1. A precision measurement of the $p$($e,e^\prime p\,$)$\pi^0$ reaction at threshold
- Author
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Chirapatpimol, K., Shabestari, M. H., Lindgren, R. A., Smith, L. C., Annand, J. R. M., Higinbotham, D. W., Moffit, B., Nelyubin, V., Norum, B. E., Allada, K., Aniol, K., Ardashev, K., Armstrong, D. S., Arndt, R. A., Benmokhtar, F., Bernstein, A. M., Bertozzi, W., Briscoe, W. J., Bimbot, L., Camsonne, A., Chen, J. -P., Choi, S., Chudakov, E., Cisbani, E., Cusanno, F., Dalton, M. M., Dutta, C., Egiyan, K., Fernandez-Ramirez, C., Feuerbach, R., Fissum, K. G., Frullani, S., Garibaldi, F., Gayou, O., Gilman, R., Gilad, S., Goity, J., Gomez, J., Hahn, B., Hamilton, D., Hansen, J. -O., Huang, J., Igarashi, R., Ireland, D., de Jager, C. W., Jin, X., Jiang, X., Jinasundera, T., Kellie, J., Keppel, C. E., Kolb, N., LeRose, J., Liyanage, N., Livingston, K., McNulty, D., Mercado, L., Michaels, R., Mihovilovic, M., Qian, S., Qian, X., Mailyan, S., Mamyan, V., Marrone, S., Monaghan, P., Nanda, S., Perdrisat, C. F., Piasetzky, E., Protopopescu, D., Punjabi, V., Qiang, Y., Rachek, I. A., Rakhman, A., Ron, G., Rosner, G., Saha, A., Sawatzky, B., Shahinyan, A., Sirca, S., Sparveris, N., Subedi, R. R., Suleiman, R., Strakovsky, I., Sulkosky, V., Moinelo, J., Voskanyan, H., Wang, K., Wang, Y., Watson, J., Watts, D., Wojtsekhowski, B., Workman, R. L., Yao, H., Zhan, X., and Zhang, Y.
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Nuclear Experiment - Abstract
New results are reported from a measurement of $\pi^0$ electroproduction near threshold using the $p(e,e^{\prime} p)\pi^0$ 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 $\phi^*_{\pi}$ and $\theta^*_{\pi}$ angles in the $p \pi^0$ center-of-mass was obtained for invariant energies above threshold from 0.5 MeV up to 15 MeV. The 4-momentum transfer $Q^2$ 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 $Q^2>0.07$ (GeV/c)$^2$, while the $s-$wave predictions are in reasonable agreement., Comment: 5 pages, 6 figures
- Published
- 2015
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