ee$\in$MC: Simulation of ${\mathbf{e}}^{+}{\mathbf{e}}^{-}\to {\mu }^{+}{\mu }^{-}(\gamma )$ and ${\mathbf{e}}^{+}{\mathbf{e}}^{-}\to {\tau }^{+}{\tau }^{-}(\gamma )$ Events

Abstract

We present a new Monte-Carlo generator, {\tt ee$\in$MC}, for the simulation of $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}(\gamma )$, $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}(\gamma )$ and $\tau$ lepton decays which is suitable for $e^{+}{e}^{-}$ colliders from threshold up to energy of $\sim 10.58GeV$. The $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}(\gamma )$, $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}(\gamma )$ interactions are computed up to the exact LO matrix element where the running of ${\alpha }_{QED}$ includes both the LO leptonic and hadronic vacuum polarization. Infra-red divergences are investigated within the Yennie-Frautschi-Suura Exponentiation formalism, where several well-known approximations and a formulation based on the exact LO contribution to the soft and virtual photons are applied. The simulation of the $\tau$ lepton consists of the leptonic decay modes at Born level and theoretical models based on Flux-Tube Breaking Models and Chiral Resonance Lagrangian Models as well as experimental models for the majority of semi-leptonic decay modes. This includes hadronic models for investigating the origin of low mass scalar sector recently observed in decays of the $\tau$ lepton and their association with the origin of the constituent-quark mass through Chiral-symmetry Breaking.

Comments: 35 pages, 15 Figures, 7 Tables. Submitted to Physics Letter B 2021-05-02, Nuclear Physics B 2021-10-28