Searches for Neutral Higgs Bosons in Extended Models

TL;DR

This paper reports on searches for neutral Higgs bosons at LEP, examining various production modes and decay channels, but finds no evidence for signals and sets upper bounds on couplings across accessible mass ranges.

Contribution

It provides comprehensive searches for neutral Higgs bosons in extended models using LEP data, covering multiple production and decay modes with mass-dependent limits.

Findings

No evidence for neutral Higgs bosons was observed.

Upper bounds on coupling factors were established across the accessible mass spectrum.

The analysis covers both LEP1 and LEP2 energy ranges.

Abstract

Searches for neutral Higgs bosons produced at LEP in association with Z bosons, in pairs and in the Yukawa process are presented in this paper. Higgs boson decays into b quarks, tau leptons, or other Higgs bosons are considered, giving rise to four-b, four-b+jets, six-b and four-tau final states, as well as mixed modes with b quarks and tau leptons. The whole mass domain kinematically accessible at LEP in these topologies is searched. The analysed data set covers both the LEP1 and LEP2 energy ranges and exploits most of the luminosity recorded by the DELPHI experiment. No convincing evidence for a signal is found, and results are presented in the form of mass-dependent upper bounds on coupling factors (in units of model-independent reference cross-sections) for all processes, allowing interpretation of the data in a large class of models.