D+→π+v■decayprocesswithintheQCDSRapproach

In this paper,we investigate the charmed meson rare decay process ■ using an approach based on QCD sum rules.First,the pion twist-2,3 distribution amplitude（DA） moments <ζ2;π~n>|μ and <ζ3;π（p,σ）,n>|μ are calculated up to the tenth and fourth orders,respectively,in the QCD sum rules according to the background field theory.After constructing the light-cone harmonic oscillator model for the pion twist-2,3 D As,we obtain their behaviors by matching the calculated ζ-moments.Then,the D→π transition form factors（TFFs） are calculated using an approach based on QCD light-cone sum rules.The vector form factor at the large recoil region is f+D→π（0）=0.627-0.080+0.120.Using the rapidly converging simplified series expansion of z（q2,t）,we present the TFFs and corresponding angular coefficients in the whole squared momentum transfer physical region.Based on nonstandard neutrino interactions,the ■ decay can be related to the ■ decay indirectly.Thus,we first describe the semileptonic decay process ■,differential decay widths,and branching fraction with ■.The ■ differential/total predictions for forward-backward asymmetry,q2-differential flat terms,and lepton polarization asymmetry are also reported.The prediction for the ■ branching fraction is ■.