Top quark forward-backward asymmetry at Tevatron and its implications at the LHC

TL;DR

This paper investigates the top quark forward-backward asymmetry observed at Tevatron, explores new physics models with W' and Z' bosons to explain it, and assesses their implications for LHC measurements, especially the one-sided forward-backward asymmetry.

Contribution

It performs a comprehensive analysis of Z' and W' models explaining the Tevatron asymmetry and predicts their observable effects at the LHC, including the one-sided asymmetry.

Findings

Z' models can be tested via same sign top production at Tevatron.

Both W' and Z' models can produce sizable asymmetries at the LHC.

Parameter space consistent with Tevatron data can lead to observable effects at LHC.

Abstract

The measurement of forward-backward asymmetry in the top and anti-top quark ($t \bar{t}$) production has been recently reconfirmed by the CDF Collaboration and shows a more than $3\sigma$ deviation from the Standard Model(SM) prediction in the large $t \bar{t}$ invariant mass region. Models with new W$^{\prime}$ or Z$^{\prime}$ bosons have been invoked to explain this deviation. In the context of these models we perform a $\chi^2$ analysis with all the available experimental numbers in different $\Delta Y$ and $M_{t \bar{t}}$ bins. We show that for the $Z^{\prime}$ model the region of parameter space which explain the Tevatron asymmetry can be probed in the same sign top production channel by Tevatron itself. Moreover, we consider a recently proposed observable, the one sided forward-backward asymmetry ($A_{OFB}$) at the LHC and conclude that both the W$^{\prime}$ and Z$^{\prime}$ models can lead to sizable $A_{OFB}$ even at the LHC running at a center of mass energy of 7 TeV for the model parameters consistent with the Tevatron measurements.