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  1. Article ; Online: Nucleon form factor studies at JLab.

    Giusa, A / Bellini, V / Mammoliti, F / Russo, G / Sperduto, M L / Sutera, C M / Cisbani, E / Garibaldi, F / Urciuoli, G M / Capogni, M / Cates, G D / de Jager, K / Wojtsekhowski, B

    Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine

    2011  Volume 69, Issue 8, Page(s) 1125–1127

    Abstract: The ratio of the electromagnetic proton elastic form factors, G(p)(E)/G(p)(M), has been measured at Jefferson Lab up to Q(2) approximately 9(GeV/c)(2), by using the CEBAF 6GeV electron beam, and revealing an unexpected and challenging physical behaviour. ...

    Abstract The ratio of the electromagnetic proton elastic form factors, G(p)(E)/G(p)(M), has been measured at Jefferson Lab up to Q(2) approximately 9(GeV/c)(2), by using the CEBAF 6GeV electron beam, and revealing an unexpected and challenging physical behaviour. The 2014 scheduled 12GeV upgrade will allow the measurement of G(p)(E)/G(p)(M) up to Q(2) approximately 15(GeV/c)(2), by taking advantage of the new large-acceptance forward spectrometer Super BigBite (SBS) in Hall A. Measurements of neutron form factors in the region around 10(GeV/c)(2), where quark confinement plays an important role, are expected to show the behaviour already observed in the proton case.
    MeSH term(s) Electrons ; Elementary Particle Interactions ; Elementary Particles ; Equipment Design ; Neutrons ; Protons ; Radiation Monitoring/instrumentation ; Spectrum Analysis/instrumentation
    Chemical Substances Protons
    Language English
    Publishing date 2011-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 1142596-9
    ISSN 1872-9800 ; 0883-2889 ; 0969-8043
    ISSN (online) 1872-9800
    ISSN 0883-2889 ; 0969-8043
    DOI 10.1016/j.apradiso.2010.11.009
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: A RICH detector for hadron identification at JLab.

    Mammoliti, F / Bellini, V / Cisbani, E / Cusanno, F / Garibaldi, F / Giusa, A / de Jager, K / Russo, G / Sperduto, M L / Sutera, C M / Urciuoli, G M

    Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine

    2011  Volume 69, Issue 8, Page(s) 1118–1120

    Abstract: The "standard" Hall A apparatus at Jefferson Lab (TOF and aerogel threshold Cherenkov detectors) does not provide complete identification for proton, kaon and pion. To this aim, a proximity focusing C(6)F(14)/CsI RICH (Ring Image CHerenkov) detector has ... ...

    Abstract The "standard" Hall A apparatus at Jefferson Lab (TOF and aerogel threshold Cherenkov detectors) does not provide complete identification for proton, kaon and pion. To this aim, a proximity focusing C(6)F(14)/CsI RICH (Ring Image CHerenkov) detector has been designed, built, tested and operated to separate kaons from pions with a pion contamination of a few percent up to 2.4GeV/c. Two quite different experimental investigations have benefitted of the RICH identification: on one side, the high-resolution hypernuclear spectroscopy series of experiments on carbon, beryllium and oxygen, devoted to the study of the lambda-nucleon potential. On the other side, the measurements of the single spin asymmetries of pion and kaon on a transversely polarized (3)He target are of utmost interest in understanding QCD dynamics in the nucleon. We present the technical features of such a RICH detector and comment on the presently achieved performance in hadron identification.
    MeSH term(s) Beryllium/chemistry ; Carbon/chemistry ; Electrons ; Elementary Particle Interactions ; Elementary Particles ; Equipment Design ; Mesons ; Monte Carlo Method ; Nuclear Physics ; Oxygen/chemistry ; Protons ; Spectrum Analysis
    Chemical Substances Protons ; Carbon (7440-44-0) ; Beryllium (OW5102UV6N) ; Oxygen (S88TT14065)
    Language English
    Publishing date 2011-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 1142596-9
    ISSN 1872-9800 ; 0883-2889 ; 0969-8043
    ISSN (online) 1872-9800
    ISSN 0883-2889 ; 0969-8043
    DOI 10.1016/j.apradiso.2010.10.020
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Beam asymmetry Σ in η′ photoproduction off the proton at the GRAAL experiment

