Forward-backward asymmetries of the bottom and top quarks in warped extra-dimensional models: LHC predictions from the LEP and Tevatron anomalies

TL;DR

This paper explores warped extra-dimensional models with gauge custodial symmetry to explain anomalies in bottom and top quark forward-backward asymmetries observed at LEP and Tevatron, and predicts new signatures at the LHC.

Contribution

It presents a specific warped extra-dimensional model addressing both A_FB^b and A_FB^t anomalies with phenomenological consistency and predicts a Kaluza-Klein gluon signature at the LHC.

Findings

Model can simultaneously explain LEP and Tevatron anomalies.

Predicts a ~1.5-2 TeV Kaluza-Klein gluon affecting top pair production.

Constraints from LEP, Tevatron, and LHC are satisfied.

Abstract

Within the paradigm of warped extra dimensions, third generation quarks are expected to be the most sensitive to effects beyond the Standard Model. The anomalies observed at the LEP and Tevatron colliders in the forward-backward asymmetries of the bottom (A_FB^b) and top (A_FB^t) quarks can thus be seen as early signatures of warped extra-dimensional scenarios. We propose a realization of such a scenario, with a gauge custodial symmetry in the bulk, which allows to address simultaneously the A_FB^b anomaly and the discrepancies observed recently on A_FB^t at high top quark rapidities and ttbar invariant masses. We also show that the various phenomenological constraints arising from LEP, Tevatron and LHC can be satisfied within the considered model. The model predicts new features, induced by a Kaluza-Klein excitation of the gluon at a mass ~1.5-2 TeV, in top quark pair production at the 7 TeV LHC.