Pion electromagnetic form factor at spacelike momenta
Abstract
A novel method is employed to compute the pion electromagnetic form factor, F_\pi(Q^2), on the entire domain of spacelike momentum transfer using the Dyson-Schwinger equation (DSE) framework in quantum chromodynamics (QCD). The DSE architecture unifies this prediction with that of the pion's valence-quark parton distribution amplitude (PDA). Using this PDA, the leading-order, leading-twist perturbative QCD result for Q^2 F_\pi(Q^2) underestimates the full computation by just 15% on Q^2>~8GeV^2, in stark contrast with the result obtained using the asymptotic PDA. The analysis shows that hard contributions to the pion form factor dominate for Q^2>~8GeV^2 but, even so, the magnitude of Q^2 F_\pi(Q^2) reflects the scale of dynamical chiral symmetry breaking, a pivotal emergent phenomenon in the Standard Model.
Cite
@article{arxiv.1307.0026,
title = {Pion electromagnetic form factor at spacelike momenta},
author = {L. Chang and I. C. Cloet and C. D. Roberts and S. M. Schmidt and P. C. Tandy},
journal= {arXiv preprint arXiv:1307.0026},
year = {2015}
}
Comments
5 pages, 2 figures. To appear in Phys. Rev. Lett