Nonperturbative features of the axial current

Abstract

We study the nonperturbative structure of the axial current and evaluate the two-point light-cone distribution amplitudes (DA) associated with the correlator \int dξexp(-iqξ)<0|\barψ(x)Γψ(y)J_μ^{5}(ξ)|0> within the instanton vacuum model in the leading order in O(1/N_c). Due to the built-in chiral symmetry, four of eight axial DAs are related to that for pions. Knowledge of these nonperturbative objects is important for phenomenological study of high-energy neutrino interactions and semileptonic decays of heavy quarks. We provide a code for evaluation of these DAs and an interpolation formula valid in the region Q^2 < 1 GeV^2.

22 pages, 10 Figures, improved and extended presentation. We provide a code which can be used for evaluations of the distribution amplitudes (see "Ancillary files" attached to this arXiv preprint)