion electroproduction is taken from the MAID-2007 model. The effect seems to be very small and slightly increases with increasing virtual photon lab energy. © 2018. All Rights Reserved.

Published
2018

24. Electroexcitation of the Δ+(1232) at low momentum transfer

Subjects
High Energy Physics::Lattice, Pion electroproduction, CMR, Nucleon deformation
Abstract

© 2016 The Authors We report on new measurements at the resonance at the low momentum transfer region, where the mesonic cloud dynamics is predicted to be dominant and rapidly changing, offering a test bed for chiral effective field theory calculations. The new data explore the dependence of the resonant quadrupole amplitudes and for the first time indicate that the Electric and the Coulomb quadrupole amplitudes converge as. The measurements of the Coulomb quadrupole amplitude have been extended to the lowest momentum transfer ever reached, and suggest that more than half of its magnitude is attributed to the mesonic cloud in this region. The new data disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations that include pion cloud effects, chiral effective field theory and lattice calculations. The measurements indicate that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements.

Published
2016
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25. Precise measurements of beam spin asymmetries in semi-inclusive π0 production

Author

J. McAndrew, E. De Sanctis, E. Voutier, Michael Wood, K. Hafidi, Y. Prok, M. Aghasyan, D. I. Sober, S. Strauch, S. S. Stepanyan, D. P. Watts, R. Dupre, P. Eugenio, H. Egiyan, D. Keller, N. D. Kvaltine, F. Sabatié, M. Battaglieri, W. Gohn, M. Taiuti, S. Tkachenko, L. Guo, M. Khandaker, G. E. Dodge, H. Y. Lu, M. Y. Gabrielyan, D. Adikaram, M. Guidal, H. Avakian, M. Anghinolfi, E. Munevar, M. Holtrop, R. De Vita, Victor Mokeev, H. Seraydaryan, G. Rosner, C. E. Taylor, I. Niculescu, N. Guler, M. Ungaro, Y. G. Sharabian, A. Daniel, P. Nadel-Turonski, Luciano Pappalardo, W. J. Briscoe, V. Crede, S. Anefalos Pereira, D. Schott, J. P. Ball, S. Chandavar, D. S. Carman, A. M. Micherdzinska, E. Pasyuk, V. Kuznetsov, E. Seder, E. Golovatch, A. El Alaoui, H. Voskanyan, Y. Ilieva, A. I. Ostrovidov, K. Park, M. J. Amaryan, E. L. Isupov, Z. W. Zhao, N. Gevorgyan, K. Joo, George Davey Smith, D. G. Ireland, R. A. Schumacher, A. Ni, Sergey Kuleshov, S. E. Kuhn, S. Procureur, L. Graham, C. Djalali, V. P. Kubarovsky, B. McKinnon, C. E. Hyde, O. Pogorelko, Volker D. Burkert, A. S. Biselli, S. Bültmann, S. Park, B. Guegan, R. W. Gothe, Lorenzo Zana, S. Stepanyan, S. Fegan, P. Rossi, D. Branford, H. S. Jo, K. L. Giovanetti, Avraham Klein, M. Mirazita, I. I. Strakovsky, P. Khetarpal, C. Salgado, A. Fradi, S. Niccolai, A. Deur, W. Kim, Larry Weinstein, V. Batourine, Martin K. Mayer, P. L. Cole, N. Dashyan, G. Niculescu, H. Moutarde, B. Moreno, M. S. Saini, P. Stoler, K. Livingston, D. Doughty, H. Baghdasaryan, Gerard Gilfoyle, M. Contalbrigo, R. Dickson, Jie Zhang, G. Ricco, I. Bedlinskiy, N. Markov, B. Dey, R. Paremuzyan, M. Paolone, Friedrich Klein, S. Pisano, D. Protopopescu, Brian Raue, S. Pozdniakov, M. Garçon, K. Hicks, A. Kim, D. Rimal, W. Tang, M. Osipenko, B. Zhao, S. S. Jawalkar, I. J. D. MacGregor, D. Hasch, E. Phelps, D. G. Jenkins, F. X. Girod, A. DʼAngelo, J. W. Price, M. Ripani, C. Hanretty, J. T. Goetz, R. P. Bennett, Latifa Elouadrhiri, C. A. Meyer, G. V. Fedotov, D. P. Weygand, K. A. Griffioen, P. Collins, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear and High Energy Physics, Angular momentum, Particle physics, DEEP-INELASTIC SCATTERING, FINAL-STATE INTERACTIONS, PION ELECTROPRODUCTION, PARTON DISTRIBUTIONS, DRELL-YAN, LEPTOPRODUCTION, DEPENDENCE, Meson, media_common.quotation_subject, Nuclear Theory, Inelastic scattering, 01 natural sciences, Asymmetry, Settore FIS/04 - Fisica Nucleare e Subnucleare, High Energy Physics - Experiment, Nuclear physics, Pion, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment, 010306 general physics, QC, media_common, Physics, 010308 nuclear & particles physics, Deep inelastic scattering, Amplitude, Physics::Accelerator Physics, High Energy Physics::Experiment, Lepton
Abstract

We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial $\sin \phi_h$ amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle $\phi_h$ of the produced neutral pion. The dependence of this amplitude on Bjorken $x$ and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations., Comment: to be submitted PLB

Published
2011

26. Exclusive π0 electroproduction at W>2 GeV with CLAS

Author

Bedlinskiy, I., Kubarovsky, V., Niccolai, S., Stoler, P., Adhikari, K. P., Anderson, M. D., Pereira, S. Anefalos, Avakian, H., Ball, J., Baltzell, N. A., Battaglieri, M., Batourine, V., Biselli, A. S., Boiarinov, S., Bono, J., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Colaneri, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Doughty, D., Dupre, R., Egiyan, H., El Alaoui, A., El Fassi, L., Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Fleming, J. A., Forest, T. A., Garillon, B., Garcon, M., Gavalian, G., Gevorgyan, N., Ghandilyan, Y., Watts, D., and Zana, L.

