Azimuthal Correlations in Top Pair Decays and The Effects of New Heavy Scalars

TL;DR

This paper analyzes azimuthal correlations in top quark pair decays within QCD and explores how new heavy scalars, including CP-violating effects, could alter these distributions, providing insights into potential new physics signals.

Contribution

It introduces a leading-order QCD calculation of azimuthal correlations and examines the impact of new heavy scalars with CP violation on these observables.

Findings

Deviations in azimuthal correlations can indicate new heavy scalars.

Interference effects between QCD and new physics alter the distributions.

CP-violating couplings significantly affect the correlation patterns.

Abstract

We present the azimuthal correlations in the decay products of the top quark pair created in the process $gg \to t \tbar \to b \bbar \wplus \wminus$ calculated in leading-order QCD. We then discuss deviations in this distribution that could arise from New Physics contributions, focusing, in particular, on the case of a new heavy scalar coupling to the top quark and produced via the gluon fusion mechanism. Within this scenario we consider two cases: one in which the top quark is the only particle with a significant coupling to the scalar and another in which there are additional heavy fermions that modify the effective coupling of the scalar to gluons. We discuss the effects on the overall cross section and azimuthal correlations of the top quark decay products, with particular emphasis on the effect of interference between the QCD and New Physics contributions and on the existence of CP-nonconserving couplings.