Discovery Prospects of a Light Scalar in the NMSSM

TL;DR

This paper explores the potential to discover a light scalar in the NMSSM by analyzing specific parameter regions that uplift the Higgs mass, proposing search strategies at the LHC to detect such states through various decay channels.

Contribution

It identifies NMSSM parameter regions allowing Higgs mass uplift with less fine-tuning and proposes experimental search channels for a light singlet-like Higgs at the LHC.

Findings

Singlet-doublet mixing region can be tested with diphoton searches at the LHC.

Reduced coupling measurements can exclude or confirm the parameter region.

Mass range 88-102 GeV for H_S is promising for future searches.

Abstract

We study a region in the NMSSM parameter space in which the mass of the SM-like Higgs boson is uplifted by ~4-17 GeV, allowing for stop masses and |A_t| <= 1 TeV alleviating the little fine tuning problem of the MSSM. An uplift of the mass of the SM-like Higgs boson is possible in two distinct regions in the NMSSM parameter space: Either for large lambda and small tan(beta) or, through singlet-doublet mixing, for small lambda and large tan(beta). For a mostly singlet-like Higgs state H_S with a mass below 125 GeV we investigate possible direct or indirect search channels at the run II of the LHC as function of the NMSSM-specific uplift of the mass of the SM-like Higgs boson: Direct production of H_S in gluon fusion with H_S decaying into diphotons, modified reduced couplings of the SM-like Higgs state, and the possible production of H_S in ggF -> A -> Z + H_S. We find that the region featuring singlet-doublet mixing can be tested if searches at the LHC at 13 TeV for BSM Higgs bosons in the mass range 88 - 102 GeV decaying into diphotons become sensitive to signal cross sections sigma(gg -> H_S -> diphotons) ~ 20 fb, or if measurements of the reduced coupling kappa_V(H_{SM}) of the SM Higgs boson to electroweak gauge boson exclude (or confirm) the region kappa_V(H_{SM}) <~ 0.93.