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

Abstract

FASTERD is a Monte Carlo event generator to study the final state radiation both in the $e^+e^-\toπ^+π^-γ$ and $e^+e^-\toπ^0π^0γ$ processes in the energy region of the $ϕ$-factory DA$Φ$NE. Differential spectra that include both initial and final state radiation and the interference between them are produced. Three different mechanisms for the $ππγ$ final state are considered: Bremsstrahlung process (both in the framework of sQED and Resonance Perturbation Theory), the $ϕ$ direct decay ($e^+e^-\toϕ\to (f_0;f_0+σ)γ\to ππγ$) and the double resonance mechanism (as $e^+e^-\toϕ\to ρ^\pmπ^\mp\to π^+π^-γ$ and $e^+e^-\toρ\to ωπ^0\to π^0π^0γ$). Additional models can be incorporated as well.