Pion electromagnetic form factor, perturbative QCD, and large-Nc Regge models

TL;DR

This paper constructs a model for the pion electromagnetic form factor that smoothly transitions from large-Nc Regge vector meson dominance models with many resonances to perturbative QCD, matching experimental data and theoretical constraints.

Contribution

It explicitly combines Regge models with perturbative QCD using residue assignments that satisfy duality and QCD constraints, extending the applicability to other form factors.

Findings

Model describes experimental data within uncertainties

Asymptotic QCD behavior appears at very high momenta (~10^3-10^4 GeV)

Converging pattern observed in leading and next-to-leading order calculations

Abstract

We present a construction of the pion electromagnetic form factor where the transition from large-Nc Regge vector meson dominance models with infinitely many resonances to perturbative QCD is built in explicitly. The construction is based on an appropriate assignment of residues to the Regge poles, which fulfills the constraints of the parton-hadron duality and perturbative QCD. The model contains a slowly falling off non-perturbative contribution which dominates over the perturbative QCD radiative corrections for the experimentally accessible momenta. The leading order and next-to-leading order calculations show a converging pattern which describes the available data within uncertainties, while the onset of asymptotic QCD takes place at extremely high momenta, Q ~ 10^3-10^4 GeV. The method can be straightforwardly extended to study other form factors where the perturbative QCD result is available.