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

Ulrich Ellwanger, John F. Gunion, Cyril Hugonie, Stefano Moretti

TL;DR

This paper extends the MSSM no-lose Higgs discovery theorem to the NMSSM by exploring parameter regions where the light SM-like Higgs decays predominantly as $h\to aa$, rendering standard LHC search channels ineffective. By scanning NMSSM parameters, applying LEP constraints, and computing Higgs masses, mixings, and BRs with radiative corrections, the authors identify benchmark points where an alternative channel, $WW\to h\to aa$, could enable discovery at the LHC with $L=300~{\rm fb}^{-1}$ per detector, provided the $aa$-decay background is controllable. They show that these difficult points can still be probed through a combination of LHC channels, and that a Linear Collider would robustly confirm and elucidate the $h\to aa$ channel, measuring BRs and the $haa$ coupling. The work predicts that the LHC could deliver strong hints via the $WW\to h\to aa$ signal, while the LC would deliver precise measurements and unambiguous confirmation, together achieving comprehensive NMSSM Higgs coverage across parameter space.

Abstract

We scan the parameter space of the NMSSM for the observability of a Higgs boson at the LHC with $300 {\rm fb}^{-1}$ integrated luminosity per detector, taking the present LEP constraints into account. We focus on the regions of parameter space for which none of the usually considered LHC detection modes are viable due to the fact that the only light non-singlet (and, therefore, potentially visible) Higgs boson, $h$, decays mainly to two CP-odd light Higgs bosons, $h\to a a$. We simulate the $WW\to h \to aa$ detection mode. We find that this signal may be detectable at the LHC as a signal/background $\sim 600/600$ bump in the tail of a rapidly falling mass distribution. If further study gives us confidence that the shape of the background tail is predictable, then we can conclude that NMSSM Higgs detection at the LHC will be possible throughout all of parameter space by combining this signal with the usual detection modes previously simulated by ATLAS and CMS. We also show that this $WW\to h\to aa$ signal will be highly visible at the LC due to its cleaner environment and high luminosity. We present a study of the production modes and decay channels of interest at the LC.

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

TL;DR

This paper extends the MSSM no-lose Higgs discovery theorem to the NMSSM by exploring parameter regions where the light SM-like Higgs decays predominantly as , rendering standard LHC search channels ineffective. By scanning NMSSM parameters, applying LEP constraints, and computing Higgs masses, mixings, and BRs with radiative corrections, the authors identify benchmark points where an alternative channel, , could enable discovery at the LHC with per detector, provided the -decay background is controllable. They show that these difficult points can still be probed through a combination of LHC channels, and that a Linear Collider would robustly confirm and elucidate the channel, measuring BRs and the coupling. The work predicts that the LHC could deliver strong hints via the signal, while the LC would deliver precise measurements and unambiguous confirmation, together achieving comprehensive NMSSM Higgs coverage across parameter space.

Abstract

We scan the parameter space of the NMSSM for the observability of a Higgs boson at the LHC with integrated luminosity per detector, taking the present LEP constraints into account. We focus on the regions of parameter space for which none of the usually considered LHC detection modes are viable due to the fact that the only light non-singlet (and, therefore, potentially visible) Higgs boson, , decays mainly to two CP-odd light Higgs bosons, . We simulate the detection mode. We find that this signal may be detectable at the LHC as a signal/background bump in the tail of a rapidly falling mass distribution. If further study gives us confidence that the shape of the background tail is predictable, then we can conclude that NMSSM Higgs detection at the LHC will be possible throughout all of parameter space by combining this signal with the usual detection modes previously simulated by ATLAS and CMS. We also show that this signal will be highly visible at the LC due to its cleaner environment and high luminosity. We present a study of the production modes and decay channels of interest at the LC.

Paper Structure

This paper contains 7 sections, 9 equations, 1 figure, 1 table.

Table of Contents

  1. Introduction
  2. NMSSM Parameters
  3. Invisible Points at the LHC
  4. New Channels at the LHC and LC
  5. Results for the LHC
  6. The LC scenario
  7. Conclusions

Figures (1)

  • Figure 1: Reconstructed mass of the $jj\tau^+\tau^-$ system for signals and backgrounds after the selections described, at the LHC (top) and a LC (bottom). We plot $d\sigma/dM_{jj\tau^+\tau^-}$ [fb/10 GeV] vs $M_{jj\tau^+\tau^-}$ [GeV] using GETJET and HERWIG 6.4 with: IPROC=3720 adapted to NMSSM couplings and decay rates for the signal and IPROC=1706 for the background at the LHC; IPROC=920 adapted to NMSSM couplings and decay rates for the signal and IPROC=126(250) for the $t\bar{t}[ZZ]$ background at a LC). Statistics used: 500,000 points. Normalization is to the total cross section after cuts. In both plots, the lines corresponding to points 4 and 5 are visually indistinguishable. No $K$ factors are included.