Charge asymmetries of top quarks: a window to new physics at hadron colliders

TL;DR

This paper explores how charge asymmetries in top quark production at hadron colliders can serve as a sensitive indicator of new physics, especially for heavy resonances decaying into top quarks, surpassing traditional differential cross section methods.

Contribution

It demonstrates that charge asymmetry is a more effective observable than differential cross section for detecting heavy resonances in top quark production at the LHC.

Findings

Charge asymmetry provides higher statistical significance for new physics detection.

Resonance effects are more detectable at low invariant masses of top-antitop pairs.

Charge asymmetry is less affected by experimental challenges related to boosted top quarks.

Abstract

With the next start of LHC, a huge production of top quarks is expected. There are several models that predict the existence of heavy colored resonances decaying to top quarks in the TeV energy range. A peak in the differential cross section could reveal the existence of such a resonance, but this is experimentally challenging, because it requires selecting data samples where top and antitop quarks are highly boosted. Nonetheless, the production of such resonances might generate a sizable charge asymmetry of top versus antitop quarks. We consider a toy model with general flavour independent couplings of the resonance to quarks, of both vector and axial-vector kind. The charge asymmetry turns out to be a more powerful observable to detect new physics than the differential cross section, because its highest statistical significance is achieved with data samples of top-antitop quark pairs of low invariant masses.