Probing the Tevatron t tbar asymmetry at LHC

TL;DR

This paper investigates how new vector bosons and scalars could explain the Tevatron t tbar asymmetry and predicts their effects on the LHC t tbar tail, providing constraints on such models.

Contribution

It presents a model-independent analysis of potential new particles affecting the t tbar asymmetry and explores Standard Model extensions that fit the asymmetry without large tail enhancements.

Findings

Models with Z' and W' bosons or color-triplet scalars predict large LHC tail enhancements.

Data from CMS and ATLAS can exclude certain models as sole explanations.

Some Standard Model extensions can explain the asymmetry with moderate tail effects.

Abstract

We use an effective operator framework to study the contributions to the Tevatron t tbar asymmetry from arbitrary vector bosons and scalars, and compare with their effect on the t tbar tail at LHC. Our study shows, for example, that models reproducing the t tbar asymmetry by exchange of Z' and W' bosons or colour-triplet scalars lead to a large enhancement in the t tbar tail at LHC. This fact can be used to exclude these models as the sole explanation for the asymmetry, using the data already collected by CMS and ATLAS. Our analysis is model independent in the sense that we scan over all possible extra particles contributing to the asymmetry, and allow for general couplings. We also explore a class of Standard Model extensions which can accommodate the Tevatron asymmetry without contributing to the total t tbar cross section at first order, so that the enhancement of the tail at Tevatron and LHC is moderate.