Constraints on the Unhiggs Model from Top Quark Decay

TL;DR

This paper calculates the top quark decay rate within the Unhiggs model, revealing differences from the Standard Model and using experimental data to constrain the model's parameters.

Contribution

It provides the first detailed calculation of top decay rates in the Unhiggs model and compares predictions with experimental data to set bounds on the model.

Findings

Certain Unhiggs parameters are ruled out by CDF data.

Predicted deviations in W polarization fractions differ from Standard Model.

Future LHC measurements could further constrain the model.

Abstract

We compute the top quark decay rate in the Unhiggs model. In this model, the longitudinally polarized W's are unparticles, owing to their Goldstone boson nature, while the transversely polarized W's are not. Thus the fraction of decays with a longitudinal W emitted is different than in the Standard Model. Comparing this calculation to CDF data, we are able to rule out some of the Unhiggs model parameter space. We also use the expected increased accuracy of top decay measurements at the LHC to anticipate further constraints on the Unhiggs.