On interference effects in top-philic decay chains

TL;DR

This paper explores interference effects in top-philic decay chains, emphasizing their impact on Higgs boson signals and proposing asymmetric cascade decays as promising signatures for discovering new physics and probing CP properties.

Contribution

It introduces the significance of interference effects in decay chains, especially asymmetric cascades, as robust signatures for new physics and CP spectroscopy in scalar extensions of the Standard Model.

Findings

Interference effects can significantly alter Higgs decay signals.

Asymmetric cascade decays are promising for discovering new physics.

Interference patterns can aid in CP property determination.

Abstract

Sizeable exotic Higgs boson production through gluon fusion via top quark loops is correlated with large Higgs decay probabilities into top quark final states, if these are kinematically accessible. It is known that $gg\to S \to t\bar t$ is particularly susceptible to signal-background interference effects that can significantly impact discovery sensitivities. In such an instance, identifying more robust signatures to enhance the discovery sensitivity becomes necessary, shifting phenomenological focus to final states that show a reduced destructive signal-background interference. In this work, we discuss the phenomenological relevance of signal-signal and signal-background interference effects for decay chains. In particular, we identify asymmetric cascade decays in models of scalar extensions of the SM Higgs sector as new promising candidates. In parallel, characteristic interference patterns can provide a formidable tool for indirect CP spectroscopy of BSM sectors if a discovery is made in the future. This motivates associated searches at present and future colliders as robust discovery modes of new physics, in addition to serving as a sensitive tool for the reconstruction of the underlying UV electroweak potential.