A Comparison of Mixed-Higgs Scenarios In the NMSSM and the MSSM

TL;DR

This paper compares mixed-Higgs scenarios in the NMSSM and MSSM, focusing on how Higgs mixing can evade LEP bounds and the implications for superpartner corrections and electroweak naturalness.

Contribution

It analyzes the parameter space of both models to identify natural scenarios with reduced fine-tuning, emphasizing the role of stop mixing and boundary conditions at high scales.

Findings

Mixed-Higgs scenarios can evade LEP bounds with reduced ZZ coupling.

Large stop mixing is favored for natural electroweak symmetry breaking.

Certain boundary conditions lead to viable scenarios with modest fine-tuning.

Abstract

We study scenarios in the minimal and next-to minimal supersymmetric models in which the lightest CP-even Higgs boson can have mass below the 114 GeV standard model LEP limit by virtue of reduced ZZ coupling due to substantial mixing among the Higgs bosons. We pay particular attention to the size of corrections from superpartners needed for these scenarios to be viable and point to boundary conditions at large scales which lead to these scenarios while at the same time keeping electroweak fine tuning modest in size. We find that naturalness of electroweak symmetry breaking in the mixed-Higgs scenarios of both models points to the same region of soft supersymmetry breaking terms, namely those leading to large mixing in the stop sector at the electroweak scale, especially if we also require that the lightest CP-even Higgs explains the Higgs-like LEP events at about 98 GeV.