    Mandaglio G. / Bellini V. / Bocquet J. P. / Capogni M. / Curciarello F. / D'Angelo A. / De Leo V. / Didelez J.P. / Di Salvo R. / Fantini A. / Franco D. / Gervino G. / Ghio F. / Giardina G. / Girolami B. / Lapik A.M. / Levi Sandri P. / Lleres A. / Mammoliti F. /
    Manganaro M. / Moricciani D. / Mushkarenkov A.N. / Nedorezov V.G. / Rebreyend D. / Rudnev N.V. / Schaerf C. / Sperduto M.L. / Sutera M.C. / Turinge A. / Vegna V. / Zonta I.

    EPJ Web of Conferences, Vol 73, p

    2014  Volume 04006

    Abstract: The only recent η′ photoproduction data off proton available in literature are the differential and total cross sections published by the CLAS and CB-ELSA-TAPS Collaborations. However, the wide information about reaction cross sections are not sufficient ...

    Abstract The only recent η′ photoproduction data off proton available in literature are the differential and total cross sections published by the CLAS and CB-ELSA-TAPS Collaborations. However, the wide information about reaction cross sections are not sufficient to understand the role of resonances involved in the process. Different theoretical works stressed the importance to measure also polarization observables in order to solve the ambiguities in the choice of the parameters used in their models. We present the analysis of η′ photoproduction off the proton analysis, identifying the investigated meson by the π+π−η, π0π0η, and γγ decay modes by using the GRAAL apparatus; and we show the preliminary GRAAL results on the beam asymmetry Σ at beam energy of 1475 MeV.
    Keywords Physics ; QC1-999 ; Science ; Q
    Language English
    Publishing date 2014-06-01T00:00:00Z
    Publisher EDP Sciences
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Analysis of the η′ photoproduction off the proton and preliminary beam asymmetry results at the GRAAL experiment

    Mandaglio G. / Bellini V. / Bocquet J. P. / Capogni M. / Curciarello F. / D’Angelo A. / De Leo V. / Didelez J.P. / Di Salvo R. / Fantini A. / Franco D. / Gervino G. / Ghio F. / Giardina G. / Girolami B. / Lapik A.M. / Levi Sandri P. / Lleres A. / Mammoliti F. /
    Manganaro M. / Moricciani D. / Mushkarenkov A.N. / Nedorezov V.G. / Rebreyend D. / Rudnev N.V. / Schaerf C. / Sperduto M.L. / Sutera M.C. / Turinge A. / Vegna V. / Zonta I.

    EPJ Web of Conferences, Vol 72, p

    2014  Volume 00016

    Abstract: Differential and total cross section measurements on η′ photoproduction were published by the CLAS Collaboration (M. Dugger et al., Phys.Rev.Lett.96, 062001 (2006) and M. Williams et al., Phys.Rev.C80, 045213 (2009)) for center-of-mass energies from near ...

    Abstract Differential and total cross section measurements on η′ photoproduction were published by the CLAS Collaboration (M. Dugger et al., Phys.Rev.Lett.96, 062001 (2006) and M. Williams et al., Phys.Rev.C80, 045213 (2009)) for center-of-mass energies from near the threshold up to 2.84 GeV, and by the CB-ELSA-TAPS Collaboration (V. Crede et al., Phys.Rev.C80, 055202 (2009)) up to 2.36 GeV and also making a precise threshold scan of the differential cross section in the 1446 – 1527.4 MeV γ beam energy range. However, the wide information about reaction cross sections are not sufficient to understand the role of resonances involved in the process. Different theoretical works stressed the importance to have also polarization observables in order to solve the ambiguity in the choice of the parameters used in their models. We present the analysis of the η′ photoproduction off the proton, identifying the meson via the γγ, π0π0η, and π+π−η decay modes by using the GRAAL apparatus; and we show the preliminary GRAAL results on the beam asymmetry Σ from the threshold (1.446 GeV) up to 1.5 GeV.
    Keywords Physics ; QC1-999 ; Science ; Q
    Subject code 541
    Language English
    Publishing date 2014-05-01T00:00:00Z
    Publisher EDP Sciences
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Chronology of particle emission from the E/A=61 MeV 36Ar+27Al reaction.

