Measurement of the N→Δ+(1232) transition at high-momentum transfer by π0 electroproduction

Ungaro, M. et al. (2006) Measurement of the N→Δ+(1232) transition at high-momentum transfer by π0 electroproduction. Physical Review Letters, 97(11), p. 112003. (doi:10.1103/PhysRevLett.97.112003)

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Abstract

We report a new measurement of the exclusive electroproduction reaction γ∗p→π<sup>0</sup>p to explore the evolution from soft nonperturbative physics to hard processes via the Q<sup>2</sup> dependence of the magnetic (M<sub>1+</sub>), electric (E<sub>1+</sub>), and scalar (S<sub>1+</sub>) multipoles in the N→Δ transition. 9000 differential cross section data points cover W from threshold to 1.4  GeV/c<sup>2</sup>, 4π center-of-mass solid angle, and Q<sup>2</sup> from 3 to 6  GeV<sup>2</sup>/c<sup>2</sup>, the highest yet achieved. It is found that the magnetic form factor G∗M decreases with Q<sup>2</sup> more steeply than the proton magnetic form factor, the ratio E<sub>1+</sub>/M<sub>1+</sub> is small and negative, indicating strong helicity nonconservation, and the ratio S<sub>1+</sub>/M<sub>1+</sub> is negative, while its magnitude increases with Q<sup>2</sup>.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:McKinnon, Dr Bryan and Livingston, Dr Kenneth and Protopopescu, Dr Dan and Ireland, Professor David and Kellie, Dr James and Rosner, Professor Guenther
Authors: Ungaro, M., Stoler, P., Aznauryan, I., Burkert, V., Joo, K., Smith, L., Adams, G., Amarian, M., Ambrozewicz, P., Anghinolfi, M., Asryan, G., Audit, G., Avakian, H., Bagdasaryan, H., Ball, J., Baltzell, N., Barrow, S., Batourine, V., Battaglieri, M., Bedliski, I., Bektasoglu, M., Bellis, M., Benmouna, N., Berman, B., Biselli, A., Bonner, B., Bouchigny, S., Boiarinov, S., Bradford, R., Branford, D., Briscoe, W., Brooks, W., Bultmann, S., Butuceanu, C., Calarco, J., Careccia, S., Carman, D., Cazes, A., Chen, S., Cole, P., Coltharp, P., Cords, D., Corvisiero, P., Crabb, D., Cummings, J., Sanctis, E., DeVita, R., Degtyarenko, P., Denizli, H., Dennis, L., Deur, A., Dharmawardane, K., Djalali, C., Dodge, G., Donnelly, J., Doughty, D., Dugger, M., Dytman, S., Dzyubak, O., Egiyan, H., Egiyan, K., Elouadrhiri, L., Eugenio, P., Fatemi, R., Fedotov, G., Feldman, G., Feuerbach, R., Funsten, H., Garcon, M., Gavalian, G., Gilfoyle, G., Giovanetti, K., Girod, F., Goetz, J., Gordon, C., Gothe, R., Griffioen, K., Guidal, M., Guillo, M., Guler, N., Guo, L., Gyurjyan, V., Hadjidakis, C., Hakobyan, R., Hardie, J., Heddle, D., Hersman, F., Hleiqawi, I., Holtrop, M., Hicks, K., Hyde-Wright, C., Ilieva, Y., Ireland, D., Ishkhanov, B., Ito, M., Jenkins, D., Jo, H., Juengst, H., Kellie, J., Khandaker, M., Kim, W., Klein, A., Klein, F., Klimenko, A., Kossov, M., Kramer, L., Kubarovsky, V., Kuhn, J., Kuhn, S., Lachniet, J., Laget, J., Langheinrich, J., Lawrence, D., Lee, T., Li, J., Livingston, K., Marchand, C., Markov, N., McAleer, S., McKinnon, B., McNabb, J., Mecking, B., Mehrabyan, S., Melone, J., Mestayer, M., Meyer, C., Mikhailov, K., Minehart, R., Mirazita, M., Miskimen, R., Mokeev, V., Morand, L., Morrow, S., Mueller, J., Mutchler, G., Napolitano, J., Nasseripour, R., Niccolai, S., Niculescu, G., Niculescu, I., Niczyporuk, B., Niroula, M., Niyazov, R., Nozar, M., ORielly, G., Osipenko, M., Ostrovidov, A., Park, K., Pasyuk, E., Philips, S., Pivnyuk, N., Pocanic, D., Pogorelko, O., Polli, E., Pozdniakov, S., Preedom, B., Price, J., Prok, Y., Protopopescu, D., Qin, L., Raue, B., Riccardi, G., Ricco, G., Ripani, M., Ritchie, B., Ronchetti, F., Rosner, G., Rossi, P., Rubin, P., Sabatie, F., Salgado, C., Santoro, J., Sapunenko, V., Schumacher, R., Serov, V., Sharabian, Y., Skabelin, A., Smith, E., Sober, D., Stavinsky, A., Stepanyan, S., Stepanyan, S., Stokes, B., Strakovsky, I., Strauch, S., Taiuti, M., Tedeschi, D., Thoma, U., Tkabladze, A., Todor, L., Tkachenko, S., Tur, C., Vineyard, M., Vlassov, A., Weinstein, L., Weygand, D., Williams, M., Wolin, E., Wood, M., Yegneswaran, A., Zana, L., Zhang, B., Zhang, J., Zhao, B., and CLAS Collaboration,
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review Letters
Publisher:American Physical Society
ISSN:0031-9007
ISSN (Online):1079-7114
Published Online:15 September 2006

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