A Detailed Analysis of Flavour-changing Decays of Top Quarks as a Probe of New Physics at the LHC

TL;DR

This paper explores how rare flavour-changing top quark decays could serve as indicators of new physics at the LHC, especially if direct detection of new particles fails, by analyzing supersymmetry models and providing general predictive formulas.

Contribution

It develops a theoretical framework for predicting flavour-changing top decays in new physics models and illustrates these predictions with supersymmetry scenarios, including a general formula set for diverse models.

Findings

Potential detection of $t o c + Z^0$ decay at the LHC in certain supersymmetry models

Framework enables predictions of flavour-changing signals in various new physics scenarios

Provides general calculational formulas applicable to multiple models

Abstract

If the LHC should fail to observe direct signals for new physics, it may become necessary to look for new physics effects in rare events such as flavour-changing decays of the top quark, which, in the Standard Model, are predicted to be too small to be observed. We set up the theoretical framework in which experimentally accessible results can be expected in models of new physics, and go on to discuss two models of supersymmetry -- one with conserved $R$-parity, and one without $R$-parity -- to illustrate how the flavour-changing signals are predicted in these models. In the latter case, there is a distinct possibility of detecting the rare decay $t \to c + Z^0$ at the LHC. We also present a detailed set of very general formulae which can be used to make similar calculations in diverse models of new physics.