    Ghetti, R / Helgesson, J / Avdeichikov, V / Golubev, P / Jakobsson, B / Colonna, N / Tagliente, G / Kopecky, S / Kravchuk, V L / Wilschut, H W / Anderson, E W / Nadel-Turonski, P / Westerberg, L / Bellini, V / Sperduto, M L / Sutera, C

    Physical review letters

    2003  Volume 91, Issue 9, Page(s) 92701

    Abstract: The emission time chronology of neutrons, protons, and deuterons from the E/A=61 MeV 36Ar+27Al reaction is deduced from two-particle correlation functions. ...

    Abstract The emission time chronology of neutrons, protons, and deuterons from the E/A=61 MeV 36Ar+27Al reaction is deduced from two-particle correlation functions.
    Language English
    Publishing date 2003-08-29
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.91.092701
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Limits on light-speed anisotropies from Compton scattering of high-energy electrons.

    Bocquet, J-P / Moricciani, D / Bellini, V / Beretta, M / Casano, L / D'Angelo, A / Di Salvo, R / Fantini, A / Franco, D / Gervino, G / Ghio, F / Giardina, G / Girolami, B / Giusa, A / Gurzadyan, V G / Kashin, A / Knyazyan, S / Lapik, A / Lehnert, R /
    Levi Sandri, P / Lleres, A / Mammoliti, F / Mandaglio, G / Manganaro, M / Margarian, A / Mehrabyan, S / Messi, R / Nedorezov, V / Perrin, C / Randieri, C / Rebreyend, D / Rudnev, N / Russo, G / Schaerf, C / Sperduto, M L / Sutera, M C / Turinge, A / Vegna, V

    Physical review letters

    2010  Volume 104, Issue 24, Page(s) 241601

    Abstract: The possibility of anisotropies in the speed of light relative to the limiting speed of electrons is considered. The absence of sidereal variations in the energy of Compton-edge photons at the European Synchrotron Radiation Facility's GRAAL facility ... ...

    Abstract The possibility of anisotropies in the speed of light relative to the limiting speed of electrons is considered. The absence of sidereal variations in the energy of Compton-edge photons at the European Synchrotron Radiation Facility's GRAAL facility constrains such anisotropies representing the first nonthreshold collision-kinematics study of Lorentz violation. When interpreted within the minimal standard-model extension, this result yields the two-sided limit of 1.6×10(-14) at 95% confidence level on a combination of the parity-violating photon and electron coefficients (κ(o+))(YZ), (κ(o+))(ZX), c(TX), and c(TY). This new constraint provides an improvement over previous bounds by 1 order of magnitude.
    Language English
    Publishing date 2010-06-18
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.104.241601
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  7. Article ; Online: A glimpse of gluons through deeply virtual compton scattering on the proton.

