Experimental signatures of a light singlet-like scalar in NMSSM

TL;DR

This paper explores a scenario in the NMSSM where a light singlet-like scalar can produce an enhanced diphoton signal within experimental bounds, affecting Higgs couplings and signals.

Contribution

It demonstrates that a light singlet-like scalar in NMSSM can have a larger diphoton signal than the SM Higgs and correlates this with Higgs mass corrections and coupling anti-correlations.

Findings

Singlet-like scalar diphoton signal can exceed SM Higgs for 60-110 GeV.

Enhanced diphoton signal correlates with positive Higgs mass correction.

Enhanced singlet-like scalar signal implies reduced 125 GeV Higgs signal in diphoton and WW/ZZ channels.

Abstract

NMSSM with a light singlet-like scalar and strongly suppressed couplings to $b$ and $\tau$ is investigated. It is shown that in such a scenario the singlet-like scalar to diphoton signal can be larger than for the SM Higgs for a wide range of masses between 60 and 110 GeV, in agreement with all the LEP and LHC data. Enhancement of the singlet-like scalar to diphoton signal is correlated with positive correction to the SM-like Higgs mass from mixing between SM-like Higgs and the singlet. It is also shown that the couplings to $b$ and $\tau$ and, in consequence, branching ratios of the SM-like Higgs are anti-correlated with those of the singlet-like scalar. If the singlet-like scalar to diphoton signal is enhanced, the signal strengths of the 125 GeV Higgs in the diphoton and $WW^*/ZZ^*$ channels are predicted to be smaller than for the SM Higgs.