1. Precision Measurement of the p(e,e^{'}p)π^{0} Reaction at Threshold.
- Author
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Chirapatpimol K, Shabestari MH, Lindgren RA, Smith LC, Annand JR, Higinbotham DW, Moffit B, Nelyubin V, Norum BE, Allada K, Aniol K, Ardashev K, Armstrong DS, Arndt RA, Benmokhtar F, Bernstein AM, Bertozzi W, Briscoe WJ, Bimbot L, Camsonne A, Chen JP, Choi S, Chudakov E, Cisbani E, Cusanno F, Dalton MM, Dutta C, Egiyan K, Fernàndez-Ramìrez C, Feuerbach R, Fissum KG, Frullani S, Garibaldi F, Gayou O, Gilman R, Gilad S, Goity J, Gomez J, Hahn B, Hamilton D, Hansen JO, Huang J, Igarashi R, Ireland D, de Jager CW, Jin X, Jiang X, Jinasundera T, Kellie J, Keppel CE, Kolb N, LeRose J, Liyanage N, Livingston K, McNulty D, Mercado L, Michaels R, Mihovilovič M, Qian S, Qian X, Mailyan S, Mamyan V, Marrone S, Monaghan P, Nanda S, Perdrisat CF, Piasetzky E, Protopopescu D, Punjabi V, Qiang Y, Rachek IA, Rakhman A, Riordan S, Ron G, Rosner G, Saha A, Sawatzky B, Shahinyan A, Širca S, Sparveris N, Subedi RR, Suleiman R, Strakovsky I, Sulkosky V, Moinelo J, Voskanyan H, Wang K, Wang Y, Watson J, Watts D, Wojtsekhowski B, Workman RL, Yao H, Zhan X, and Zhang Y
- Abstract
New results are reported from a measurement of π^{0} electroproduction near threshold using the p(e,e^{'}p)π^{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_{π}^{*} and θ_{π}^{*} angles in the pπ^{0} center of mass was obtained for invariant energies above threshold from 0.5 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.
- Published
- 2015
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