    Defurne, M / Jiménez-Argüello, A Martí / Ahmed, Z / Albataineh, H / Allada, K / Aniol, K A / Bellini, V / Benali, M / Boeglin, W / Bertin, P / Brossard, M / Camsonne, A / Canan, M / Chandavar, S / Chen, C / Chen, J-P / de Jager, C W / de Leo, R / Desnault, C /
    Deur, A / El Fassi, L / Ent, R / Flay, D / Friend, M / Fuchey, E / Frullani, S / Garibaldi, F / Gaskell, D / Giusa, A / Glamazdin, O / Golge, S / Gomez, J / Hansen, O / Higinbotham, D / Holmstrom, T / Horn, T / Huang, J / Huang, M / Hyde, C E / Iqbal, S / Itard, F / Kang, H / Kelleher, A / Keppel, C / Koirala, S / Korover, I / LeRose, J J / Lindgren, R / Long, E / Magne, M / Mammei, J / Margaziotis, D J / Markowitz, P / Mazouz, M / Meddi, F / Meekins, D / Michaels, R / Mihovilovic, M / Camacho, C Muñoz / Nadel-Turonski, P / Nuruzzaman, N / Paremuzyan, R / Puckett, A / Punjabi, V / Qiang, Y / Rakhman, A / Rashad, M N H / Riordan, S / Roche, J / Russo, G / Sabatié, F / Saenboonruang, K / Saha, A / Sawatzky, B / Selvy, L / Shahinyan, A / Sirca, S / Solvignon, P / Sperduto, M L / Subedi, R / Sulkosky, V / Sutera, C / Tobias, W A / Urciuoli, G M / Wang, D / Wojtsekhowski, B / Yao, H / Ye, Z / Zhan, X / Zhang, J / Zhao, B / Zhao, Z / Zheng, X / Zhu, P

    Nature communications

    2017  Volume 8, Issue 1, Page(s) 1408

    Abstract: The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their ... ...

    Abstract The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their momenta and positions. Here we investigate the dynamics of quarks and gluons inside nucleons using deeply virtual Compton scattering (DVCS)-a highly virtual photon scatters off the proton, which subsequently radiates a photon. DVCS interferes with the Bethe-Heitler (BH) process, where the photon is emitted by the electron rather than the proton. We report herein the full determination of the BH-DVCS interference by exploiting the distinct energy dependences of the DVCS and BH amplitudes. In the regime where the scattering is expected to occur off a single quark, measurements show an intriguing sensitivity to gluons, the carriers of the strong interaction.
    Language English
    Publishing date 2017-11-10
    Publishing country England
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, Non-U.S. Gov't
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-017-01819-3
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  8. Article ; Online: Rosenbluth Separation of the π^{0} Electroproduction Cross Section Off the Neutron.

    Mazouz, M / Ahmed, Z / Albataineh, H / Allada, K / Aniol, K A / Bellini, V / Benali, M / Boeglin, W / Bertin, P / Brossard, M / Camsonne, A / Canan, M / Chandavar, S / Chen, C / Chen, J-P / Defurne, M / de Jager, C W / de Leo, R / Desnault, C /
    Deur, A / El Fassi, L / Ent, R / Flay, D / Friend, M / Fuchey, E / Frullani, S / Garibaldi, F / Gaskell, D / Giusa, A / Glamazdin, O / Golge, S / Gomez, J / Hansen, O / Higinbotham, D / Holmstrom, T / Horn, T / Huang, J / Huang, M / Huber, G M / Hyde, C E / Iqbal, S / Itard, F / Kang, Ho / Kang, Hy / Kelleher, A / Keppel, C / Koirala, S / Korover, I / LeRose, J J / Lindgren, R / Long, E / Magne, M / Mammei, J / Margaziotis, D J / Markowitz, P / Martí Jiménez-Argüello, A / Meddi, F / Meekins, D / Michaels, R / Mihovilovic, M / Muangma, N / Muñoz Camacho, C / Nadel-Turonski, P / Nuruzzaman, N / Paremuzyan, R / Puckett, A / Punjabi, V / Qiang, Y / Rakhman, A / Rashad, M N H / Riordan, S / Roche, J / Russo, G / Sabatié, F / Saenboonruang, K / Saha, A / Sawatzky, B / Selvy, L / Shahinyan, A / Sirca, S / Solvignon, P / Sperduto, M L / Subedi, R / Sulkosky, V / Sutera, C / Tobias, W A / Urciuoli, G M / Wang, D / Wojtsekhowski, B / Yao, H / Ye, Z / Zana, L / Zhan, X / Zhang, J / Zhao, B / Zhao, Z / Zheng, X / Zhu, P

    Physical review letters

    2017  Volume 118, Issue 22, Page(s) 222002

    Abstract: We report the first longitudinal-transverse separation of the deeply virtual exclusive π^{0} electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions dσ_{L}/dt, dσ_{T}/dt, dσ_{LT}/dt, and dσ_{TT}/ ... ...

