On the Form Factors of the $D_{s}^{+}\to ϕμ^{+}ν_μ decay

Abstract

We apply the infinite mass effective theory, when a heavy quark mass tends to infinity, and Chiral perturbation theory at the quark level, based on the extended Nambu -- Jona -- Lasinio model with linear realization of chiral $U(3)\times U(3)$ symmetry, to calculate the form factors of the $D^{\,+}_{\,s}\toϕ~μ^+~ν_{\,μ}$ decay up to the first order in current $s$ -- quark mass. The theoretical results are compared with experimental data and found to be in good agreement.