Precision measurement of the p (e,e'p)π0 reaction at threshold

• Main Authors: K. Chirapatpimol, M. H. Shabestari, R. A. Lindgren, L. C. Smith, J. R.M. Annand, D. W. Higinbotham, B. Moffit, V. Nelyubin, B. E. Norum, K. Allada, K. Aniol, K. Ardashev, D. S. Armstrong, R. A. Arndt, F. Benmokhtar, A. M. Bernstein, W. Bertozzi, W. J. Briscoe, L. Bimbot, A. Camsonne, J. P. Chen, S. Choi, E. Chudakov, E. Cisbani, F. Cusanno, M. M. Dalton, C. Dutta, K. Egiyan, C. Fernàndez-Ramìrez, R. Feuerbach, K. G. Fissum, S. Frullani, F. Garibaldi, O. Gayou, R. Gilman, S. Gilad, J. Goity, J. Gomez, B. Hahn, D. Hamilton, J. O. Hansen, J. Huang, R. Igarashi, D. Ireland, C. W. De Jager, X. Jin, X. Jiang, T. Jinasundera, J. Kellie, C. E. Keppel, N. Kolb, J. Lerose, N. Liyanage, K. Livingston, D. McNulty, L. Mercado, R. Michaels, M. Mihovilovič, S. Qian, X. Qian, S. Mailyan, V. Mamyan, S. Marrone, P. Monaghan, S. Nanda, C. F. Perdrisat, E. Piasetzky, D. Protopopescu, V. Punjabi, Y. Qiang, I. A. Rachek, A. Rakhman, S. Riordan, G. Ron, G. Rosner, A. Saha, B. Sawatzky, A. Shahinyan, S. Širca, N. Sparveris, R. R. Subedi, R. Suleiman, I. Strakovsky, V. Sulkosky, J. Moinelo, H. Voskanyan, K. Wang, Y. Wang, J. Watson, D. Watts
• Format: Journal
• Published: 2018
• Subjects: Agricultural and Biological Sciences
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84930225261&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/44355
• Institution: Chiang Mai University

© 2015 American Physical Society. New results are reported from a measurement of π0 electroproduction near threshold using the p(e,e'p)π0 reaction. The experiment was designed to determine precisely the energy dependence of s- and p-wave electromagnetic multipoles as a stringent test of the predictions of chiral perturbation theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the φπ∗ and θπ∗ angles in the pπ0 center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. The 4-momentum transfer Q2 coverage ranges from 0.05 to 0.155(GeV/c)2 in fine steps. A simple phenomenological analysis of our data shows strong disagreement with p-wave predictions from ChPT for Q2 > 0.07(GeV/c)2, while the s-wave predictions are in reasonable agreement.