1Mc corrections to form factors of D-meson semileptonic decays

Next-to-leading corrections in large Mc expansion are calculated to the form factors of semileptonic decays of nonstange and strange charmed pseudoscalar mesons: D → K(K∗)ℓ+νℓ and Ds+ → Φℓ+νℓ. Calculations are performed within Heavy quark effective thoery (HQET) supplemented by Chiral perturbation theory at the quark level (CHPT)q based on the extended Nambu-Jona-Lasinio model with linear realization of chiral U(3) × U(3) symmetry. The 1Mc corrections are found commensurable in order of magnitude with first order corrections in current s-quark mass expansion. The results are compared with the experimental average data within the accuracy better than 28%.