Subjects
TRANSVERSITY, PARTON DISTRIBUTIONS, High Energy Physics::Experiment, Nuclear Experiment, PION ELECTROPRODUCTION, MESONS, SYSTEM
Abstract

Exclusive neutral-pion electroproduction (ep→e′p′π0) was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections d4σ/dtdQ2dxBdϕπ and structure functions σT+εσL,σTT, and σLT as functions of t were obtained over a wide range of Q2 and xB. The data are compared with Regge and handbag theoretical calculations. Analyses in both frameworks find that a large dominance of transverse processes is necessary to explain the experimental results. For the Regge analysis it is found that the inclusion of vector meson rescattering processes is necessary to bring the magnitude of the calculated and measured structure functions into rough agreement. In the handbag framework, there are two independent calculations, both of which appear to roughly explain the magnitude of the structure functions in terms of transversity generalized parton distributions.

Published
2014

27. Exclusive pi(0) electroproduction at W > 2 GeV with CLAS

Author

Bedlinskiy, I, Kubarovsky, V, Niccolai, S, Stoler, P, Adhikari, K, Anderson, M, Pereira, S, Avakian, H, Ball, J, Baltzell, N, Battaglieri, M, Batourine, V, Biselli, A, Boiarinov, S, Bono, J, Briscoe, W, Brooks, W, Burkert, V, Carman, D, Celentano, A, Chandavar, S, Colaneri, L, Cole, P, Contalbrigo, M, Cortes, O, Crede, V, D'Angelo, A, Dashyan, N, De Vita, R, De Sanctis, E, Deur, A, Djalali, C, Doughty, D, Dupre, R, Egiyan, H, El Alaoui, A, El Fassi, L, Elouadrhiri, L, Eugenio, P, Fedotov, G, Fegan, S, Fleming, J, Forest, T, Garillon, B, Garcon, M, Gavalian, G, Gevorgyan, N, Ghandilyan, Y, Gilfoyle, G, Giovanetti, K, Girod, F, Golovatch, E, Gothe, R, Griffioen, K, Guegan, B, Guidal, M, Guo, L, Hafidi, K, Hakobyan, H, Harrison, N, Hattawy, M, Hicks, K, Holtrop, M, Ireland, D, Ishkhanov, B, Isupov, E, Jenkins, D, Jo, H, Joo, K, Keller, D, Khandaker, M, Kim, A, Kim, W, Klein, A, Klein, F, Koirala, S, Kuhn, S, Kuleshov, S, Lenisa, P, Levine, W, Livingston, K, Lu, H, Macgregor, I, Markov, N, Mayer, M, Mckinnon, B, Mirazita, M, Mokeev, V, Montgomery, R, Moody, C, Moutarde, H, Movsisyan, A, Camacho, C, Nadel Turonski, P, Niculescu, I, Osipenko, M, Ostrovidov, A, Pappalardo, L, Park, K, Park, S, Pasyuk, E, Phelps, E, Phelps, W, Phillips, J, Pisano, S, Pogorelko, O, Price, J, Prok, Y, Protopopescu, D, Procureur, S, Puckett, A, Raue, B, Ripani, M, Ritchie, B, Rizzo, A, Rossi, P, Roy, P, Sabatie, F, Salgado, C, Schott, D, Schumacher, R, Seder, E, Senderovich, I, Sharabian, Y, Simonyan, A, Smith, G, Sober, D, Sokhan, D, Stepanyan, S, Strauch, S, Sytnik, V, Tang, W, Tian, Y, Ungaro, M, Vlassov, A, Voskanyan, H, Voutier, E, Walford, N, Watts, D, Wei, X, Weinstein, L, Yurov, M, Zachariou, N, Zana, L, Zhang, J, Zhao, Z, and Zonta, I

Subjects
TRANSVERSITY, PARTON DISTRIBUTIONS, PION ELECTROPRODUCTION, MESONS, SYSTEM, Settore FIS/04 - Fisica Nucleare e Subnucleare
Published
2014

28. Measurement of Exclusive π0 Electroproduction Structure Functions and their Relationship to Transverse Generalized Parton Distributions

Author

Bedlinskiy, I., Kubarovsky, V., Niccolai, S., Stoler, P., Adhikari, K. P., Aghasyan, M., Amaryan, M. J., Anghinolfi, M., Avakian, H., Baghdasaryan, H., Ball, J., Baltzell, N. A., Battaglieri, M., Bennett, R. P., Biselli, A. S., Bookwalter, C., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Contalbrigo, M., Crede, V., D'Angelo, A., Daniel, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Doughty, D., Dupre, R., Egiyan, H., El Alaoui, A., El Fassi, L., Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Fleming, J. A., Forest, T. A., Fradi, A., Garcon, M., Gevorgyan, N., Giovanetti, K. L., Watts, D. P., and Zhang, J.

Subjects
PION ELECTROPRODUCTION
Abstract

Exclusive pi(0) electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q(2), x(B), t, and phi(pi), in the Q(2) range from 1.0 to 4.6 GeV2, -t up to 2 GeV2, and x(B) from 0.1 to 0.58. Structure functions sigma(T) + epsilon sigma(L), sigma(TT), and sigma(LT) were extracted as functions of t for each of 17 combinations of Q(2) and x(B). The data were compared directly with two handbag-based calculations including both longitudinal and transversity generalized parton distributions (GPDs). Inclusion of only longitudinal GPDs very strongly underestimates sigma(T) + epsilon sigma(L) and fails to account for sigma(TT) and sigma(LT), while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity-flip and helicity nonflip processes. The results confirm that exclusive pi(0) electroproduction offers direct experimental access to the transversity GPDs.

