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Joo K, Smith LC, Burkert VD, Minehart R, Aznauryan IG, Elouadrhiri L, Stepanyan S, Adams GS, Amaryan MJ, Anciant E, Anghinolfi M, Armstrong DS, Asavapibhop B, Audit G, Auger T, Avakian H, Barrow S, Bagdasaryan H, Battaglieri M, Beard K, Bektasoglu M, Bertozzi W, Bianchi N, Biselli AS, Boiarinov S, Bonner BE, Brooks WK, Calarco JR, Capitani GP, Carman DS, Carnahan B, Cole PL, Coleman A, Cords D, Corvisiero P, Crabb D, Crannell H, Cummings J, De Sanctis E, De Vita R, Degtyarenko PV, Demirchyan RA, Denizli H, Dennis LC, Deppman A, Dharmawardane KV, Dhuga KS, Djalali C, Dodge GE, Doughty D, Dragovitsch P, Dugger M, Dytman S, Eckhause M, Efremenko YV, Egiyan H, Egiyan KS, Farhi L, Feuerbach RJ, Ficenec J, Fissum K, Forest TA, Funsten H, Gai M, Gavrilov VB, Gilad S, Gilfoyle GP, Giovanetti KL, Girard P, Griffioen KA, Guidal M, Guillo M, Gyurjyan V, Hancock D, Hardie J, Heddle D, Heisenberg J, Hersman FW, Hicks K, Hicks RS, Holtrop M, Hyde-Wright CE, Ito MM, Jenkins D, Kelley JH, Khandaker M, Kim KY, Kim W, Klein A, Klein FJ, Klusman M, Kossov M, Kuang Y, Kuhn SE, Laget JM, Lawrence D, Longhi A, Loukachine K, Lucas M, Major RW, Manak JJ, Marchand C, Matthews SK, McAleer S, McNabb JWC, Mecking BA, Mestayer MD, Meyer CA, Mirazita M, Miskimen R, Muccifora V, Mueller J, Mutchler GS, Napolitano J, Niculescu G, Niczyporuk B, Niyazov RA, Ohandjanyan MS, Opper A, Patois Y, Peterson GA, Philips S, Pivnyuk N, Pocanic D, Pogorelko O, Polli E, Preedom BM, Price JW, Qin LM, Raue BA, Reolon AR, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rossi P, Rowntree D, Rubin PD, Salgado CW, Sanzone M, Sapunenko V, Sargsyan M, Schumacher RA, Sharabian YG, Shaw J, Shuvalov SM, Skabelin A, Smith ES, Smith T, Sober DI, Spraker M, Stoler P, Taiuti M, Taylor S, Tedeschi D, Thompson R, Todor L, Tung TY, Vineyard MF, Vlassov A, Weller H, Weinstein LB, Welsh R, Weygand DP, Whisnant S, Witkowski M, Wolin E, Yegneswaran A, Yun J, Zhou Z, Zhao J. Q2 Dependence of quadrupole strength in the gamma*p --> Delta(+)(1232) --> p pi(0) transition. Phys Rev Lett 2002; 88:122001. [PMID: 11909446 DOI: 10.1103/physrevlett.88.122001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2001] [Indexed: 05/23/2023]
Abstract
Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.
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Affiliation(s)
- K Joo
- University of Virginia, Department of Physics, Charlottesville, Virginia 22903, USA
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Thompson R, Dytman S, Kim KY, Mueller J, Adams GS, Amaryan MJ, Anciant E, Anghinolfi M, Asavapibhop B, Auger T, Audit G, Avakian H, Barrow S, Battaglieri M, Beard K, Bektasoglu M, Bertozzi W, Bianchi N, Biselli A, Boiarinov S, Bonner BE, Briscoe WJ, Brooks W, Burkert VD, Calarco JR, Capitani G, Carman DS, Carnahan B, Cole PL, Coleman A, Connelly J, Cords D, Corvisiero P, Crabb D, Crannell H, Cummings J, Day D, Degtyarenko PV, Demirchyan RA, Dennis LC, Deppman A, De Sanctis E, De Vita R, Dhuga KS, Djalali C, Dodge GE, Doughty D, Dragovitsch P, Dugger M, Eckhause M, Efremenko YV, Egiyan H, Egiyan KS, Elouadrhiri L, Farhi L, Feuerbach RJ, Ficenec J, Fissum K, Freyberger A, Funsten H, Gai M, Gavrilov VB, Gilfoyle GP, Giovanetti K, Gilad S, Girard P, Griffioen KA, Guidal M, Guillo M, Gyurjyan V, Hancock D, Hardie J, Heddle D, Heisenberg J, Hersman FW, Hicks K, Hicks RS, Holtrop M, Hyde-Wright CE, Ito MM, Jenkins D, Joo K, Kane J, Khandaker M, Kim W, Klein A, Klein FJ, Klusman M, Kossov M, Kuhn SE, Kuang Y, Laget JM, Lawrence D, Leskin GA, Longhi A, Loukachine K, Lucas M, Magahiz R, Major RW, Manak JJ, Marchand C, Matthews SK, McAleer S, McCarthy J, McNabb JW, Mecking BA, Mestayer MD, Meyer CA, Minehart R, Mirazita M, Miskimen R, Muccifora V, Mutchler GS, Napolitano J, Niyazov RA, Ohandjanyan MS, O'Brien JT, Opper A, Patois Y, Peterson GA, Philips S, Pivnyuk N, Pocanic D, Pogorelko O, Polli E, Preedom BM, Price JW, Qin LM, Raue BA, Reolon AR, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rossi P, Roudot F, Rowntree D, Rubin PD, Salgado CW, Sanzone M, Sapunenko V, Sarty A, Sargsyan M, Schumacher RA, Shafi A, Sharabian YG, Shaw J, Shuvalov SM, Skabelin A, Smith T, Smith C, Smith ES, Sober DI, Spraker M, Stepanyan S, Stoler P, Taiuti M, Taylor S, Tedeschi D, Tung TY, Vineyard MF, Vlassov A, Weller H, Weinstein LB, Welsh R, Weygand DP, Whisnant S, Witkowski M, Wolin E, Yegneswaran A, Yun J, Zhou Z, Zhao J. The ep -->e'p eta reaction at and above the S11(1535) baryon resonance. Phys Rev Lett 2001; 86:1702-1706. [PMID: 11290228 DOI: 10.1103/physrevlett.86.1702] [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: 11/08/2000] [Indexed: 05/23/2023]
Abstract
New cross sections for the reaction e p-->e p eta are reported for total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 = 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction of important new information about response functions, photocouplings, and eta N coupling strengths of baryon resonances. Newly observed structure at W approximately 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.
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Affiliation(s)
- R Thompson
- Department of Physics and Astronomy, University of Pittsburgh, Pennsylvania 15260, USA
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