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

Figures (1)

• Figure 1: Contour levels in the plane $[c_{q_L}, c_{t_R}]$ ($c_{q_L}$ is for first generation) for the total cross section $\sigma(t\bar{t})$ (dashed lines) and the forward--backward asymmetry $A^t_{FB}$ [in %] for constant (thin solid lines) and variable (thick solid lines) total decay width for the KK gluon; the other parameters are as in eq. (\ref{['RSparametersBIS']}).