$t\to cg$ and $t\to cZ$ in Universal Extra Dimensional Models

TL;DR

This paper performs a detailed one-loop analysis of rare top quark decays in universal extra dimensional models, showing minimal scenarios align with Standard Model predictions, while non-minimal setups can enhance decay rates.

Contribution

It provides the first comprehensive one-loop calculation of $t o cg$ and $t o cZ$ decays in UED models, including non-minimal boundary effects.

Findings

Branching ratios unchanged in minimal UED scenarios.

Non-minimal boundary terms can significantly enhance decay rates.

Enhanced decay rates are compatible with current experimental constraints.

Abstract

In this work we perform a complete one-loop calculation of the flavor-changing top quark decays $t\to cg$ and $t\to cZ$ in the universal extra dimensional models. We find that the branching ratios of these decays in the minimal scenario remain unaltered from the Standard Model expectations for currently allowed values of the inverse compactification radius. In the non-minimal setup, the branching ratios can be enhanced from the Standard Model due to the presence of boundary localized terms which modify the mass spectrum and couplings in the theory in a non-trivial way. We also check the compatibility of the parameter choices that result in enhancements in these rare decays with other experimental observations.