Pion Form Factor in QCD: How to Calculate?

Abstract

We discuss the pion form factor calculation in QCD.We shortly consider the main points of the nonlocal condensate QCD sum rule approach and show its results for the pion form factor, $F_\pi(Q^2)$. These results are compared with predictions of the perturbative and lattice QCD. Then we consider the Local Duality (LD) approach for the pion FF in QCD and show that for $Q^2\gtrsim 2$ GeV$^2$ the main parameter of the approach, namely, $s_0^{\text{LD}}(Q^2)$ should grow with $Q^2$ rather than be a constant.