QCD Sum Rules For Pion Wave Function Revisited
  We analyze new QCD sum rules for the pion wave function $\phi_{\pi}(x)$, obtained recently by A.V. Radyushkin in the framework of the non-local vacuum condensates method for non-diagonal correlators, and suggest a new approach for extracting wave functions of the $\pi$-meson and of its first resonances. As a result we obtain approximately the same form of the pion wave function by using two different methods and for two different ansatzes of non-local quark condensates. We predict the mass of the $\pi'$-resonance and obtain the form of its wave function. The first method uses integrated (in a sense) properties of ansatzes and may be considered as an alternative to traditional borel SR. 
A.P. Bakulev and S.V. Mikhailov