Published
2012

29. Measurement of exclusive π(0) electroproduction structure functions and their relationship to transverse generalized parton distributions

Author

Bedlinskiy, I, Kubarovsky, V, Niccolai, S, Stoler, P, Adhikari, K, Aghasyan, M, Amaryan, M, Anghinolfi, M, Avakian, H, Baghdasaryan, H, Ball, J, Baltzell, N, Battaglieri, M, Bennett, R, Biselli, A, Bookwalter, C, Boiarinov, S, Briscoe, W, Brooks, W, Burkert, V, Carman, D, Celentano, A, Chandavar, S, Charles, G, Contalbrigo, M, Crede, V, D'Angelo, A, Daniel, A, Dashyan, N, De Vita, R, De Sanctis, E, Deur, A, Djalali, C, Doughty, D, Dupre, R, Egiyan, H, El Alaoui, A, El Fassi, L, Elouadrhiri, L, Eugenio, P, Fedotov, G, Fegan, S, Fleming, J, Forest, T, Fradi, A, Garcon, M, Gevorgyan, N, Giovanetti, K, Girod, F, Gohn, W, Gothe, R, Graham, L, Griffioen, K, Guegan, B, Guidal, M, Guo, L, Hafidi, K, Hakobyan, H, Hanretty, C, Heddle, D, Hicks, K, Holtrop, M, Ilieva, Y, Ireland, D, Ishkhanov, B, Isupov, E, Jo, H, Joo, K, Keller, D, Khandaker, M, Khetarpal, P, Kim, A, Kim, W, Klein, F, Koirala, S, Kubarovsky, A, Kuhn, S, Kuleshov, S, Kvaltine, N, Livingston, K, Lu, H, Macgregor, I, Mao, Y, Markov, N, Martinez, D, Mayer, M, Mckinnon, B, Meyer, C, Mineeva, T, Mirazita, M, Mokeev, V, Moutarde, H, Munevar, E, Camacho, C, Nadel Turonski, P, Niculescu, G, Niculescu, I, Osipenko, M, Ostrovidov, A, Pappalardo, L, Paremuzyan, R, Park, K, Park, S, Pasyuk, E, Pereira, S, Phelps, E, Pisano, S, Pogorelko, O, Pozdniakov, S, Price, J, Procureur, S, Prok, Y, Protopopescu, D, Puckett, A, Raue, B, Ricco, G, Rimal, D, Ripani, M, Rosner, G, Rossi, P, Sabatie, F, Saini, M, Salgado, C, Saylor, N, Schott, D, Schumacher, R, Seder, E, Seraydaryan, H, Sharabian, Y, Smith, G, Sober, D, Sokhan, D, Stepanyan, S, Strauch, S, Taiuti, M, Tang, W, Taylor, C, Tian, Y, Tkachenko, S, Ungaro, M, Vineyard, M, Vlassov, A, Voskanyan, H, Voutier, E, Walford, N, Watts, D, Weinstein, L, Weygand, D, Wood, M, Zachariou, N, Zhang, J, Zhao, Z, and Zonta, I

Subjects
PION ELECTROPRODUCTION, Settore FIS/04 - Fisica Nucleare e Subnucleare
Abstract

Exclusive π(0) electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q(2), x(B), t, and ϕ(π), in the Q(2) range from 1.0 to 4.6 GeV(2), -t up to 2 GeV(2), and x(B) from 0.1 to 0.58. Structure functions σ(T)+ϵσ(L), σ(TT), and σ(LT) were extracted as functions of t for each of 17 combinations of Q(2) and x(B). The data were compared directly with two handbag-based calculations including both longitudinal and transversity generalized parton distributions (GPDs). Inclusion of only longitudinal GPDs very strongly underestimates σ(T)+ϵσ(L) and fails to account for σ(TT) and σ(LT), while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity-flip and helicity nonflip processes. The results confirm that exclusive π(0) electroproduction offers direct experimental access to the transversity GPDs.

Published
2012

30. Measurement of the generalized form factors near threshold via gamma* p -> n pi(+) at high Q(2)

Author

Park, K., Gothe, R. W., Adhikari, K. P., Adikaram, D., Anghinolfi, M., Baghdasaryan, H., Ball, J., Battaglieri, M., Batourine, V., Bedlinskiy, I., Bennett, R. P., Biselli, A. S., Bookwalter, C., Boiarinov, S., Branford, D., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Cole, P. L., Contalbrigo, Marco, Crede, V., D'Angelo, A., Daniel, A., Dashyan, N., Vita, R. D., Sanctis, E. D., Deur, A., Djalali, C., Doughty, D., Dupre, R., Alaoui, A. E., Fassi, L. E., Eugenio, P., Fedotov, G., Fradi, A., Gabrielyan, M. Y., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Gohn, W., Golovatch, E., Graham, L., Griffioen, K. A., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., Hanretty, C., Heddle, D., Hicks, K., Holtrop, M., Hyde, C. E., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., H. S., Jo, Joo, K., Kalantarians, N., Khandaker, M., Khetarpal, P., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, A., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Kvaltine, N. D., Livingston, K., H. Y., Lu, I. J. D., Markov, N., Mayer, M., Mckinnon, B., Mestayer, M. D., Meyer, C. A., Mineeva, T., Mirazita, M., Mokeev, V., Moutarde, H., Munevar, E., Nadel Turonski, P., Nasseripour, R., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paolone, M., Pappalardo, Luciano Libero, Paremuzyan, R., Park, S., Pereira, S. A., Phelps, E., Pisano, S., Pogorelko, O., Pozdniakov, S., Price, J. W., Procureur, S., Prok, Y., Ricco, G., Rimal, D., Ripani, M., Ritchie, B. G., Rosner, G., Rossi, P., Sabatie, F., Saini, M. S., Salgado, C., Schott, D., Schumacher, R. A., Seraydaryan, H., Sharabian, Y. G., Smith, E. S., Smith, G. D., Sober, D. I., Sokhan, D., Stepanyan, S. S., Stepanyan, S., Stoler, P., Strakovsky, I. I., Strauch, S., Taiuti, M., Tang, W., Taylor, C. E., Tian, Y., Tkachenko, S., Trivedi, A., Ungaro, M., Vernarsky, B., Vlassov, A. V., Voutier, E., Watts, D. P., Weygand, D. P., Wood, M. H., Zachariou, N., Zhao, B., and Zhao, Z. W.

