Narrow Results

The next-to-minimal supersymmetric extension of the Standard Model (NMSSM) is one of the most favored supersymmetric models. After an introduction to the model, the Higgs sector and the neutralino sector are discussed in detail. Theoretical, experimental, and cosmological constraints are studied. Eventually, the Higgs potential is investigated in the approach of bilinear functions. Emphasis is placed on aspects which are different from the minimal supersymmetric extension.

We briefly summarize some searches for Higgs bosons with a mass of $\lesssim 110$ GeV at LEP and the LHC. We discuss a possible signal in the diphoton decay mode at $m_{\varphi }\sim 96$ GeV as reported by CMS, together with a $\sim 2\sigma$ hint in the $b\bar{b}$ final state at LEP. We briefly review possible interpretation of such a new particle in various BSM models. We focus on possible explanations as reported within the NMSSM and the $\mu \nu$SSM. Conclusions for future collider projects are briefly outlined.

We update the upper bound on the lightest CP-even Higgs mass in the NMSSM, which is given as a function of tan β and λ. It is pointed out that large values of tan β, with λ not too small, imply a large value for the MSSM-like parameter M_A. We include the available one- and two-loop corrections to the NMSSM Higgs masses, and constraints from the absence of Landau singularities below the GUT scale as well as from the stability of the NMSSM Higgs potential. For m_top varying between 171.4 and 178 GeV, squark masses of 1 TeV and maximal mixing the upper bound is assumed near tan β ~ 2 and varies between 139.9 and 141.4 GeV.

In this work, we investigate the degenerate heavy Higgs bosons in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) by introducing vector-like particles. Such an extension is well motivated from the top-down view since some grand unified theories usually predict the existence of singlet scalars and vector-like particles at weak scale. Under the constraints from the Large Hadron Collider (LHC) and dark matter experiments, we find that (1) the null results of searching for high mass resonances have tightly constrained the parameter space; (2) two degenerate heavy singlet Higgs bosons $h_2$ and $a_1$ can sizably decay to ${\chi }_1^0{\chi }_1^0$ invisibly. Therefore, search for the monojet events through the process $gg\to h_2/a_1(\to {\chi }_1^0{\chi }_1^0)j$ may further test our scenario at the future LHC.

A light, Standard Model-like Higgs scalar in the NMSSM will decay predominantly into a pair of Higgs pseudoscalars, these decaying into a four-fermion final state. We study the potential of the CLIC Higgs Experiment to detect such scenario via the search for the final states and . We find excellent prospects for the observation of the Higgs peak in both channels.

We analyze the Next-to-minimal supersymmetric Standard Model with Grand unification boundary conditions under current theoretical and experimental constraints. We compute the mass spectrum of the model and focus on the three lightest particles in the Higgs sector (two CP-even scalars, $h_1$, $h_2$ and one CP-odd, $a_1$). The reduced couplings of such particles, singlet-doublet components, their branching ratios to bosons and reduced cross-section to photons and massive gauge bosons via gluon fusion are thoroughly and systematically scrutinized. Our analysis is focused on the parameter space where the singlet-doublet coupling $\lambda$ is as large as possible (keeping the perturbativity bound intact) and the ratio between the vacuum expectation values of the up-type and down-type Higgses $(\mathrm{\text{tan}}\beta )$ is as small as possible, which is the region representing the most natural case of the NMSSM. We show the impact of recent constraints from the LHC on the SM-Higgs couplings to bosons and fermions on the parameter space of the model and the consequent implications on the Higgs sector. The results show that while the model is still able to account for current data, and provide an opportunity for discovery of extended Higgs sectors, recent LHC Higgs couplings constraints rule-out parts of the parameter space where $h_2$ (non-SM-like) and $a_1$ are non-singlet with masses below 400 GeV.