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We study the pion leading-twist distribution amplitude (DA) within theframework of SVZ sum rules under the background field theory. To improve theaccuracy of the sum rules, we expand both the quark propagator and the vertex$(z\cdot \tensor{D})^n$ of the correlator up to dimension-six operators in thebackground field theory. The sum rules for the pion DA moments are obtained, inwhich all condensates up to dimension-six have been taken into consideration.Using the sum rules, we obtain $\left<\xi^2\right>|_{\rm 1\;GeV} = 0.338 \pm0.032$, $\left<\xi^4\right>|_{\rm 1\;GeV} = 0.211 \pm 0.030$ and$\left<\xi^6\right>|_{\rm 1\;GeV} = 0.163 \pm 0.030$. It is shown that thedimension-six condensates shall provide sizable contributions to the pion DAmoments. We show that the first Gegenbauer moment of the pion leading-twist DAis $a^\pi_2|_{\rm 1\;GeV} = 0.403 \pm 0.093$, which is consistent with thoseobtained in the literature within errors but prefers a larger central value asindicated by lattice QCD predictions.

Revisiting the Pion Leading-Twist Distribution Amplitude within the QCD Background Field Theory