Subjects
QUANTUM CHROMODYNAMICS, PI-0, PION ELECTROPRODUCTION, NUCLEONS, PROTON, PHOTOPRODUCTION, Settore FIS/04 - Fisica Nucleare e Subnucleare
Published
2012

31. Transverse Momentum Dependent Parton Distribution/Fragmentation Functions at an Electron-Ion Collider

Author

M. Contalbrigo, Matthias Burkardt, J. C. Peng, Jian-Wei Qiu, Minghui Liu, Xin Qian, Daniël Boer, Dipangkar Dutta, Q. J. Ye, Zhong-Bo Kang, Peter Schweitzer, Z. T. Liang, H. Avakian, P. Rossi, X. Zhan, G. Laskaris, A. Prokudin, R. D. McKeown, Leonard Gamberg, J. Soffer, J.P. Chen, N. C. R. Makins, Cynthia Keppel, J. Huang, Y.-H. Zhang, Yujie Qiang, Bernhard Musch, E. Cisbani, J. Zhou, Feng Yuan, Q. Ye, W. Zheng, Donald Crabb, Franco Bradamante, Vincent Sulkosky, Mauro Anselmino, Yi Wang, Zein-Eddine Meziani, Andreas Metz, Haiyan Gao, D. Hasch, M. Huang, and Bo-Wen Xiao

Subjects
Quark, Particle physics, Nuclear and High Energy Physics, media_common.quotation_subject, FRAGMENTATION FUNCTIONS, Hadron, Nuclear Theory, FOS: Physical sciences, Parton, DRELL-YAN PROCESSES, Asymmetry, law.invention, High Energy Physics - Experiment, DEEP-INELASTIC SCATTERING, HARD-SCATTERING, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), law, Nuclear Experiment (nucl-ex), Collider, PION ELECTROPRODUCTION, Nuclear Experiment, media_common, Spin-½, Physics, FINAL-STATE INTERACTIONS, High Energy Physics::Phenomenology, SINGLE-SPIN, AZIMUTHAL ASYMMETRIES, Gluon, High Energy Physics - Phenomenology, SPIN PRODUCTION ASYMMETRIES, High Energy Physics::Experiment, HADRON STRUCTURE, Nucleon
Abstract

We present a summary of a recent workshop held at Duke University on Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions. The transverse momentum dependent parton distribution functions (TMDs), parton-to-hadron fragmentation functions, and multi-parton correlation functions, were discussed extensively at the Duke workshop. In this paper, we summarize first the theoretical issues concerning the study of partonic structure of hadrons at a future electron-ion collider (EIC) with emphasis on the TMDs. We then present simulation results on experimental studies of TMDs through measurements of single spin asymmetries (SSA) from semi-inclusive deep-inelastic scattering (SIDIS) processes with an EIC, and discuss the requirement of the detector for SIDIS measurements. The dynamics of parton correlations in the nucleon is further explored via a study of SSA in D (`D) production at large transverse momenta with the aim of accessing the unexplored tri-gluon correlation functions. The workshop participants identified the SSA measurements in SIDIS as a golden program to study TMDs in both the sea and valence quark regions and to study the role of gluons, with the Sivers asymmetry measurements as examples. Such measurements will lead to major advancement in our understanding of TMDs in the valence quark region, and more importantly also allow for the investigation of TMDs in the sea quark region along with a study of their evolution., Comment: 44 pages 23 figures, summary of Duke EIC workshop on TMDs accepted by EPJA

Published
2011
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32. Measurement of semi-inclusive pi+ electroproduction off the proton

