Effective Field Theory for Nonstandard Top Quark Couplings

TL;DR

This paper develops an effective field theory framework to analyze nonstandard top quark couplings, demonstrating its renormalizability and deriving bounds from electroweak precision data and top decay measurements.

Contribution

It introduces a renormalizable effective field theory approach for dimension-six top quark operators affecting electroweak observables.

Findings

Bound on operator coefficient from oblique parameter U

Comparison with bounds from top-quark decay

Validation of the effective field theory's renormalizability

Abstract

We present an effective-field-theory calculation of the effect of a dimension-six operator involving the top quark on precision electroweak data via a top-quark loop. We demonstrate the renormalizability, in the modern sense, of the effective field theory. We use the oblique parameter U to bound the coefficient of the operator, and compare with the bound derived from top-quark decay.