    Abstract We report the first longitudinal-transverse separation of the deeply virtual exclusive π^{0} electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions dσ_{L}/dt, dσ_{T}/dt, dσ_{LT}/dt, and dσ_{TT}/dt are extracted as a function of the momentum transfer to the recoil system at Q^{2}=1.75  GeV^{2} and x_{B}=0.36. The ed→edπ^{0} cross sections are found compatible with the small values expected from theoretical models. The en→enπ^{0} cross sections show a dominance from the response to transversely polarized photons, and are in good agreement with calculations based on the transversity generalized parton distributions of the nucleon. By combining these results with previous measurements of π^{0} electroproduction off the proton, we present a flavor decomposition of the u and d quark contributions to the cross section.
    Language English
    Publishing date 2017-06-02
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.118.222002
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  9. Article ; Online: Rosenbluth Separation of the π^{0} Electroproduction Cross Section.

    Defurne, M / Mazouz, M / Ahmed, Z / Albataineh, H / Allada, K / Aniol, K A / Bellini, V / Benali, M / Boeglin, W / Bertin, P / Brossard, M / Camsonne, A / Canan, M / Chandavar, S / Chen, C / Chen, J-P / de Jager, C W / de Leo, R / Desnault, C /
    Deur, A / El Fassi, L / Ent, R / Flay, D / Friend, M / Fuchey, E / Frullani, S / Garibaldi, F / Gaskell, D / Giusa, A / Glamazdin, O / Golge, S / Gomez, J / Hansen, O / Higinbotham, D / Holmstrom, T / Horn, T / Huang, J / Huang, M / Huber, G M / Hyde, C E / Iqbal, S / Itard, F / Kang, Ho / Kang, Hy / Kelleher, A / Keppel, C / Koirala, S / Korover, I / LeRose, J J / Lindgren, R / Long, E / Magne, M / Mammei, J / Margaziotis, D J / Markowitz, P / Martí Jiménez-Argüello, A / Meddi, F / Meekins, D / Michaels, R / Mihovilovic, M / Muangma, N / Muñoz Camacho, C / Nadel-Turonski, P / Nuruzzaman, N / Paremuzyan, R / Puckett, A / Punjabi, V / Qiang, Y / Rakhman, A / Rashad, M N H / Riordan, S / Roche, J / Russo, G / Sabatié, F / Saenboonruang, K / Saha, A / Sawatzky, B / Selvy, L / Shahinyan, A / Sirca, S / Solvignon, P / Sperduto, M L / Subedi, R / Sulkosky, V / Sutera, C / Tobias, W A / Urciuoli, G M / Wang, D / Wojtsekhowski, B / Yao, H / Ye, Z / Zana, L / Zhan, X / Zhang, J / Zhao, B / Zhao, Z / Zheng, X / Zhu, P

    Physical review letters

    2016  Volume 117, Issue 26, Page(s) 262001

    Abstract: We present deeply virtual π^{0} electroproduction cross-section measurements at x_{B}=0.36 and three different Q^{2} values ranging from 1.5 to 2  GeV^{2}, obtained from Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used to ... ...

