Precision Measurement of the p(e,e′p)π[superscript 0] Reaction at Threshold
Name
PhysRevLett.114.192503.pdf
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Author(s)
Chirapatpimol, K.
Shabestari, M. H.
Lindgren, R. A.
Smith, L. C.
Annand, J. R. M.
Higinbotham, D. W.
Moffit, Bryan J.
Nelyubin, V.
Norum, B. E.
Aniol, K.
Date Issued
May 2015
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Chirapatpimol, K., M.H. Shabestari, R.A. Lindgren, L.C. Smith, J.R.M. Annand, D.W. Higinbotham, B. Moffit, et al. “Precision Measurement of the p(e,e′p)π[superscript 0] Reaction at Threshold.” Physical Review Letters 114, no. 19 (May 2015). © 2015 American Physical Society
Version
Final published version
Abstract
New results are reported from a measurement of π[superscript 0] electroproduction near threshold using the p(e,e[superscript ′]p)π[superscript 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 ϕ[* over π] and θ[* over π] angles in the pπ[superscript 0] center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. The 4-momentum transfer Q[superscript 2] coverage ranges from 0.05 to 0.155 (GeV/c)[superscript 2] in fine steps. A simple phenomenological analysis of our data shows strong disagreement with p-wave predictions from ChPT for Q[superscript 2] > 0.07 (GeV/c)[superscript 2], while the s-wave predictions are in reasonable agreement.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.114.192503
