Measurement of ep-->ep[pi]0 beam spin asymmetries above the resonance region

• Published in: Physical review letters 2008-04, Vol.77
• Main Authors: De Masi, Rita, Garcon, Michel, Amaryan, Moskov, Asryan, Gegham, Avagyan, Harutyun, Baillie, Nathan, Ball, J P, Ball, Jacques, Battaglieri, Marco, Bedlinskiy, Ivan, Benmouna, Nawal, Blaszczyk, Lukasz, Briscoe, William, Bultmann, S, Bueltmann, Stephen, Butuceanu, Cornel, Calarco, John, Casey, Liam, Chen, Shifeng, Cheng, Lu, Collins, Patrick, Crabb, Donald, Dashyan, Natalya, Degtiarenko, Pavel, Deur, Alexandre, Dickson, Richard, Dugger, Michael, Egiyan, Kim, Fedotov, Gleb, Feldman, Gerald, Gilfoyle, Gerard, Girod, Francois-Xavier, Gonenc, Atilla, Gyurjyan, Vardan, Hanretty, Charles, Hleiqawi, Ishaq, Ilieva, Yordanka, Isupov, Evgeny, Jenkins, David, Jo, Hyon-Suk, Joo, Kyungseon, Juengst, Henry, Kalantarians, Narbe, Khandaker, Mahbubul, Kim, Wooyoung, Klimenko, Alexei, Kossov, Mikhail, Krahn, Zebulun, Kuhn, Joachim, Langheinrich, Jorn, Lee, Tsung-Shung, MacCormick, Marion, Mattione, Paul, Mazouz, Malek, McKinnon, Bryan, Mecking, Bernhard, Meyer, Curtis, Mibe, Tsutomu, Michel, Bernard, Miskimen, Rory, Mokeev, Viktor, Moriya, Kei, Munevar Espitia, Edwin, Mutchler, Gordon, Nadel-Turonski, Pawel, Nasseripour, Rakhsha, Niccolai, Silvia, Niculescu, Maria-Ioana, Niroula, Megh, Niyazov, Rustam, Nozar, Mina, Pereira, Sergio, Pivnyuk, Nikolay, Pocanic, Dinko, Pogorelko, Oleg, Price, John, Prok, Yelena, Protopopescu, Dan, Raue, Brian, Ricco, Giovanni, Ripani, Marco, Ritchie, Barry, Ronchetti, Federico, Salamanca, Julian, Sharov, Dmitri, Shvedunov, Nikolay, Smith, Elton, Smith, Lee, Sokhan, Daria, Stoler, Paul, Strakovski, Igor, Strauch, Steffen, Tedeschi, David, Tur, Clarisse, Ungaro, Maurizio, Vineyard, Michael, Vlassov, Alexander, Weygand, Dennis, Zhang, Jixie, Zhao, Zhiwen
• Format: Article
• Language: English
• Subjects: AMPLITUDES; ASYMMETRY; ELECTRON BEAMS; PHOTONS; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; RESONANCE; SPECTROMETERS; SPIN
• ISSN: 0031-9007; 1079-7114

The beam spin asymmetry (BSA) in the exclusive reaction e-vector p-->eppi0 was measured with the CEBAF 5.77 GeV polarized electron beam and Large Acceptance Spectrometer (CLAS). The xB,Q2,t, and phi dependences of the pi0 BSA are presented in the deep inelastic regime. The asymmetries are fitted with a sinphi function and their amplitudes are extracted. Overall, they are of the order of 0.04â 0.11 and roughly independent of t. This is the signature of a nonzero longitudinal-transverse interference. The implications concerning the applicability of a formalism based on generalized parton distributions, as well as the extension of a Regge formalism at high photon virtualities, are discussed.