$tbW$ Anomalous Couplings in the Two Higgs Doublet Model

TL;DR

This paper performs a detailed one-loop calculation of $tbW$ couplings in the Two Higgs Doublet Model, assessing their small deviations and impact on top quark observables.

Contribution

It provides the first comprehensive one-loop analysis of $tbW$ anomalous couplings within the Two Higgs Doublet Model, including their effects on top quark polarization and $W$ helicity fractions.

Findings

Relative corrections to anomalous couplings are generally small.

Anomalous couplings have limited impact on top polarization.

Effects on $W$ helicity fractions are minimal.

Abstract

We make a complete one loop calculation of the $tbW$ couplings in the Two Higgs Doublet Model. We evaluate both the anomalous couplings $g_L$ and $g_R$ as well as left handed and right handed component of $tbW$. The computation is done in the Feynman gauge using the on-shell scheme renormalization for the Standard Model wave functions and parameters. We first show that the relative corrections to these anomalous couplings are rather small in most regions of the parameter space. We then analyze the effects of these anomalous couplings on certain observables such as top quark polarization in single top production through $t-$channel as well as $W^\pm$ boson helicity fractions in top decay.