FASTERD: a Monte Carlo event generator for the study of final state radiation in the process $e^{+}{e}^{-}\to \pi \pi \gamma$ at DA$\mathrm{\Phi }$NE

FASTERD is a Monte Carlo event generator to study the final state radiation both in the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ and $e^{+}{e}^{-}\to {\pi }^0{\pi }^0\gamma$ processes in the energy region of the $\varphi$-factory DA$\mathrm{\Phi }$NE. Differential spectra that include both initial and final state radiation and the interference between them are produced. Three different mechanisms for the $\pi \pi \gamma$ final state are considered: Bremsstrahlung process (both in the framework of sQED and Resonance Perturbation Theory), the $\varphi$ direct decay ($e^{+}{e}^{-}\to \varphi \to (f_0;f_0+\sigma )\gamma \to \pi \pi \gamma$) and the double resonance mechanism (as $e^{+}{e}^{-}\to \varphi \to {\rho }^{\pm }{\pi }^{\mp }\to {\pi }^{+}{\pi }^{-}\gamma$ and $e^{+}{e}^{-}\to \rho \to \omega {\pi }^0\to {\pi }^0{\pi }^0\gamma$). Additional models can be incorporated as well.