CP--odd Correlation in the Decay of Neutral Higgs Boson into $ZZ$, $W^+W^-$, or $t{\bar t}$

TL;DR

This paper investigates CP violation in the neutral Higgs sector by constructing CP-odd correlations of final-state momenta in H→ZZ, H→W^+W^-, and H→t t̄ decays, without requiring final-state interactions. It introduces a CP-violating Yukawa source and derives momentum-based observables, notably the O'_{odd} combination, along with full angular distributions and integrated asymmetries to isolate CP-odd, CP̂T-even effects, applicable to hadronic and leptonic final states as well as e^+e^-–based production. The authors connect these observables to loop-induced CP-odd form factors D and D^W arising from top-quark loops, provide general substitutions for different fermion final states, and discuss potential enhancements in strongly interacting Higgs scenarios. The work offers a practical, model-independent framework for probing Higgs CP properties at future colliders via angular correlations in multiple decay channels and production processes.

Abstract

We investigate the possibility of detecting CP--odd angular correlations in the various decay modes of the neutral Higgs boson including the modes of a $ZZ$ pair, a $W^+W^-$ pair, or a heavy quark pair. It is a natural way to probe the CP character of the Higgs boson once it is identified. Final state interactions (i.e. the absorptive decay amplitude) is not required in such correlations. As an illustrative example we take the fundamental source of the CP nonconservation to be in the Yukawa couplings of the Higgs boson to the heavy fermions. A similar correlation in the process $e^+e^- \to l^+ l^- H$ is also proposed. Our analysis of these correlations will be useful for experiments in future colliders such as LEP II, SSC, LHC or NLC.