125 GeV Higgs and enhanced diphoton signal 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 between 60 and 110 GeV, consistent with collider data, and examines its implications for the 125 GeV Higgs properties.

Contribution

It demonstrates that a light singlet-like scalar in NMSSM can have an enhanced diphoton signal and analyzes the correlations with the SM-like Higgs mass and couplings.

Findings

Enhanced diphoton signal for the singlet-like scalar between 60-110 GeV.

Anti-correlation between the couplings of the singlet-like scalar and the SM-like Higgs.

Predicted reduction in the 125 GeV Higgs signal strengths 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.