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Krambrich D, Zehr F, Fix A, Roca L, Aguar P, Ahrens J, Annand JRM, Arends HJ, Beck R, Bekrenev V, Boillat B, Braghieri A, Branford D, Briscoe WJ, Brudvik J, Cherepnya S, Codling R, Downie EJ, Dexler P, Glazier DI, Grabmayr P, Gregor R, Heid E, Hornidge D, Jahn O, Kashevarov VL, Knezevic A, Kondratiev R, Korolija M, Kotulla M, Krusche B, Kulbardis A, Lang M, Lisin V, Livingston K, Lugert S, MacGregor IJD, Manley DM, Martinez M, McGeorge JC, Mekterovic D, Metag V, Nefkens BMK, Nikolaev A, Pedroni P, Pheron F, Polonski A, Prakhov SN, Price JW, Rosner G, Rost M, Rostomyan T, Schumann S, Sober D, Starostin A, Supek I, Tarbert CM, Thomas A, Unverzagt M, Walcher T, Watts DP. Beam-helicity asymmetries in double-pion photoproduction off the proton. Phys Rev Lett 2009; 103:052002. [PMID: 19792489 DOI: 10.1103/physrevlett.103.052002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 06/18/2009] [Indexed: 05/28/2023]
Abstract
Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz in the three isospin channels gamma[over -->]p-->pi(+)pi(0)n, gamma[over -->]p-->pi(0)pi(0)p, and gamma[over -->]p-->pi(+)pi(-)p. The circularly polarized photons, produced from bremsstrahlung of longitudinally polarized electrons, were tagged with the Glasgow magnetic spectrometer. Charged pions and the decay photons of pi(0) mesons were detected in a 4pi electromagnetic calorimeter which combined the Crystal Ball detector with the TAPS detector. The precisely measured asymmetries are very sensitive to details of the production processes and are thus key observables in the modeling of the reaction dynamics.
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Affiliation(s)
- D Krambrich
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
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Strauch S, Berman BL, Adams G, Ambrozewicz P, Anghinolfi M, Asavapibhop B, Asryan G, Audit G, Avakian H, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Barrow S, Batourine V, Battaglieri M, Beard K, Bedlinskiy I, Bektasoglu M, Bellis M, Benmouna N, Bennhold C, Biselli AS, Boiarinov S, Bouchigny S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Burkert VD, Butuceanu C, Calarco JR, Careccia SL, Carman DS, Carnahan B, Chen S, Cole PL, Coleman A, Coltharp P, Cords D, Corvisiero P, Crabb D, Crannell H, Cummings JP, Degtyarenko PV, Denizli H, Dennis L, De Sanctis E, Deur A, Devita R, Dharmawardane KV, Dhuga KS, Djalali C, Dodge GE, Donnelly J, Doughty D, Dragovitsch P, Dugger M, Dytman S, Dzyubak OP, Egiyan H, Egiyan KS, Elouadrhiri L, Empl A, Eugenio P, Fatemi R, Fedotov G, Feldman G, Feuerbach RJ, Fix A, Forest TA, Funsten H, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Gothe RW, Griffioen KA, Guidal M, Guler N, Guo L, Gyurjyan V, Hadjidakis C, Hakobyan RS, Hardie J, Heddle D, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Hu J, Huertas M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Ito MM, Jenkins D, Jo HS, Joo K, Juengst HG, Kellie JD, Khandaker M, Kim KY, Kim K, Kim W, Klein A, Klein FJ, Klimenko AV, Klusman M, Kossov M, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Lachniet J, Laget JM, Langheinrich J, Lawrence D, Lee T, Lima ACS, Livingston K, Lukashin K, Manak JJ, Marchand C, McAleer S, McKinnon B, McNabb JWC, Mecking BA, Mestayer MD, Meyer CA, Mibe T, Mikhailov K, Minehart R, Mirazita M, Miskimen R, Mokeev V, Morrow SA, Muccifora V, Mueller J, Mutchler GS, Nadel-Turonski P, Napolitano J, Nasseripour R, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niyazov RA, Nozar M, O'rielly GV, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Philips SA, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Polli E, Pozdniakov S, Preedom BM, Price JW, Prok Y, Protopopescu D, Qin LM, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Roberts W, Ronchetti F, Rosner G, Rossi P, Rowntree D, Rubin PD, Sabatié F, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Shafi A, Sharabian YG, Shaw J, Skabelin AV, Smith ES, Smith LC, Sober DI, Stavinsky A, Stepanyan SS, Stepanyan S, Stokes BE, Stoler P, Strakovsky II, Suleiman R, Taiuti M, Taylor S, Tedeschi DJ, Thoma U, Thompson R, Tkabladze A, Tkachenko S, Todor L, Tur C, Ungaro M, Vineyard MF, Vlassov AV, Wang K, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Yun J, Zana L, Zhang J. Beam-helicity asymmetries in double-charged-pion photoproduction on the proton. Phys Rev Lett 2005; 95:162003. [PMID: 16241787 DOI: 10.1103/physrevlett.95.162003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2005] [Indexed: 05/05/2023]
Abstract
Beam-helicity asymmetries for the two-pion-photoproduction reaction gammap-->ppi(+)pi(-) have been studied for the first time in the resonance region for center-of-mass energies between 1.35 and 2.30 GeV. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons incident on an unpolarized hydrogen target. Beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics and dynamics of the reaction. The data are compared with the results of various phenomenological model calculations, and show that these models currently do not provide an adequate description for the behavior of this new observable.
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Affiliation(s)
- S Strauch
- The George Washington University, Washington, District of Columbia 20052, USA
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Messchendorp JG, Janssen S, Kotulla M, Ahrens J, Annand JRH, Beck R, Bloch F, Caselotti G, Fog L, Hornidge D, Krusche B, Langgärtner W, McGeorge JC, MacGregor IJD, Mengel K, Metag V, Novotny R, Owens RO, Pfeiffer M, Sack S, Sanderson R, Schadmand S. In-medium modifications of the pipi interaction in photon-induced reactions. Phys Rev Lett 2002; 89:222302. [PMID: 12485064 DOI: 10.1103/physrevlett.89.222302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2002] [Indexed: 05/24/2023]
Abstract
Differential cross sections of the reactions (gamma,pi(0)pi(0)) and (gamma,pi(0)pi(+/-)) have been measured for several nuclei (1H,12C, and (nat)Pb) at an incident-photon energy of E(gamma)=400-460 MeV at the tagged-photon facility at MAMI-B using the TAPS spectrometer. A significant nuclear-mass dependence of the pipi invariant-mass distribution is found in the pi(0)pi(0) channel. This dependence is not observed in the pi(0)pi(+/-) channel and is consistent with an in-medium modification of the pipi interaction in the I=J=0 channel. The data are compared to pi-induced measurements and to calculations within a chiral-unitary approach.
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