The pion charge radius from charged pion electroproduction

Abstract

We analyze a low-energy theorem of threshold pion electroproduction which allows one to determine the charge radius of the pion. We show that at the same order where the radius appears, pion loops induce a correction to the momentum dependence of the longitudinal dipole amplitude $L_{0+}^{(-)}$. This model-independent correction amounts to an increase of the pion charge radius squared from the electroproduction data by about 0.26~fm${}^2$. It sheds light on the apparent discrepancy between the recent determination of the pion radius from electroproduction data and the one based on pion-electron scattering.

3 pp, REVTeX, uses epsf

References in corpus (2)

• Baryon Chiral Perturbation Theory in Manifestly Lorentz Invariant Form
• A measurement of the axial form factor of the nucleon by the p(e,e'pi+)n reaction at W=1125 MeV

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• Fluctuations and clustering of multiplicity in collisions of relativistic ions
• Midrapidity inclusive densities in high energy $pp$ collisions in additive quark model
• On the pion electroproduction amplitude
• Statistical model for pionic partons