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Difficult Scenarios for NMSSM Higgs Discovery at the LHC

Ulrich Ellwanger, John F. Gunion, Cyril Hugonie

TL;DR

The paper examines NMSSM Higgs discovery at the LHC, showing that NMSSM Higgs-to-Higgs decays can suppress standard search channels and undermine MSSM-like no-lose theorems. Using NMHDECAY and channel-rescaling methods, it analyzes parameter space and finds a small region where a 5σ discovery is guaranteed with L=300 fb^-1, but in the majority, Higgs-to-Higgs decays necessitate Higgs-pair final-state searches (notably h_H → h_L h_L). Eight benchmark points illustrate scenarios where standard channels fail and WW fusion with Higgs-pair decays may be the only viable discovery mode, while collider implications extend to Tevatron, e+e−, and γγ facilities for cross-checks and precision tests. The work underscores the need for alternative search strategies and future colliders to fully probe NMSSM Higgs dynamics.

Abstract

We identify scenarios not ruled out by LEP data in which NMSSM Higgs detection at the LHC will be particularly challenging. We first review the `no-lose' theorem for Higgs discovery at the LHC that applies if Higgs bosons do not decay to other Higgs bosons - namely, with L=300 fb^-1, there is always one or more `standard' Higgs detection channel with at least a 5 sigma signal. However, we provide examples of no-Higgs-to-Higgs cases for which all the standard signals are no larger than 7 sigma implying that if the available L is smaller or the simulations performed by ATLAS and CMS turn out to be overly optimistic, all standard Higgs signals could fall below 5 sigma even in the no-Higgs-to-Higgs part of NMSSM parameter space. In the vast bulk of NMSSM parameter space, there will be Higgs-to-Higgs decays. We show that when such decays are present it is possible for all the standard detection channels to have very small significance. In most such cases, the only strongly produced Higgs boson is one with fairly SM-like couplings that decays to two lighter Higgs bosons (either a pair of the lightest CP-even Higgs bosons, or, in the largest part of parameter space, a pair of the lightest CP-odd Higgs bosons). A number of representative bench-mark scenarios of this type are delineated in detail and implications for Higgs discovery at various colliders are discussed.

Difficult Scenarios for NMSSM Higgs Discovery at the LHC

TL;DR

The paper examines NMSSM Higgs discovery at the LHC, showing that NMSSM Higgs-to-Higgs decays can suppress standard search channels and undermine MSSM-like no-lose theorems. Using NMHDECAY and channel-rescaling methods, it analyzes parameter space and finds a small region where a 5σ discovery is guaranteed with L=300 fb^-1, but in the majority, Higgs-to-Higgs decays necessitate Higgs-pair final-state searches (notably h_H → h_L h_L). Eight benchmark points illustrate scenarios where standard channels fail and WW fusion with Higgs-pair decays may be the only viable discovery mode, while collider implications extend to Tevatron, e+e−, and γγ facilities for cross-checks and precision tests. The work underscores the need for alternative search strategies and future colliders to fully probe NMSSM Higgs dynamics.

Abstract

We identify scenarios not ruled out by LEP data in which NMSSM Higgs detection at the LHC will be particularly challenging. We first review the `no-lose' theorem for Higgs discovery at the LHC that applies if Higgs bosons do not decay to other Higgs bosons - namely, with L=300 fb^-1, there is always one or more `standard' Higgs detection channel with at least a 5 sigma signal. However, we provide examples of no-Higgs-to-Higgs cases for which all the standard signals are no larger than 7 sigma implying that if the available L is smaller or the simulations performed by ATLAS and CMS turn out to be overly optimistic, all standard Higgs signals could fall below 5 sigma even in the no-Higgs-to-Higgs part of NMSSM parameter space. In the vast bulk of NMSSM parameter space, there will be Higgs-to-Higgs decays. We show that when such decays are present it is possible for all the standard detection channels to have very small significance. In most such cases, the only strongly produced Higgs boson is one with fairly SM-like couplings that decays to two lighter Higgs bosons (either a pair of the lightest CP-even Higgs bosons, or, in the largest part of parameter space, a pair of the lightest CP-odd Higgs bosons). A number of representative bench-mark scenarios of this type are delineated in detail and implications for Higgs discovery at various colliders are discussed.

Paper Structure

This paper contains 6 sections, 10 equations, 3 figures, 6 tables.

Table of Contents

  1. Introduction
  2. The model, the NMHDECAY program and the scanning procedures
  3. LHC prospects when Higgs-to-Higgs decays are forbidden
  4. LHC prospects when Higgs-to-Higgs decays are allowed
  5. Collider Implications
  6. Conclusions

Figures (3)

  • Figure 1: We display the contours for $5\sigma$ charged Higgs detection from Assamagan:2004gv.
  • Figure 2: $N_{SD}^{\rm max}$ for the neutral Higgs bosons vs. $m_{h^\pm}$ for $m_{h^\pm}\geq 155~{\rm GeV}$. Here, $N_{SD}^{\rm max}$ is the largest of the significances for any one of the neutral Higgs bosons in channels 1) - 9). We assume LHC luminosity of $L=300~{\rm fb}^{-1}$.
  • Figure 3: The top, middle and bottom plots give a scatter plot of $m_{h_L}$, $R_{h_H}$ and $BR(h_H\to h_Lh_L)$, respectively, versus $m_{h_H}$ for the $3480$ sample scan points with $h_H\to h_Lh_L$ decays.