Top Quark Rare Decays via Loop-Induced FCNC Interactions in Extended Mirror Fermion Model

TL;DR

This paper investigates rare top quark decays via loop-induced FCNC interactions within an extended mirror fermion model, revealing potential branching ratios that could be detectable and comparable to other new physics scenarios.

Contribution

It introduces an extended mirror fermion model to study top FCNC decays, predicting branching ratios within experimental reach, expanding the understanding of new physics effects on rare top decays.

Findings

Branching ratios for $t o Zc$ range from $10^{-6}$ to $10^{-8}$.

Predicted decay rates are comparable to other new physics models.

Potential to probe these decays at current collider experiments.

Abstract

Flavor changing neutral current (FCNC) interactions for a top quark $t$ decays into $Xq$ with $X$ represents a neutral gauge or Higgs boson, and $q$ a up- or charm-quark are highly suppressed in the Standard Model (SM) due to the Glashow-Iliopoulos-Miami mechanism. Whilst current limits on the branching ratios of these processes have been established at the order of $10^{-4}$ from the Large Hadron Collider experiments, SM predictions are at least nine orders of magnitude below. In this work, we study some of these FCNC processes in the context of an extended mirror fermion model, originally proposed to implement the electroweak scale seesaw mechanism for non-sterile right-handed neutrinos. We show that one can probe the process $t \to Zc$ for a wide range of parameter space with branching ratios varying from $10^{-6}$ to $10^{-8}$, comparable with various new physics models including the general two Higgs doublet model with or without flavor violations at tree level, minimal supersymmetric standard model with or without $R$-parity, and extra dimension model.