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Title: Target and double spin asymmetries of deeply virtual π 0 production with a longitudinally polarized proton target and CLAS

Abstract

The target and double spin asymmetries of the exclusive pseudoscalar channel $$\vec e\vec p\to ep\pi^0$$ were measured for the first time in the deep-inelastic regime using a longitudinally polarized 5.9 GeV electron beam and a longitudinally polarized proton target at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS). The data were collected over a large kinematic phase space and divided into 110 four-dimensional bins of $Q^2$, $$x_B$$, $-t$ and $$\phi$$. Large values of asymmetry moments clearly indicate a substantial contribution to the polarized structure functions from transverse virtual photon amplitudes. The interpretation of experimental data in terms of generalized parton distributions (GPDs) provides the first insight on the chiral-odd GPDs $$\tilde{H}_T$$ and $$E_T$$, and complement previous measurements of unpolarized structure functions sensitive to the GPDs $$H_T$$ and $$\bar E_T$$. Finally, these data provide necessary constraints for chiral-odd GPD parametrizations and will strongly influence existing theoretical handbag models.

Authors:
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Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1344582
Alternate Identifier(s):
OSTI ID: 1351109
Report Number(s):
JLAB-PHY-17-2440; DOE/OR/23177-4111; arXiv:1511.03338
Journal ID: ISSN 0370-2693; PII: S037026931730134X; TRN: US1700695
Grant/Contract Number:
AC05-06OR23177
Resource Type:
Journal Article: Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 768; Journal Issue: C; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; nucleon structure; CLAS collaboration; deeply virtual meson production; chiral-odd generalized parton distributions; longitudinally polarized target

