Electroexcitation of the Δ + (1232) at low momentum transfer

Blomberg, A. et al. (2016) Electroexcitation of the Δ + (1232) at low momentum transfer. Physics Letters B, 760, pp. 267-272. (doi:10.1016/j.physletb.2016.06.076)

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Abstract

We report on new p(e, ep)π◦ measurements at the Δ + (1232) resonance at the low momentum transfer region, where the mesonic cloud dynamics is predicted to be dominant and rapidly changing, offering a test bed for chiral effective field theory calculations. The new data explore the dependence of the resonant quadrupole amplitudes and for the first time indicate that the Electric and the Coulomb quadrupole amplitudes converge as Q 2 → 0. The measurements of the Coulomb quadrupole amplitude have been extended to the lowest momentum transfer ever reached, and suggest that more than half of its magnitude is attributed to the mesonic cloud in this region. The new data disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations that include pion cloud effects, chiral effective field theory and lattice calculations. The measurements indicate that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Annand, Dr John and Hamilton, Dr David
Authors: Blomberg, A., Anez, D., Sparveris, N., Sarty, A.J., Paolone, M., Gilad, S., Higinbotham, D., Ahmed, Z., Albataineh, H., Allada, K., Anderson, B., Aniol, K., Annand, J., Arrington, J., Averett, T., Baghdasaryan, H., Bai, X., Beck, A., Beck, S., Bellini, V., Benmokhtar, F., Boeglin, W., Camacho, C.M., Camsonne, A., Chen, C., Chen, J.P., Chirapatpimol, K., Cisbani, E., Dalton, M., Deconinck, W., Defurne, M., De Leo, R., Flay, D., Fomin, N., Friend, M., Frullani, S., Fuchey, E., Garibaldi, F., Gilman, R., Gu, C., Hamilton, D., Hanretty, C., Hansen, O., Hashemi Shabestari, M., Hen, O., Holmstrom, T., Huang, M., Iqbal, S., Kalantarians, N., Kang, H., Kelleher, A., Khandaker, M., Korover, I., Leckey, J., LeRose, J., Lindgren, R., Long, E., Mammei, J., Margaziotis, D.J., Martí Jimenez-Arguello, A., Meekins, D., Meziani, Z.E., Mihovilovic, M., Muangma, N., Norum, B., Nuruzzaman, , Pan, K., Phillips, S., Piasetzky, E., Polychronopoulou, A., Pomerantz, I., Posik, M., Punjabi, V., Qian, X., Rakhman, A., Reimer, P.E., Riordan, S., Ron, G., Saha, A., Schulte, E., Selvy, L., Shneor, R., Sirca, S., Sjoegren, J., Subedi, R., Sulkosky, V., Tireman, W., Wang, D., Watson, J., Wojtsekhowski, B., Yan, W., Yaron, I., Ye, Z., Zhan, X., Zhang, J., Zhang, Y., Zhao, B., Zhao, Z., Zheng, X., and Zhu, P.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physics Letters B
Publisher:Elsevier
ISSN:0370-2693
ISSN (Online):1873-2445
Published Online:05 July 2016
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Physics Letters B 760:267-272
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
570711Nuclear Physics GroupDavid IrelandScience & Technology Facilities Council (STFC)ST/J000175/1P&A - PHYSICS & ASTRONOMY
507271Illuminating strongly interacting matterI MacgregorScience & Technology Facilities Council (STFC)ST/G008604/1P&A - PHYSICS & ASTRONOMY