Phenomenology and Theory of Possible Light Higgs Bosons

TL;DR

This paper explores the theoretical possibilities and phenomenological implications of light Higgs bosons that could exist despite the lack of direct detection at LEP, analyzing fine-tuning issues in supersymmetric models.

Contribution

It identifies 15 scenarios for light Higgs bosons below LEP limits and discusses fine-tuning challenges in the MSSM and its extensions.

Findings

15 different scenarios for light Higgs bosons

Fine-tuning issues in MSSM for Higgs mass predictions

Extensions of MSSM can naturally accommodate larger Higgs masses

Abstract

We study the implications of the absence of a direct discovery of a Higgs boson at LEP. First we exhibit 15 physically different ways in which one or more Higgs bosons lighter than the LEP limit could still exist. In the minimal supersymmetric standard model (MSSM) all of these, as well as the cases where the Higgs mass equals or exceeds 115 GeV, seem fine-tuned. We examine some interpretations of the fine tuning in high scale theories. The least fine-tuned MSSM outcome will have a Higgs mass at 115 GeV, while approaches that extend the MSSM at the weak scale can naturally have larger Higgs masses.