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FIZIKA B 13 (2004) 1, 193-200
INSTANTON CONTRIBUTION TO THE PION AND PROTON
ELECTROMAGNETIC FORM FACTORS AT Q2 ³ 1 GeV2
P. FACCIOLIa, A. SCHWENKb and E. V. SHURYAKc
aE.C.T., Strada delle Tabarelle 286, Villazzano (Trento),
I-38050, Italy
bDepartment of Physics, The Ohio State University, Columbus, OH 43210, USA
cDepartment of Physics and Astronomy, State University of New York,
Stony Brook, NY 11794-3800, USA
E-mail addresses: faccioli@ect.it, aschwenk@mps.ohio-state.edu,
shuryak@tonic.physics.sunysb.edu
Received 1 September 2003;
Accepted 26 April 2004
Online 10 October 2004
Studying the instanton-induced contributions to various hard exclusive reactions
provides physical insight into the transition from the non-perturbative to the
perturbative regime of QCD. To this end, we calculate the leading-instanton contributions
to the electromagnetic and transition form factors using an effective theory of the
instanton liquid model. We report predictions for the electromagnetic form factor Fp(Q2) of the pion as well as novel results for the
proton Dirac form factor F1(Q2).
PACS numbers: 13.40.Gp, 12.38.Lg, 14.20.Dh
UDC 539.12
Keywords: instanton-induced contributions, strong interactions, electromagnetic form
factor, Dirac form factor
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