Author

L. C. Smith, E. Munevar, M. H. Wood, Y. Ilieva, M. E. McCracken, P. Nadel-Turonski, E. Wolin, R. J. Feuerbach, B. S. Ishkhanov, G. E. Dodge, Tsutomu Mibe, P. V. Degtyarenko, J. P. Ball, Y. Prok, D. S. Carman, M. R. Niroula, Alexander Ilyichev, O. P. Dzyubak, I. I. Strakovsky, Paolo Rossi, K. S. Egiyan, P. L. Cole, Z. W. Zhao, J. Lachniet, A. Tkabladze, W. Kim, I. Niculescu, R. A. Niyazov, D. G. Crabb, R. S. Hakobyan, L. El Fassi, Elton Smith, A. Deur, G. Niculescu, R. De Masi, B. L. Berman, J. Kuhn, B. McKinnon, W. K. Brooks, G. P. Gilfoyle, K. Livingston, R. Fatemi, N. Markov, A. V. Vlassov, J. P. Cummings, M. Anghinolfi, G. Ricco, B. Zhao, D. J. Tedeschi, S. Niccolai, R. Dickson, Ji Li, Y. G. Sharabian, S. Strauch, D. P. Watts, H. Egiyan, L. M. Qin, C. Paterson, L. Zana, D. Branford, J. M. Laget, M. Khandaker, G. Riccardi, N. Hassall, M. Bellis, Cynthia Marie Hadjidakis, R. De Vita, A. I. Ostrovidov, K. A. Griffioen, N. Guler, F. W. Hersman, J. Hardie, C. Butuceanu, M. J. Amaryan, M. Kossov, Shifeng Chen, E. N. Golovach, Volker D. Burkert, A. S. Biselli, Michael Dugger, J. Langheinrich, H. O. Funsten, H. G. Juengst, Luca Trentadue, M. MacCormick, I. Hleiqawi, M. D. Mestayer, C. Djalali, H. Denizli, P. Eugenio, S. Dytman, A. V. Skabelin, S. L. Careccia, I. Popa, P. Coltharp, R. A. Schumacher, P. Mattione, M. Osipenko, S. Barrow, M. Taiuti, A.V. Stavinsky, S. Anefalos Pereira, P. D. Rubin, R. W. Gothe, Laird Kramer, E. L. Isupov, D. Lawrence, D. Sokhan, M. M. Ito, H. Hakobyan, A. Cazes, J. R. Calarco, C. I O Gordon, K. L. Giovanetti, S. Mehrabyan, Alexei V. Klimenko, J. T. Goetz, R. Miskimen, C. Hanretty, G. V. O'Rielly, E. Polli, Michael L. Williams, Larry Weinstein, M. Mirazita, Kalvir S. Dhuga, J. D. Kellie, P. Collins, Friedrich Klein, F. Sabatié, Nikolay Shvedunov, J. J. Melone, V. Sapunenko, Sylvain Bouchigny, S. Bültmann, L. Todor, Barry Ritchie, Dinko Pocanic, Victor Mokeev, Brian Raue, G. Asryan, E. De Sanctis, M. Battaglieri, I. Bedlinskiy, V. A. Drozdov, S. Stepanyan, S. E. Kuhn, N. A. Baltzell, D. Protopopescu, S. Pozdniakov, M. Garçon, M. F. Vineyard, J. Pierce, Avraham Klein, Z. Krahn, N. Dashyan, S. Boiarinov, U. Thoma, D. I. Sober, R. Bradford, N. Kalantarians, Latifa Elouadrhiri, V. Gyurjyan, G. S. Mutchler, D. G. Ireland, V. Crede, N. Baillie, B. B. Niczyporuk, R. C. Minehart, Kei Moriya, S. McAleer, N. Pivnyuk, B. E. Stokes, J. Napolitano, G. S. Adams, J. Zhang, B. M. Preedom, F. X. Girod, L. Blaszczyk, H. Bagdasaryan, J. P. Santoro, C. Tur, C. A. Meyer, L. Guo, M. Ungaro, G. Gavalian, J. Donnelly, S. Tkachenko, D. Heddle, J. Salamanca, N. Benmouna, G. V. Fedotov, M. Ripani, J. W C McNabb, D. Jenkins, R. Nasseripour, S. A. Morrow, K. Joo, Maryam Moteabbed, Bernhard Mecking, K. V. Dharmawardane, A. Yegneswaran, Atilla Gonenc, P. Ambrozewicz, J. W. Price, M. Holtrop, D. P. Weygand, P. Corvisiero, H. S. Jo, Gerald Feldman, Federico A. Ceccopieri, C. Salgado, G. Rosner, M. Guillo, K. Mikhailov, M. Guidal, H. Y. Lu, C. E. Hyde-Wright, P. Stoler, Sergey Kuleshov, M. Bektasoglu, M. Nozar, K. Hicks, S. S. Stepanyan, S. A. Philips, J. Mueller, K. Hafidi, V. S. Serov, K. Park, V. P. Kubarovsky, O. Pogorelko, L. C. Dennis, B. E. Bonner, H. Avakian, W. J. Briscoe, E. Pasyuk, D. Doughty, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CLAS, and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Particle physics, Nuclear and High Energy Physics, Proton, DEEP-INELASTIC-SCATTERING, TARGET FRAGMENTATION REGION, TRANSVERSE-MOMENTUM, PARTON DISTRIBUTIONS, AZIMUTHAL ASYMMETRY, PION ELECTROPRODUCTION, CHARGED HADRONS, HARD PROCESSES, LEADING ORDER, CROSS-SECTION, TARGET FRAGMENTATION REGION, Hadron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Spectral line, Nuclear physics, Pion, Factorization, 0103 physical sciences, 010306 general physics, Nuclear Experiment, PION ELECTROPRODUCTION, Physics, DEEP-INELASTIC-SCATTERING, 010308 nuclear & particles physics, LEADING ORDER, TRANSVERSE-MOMENTUM, Azimuth, Diquark, CHARGED HADRONS, HARD PROCESSES, PARTON DISTRIBUTIONS, Cathode ray, AZIMUTHAL ASYMMETRY, High Energy Physics::Experiment, CROSS-SECTION
Abstract

Semi-inclusive {pi}{sup +} electroproduction on protons has been measured with the CLAS detector at Jefferson Lab. The measurement was performed on a liquid-hydrogen target using a 5.75 GeV electron beam. The complete five-fold differential cross sections were measured over a wide kinematic range including the complete range of azimuthal angles between hadronic and leptonic planes, {phi}, enabling us to separate the {phi}-dependent terms. Our measurements of the {phi}-independent term of the cross section at low Bjorken x were found to be in fairly good agreement with pQCD calculations. Indeed, the conventional current fragmentation calculation can account for almost all of the observed cross section, even at small {pi}{sup +} momentum. The measured center-of-momentum spectra are in qualitative agreement with high-energy data, which suggests a surprising numerical similarity between the spectator diquark fragmentation in the present reaction and the antiquark fragmentation measured in e{sup +}e{sup -} collisions. We have observed that the two {phi}-dependent terms of the cross section are small. Within our precision the cos2{phi} term is compatible with zero, except for the low-z region, and the measured cos{phi} term is much smaller in magnitude than the sum of the Cahn and Berger effects.

Published
2009

33. Twist Three Distribution e(x) : Sum Rules and Equation of Motion Relations

Author

MUKHERJEE, A

Subjects
High Energy Physics - Phenomenology, Pion Electroproduction, Spin, High Energy Physics - Phenomenology (hep-ph), Light-Front Qcd, Parton Distributions, Transverse Momentum Dependent Distribution, High Energy Physics::Lattice, High Energy Physics::Phenomenology, Twist Three, Fragmentation Functions, FOS: Physical sciences, Sum Rule
Abstract

We investigate the twist three distribution function $e(x)$ in light-front Hamiltonian perturbation theory. In light-front gauge, by eliminating the constrained field, we find a mass term, an intrinsic transverse momentum dependent term and a 'genuine twist three' quark-gluon interaction term in the operator. The equation of motion relation, moment relation and the sum rules are satisfied for a quark at one loop. We compare the results with other model calculations., Comment: genuine twist three part added, conclusions on sum rules and equation of motion unchanged

Published
2009
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34. Recoil polarization for neutral pion electroproduction near the delta resonance

Author

Kelly (for the Jefferson Laboratory Hall A Collaboration), James J.

