Examinando por Autor "Chirapatpimol, K,"

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    A precision measurement of the 𝑝⁡(𝑒,𝑒′⁢𝑝)⁢𝜋0 reaction at threshold
    (American Physical Society, 2015-05-13) Chirapatpimol, K,; Shabestari, M. H.; Lindgren, R. A.; Fernández Ramírez, César
    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 𝜙*𝜋 and 𝜃*𝜋 angles in the 𝑝⁢𝜋0 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.