Trilinear gauge boson couplings in the standard model with one universal extra dimension

TL;DR

This paper calculates one-loop effects of universal extra dimensions on gauge boson couplings in the Standard Model, finding results comparable to SM contributions and potentially observable at future colliders.

Contribution

It provides the first detailed calculation of one-loop KK mode contributions to WWgamma and WWZ couplings in a five-dimensional SM extension with universal extra dimensions.

Findings

Results are comparable to SM one-loop contributions.

Contributions decouple at large compactification scales.

Potential observability at next linear collider.

Abstract

One-loop effects of Standard Model (SM) extensions comprising universal extra dimensions are essential as a consequence of Kaluza-Klein (KK) parity conservation, for they represent the very first presumable virtual effects on low-energy observables. In this paper, we calculate the one-loop CP-even contributions to the SM WWgamma and WWZ gauge couplings produced by the KK excited modes that stand for the dynamical variables of the effective theory emerged from a generalization of the SM to five dimensions, in which the extra dimension is assumed to be universal, after compactification. The employment of a covariant gauge-fixing procedure that removes gauge invariance associated to gauge KK excited modes, while keeping electroweak gauge symmetry manifest, is a main feature of this calculation, which is performed in the Feynman 't Hooft gauge and yields finite results that consistently decouple for a large compactification scale. After numerical evaluation, our results show to be comparable with the one-loop SM contributions and well within the reach of a next linear collider.