Subjects
pion electroproduction, recoil polarization, delta resonance, multipole analysis
Abstract

We have measured angular distributions for recoil polarization in the p(~e, e ′ ~p)π 0 reaction at Q2 ≈ 1 (GeV/c) 2 with 1.16 ≤ W ≤ 1.36 GeV across the ∆ resonance. The data are compared with representative models and a truncated Legendre analysis is compared with a more general multipole analysis., Mjerili smo kutne raspodjele polarizacije u odboju u reakciji p(~e, e ′ ~p)π 0 za Q2 ≈ 1 (GeV/c) 2 i 1.16 ≤ W ≤ 1.36 GeV u području ∆ rezonancije. Podaci se uspoređuju s odabranim modelima, a krnja Legendreova analiza uspoređuje se s općenitijom multipolnom analizom.

Published
2004

35. Recoil polarization measurements for neutral pion electroproduction at Q2=1(GeV/c)2 near the Δ resonance

Author

Kelly, J.J., Kelly, J.J., Gayou, O., Roche, R.E., Chai, Z., Jones, M.K., Sarty, A.J., Frullani, S., Aniol, K., Beise, E.J., Benmokhtar, F., Bertozzi, W., Boeglin, W.U., Botto, T., Brash, E.J., Breuer, H., Brown, E., Burtin, E., Calarco, J.R., Cavata, C., Chang, C.C., Chant, N.S., Chen, J.-P., Coman, M., Crovelli, D., De Leo, R., Dieterich, S., Escoffier, S., Fissum, K.G., Garde, V., Garibaldi, F., Georgakopoulos, S., Gilad, S., Gilman, R., Glashausser, C., Hansen, J.-O., Higinbotham, D.W., Hotta, A., Huber, G.M., Ibrahim, H., Iodice, M., de Jager, C.W., Jiang, X., Kimenko, A., Kozlov, A., Kumbartzki, G., Kuss, M., Lagamba, L., Laveissiere, G., LeRose, J.J., Lindgren, R.A., Liyange, N., Lolos, G.J., Lourie, R.W., Margaziotis, D.J., Marie, F., Markowitz, P., McAleer, S., Meekins, D., Michaels, R., Milbrath, B.D., Mitchell, J., Nappa, J., Neyret, D., Perdrisat, C.F., Potokar, M., Punjabi, V.A., Pussieux, T., Ransome, R.D., Roos, P.G., Rvachev, M., Saha, A., Sirca, S., Suleiman, R., Strauch, S., Templon, J.A., Todor, L., Ulmer, P.E., Urciuoli, G.M., Weinstein, L.B., Wijsooriya, K., Wojtsekhowski, B., Zheng, X., Zhu, L., Jefferson Laboratory E91011 and Hall A Collaborations, Kelly, J.J., Kelly, J.J., Gayou, O., Roche, R.E., Chai, Z., Jones, M.K., Sarty, A.J., Frullani, S., Aniol, K., Beise, E.J., Benmokhtar, F., Bertozzi, W., Boeglin, W.U., Botto, T., Brash, E.J., Breuer, H., Brown, E., Burtin, E., Calarco, J.R., Cavata, C., Chang, C.C., Chant, N.S., Chen, J.-P., Coman, M., Crovelli, D., De Leo, R., Dieterich, S., Escoffier, S., Fissum, K.G., Garde, V., Garibaldi, F., Georgakopoulos, S., Gilad, S., Gilman, R., Glashausser, C., Hansen, J.-O., Higinbotham, D.W., Hotta, A., Huber, G.M., Ibrahim, H., Iodice, M., de Jager, C.W., Jiang, X., Kimenko, A., Kozlov, A., Kumbartzki, G., Kuss, M., Lagamba, L., Laveissiere, G., LeRose, J.J., Lindgren, R.A., Liyange, N., Lolos, G.J., Lourie, R.W., Margaziotis, D.J., Marie, F., Markowitz, P., McAleer, S., Meekins, D., Michaels, R., Milbrath, B.D., Mitchell, J., Nappa, J., Neyret, D., Perdrisat, C.F., Potokar, M., Punjabi, V.A., Pussieux, T., Ransome, R.D., Roos, P.G., Rvachev, M., Saha, A., Sirca, S., Suleiman, R., Strauch, S., Templon, J.A., Todor, L., Ulmer, P.E., Urciuoli, G.M., Weinstein, L.B., Wijsooriya, K., Wojtsekhowski, B., Zheng, X., Zhu, L., and Jefferson Laboratory E91011 and Hall A Collaborations

Abstract

We measured angular distributions of differential cross section, beam analyzing power, and recoil polarization for neutral pion electroproduction at Q2=1.0 (GeV/c)2 in 10 bins of 1.17⩽W⩽1.35 GeV across the Δ resonance. A total of 16 independent response functions were extracted, of which 12 were observed for the first time. Comparisons with recent model calculations show that response functions governed by real parts of interference products are determined relatively well near the physical mass, W=MΔ≈1.232 GeV, but the variation among models is large for response functions governed by imaginary parts, and for both types of response functions, the variation increases rapidly with W>MΔ. We performed a multipole analysis that adjusts suitable subsets of ℓπ⩽2 amplitudes with higher partial waves constrained by baseline models. This analysis provides both real and imaginary parts. The fitted multipole amplitudes are nearly model independent—there is very little sensitivity to the choice of baseline model or truncation scheme. By contrast, truncation errors in the traditional Legendre analysis of N→Δ quadrupole ratios are not negligible. Parabolic fits to the W dependence around MΔ for the multiple analysis gives values for Re(S1+/M1+)=(-6.61±0.18)% and Re(E1+/M1+)=(-2.87±0.19)% for the pπ0 channel at W=1.232 GeV and Q2=1.0 (GeV/c)2 that are distinctly larger than those from the Legendre analysis of the same data. Similarly, the multipole analysis gives Re(S0+/M1+)=(+7.1±0.8)% at W=1.232 GeV, consistent with recent models, while the traditional Legendre analysis gives the opposite sign because its truncation errors are quite severe.

