The tau lepton Monte Carlo Event Generation -- imprinting New Physics models with exotic scalar or vector states into simulation samples

TL;DR

This paper discusses the adaptation of Monte Carlo simulation tools for lepton pair production and tau decays to include new physics models involving exotic scalar or vector states, specifically focusing on phi resonances related to dark matter and g-2 anomalies.

Contribution

It introduces modifications to existing Monte Carlo programs to simulate processes involving narrow resonances like dark photons and phi particles, enhancing precision in Belle II data analysis.

Findings

Extended simulation capabilities for phi resonance processes.

Availability of modified programs for broader physics studies.

Application to g-2 anomaly investigations.

Abstract

The Monte Carlo for lepton pair production andtau decays consist of KKMC for lepton pair production, tauola for tau lepton decays and photos for radiative corrections in decays. An effort for adaptation of the system for precision data being collected at the Belle II experiment included simulation of additional light lepton pairs. Extension to processes where lepton pair is produced through narrow resonances, like dark photon or dark scalar phi resonances, was straight forward. Modified programs versions are available in stand-alone format from gitlab repository or through the basf2 system of Belle II software. It was explained recently during the International Workshop on Tau Lepton Physics September, 2021, Bloomington IN. Now we concentrate on simulations for phi resonance, a hypothetical object which could be responsible for anomalous moment g-2 in Z-\tau-\tau interactions through virtual contributions.