Self-consistent covariant description of vector meson decay constants and chirality-even quark-antiquark distribution amplitudes up to twist 3 in the light-front quark model

Although the meson decay amplitude described by a two-point function may be regarded as one of the simplest possible physical observables, it is interesting that this apparently simple amplitude bears abundant fundamental information on QCD vacuum dynamics and chiral symmetry. The light-front zero-mode issue of the vector meson decay constant fV is in this respect highly nontrivial and deserves careful analysis. We discuss the zero-mode issue in the light-front quark model (LFQM) prediction of fV from the perspective of the vacuum fluctuation consistent with the chiral symmetry of QCD. We extend the exactly solvable, manifestly covariant Bethe-Salpeter model calculation to the more phenomenologically accessible, realistic light-front quark model and present a self-consistent covariant description of fV, analyzing the twist-2 and twist-3 quark-antiquark distribution amplitudes with even chirality.