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.
PHYSICAL REVIEW LETTERS 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] [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.
Collapse