Collider-independent t tbar forward-backward asymmetries

TL;DR

This framework shows in a model independent fashion that a positive Tevatron asymmetry exceeding the standard model expectation is compatible with the small asymmetry measured at the LHC.

Abstract

We introduce the forward-backward asymmetries A_u, A_d corresponding to u ubar, d dbar -> t tbar production, respectively, at hadron colliders. These are collider- and center-of-mass-independent observables, directly related to the forward-backward and charge asymmetries measured at the Tevatron and the LHC, respectively. We discuss how to extract these asymmetries from data. Because these asymmetries are collider-independent, their measurement at these two colliders could elucidate the nature of the anomalous forward-backward asymmetry measured at the Tevatron. Our framework also shows in a model-independent fashion that a positive Tevatron asymmetry exceeding the standard model expectation is compatible with the small asymmetry measured at the LHC.

Figures (4)

• Figure 1: Ratio $R$ (defined in the text) between $u$ and $d$ functions, for $400 \leq m_{t \bar{t}} \leq 450$ GeV.
• Figure 2: Allowed region at 68% C.L. on $(A_u,A_d)$ in the $400 \leq m_{t \bar{t}} \leq 450$ GeV bin for the axigluon benchmark model. The dot represents the best-fit values.
• Figure 3: Allowed regions at 68% C.L. on $(A_u,A_d)$ resulting from a Tevatron-LHC combination for the axigluon benchmark model. The labels indicate the different $m_{t \bar{t}}$ bins (in GeV) considered.
• Figure 4: Allowed values for $A_{FB}$ and $A_C$, for several $m_{t \bar{t}}$ bins (in GeV).