    Abstract We present deeply virtual π^{0} electroproduction cross-section measurements at x_{B}=0.36 and three different Q^{2} values ranging from 1.5 to 2  GeV^{2}, obtained from Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component and, thus, is far from the asymptotic limit predicted by perturbative quantum chromodynamics. Nonetheless, an indication of a nonzero longitudinal contribution is provided by the measured interference term σ_{LT}. Results are compared with several models based on the leading-twist approach of generalized parton distributions (GPDs). In particular, a fair agreement is obtained with models in which the scattering amplitude includes convolution terms of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. This experiment, together with previous extensive unseparated measurements, provides strong support to the exciting idea that transversity GPDs can be accessed via neutral pion electroproduction in the high-Q^{2} regime.
    Language English
    Publishing date 2016-12-23
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.117.262001
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  10. Book ; Online: Rosenbluth separation of the $\pi^0$ electroproduction cross section

    Defurne, M. / Mazouz, M. / Albataineh, H. / Allada, K. / Aniol, K. A. / Bellini, V. / Benali, M. / Boeglin, W. / Bertin, P. / Brossard, M. / Camsonne, A. / Canan, M. / Chandavar, S. / Chen, C. / Chen, J. -P. / de Jager, C. W. / de Leo, R. / Desnault, C. / Deur, A. /
    Fassi, L. El / Ent, R. / Flay, D. / Friend, M. / Fuchey, E. / Frullani, S. / Garibaldi, F. / Gaskell, D. / Giusa, A. / Glamazdin, O. / Golge, S. / Gomez, J. / Hansen, O. / Higinbotham, D. / Holmstrom, T. / Horn, T. / Huang, J. / Huang, M. / Hyde, C. E. / Iqbal, S. / Itard, F. / Kang, H. / Kelleher, A. / Keppel, C. / Koirala, S. / Korover, I. / LeRose, J. J. / Lindgren, R. / Long, E. / Magne, M. / Mammei, J. / Margaziotis, D. J. / Markowitz, P. / Jimenez-Arguello, A. Marti / Meddi, F. / Meekins, D. / Michaels, R. / Mihovilovic, M. / Camacho, C. Munoz / Nadel-Turonski, P. / Nuruzzaman, N. / Paremuzyan, R. / Puckett, A. / Punjabi, V. / Qiang, Y. / Rakhman, A. / Rashad, M. N. H. / Riordan, S. / Roche, J. / Russo, G. / Sabati, F. / Saenboonruang, K. / Saha, A. / Sawatzky, B. / Selvy, L. / Shahinyan, A. / Sirca, S. / Solvignon, P. / Sperduto, M. L. / Subedi, R. / Sulkosky, V. / Sutera, C. / Tobias, W. A. / Urciuoli, G. M. / Wang, D. / Wojtsekhowski, B. / Yao, H. / Ye, Z. / Zafar, A. / Zhan, X. / Zhang, J. / Zhao, B. / Zhao, Z. / Zheng, X. / Zhu, P.

    2016  

    Abstract: We present deeply virtual $\pi^0$ electroproduction cross-section measurements at $x_B$=0.36 and three different $Q^2$--values ranging from 1.5 to 2 GeV$^2$, obtained from experiment E07-007 that ran in the Hall A at Jefferson Lab. The Rosenbluth ... ...

    Abstract We present deeply virtual $\pi^0$ electroproduction cross-section measurements at $x_B$=0.36 and three different $Q^2$--values ranging from 1.5 to 2 GeV$^2$, obtained from experiment E07-007 that ran in the Hall A at Jefferson Lab. The Rosenbluth technique was used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component, and thus is far from the asymptotic limit predicted by perturbative Quantum Chromodynamics. An indication of a non-zero longitudinal contribution is provided by the interference term $\sigma_{LT}$ also measured. Results are compared with several models based on the leading twist approach of Generalized Parton Distributions (GPDs). In particular, a fair agreement is obtained with models where the scattering amplitude is described by a convolution of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. Therefore, neutral pion electroproduction may offer the exciting possibility of accessing transversity GPDs through experiment.

    Comment: Submitted to Physical Review Letters
    Keywords High Energy Physics - Experiment ; Nuclear Experiment
    Subject code 621
    Publishing date 2016-08-02
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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