Twist-3 distribution amplitude of the pion in QCD sum rules

We apply the background field method to calculate the moments of the pion two-particle twist-3 distribution amplitude phi(p)(xi) in QCD sum rules. In this paper, we do not use the equation of motion for the quarks inside the pion since they are not on shell and introduce a new parameter m(0)(p) to be determined. We get the parameter m(0)(p)approximate to1.30 GeV in this approach. If assuming the expansion of phi(p)(xi) in the series in Gegenbauer polynomials C-n(1/2)(xi), one can obtain its approximate expression which can be determined by its first few moments.