Published
2007

36. Determination of the Pion Charge Form Factor at Q2=1.60 and 2.45 (GeV/c)2

Author

Horn, D.T., Horn, D.T., Aniol, K., Arrington, J., Barret, B., Beise, E.J., Blok, H.P., Boeglin, W., Brash, E.J., Breuer, H., Chang, C.C., Christy, M.E., Ent, R., Gaskell, D., Gibson, E., Holt, R.J., Huber, G.M., Jin, S., Jones, M.K., Keppel, C.E., Kim, W., King, P.M., Kovaltchouk, V., Liu, J., Lolos, G.J., Mack, D.J., Margaziotis, D.J., Markowitz, P., Matsumura, A., Meekins, D., Miyoshi, T., Mkrtchyan, H., Niculescu, I., Okayasu, Y., Pentchev, L., Perdrisat, C., Potterveld, D., Punjabi, V., Reimer, P., Reinhold, J., Roche, J., Roos, P.G., Sarty, A., Smith, G.R., Tadevosyan, V., Tang, L.G., Tvaskis, V., Vidakovic, S., Volmer, J., Vulcan, W., Warren, G., Wood, S.A., Xu, C., X. Zheng, X., Jefferson Lab F_{π} Collaboration, Horn, D.T., Horn, D.T., Aniol, K., Arrington, J., Barret, B., Beise, E.J., Blok, H.P., Boeglin, W., Brash, E.J., Breuer, H., Chang, C.C., Christy, M.E., Ent, R., Gaskell, D., Gibson, E., Holt, R.J., Huber, G.M., Jin, S., Jones, M.K., Keppel, C.E., Kim, W., King, P.M., Kovaltchouk, V., Liu, J., Lolos, G.J., Mack, D.J., Margaziotis, D.J., Markowitz, P., Matsumura, A., Meekins, D., Miyoshi, T., Mkrtchyan, H., Niculescu, I., Okayasu, Y., Pentchev, L., Perdrisat, C., Potterveld, D., Punjabi, V., Reimer, P., Reinhold, J., Roche, J., Roos, P.G., Sarty, A., Smith, G.R., Tadevosyan, V., Tang, L.G., Tvaskis, V., Vidakovic, S., Volmer, J., Vulcan, W., Warren, G., Wood, S.A., Xu, C., X. Zheng, X., and Jefferson Lab F_{π} Collaboration

Abstract

The 1H(e,e′π+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (Fπ) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which Fπ is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction.

Published
2006

37. Near threshold neutral pion electroproduction on deuterium in chiral perturbation theory

Author

H. Krebs, Véronique Bernard, and Ulf-G. Meißner

Subjects
deuteron, Nuclear and High Energy Physics, Particle physics, Chiral perturbation theory, Photon, Nuclear Theory, FOS: Physical sciences, chiral [perturbation theory], Nuclear Theory (nucl-th), High Energy Physics - Phenomenology (hep-ph), Pion, interpretation of experiments [numerical calculations], inelastic scattering [electron deuteron], threshold, ddc:530, Nuclear Experiment, Nuclear theory, chiral perturbation theory, Physics, electroproduction [pi0], inelastic scattering [photon deuteron], effective Lagrangian, multipole [partial wave analysis], energy dependence [channel cross section], Baryon, pion electroproduction, Near threshold, High Energy Physics - Phenomenology, angular dependence [differential cross section], Deuterium, Multipole expansion, polarization [photon]
Abstract

Near threshold neutral pion electroproduction on the deuteron is studied in the framework of baryon chiral perturbation theory at next-to-leading order in the chiral expansion. We develop the multipole decomposition for pion production off spin-1 particles appropriate for the threshold region. The existing data at photon virtuality k^2 = -0.1 GeV^2 can be described satisfactorily. Furthermore, the prediction for the S-wave multipole E_d at the photon point is in good agreement with the data., 27 pp, 15 figs

