[Paper Review] Higgs Sector of Non-minimal Supersymmetric Models at Future Hadron Colliders

C. Hugonie, Stefano Moretti|arXiv (Cornell University)|Oct 17, 2001

Particle physics theoretical and experimental studies4 citations

TL;DR

This paper investigates the discovery potential of additional Higgs bosons in non-minimal supersymmetric models—specifically the NMSSM and nMSSM—at future hadron colliders. Using a universal soft-SUSY breaking framework and assuming a 115 GeV CP-even Higgs, it finds that singlet-like Higgs states (especially the CP-even $S_r$) can be detected at the Tevatron and LHC, with the LHC capable of observing up to three Higgs states including the CP-odd singlet $S_i$ for masses below ~600 GeV.

ABSTRACT

We investigate the potential of current and planned hadron colliders operating at the TeV scale in disentangling the structure of the Higgs sector of non-minimal Supersymmetric extensions of the Standard Model with an extra gauge singlet. We assume universality of the soft Supersymmetry breaking terms at the GUT scale as well as a CP-even Higgs boson with mass around 115 GeV, as suggested by LEP. We find that mixing angles between the doublet and singlet Higgs states are always small. However, concrete prospects exist at both the Tevatron (Run II) and the Large Hadron Collider of detecting at least one neutral Higgs state with a dominant singlet component, in addition to those available from a doublet Higgs sector which is similar to the one of the Minimal Supersymmetric Standard Model.

Motivation & Objective

• To assess the discovery potential of extended Higgs sectors in non-minimal supersymmetric models at future hadron colliders.
• To determine whether singlet-like Higgs states—particularly CP-even $S_r$ and CP-odd $S_i$—can be observed despite small mixing angles.
• To evaluate the sensitivity of the Tevatron (Run II) and LHC (14 TeV) to these states under universal soft-SUSY breaking conditions.
• To investigate whether the presence of a 115 GeV CP-even Higgs with weak couplings to gauge bosons, as suggested by LEP, affects the visibility of additional Higgs states.
• To examine whether decay modes into singlinos ($\tilde{S}$) would render the singlet Higgs states invisible, and whether detectable decay channels dominate.

Proposed method

• Numerical scanning of the parameter space in the NMSSM and nMSSM using universal soft-SUSY breaking terms at the GUT scale.
• Solving the renormalization group equations (RGEs) from the GUT scale down to the weak scale to determine physical masses and couplings.
• Minimizing the two-loop effective Higgs potential to compute vacuum expectation values and physical Higgs masses.
• Applying experimental constraints, including LEP limits on Higgs masses and couplings, and requiring a 115 GeV CP-even Higgs with weak gauge couplings.
• Simulating direct Higgs production via gluon fusion, Higgs-strahlung, vector boson fusion, and heavy quark-associated production at Tevatron and LHC.
• Using event rate estimates (e.g., >100 events) to determine visibility thresholds for each Higgs state across the parameter space.

Experimental results

Research questions

• RQ1 Can the CP-even singlet Higgs $S_r$ be detected at the Tevatron (Run II) and LHC, and under what mass and coupling conditions?
• RQ2 What is the visibility of the CP-odd singlet Higgs $S_i$ at the Tevatron and LHC, and how does its production depend on the model parameters?
• RQ3 How do mixing angles between doublet and singlet Higgs states affect the detectability of singlet-like Higgs states in the NMSSM and nMSSM?
• RQ4 To what extent do decay modes into singlinos ($\tilde{S}$) suppress the visibility of singlet Higgs states, and are detectable decay channels dominant?
• RQ5 Can the LHC resolve the full neutral Higgs spectrum, including non-singlet states ($H_u$, $H_d$, $A$) and singlet states ($S_r$, $S_i$), with its high luminosity and center-of-mass energy?

Key findings

• Mixing angles between doublet and singlet Higgs states are always small in the studied models, indicating weak mixing.
• The CP-even singlet Higgs $S_r$ can be detected at the Tevatron if its mass is below ~200 GeV and its coupling $\lambda$ is not too small.
• At the LHC, the CP-even singlet $S_r$ is visible for masses up to ~600 GeV, covering most of the parameter space in the NMSSM.
• The CP-odd singlet $S_i$ is visible at the LHC for an appreciable part of the parameter space, particularly in the NMSSM.
• The LHC is expected to detect at least three non-singlet Higgs states ($H_u$, $H_d$, $A$) due to its high center-of-mass energy and luminosity.
• Despite high point density in event rate plots, regions invisible to $S_r$ searches at the Tevatron still exist behind visible ones, indicating that $S_r$ searches do not cover the full parameter space.