Description of radiative decays of $V \to P \gamma^{*}$ in different forms of Poincaré-invariant quantum mechanics

The description of the radiative decays of $V \to P \gamma^*$ in different forms Poincaré invariant quantum mechanics (PIQM) is considered. To construct the matrix element of the electromagnetic current we use the non-diagonal parametrization procedure. The obtained matrix element of the current satisfies the conditions of the Lorentz covariance and conservation. To illustrate this approach in a modified relativistic impulse approximation the description of the radiative transition $\rho \to \pi \gamma^{*}$ is performed. An analytic expression for the transition form factor $F_{\pi \rho}(Q^2)$, matching all forms PIQM, is obtained. Numerical calculations of the transition form factor are made with different model wave functions.