Abstract
Semileptonic decays of \(D\) mesons into orbitally excited states of strange mesons are studied in the framework of the relativistic quark model based on the quasipotential approach and quantum chromodynamics. Form factors parameterizing matrix elements of the weak current between meson states are calculated with the consistent account of relativistic effects. Their dependence on the square of the transferred momentum is explicitly determined in the whole accessible kinematic region. On the basis of these form factors and helicity formalism, differential and total semileptonic decay rates of \(D\) mesons are calculated. The detailed comparison of the obtained results with other theoretical calculations and experimental data is given.
