QCD sum rules with nonlocal condensates and the spacelike pion form factor

TL;DR

This paper uses advanced QCD sum rules with nonlocal condensates to predict the spacelike pion form factor, achieving good agreement with experimental data and comparing favorably with AdS/QCD models.

Contribution

It introduces a novel approach combining nonlocal condensates, improved Gaussian ansatz, and a Landau singularity-free scheme for more accurate pion form factor predictions.

Findings

Predictions agree with experimental data between 1-10 GeV$^2$

Incorporates $O(\alpha_s)$ corrections in spectral density

Provides error estimates from theoretical uncertainties

Abstract

We present a detailed investigation of the spacelike pion's electromagnetic form factor using three-point QCD sum rules that exclusively involve nonlocal condensates. Our main methodological tools are a spectral density which includes $O(\alpha_s)$ corrections, a suitably improved Gaussian ansatz to model the distribution of the average momentum of quarks in the QCD vacuum, and a perturbative scheme that avoids Landau singularities. Using this framework, we obtain predictions for the pion form factor together with error estimates originating from intrinsic theoretical uncertainties owing to the perturbative expansion and the nonperturbative method applied. We also discuss our results in comparison with other calculations, in particular, with those following from the AdS/QCD correspondence. We find good agreement of our predictions with measurements in the range of momenta covered by the existing experimental data between 1-10 GeV$^2$.