Constraints on the Unhiggs Model from Top Quark Decay

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.