Citation Formats

Kim, A., Avakian, H., Burkert, V., Joo, K., Kim, W., Adhikari, K. P., Akbar, Z., Anefalos Pereira, S., Badui, R. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Bosted, P., Briscoe, W. J., Brooks, W. K., Bültmann, S., Cao, T., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Chetry, T., Colaneri, L., Cole, P. L., Compton, N., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Djalali, C., Egiyan, H., El Alaoui, A., El Fassi, L., Eugenio, P., Fedotov, G., Fersch, R., Filippi, A., Fleming, J. A., Fradi, A., Garc con, M., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guo, L., Hafidi, K., Hanretty, C., Hattawy, M., Heddle, D., Hicks, K., Holtrop, M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Jenkins, D., Jiang, H., Jo, H. S., Joosten, S., Keller, D., Khachatryan, G., Khandaker, M., Klein, A., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Lanza, L., Lenisa, P., Lu, H. Y., MacGregor, I. J. D., Markov, N., Mattione, P., McCracken, M. E., McKinnon, B., Mokeev, V., Movsisyan, A., Munevar, E., Nadel-Turonski, P., Net, L. A., Niccolai, S., Osipenko, M., Ostrovidov, A. I., Paolone, M., Park, K., Pasyuk, E., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Prok, Y., Ripani, M., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Salgado, C., Schumacher, R. A., Seder, E., Sharabian, Y. G., Skorodumina, Iu., Smith, G. D., Sokhan, D., Sparveris, N., Stepanyan, S., Stoler, P., Strakovsky, I. I., Strauch, S., Sytnik, V., Taiuti, M., Torayev, B., Ungaro, M., Voskanyan, H., Voutier, E., Watts, D. P., Wei, X., Weinstein, L. B., Zachariou, N., Zana, L., and Zhang, J.. Target and double spin asymmetries of deeply virtual π0 production with a longitudinally polarized proton target and CLAS. United States: N. p., 2017. Web. doi:10.1016/j.physletb.2017.02.032.
Kim, A., Avakian, H., Burkert, V., Joo, K., Kim, W., Adhikari, K. P., Akbar, Z., Anefalos Pereira, S., Badui, R. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Bosted, P., Briscoe, W. J., Brooks, W. K., Bültmann, S., Cao, T., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Chetry, T., Colaneri, L., Cole, P. L., Compton, N., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Djalali, C., Egiyan, H., El Alaoui, A., El Fassi, L., Eugenio, P., Fedotov, G., Fersch, R., Filippi, A., Fleming, J. A., Fradi, A., Garc con, M., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guo, L., Hafidi, K., Hanretty, C., Hattawy, M., Heddle, D., Hicks, K., Holtrop, M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Jenkins, D., Jiang, H., Jo, H. S., Joosten, S., Keller, D., Khachatryan, G., Khandaker, M., Klein, A., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Lanza, L., Lenisa, P., Lu, H. Y., MacGregor, I. J. D., Markov, N., Mattione, P., McCracken, M. E., McKinnon, B., Mokeev, V., Movsisyan, A., Munevar, E., Nadel-Turonski, P., Net, L. A., Niccolai, S., Osipenko, M., Ostrovidov, A. I., Paolone, M., Park, K., Pasyuk, E., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Prok, Y., Ripani, M., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Salgado, C., Schumacher, R. A., Seder, E., Sharabian, Y. G., Skorodumina, Iu., Smith, G. D., Sokhan, D., Sparveris, N., Stepanyan, S., Stoler, P., Strakovsky, I. I., Strauch, S., Sytnik, V., Taiuti, M., Torayev, B., Ungaro, M., Voskanyan, H., Voutier, E., Watts, D. P., Wei, X., Weinstein, L. B., Zachariou, N., Zana, L., & Zhang, J.. Target and double spin asymmetries of deeply virtual π0 production with a longitudinally polarized proton target and CLAS. United States. doi:10.1016/j.physletb.2017.02.032.
Kim, A., Avakian, H., Burkert, V., Joo, K., Kim, W., Adhikari, K. P., Akbar, Z., Anefalos Pereira, S., Badui, R. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Bosted, P., Briscoe, W. J., Brooks, W. K., Bültmann, S., Cao, T., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Chetry, T., Colaneri, L., Cole, P. L., Compton, N., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Djalali, C., Egiyan, H., El Alaoui, A., El Fassi, L., Eugenio, P., Fedotov, G., Fersch, R., Filippi, A., Fleming, J. A., Fradi, A., Garc con, M., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guo, L., Hafidi, K., Hanretty, C., Hattawy, M., Heddle, D., Hicks, K., Holtrop, M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Jenkins, D., Jiang, H., Jo, H. S., Joosten, S., Keller, D., Khachatryan, G., Khandaker, M., Klein, A., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Lanza, L., Lenisa, P., Lu, H. Y., MacGregor, I. J. D., Markov, N., Mattione, P., McCracken, M. E., McKinnon, B., Mokeev, V., Movsisyan, A., Munevar, E., Nadel-Turonski, P., Net, L. A., Niccolai, S., Osipenko, M., Ostrovidov, A. I., Paolone, M., Park, K., Pasyuk, E., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Prok, Y., Ripani, M., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Salgado, C., Schumacher, R. A., Seder, E., Sharabian, Y. G., Skorodumina, Iu., Smith, G. D., Sokhan, D., Sparveris, N., Stepanyan, S., Stoler, P., Strakovsky, I. I., Strauch, S., Sytnik, V., Taiuti, M., Torayev, B., Ungaro, M., Voskanyan, H., Voutier, E., Watts, D. P., Wei, X., Weinstein, L. B., Zachariou, N., Zana, L., and Zhang, J.. Wed . "Target and double spin asymmetries of deeply virtual π0 production with a longitudinally polarized proton target and CLAS". United States. doi:10.1016/j.physletb.2017.02.032.
@article{osti_1344582,
title = {Target and double spin asymmetries of deeply virtual π0 production with a longitudinally polarized proton target and CLAS},
author = {Kim, A. and Avakian, H. and Burkert, V. and Joo, K. and Kim, W. and Adhikari, K. P. and Akbar, Z. and Anefalos Pereira, S. and Badui, R. A. and Battaglieri, M. and Batourine, V. and Bedlinskiy, I. and Biselli, A. S. and Boiarinov, S. and Bosted, P. and Briscoe, W. J. and Brooks, W. K. and Bültmann, S. and Cao, T. and Carman, D. S. and Celentano, A. and Chandavar, S. and Charles, G. and Chetry, T. and Colaneri, L. and Cole, P. L. and Compton, N. and Contalbrigo, M. and Cortes, O. and Crede, V. and D'Angelo, A. and Dashyan, N. and De Vita, R. and De Sanctis, E. and Djalali, C. and Egiyan, H. and El Alaoui, A. and El Fassi, L. and Eugenio, P. and Fedotov, G. and Fersch, R. and Filippi, A. and Fleming, J. A. and Fradi, A. and Garc con, M. and Ghandilyan, Y. and Gilfoyle, G. P. and Giovanetti, K. L. and Girod, F. X. and Gohn, W. and Golovatch, E. and Gothe, R. W. and Griffioen, K. A. and Guo, L. and Hafidi, K. and Hanretty, C. and Hattawy, M. and Heddle, D. and Hicks, K. and Holtrop, M. and Ilieva, Y. and Ireland, D. G. and Ishkhanov, B. S. and Jenkins, D. and Jiang, H. and Jo, H. S. and Joosten, S. and Keller, D. and Khachatryan, G. and Khandaker, M. and Klein, A. and Klein, F. J. and Kubarovsky, V. and Kuhn, S. E. and Kuleshov, S. V. and Lanza, L. and Lenisa, P. and Lu, H. Y. and MacGregor, I. J. D. and Markov, N. and Mattione, P. and McCracken, M. E. and McKinnon, B. and Mokeev, V. and Movsisyan, A. and Munevar, E. and Nadel-Turonski, P. and Net, L. A. and Niccolai, S. and Osipenko, M. and Ostrovidov, A. I. and Paolone, M. and Park, K. and Pasyuk, E. and Phelps, W. and Pisano, S. and Pogorelko, O. and Price, J. W. and Prok, Y. and Ripani, M. and Rizzo, A. and Rosner, G. and Rossi, P. and Roy, P. and Salgado, C. and Schumacher, R. A. and Seder, E. and Sharabian, Y. G. and Skorodumina, Iu. and Smith, G. D. and Sokhan, D. and Sparveris, N. and Stepanyan, S. and Stoler, P. and Strakovsky, I. I. and Strauch, S. and Sytnik, V. and Taiuti, M. and Torayev, B. and Ungaro, M. and Voskanyan, H. and Voutier, E. and Watts, D. P. and Wei, X. and Weinstein, L. B. and Zachariou, N. and Zana, L. and Zhang, J.},
abstractNote = {The target and double spin asymmetries of the exclusive pseudoscalar channel $\vec e\vec p\to ep\pi^0$ were measured for the first time in the deep-inelastic regime using a longitudinally polarized 5.9 GeV electron beam and a longitudinally polarized proton target at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS). The data were collected over a large kinematic phase space and divided into 110 four-dimensional bins of $Q^2$, $x_B$, $-t$ and $\phi$. Large values of asymmetry moments clearly indicate a substantial contribution to the polarized structure functions from transverse virtual photon amplitudes. The interpretation of experimental data in terms of generalized parton distributions (GPDs) provides the first insight on the chiral-odd GPDs $\tilde{H}_T$ and $E_T$, and complement previous measurements of unpolarized structure functions sensitive to the GPDs $H_T$ and $\bar E_T$. Finally, these data provide necessary constraints for chiral-odd GPD parametrizations and will strongly influence existing theoretical handbag models.},
doi = {10.1016/j.physletb.2017.02.032},
journal = {Physics Letters. Section B},
number = C,
volume = 768,
place = {United States},
year = {Wed Feb 22 00:00:00 EST 2017},
month = {Wed Feb 22 00:00:00 EST 2017}
}

