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The Charged Pion Form Factor (Run 2)
Experiment E01-004 at JLab,
ran successfully July 9 - August 12, 2003
Overview
The pion is in some sense the "hydrogen atom" of light quark
QCD, consisting of only two valence quarks. In contrast to the nucleon
form factors, the pQCD calculation of Fpi is absolutely normalized by the
pion decay constant, and the perturbative regime for Fpi is almost within
reach of a 12 GeV facility. Predictions for the pion form factor at low
momentum transfer range from QCD sum rules to constituent quark models to
lattice QCD.
In the original Fpi experiment (E93-021), we found that at lower Q2
the pion is consistent with highly non-perturbative models of the pion
structure (or with a simple extrapolation of a monopole form factor). Our
new experiment measured the pion form factor at Q2=1.6 and 2.5 GeV2,
representing the ultimate reach of JLab for this observable with the present
equipment. Although our maximum beam energy was only 5.25 GeV, we pushed
the limits of the HMS (pion arm) minimum angle and the SOS (electron arm)
maximum momentum. Measurements at even higher Q2 will require a high momentum,
small angle spectrometer like the proposed SHMS.
Physics Motivation
Collaboration
Data Analysis
Run 2 Essential Information
Useful References
- Brauel paper
- Other important papers to be added
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Publications, Conferences and Workshops
Other information
This site is maintained by David Mack and Garth Huber
Last updated 2005-Aug-17