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

TL;DR

FASTERD is a Monte Carlo event generator designed to simulate final state radiation in electron-positron collisions producing pions and a photon at DAΦNE, incorporating multiple mechanisms and interference effects.

Contribution

It introduces a comprehensive Monte Carlo generator that models various mechanisms of pion-photon final states, including interference effects, for the first time in this energy region.

Findings

Produces differential spectra with initial and final state radiation.

Includes multiple mechanisms like Bremsstrahlung, phi decay, and double resonance.

Allows incorporation of additional models.

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.