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A precision measurement of the $p$($e,e^\prime p\,$)$\pi^0$ reaction at threshold
- Source :
- Phys. Rev. Lett. 114, 192503 (2015)
- Publication Year :
- 2015
-
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.<br />Comment: 5 pages, 6 figures
- Subjects :
- Nuclear Experiment
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. Lett. 114, 192503 (2015)
- Publication Type :
- Report
- Accession number :
- edsarx.1501.05607
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevLett.114.192503