Constraints on W Prime Models for the ttbar Asymmetry

TL;DR

This paper examines the constraints on W' gauge boson models as explanations for the Tevatron ttbar asymmetry, highlighting theoretical and experimental challenges related to associated Z' bosons and symmetry breaking.

Contribution

It analyzes the theoretical implications of W' models, showing that large mass splitting with Z' requires non-perturbative symmetry breaking mechanisms.

Findings

Null dijet and dilepton resonance searches constrain W' models.

Large mass splitting between W' and Z' implies non-perturbative symmetry breaking.

Perturbative models cannot easily accommodate the required mass splitting.

Abstract

We discuss if the Tevatron ttbar asymmetry can be explained by T-channel exchange of a W' gauge boson coupling to down and top quarks. In a spontaneously broken gauge theory, such a W' is necessarily accompanied by a Z' at a similar mass scale. Null results from Tevatron searches for dijet and dilepton resonances imply large mass splitting between the $W'$ and $Z'$. We argue that such splitting can only be accomplished if the gauge symmetry is broken by a scalar in a large dimension representation of the gauge group, for which no perturbative description exists.