The twist-3 distribution amplitudes in the $B\to\pi$ transition form   factor
  We derive an expression for the $B\to\pi$ transition form factor only depending the twist-3 distribution amplitudes by choosing an adequate chiral current correlator in the light-cone QCD sum rules. Our result show that the contribution from the twist-3 distribution amplitudes to the $f_{B\pi}^+(q^2)$ give a constraint on the twist-3 light-cone distribution amplitude. 
Ming-Zhen Zhou, Xing-Hua Wu, Tao Huang