English

A precision measurement of the $p$($e,e^\prime p\,$)$\pi^0$ reaction at threshold

Nuclear Experiment 2015-05-20 v3

Abstract

New results are reported from a measurement of π0\pi^0 electroproduction near threshold using the p(e,ep)π0p(e,e^{\prime} p)\pi^0 reaction. The experiment was designed to determine precisely the energy dependence of ss- and pp-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\phi^*_{\pi} and θπ\theta^*_{\pi} angles in the pπ0p \pi^0 center-of-mass was obtained for invariant energies above threshold from 0.5 MeV up to 15 MeV. The 4-momentum transfer Q2Q^2 coverage ranges from 0.05 to 0.155 (GeV/c)2^2 in fine steps. A simple phenomenological analysis of our data shows strong disagreement with pp-wave predictions from ChPT for Q2>0.07Q^2>0.07 (GeV/c)2^2, while the ss-wave predictions are in reasonable agreement.

Keywords

Cite

@article{arxiv.1501.05607,
  title  = {A precision measurement of the $p$($e,e^\prime p\,$)$\pi^0$ reaction at threshold},
  author = {K. Chirapatpimol and M. H. Shabestari and R. A. Lindgren and L. C. Smith and J. R. M. Annand and D. W. Higinbotham and B. Moffit and V. Nelyubin and B. E. Norum and K. Allada and K. Aniol and K. Ardashev and D. S. Armstrong and R. A. Arndt and F. Benmokhtar and A. M. Bernstein and W. Bertozzi and W. J. Briscoe and L. Bimbot and A. Camsonne and J. -P. Chen and S. Choi and E. Chudakov and E. Cisbani and F. Cusanno and M. M. Dalton and C. Dutta and K. Egiyan and C. Fernandez-Ramirez and R. Feuerbach and K. G. Fissum and S. Frullani and F. Garibaldi and O. Gayou and R. Gilman and S. Gilad and J. Goity and J. Gomez and B. Hahn and D. Hamilton and J. -O. Hansen and J. Huang and R. Igarashi and D. Ireland and C. W. de Jager and X. Jin and X. Jiang and T. Jinasundera and J. Kellie and C. E. Keppel and N. Kolb and J. LeRose and N. Liyanage and K. Livingston and D. McNulty and L. Mercado and R. Michaels and M. Mihovilovic and S. Qian and X. Qian and S. Mailyan and V. Mamyan and S. Marrone and P. Monaghan and S. Nanda and C. F. Perdrisat and E. Piasetzky and D. Protopopescu and V. Punjabi and Y. Qiang and I. A. Rachek and A. Rakhman and G. Ron and G. Rosner and A. Saha and B. Sawatzky and A. Shahinyan and S. Sirca and N. Sparveris and R. R. Subedi and R. Suleiman and I. Strakovsky and V. Sulkosky and J. Moinelo and H. Voskanyan and K. Wang and Y. Wang and J. Watson and D. Watts and B. Wojtsekhowski and R. L. Workman and H. Yao and X. Zhan and Y. Zhang},
  journal= {arXiv preprint arXiv:1501.05607},
  year   = {2015}
}

Comments

5 pages, 6 figures