Degenerate Higgs bosons: hiding a second Higgs at 125 GeV

TL;DR

This paper explores the possibility of two nearly identical Higgs bosons near 125 GeV, emphasizing the importance of quantum interference effects in their detection and analysis at the LHC.

Contribution

It provides a comprehensive analysis including interference effects, suggesting that two degenerate Higgs bosons near 125 GeV are highly probable and discusses how to distinguish this scenario from a single Higgs.

Findings

Degenerate Higgs bosons near 125 GeV are highly likely.

Quantum interference effects are crucial for accurate Higgs signatures.

Distinguishing degenerate from single Higgs scenarios is feasible.

Abstract

More than one Higgs boson may be present near the currently discovered Higgs mass, which can not be properly resolved due to the limitations in the intrinsic energy resolution at the Large Hadron Collider. We investigated the scenarios where two $CP$-even Higgs bosons are degenerate in mass. To correctly predict the Higgs signatures, quantum interference effects between the two Higgs bosons must be taken into account, which, however, has been often neglected in the literature. We carried out a global analysis including the interference effects for a variety of Higgs searching channels at the Large Hadron Collider, which suggests that the existence of two degenerate Higgs bosons near 125 GeV is highly likely. Prospects of distinguishing the degenerate Higgs case from the single Higgs case are discussed.