Theoretical update of pseudoscalar meson distribution amplitudes of highertwist: the nonsinglet case

We discuss the two and three particle light-cone distribution amplitudes (D As) of pseudoscalar nonsinglet mesons of twist 3 and 4. Using nonlocal oper ator identities and conformal expansion, we derive closed expressions for s everal DAs. We also include meson-mass corrections which prove to be domina nt in the twist 4 DAs of K and eta mesons. Explicit parametrizations for th e DAs of pi, K and eta mesons are given, with the numerical input parameter s determined from QCD sum rules.