A composite Higgs model analysis of forward-backward asymmetries in the production of tops at Tevatron and bottoms at LEP and SLC

TL;DR

This paper investigates how composite Higgs models can explain observed anomalies in forward-backward asymmetries of top and bottom quarks at Tevatron and LEP+SLC, proposing a two-sector model that aligns with experimental data.

Contribution

The paper introduces a two-sector composite Higgs model that effectively describes fermionic resonances and protects Z-couplings, improving the explanation of quark asymmetry anomalies.

Findings

Model predicts up to 10% increase in top forward-backward asymmetry.

Small decrease in top-antitop production cross section.

Non-universal Z-coupling corrections to light quarks are around 0.001.

Abstract

We perform a joint analysis of the prediction of composite Higgs models for the discrepancies of the forward-backward asymmetries of top and bottom quarks at Tevatron and LEP+SLC, respectively. We build a two sector model which can be thought as an effective low energy description of 5D warped models and choose the quantum numbers of the fermionic resonances to protect the Z-couplings of the partially composite Standard Model light quarks. We analyze the cross section, forward-backward asymmetry and invariant mass distribution of the top anti-top production at Tevatron, as well as the bottom forward-backward asymmetry and the Z-branching fraction into b-quarks at LEP and SLC, for the two sector model. In the region of the parameter space that naturally leads to the Standard Model spectrum and solves the bottom anomaly, the model improves the top forward-backward asymmetry, giving a prediction of up to 10%, and predicts a small decrease of the $t \bar t$ cross section. It also predicts non-universal corrections of the Z-couplings to the light quarks of order 0.001.