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Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.physletb.2017.02.032

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  • The target and double spin asymmetries of the exclusive pseudoscalar channelmore » $$\vec e\vec p\to ep\pi^0$$ were measured for the first time in the deep-inelastic regime using a longitudinally polarized 5.9 GeV electron beam and a longitudinally polarized proton target at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS). The data were collected over a large kinematic phase space and divided into 110 four-dimensional bins of $Q^2$, $$x_B$$, $-t$ and $$\phi$$. Large values of asymmetry moments clearly indicate a substantial contribution to the polarized structure functions from transverse virtual photon amplitudes. The interpretation of experimental data in terms of generalized parton distributions (GPDs) provides the first insight on the chiral-odd GPDs $$\tilde{H}_T$$ and $$E_T$$, and complement previous measurements of unpolarized structure functions sensitive to the GPDs $$H_T$$ and $$\bar E_T$$. Finally, these data provide necessary constraints for chiral-odd GPD parametrizations and will strongly influence existing theoretical handbag models.« less
  • The target and double spin asymmetries of the exclusive pseudoscalar channel e→p→→epπ0 were measured for the first time in the deep-inelastic regime using a longitudinally polarized 5.9 GeV electron beam and a longitudinally polarized proton target at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS). The data were collected over a large kinematic phase space and divided into 110 four-dimensional bins of Q2, xB, -t and Φ. Large values of asymmetry moments clearly indicate a substantial contribution to the polarized structure functions from transverse virtual photon amplitudes. The interpretation of experimental data in terms of generalized parton distributions (GPDs)more » provides the first insight on the chiral-odd GPDs H˜T and ET, and complement previous measurements of unpolarized structure functions sensitive to the GPDs HT and E¯T. These data provide a crucial input for parametrizations of essentially unknown chiral-odd GPDs and will strongly influence existing theoretical calculations based on the handbag formalism.« less
  • Deeply virtual exclusive processes probe the internal structure of nucleons through measurements of structure functions and their ratios, which are sensitive to the chiral-even generalized parton distributions (GPDs) and the chiral-odd transversity GPDs. The GPDs encode correlations of parton distributions in longitudinal momentum space and transverse impact parameter space and are accessible through the measurements of the xB and t dependence of meson production. The wide kinematic coverage of CLAS detector allowed measurements of exclusive π 0 electroproduction in full azimuthal range. The target and double spin asymmetries for the deeply virtual exclusive π 0 electroproduction were measured for themore » first time in the DIS region. The experiment was carried out at Hall B, Jefferson Lab using the longitudinally polarized electron beam with energy of up to 6 GeV and a dynamically polarized NH 3 target with spins of free protons aligned along the beam axis. All four final-state particles from exclusive channel, electron, proton and two photons from π 0 decay, were identified. The asymmetries were fitted according to their angular modulations in the hadronic center-of-mass system, and their moments were extracted. The data comparison with two handbag-based calculations involving the contribution from both chiral-even and chiral-odd GPDs was performed in wide kinematic range. The applicability of a formalism based on generalized parton distributions within the framework of modified perturbative approach is discussed.« less
  • Single-beam, single-target, and double-spin asymmetries for hard exclusive photon production on the proton e→p→e'p'γ are presented. The data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized 14NH 3 target. The three asymmetries were measured in 165 4-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of Generalized Parton Distributions. As a result, the measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independentmore » extraction of the imaginary parts of the H and H~ Compton Form Factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.« less