Precision Measurement of the $p(e,e^′p)π^0$ Reaction at Threshold - INSPIRE

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Precision Measurement of the $p(e,e^′p)π^0$ Reaction at Threshold

Hall A

Collaboration

•

K. Chirapatpimol
(
- Virginia U. and
- Chiang Mai U.
)

Jan 22, 2015

6 pages

Published in:

Phys.Rev.Lett. 114 (2015) 19, 192503

Published: May 13, 2015

e-Print:

1501.05607 [nucl-ex]

DOI:

10.1103/PhysRevLett.114.192503

Report number:

JLAB-PHY-15-2013

View in:

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Citations per year

Abstract: (APS)

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 ϕπ* and θπ* angles in the pπ0 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.

Note:

5 pages, 6 figures

25.30.Rw
12.39.Fe
13.60.Le
electroproduction
energy dependence
wave: electromagnetic
multipole
perturbation theory: chiral
electron: beam
beam: energy

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Figures(6)

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