On the form factors of the Ds+ → φ μ+ νμ decay

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) × U(3) symmetry, to calculate the form factors of the Ds+ → φ μ+ νμ 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.