The depleted Higgs boson: searches for universal coupling suppression, invisible decays, and mixed-in scalars

TL;DR

This paper investigates how the Standard Model Higgs boson signals can be weakened by universal coupling suppression and invisible decays, exploring theories with additional scalar singlets and their detection prospects in future experiments.

Contribution

It provides a comprehensive survey of Higgs depletion mechanisms via scalar mixing and assesses current and future experimental constraints and detection strategies.

Findings

Coupling suppression and invisible decays can significantly weaken Higgs signals.

Precision Higgs measurements often outperform direct searches for extra scalars.

Next-generation experiments will enhance the ability to detect or constrain these depletion effects.

Abstract

Two simple ways by which the standard signals of the Standard Model Higgs boson can be depleted are: its couplings to fermions and gauge bosons can be suppressed by a universal factor, and part of its branching fraction can be drained into invisible final states. A large class of theories can impose one or both of these depletion factors, even if mild, by way of additional scalar bosons that are singlets under the Standard Model but mix with the Higgs boson. We perform a comprehensive survey of the present status of the depleted Higgs boson, and discuss future prospects for detecting the presence of either depletion factor. We also survey the constraints status and future detection prospects for the generic case of extra mixed-in scalars which generically lead to these depletion factors for the Higgs boson. We find, for example, that precision study of the Higgs boson in many cases is more powerful than searches for the extra scalar states, given the slate of next-generation experiments that are on the horizon.