Constraints on generalized non-standard $tbW$ couplings

TL;DR

This paper investigates model-independent constraints on generalized non-standard $tbW$ couplings using an effective Lagrangian with dimension-6 operators, analyzing their effects on top quark decay data.

Contribution

It provides the first comprehensive, model-independent analysis of all four complex non-standard $tbW$ couplings within an effective Lagrangian framework.

Findings

Constraints on some couplings are weak due to mutual cancellations.

All non-standard couplings are treated as complex numbers in the analysis.

Experimental data limits are derived for the non-standard $tbW$ interactions.

Abstract

General non-standard $tbW$ couplings are studied as model independently as possible based on the effective Lagrangian consisting of the dimension-6 operators, which is an extension of the standard-model Lagrangian. The $tbW$-interaction Lagrangian in this framework includes four kinds of couplings, which could be complex. Constraints on those non-standard $tbW$ couplings are obtained by comparing the experimental data related to the $t\to b W$ process with the corresponding theoretical formulas derived from the effective Lagrangian. The constraints on some sets of the non-standard couplings are shown not to be so strong because those couplings balance out each other as we treat all the non-standard couplings as complex numbers at the same time.