Published
2002

38. Recoil Polarization for Δ Excitation in Pion Electroproduction

Author

Kelly, J.J., Kelly, J.J., Roche, R.E., Chai, Z., Jones, M.K., Gayou, O., Sarty, A.J., Frullani, S., Aniol, K., Beise, E.J., Benmokhtar, F., Bertozzi, W., Boeglin, W.U., Botto, T., Brash, E.J., Breuer, H., Brown, E., Burtin, E., Calarco, J.R., Cavata, C., Chang, C.C., Chant, N.S., Chen, J.-P., Coman, M., Crovelli, D., De Leo, R., Dieterich, S., Escoffier, S., Fissum, K.G., Garde, V., Garibaldi, F., Georgakopoulus, S., Gilad, S., Gilman, R., Glashausser, C., Hansen, J.-O., Higinbotham, D.W., Hotta, A., Huber, G.M., Ibrahim, H., Iodice, M., de Jager, C.W., Jiang, X., Klimenko, A., Kozlov, A., Kumbartzki, G., Kuss, M., Lagamba, L., Laveissiere, G., LeRose, J.J., Lindgren, R.A., Liyanage, N., Lolos, G.J., Lourie, R.W., Margaziotis, D.J., Marie, F., Markowitz, P., McAleer, S., Meekins, D., Michaels, R., Milbrath, B.D., Mitchell, J., Nappa, J., Neyret, D., Perdrisat, C.F., Potokar, M., Punjabi, V.A., Pussieux, T., Ransome, R.D., Roos, P.G., Rvachev, M., Saha, A., Sirca, S., Suleiman, R., Strauch, S., Templon, J.A., Todor, L., Ulmer, P.E., Urciuoli, G.M., Weinstein, L.B., Wijesooriya, K., Wojtsekhowski, B., Zheng, X., Zhu, L., Jefferson Laboratory E91011 and Hall A Collaborations, Kelly, J.J., Kelly, J.J., Roche, R.E., Chai, Z., Jones, M.K., Gayou, O., Sarty, A.J., Frullani, S., Aniol, K., Beise, E.J., Benmokhtar, F., Bertozzi, W., Boeglin, W.U., Botto, T., Brash, E.J., Breuer, H., Brown, E., Burtin, E., Calarco, J.R., Cavata, C., Chang, C.C., Chant, N.S., Chen, J.-P., Coman, M., Crovelli, D., De Leo, R., Dieterich, S., Escoffier, S., Fissum, K.G., Garde, V., Garibaldi, F., Georgakopoulus, S., Gilad, S., Gilman, R., Glashausser, C., Hansen, J.-O., Higinbotham, D.W., Hotta, A., Huber, G.M., Ibrahim, H., Iodice, M., de Jager, C.W., Jiang, X., Klimenko, A., Kozlov, A., Kumbartzki, G., Kuss, M., Lagamba, L., Laveissiere, G., LeRose, J.J., Lindgren, R.A., Liyanage, N., Lolos, G.J., Lourie, R.W., Margaziotis, D.J., Marie, F., Markowitz, P., McAleer, S., Meekins, D., Michaels, R., Milbrath, B.D., Mitchell, J., Nappa, J., Neyret, D., Perdrisat, C.F., Potokar, M., Punjabi, V.A., Pussieux, T., Ransome, R.D., Roos, P.G., Rvachev, M., Saha, A., Sirca, S., Suleiman, R., Strauch, S., Templon, J.A., Todor, L., Ulmer, P.E., Urciuoli, G.M., Weinstein, L.B., Wijesooriya, K., Wojtsekhowski, B., Zheng, X., Zhu, L., and Jefferson Laboratory E91011 and Hall A Collaborations

Abstract

We measured angular distributions of recoil-polarization response functions for neutral pion electroproduction for W=1.23 GeV at Q2=1.0 (GeV/c)2, obtaining 14 separated response functions plus 2 Rosenbluth combinations; of these, 12 have been observed for the first time. Dynamical models do not describe quantities governed by imaginary parts of interference products well, indicating the need for adjusting magnitudes and phases for nonresonant amplitudes. We performed a nearly model-independent multipole analysis and obtained values for Re (S1+/M1+)=-(6.84±0.15)% and Re (E1+/M1+)=-(2.91±0.19)% that are distinctly different from those from the traditional Legendre analysis based upon M1+ dominance and ℓπ≤1 truncation.

Published
2005

39. Examining pion electroproductin at the CLAS detector

Author

Kleckner, Ian, McFarland, Kevin, Manly, Steven, Kleckner, Ian, McFarland, Kevin, and Manly, Steven

Abstract

Thesis (B.S.)--University of Rochester. Dept. of Physics and Astronomy, 2006., Hydrogen and carbon targets are bombarded by relativistic electrons at the CLAS detector in Jefferson Laboratory in VA. The incident electrons scatter on target nucleons and yield events in the elastic region, resonance region and the deep inelastic region. These regions qualify the different energies and particles that appear in the final state; most notably pions produced in the resonance region. The behavior of pions produced under these conditions is of interest in the field of Neutrino Physics.

40. Examining pion electroproductin at the CLAS detector

Author

Kleckner, Ian, McFarland, Kevin, Manly, Steven, Kleckner, Ian, McFarland, Kevin, and Manly, Steven

Abstract

Thesis (B.S.)--University of Rochester. Dept. of Physics and Astronomy, 2006., Hydrogen and carbon targets are bombarded by relativistic electrons at the CLAS detector in Jefferson Laboratory in VA. The incident electrons scatter on target nucleons and yield events in the elastic region, resonance region and the deep inelastic region. These regions qualify the different energies and particles that appear in the final state; most notably pions produced in the resonance region. The behavior of pions produced under these conditions is of interest in the field of Neutrino Physics.

41. Wide-angle photo- and electroproduction of pions to twist-3 accuracy

Author

K. Passek-Kumerički and P. Kroll

Subjects
Particle physics, High Energy Physics::Lattice, Nuclear Theory, FOS: Physical sciences, Parton, 01 natural sciences, Fock space, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Pion, High Energy Physics - Phenomenology (hep-ph), Factorization, 0103 physical sciences, Gauge theory, Twist, 010306 general physics, Nuclear Experiment, Spin-½, Quantum chromodynamics, Physics, 010308 nuclear & particles physics, QCD, exclusive processes, pion electroproduction, wide-angle, higher-twist, High Energy Physics::Phenomenology, High Energy Physics - Phenomenology, High Energy Physics::Experiment
Abstract

We investigate wide-angle photo- and electroproduction of pions within the handbag mechanism in which the $\gamma^{(*)} N\to \pi N'$ amplitudes factorize into hard partonic subprocess amplitudes, $\gamma^{(*)} q\to \pi q'$, and form factors representing $1/x$-moments of generalized parton distributions (GPDs). The subprocess is calculated to twist-3 accuracy taking into account the 2- and 3-body Fock components of the pion. Both components are required for achieving gauge invariance in QED and QCD. The twist-2 and twist-3 distribution amplitudes (DAs) of the pion as well as the form factors are taken from our study of $\pi^0$ photoproduction. Extensive results on photoproduction of charged pions are presented and compared to experiment. Predictions on electroproduction of pions as well as on spin effects are also given. As a byproduct of our analysis we also obtain the complete twist-3 subprocess amplitudes contributing to deeply-virtual electroproduction of pions., Comment: 50 pages, 11 figures; version as published in PRD up to corrected typo in Eq. (52)

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