Twist-3 Distribute Amplitude of the Pion in QCD Sum Rules

Abstract

We apply the background field method to calculate the moments of the pion two-particles twist-3 distribution amplitude (DA) ${\varphi }_p(\xi )$ 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 $m_0^p\approx 1.30GeV$ in this approach. If assuming the expansion of ${\varphi }_p(\xi )$ 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.

Comments: 12 pages, 3 figures