Minimal Flavour Violation and Anomalous Top Decays

TL;DR

This paper proposes a model-independent framework to test minimal flavour violation in anomalous top quark decays at the LHC, using effective field theory and spurion analysis, to understand potential new physics beyond the standard model.

Contribution

It introduces a novel, model-independent scheme to analyze minimal flavour violation in top quark decays within an effective field theory framework.

Findings

Calculated decay rates for anomalous top decays in terms of effective couplings.

Performed spurion analysis to relate flavour violation to effective operators.

Applied the framework to a two-Higgs doublet model of type II.

Abstract

Top quark physics at the LHC may open a window to physics beyond the standard model and even lead us to an understanding of the phenomenon "flavour". However, current flavour data is a strong hint that no "new physics" with a generic flavour structure can be expected in the TeV scale. In turn, if there is "new physics" at the TeV scale, it must be "minimally flavour violating". This has become a widely accepted assumption for "new physics" models. In this paper we propose a model-independent scheme to test minimal flavour violation for the anomalous charged $Wtq$, $q\in{d,s,b}$, and flavour-changing $Vtq$, $q\in{u,c}$ and $V\in{Z,\gamma,g}$ couplings within an effective field theory framework, i.e., in a model-independent way. We perform a spurion analysis of our effective field theory approach and calculate the decay rates for the anomalous top-quark decays in terms of the effective couplings for different helicities by using a two-Higgs doublet model of type II, under the assumption that the top-quark is produced at a high-energy collision and decays as a quasi-free particle.