One Universal Extra Dimension in Pythia

TL;DR

This paper details the implementation of the Universal Extra Dimensions model in the Pythia generator, including KK excitations, decay processes, and gravity-mediated decays, facilitating simulations of extra-dimensional physics.

Contribution

The paper introduces a comprehensive implementation of the minimal Universal Extra Dimensions model in Pythia, including KK excitations and decay channels, with calculations at one loop.

Findings

Implementation covers lowest-lying KK excitations of SM particles

Includes gravity-mediated decay channels with extra dimensions

Provides cross sections and decay modes for simulations

Abstract

The Universal Extra Dimensions model has been implemented in the Pythia generator from version 6.4.18 onwards, in its minimal formulation with one inverse-TeV-sized extra dimension. The additional possibility of gravity-mediated decays, through a variable number of inverse-eV-sized extra dimensions into which only gravity extends, is also available. The implementation covers the lowest-lying Kaluza-Klein (KK) excitations of Standard Model particles, except for the excitations of the Higgs fields, with the mass spectrum calculated at one loop. 2 -> 2 tree-level production cross sections and KK number conserving 2-body decays are included. Mixing between iso-doublet and -singlet KK excitations is neglected thus far, and is expected to be negligible for all but the top sector.