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

Abstract

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 $\phi$-factory DA$\Phi$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 $\phi$ direct decay ($e^+e^-\to\phi\to (f_0;f_0+\sigma)\gamma\to \pi\pi\gamma$) and the double resonance mechanism (as $e^+e^-\to\phi\to \rho^\pm\pi^\mp\to \pi^+\pi^-\gamma$ and $e^+e^-\to\rho\to \omega\pi^0\to \pi^0\pi^0\gamma$). Additional models can be incorporated as well.