The forward-backward asymmetry of top quark production at the Tevatron in warped extra dimensional models

TL;DR

This paper investigates whether warped extra dimensional models can explain the observed forward-backward asymmetry of top quark production at the Tevatron, considering constraints from electroweak precision data.

Contribution

It analyzes the potential of warped extra dimensional models to account for the top quark asymmetry anomaly, highlighting the challenges posed by existing electroweak constraints.

Findings

Kaluza-Klein excitations can explain bottom quark asymmetry anomalies.

Generating a significant top quark asymmetry via Kaluza-Klein gluons is difficult.

Electroweak precision data impose strong constraints on such models.

Abstract

The CDF and D0 experiments have reported on the measurement of the forward-backward asymmetry of top quark pair production at the Tevatron and the result is that it is more than 2 standard deviations above the predicted value in the Standard Model. This has to be added to the longstanding anomaly in the forward-backward asymmetry for bottom quark production at LEP which is 3 standard deviations different from the Standard Model value. The discrepancy in the bottom asymmetry can be accounted for by the contributions of Kaluza-Klein excitations of electroweak gauge bosons at LEP in warped extra dimensional models in which the fermions are localized differently along the extra dimension so that the gauge interactions of heavy third generation fermions are naturally different from that of light fermions. In this paper, we show that it is more difficult to elaborate a model generating a significant top asymmetry in a similar way -- through exchanges of Kaluza-Klein gluons at the Tevatron -- due to the indirect constraints originating from precision electroweak data.