ee$\in$MC: Simulation of $e^{+}e^{-} \to Hadrons (n\gamma)$ Events

Abstract

The ee$\in$MC generator package is extended to include $e^{+}e^{-} \to Hadrons (n\gamma)$ events where the photons can be generated in either the initial-state or final-state production. In particular, the $e^{+}e^{-} \to \pi^{+}\pi^{-} (n\gamma)$, $e^{+}e^{-} \to \Upsilon(4s) (m\gamma) \to B^{+}B^{-} (n\gamma)$ and $e^{+}e^{-} \to \Upsilon(4s) (m\gamma) \to B^{0}\bar{B}^{-} (n\gamma)$ decay channels have been implemented in the generator. The B-mesons are not decayed in ee$\in$MC, but are left for other generators that specialized in B-mesons. Both the initial-state-radiation and final-state-radiation are simulated using the Yennie-Frautschi-Suura Exponentiation procedure \cite{Yennie:1961}, where several effective models are implemented to investigate the assumption of the radiative structure of the final-state vertex. The impact of these radiative models on the $e^{+}e^{-} \to \Upsilon(4s) (m\gamma) \to B^{+}B^{-} (n\gamma)$ and $e^{+}e^{-} \to \Upsilon(4s) (m\gamma) \to B^{0}\bar{B}^{-} (n\gamma)$ processes, excludes some models, particularly, in regards to the Coulomb potential. This has an important impact for meson and baryon systems near threshold.