Establishing a No-Lose Theorem for NMSSM Higgs Boson Discovery at the LHC

TL;DR

This paper demonstrates that the LHC has a high likelihood of discovering at least one NMSSM Higgs boson across most of the parameter space, especially when including WW-fusion detection modes, despite some challenging scenarios.

Contribution

The study provides a comprehensive analysis of the NMSSM parameter space, establishing conditions under which Higgs detection at the LHC is guaranteed, thus forming a no-lose theorem for NMSSM Higgs discovery.

Findings

Including WW-fusion modes ensures detection in all scanned points.

Detection is unlikely only if Higgs decays predominantly to SUSY particles.

Combining ATLAS and CMS data enhances discovery potential.

Abstract

We scan the parameter space of the NMSSM for the observability of at least one Higgs boson at the LHC with $300\fbi$ integrated luminosity, taking the present LEP2 constraints into account. We restrict the scan to those regions of parameter space for which Higgs boson decays to other Higgs bosons and/or supersymmetric particles are kinematically forbidden. We find that if $WW$-fusion detection modes for a light Higgs boson are not taken into account, then there are still significant regions in the scanned portion of the NMSSM parameter space where no Higgs boson can be observed at the $5\sigma$ level, despite the recent improvements in ATLAS and CMS procedures and techniques and even if we combine all non-fusion discovery channels. However, if the $WW$-fusion detection modes are included using the current theoretical study estimates, then we find that for all scanned points at least one of the NMSSM Higgs bosons will be detected. If the estimated $300\fbi$ significances for ATLAS and CMS are combined, one can also achieve $5\sigma$ signals after combining just the non-$WW$-fusion channels signals. We present the parameters of several particularly difficult points, and discuss the complementary roles played by different modes. We conclude that the LHC will discover at least one NMSSM Higgs boson unless there are large branching ratios for decays to SUSY particles and/or to other Higgs bosons.