A Search for Neutral Higgs Bosons in the MSSM and Models with Two Scalar Field Doublets

TL;DR

This paper reports a search for neutral Higgs bosons in models with two scalar doublets, including the MSSM, using LEP data, and sets new limits on their masses based on observed candidate events.

Contribution

It provides the first detailed scan of the MSSM parameter space and establishes new mass limits for Higgs bosons in these models.

Findings

No significant excess over background observed.

Set lower mass limits of 59.0 GeV for h^0 and 59.5 GeV for A^0.

Explored MSSM parameter space in detail for the first time.

Abstract

A search is described for the neutral Higgs bosons h^0 and A^0 predicted by models with two scalar field doublets and, in particular, the Minimal Supersymmetric Standard Model (MSSM). The search in the Z^0 h^0 and h^0 A^0 production channels is based on data corresponding to an integrated luminosity of 25 pb^{-1} from e^+e^- collisions at centre-of-mass energies between 130 and 172 GeV collected with the OPAL detector at LEP. The observation of a number of candidates consistent with Standard Model background expectations is used in combination with earlier results from data collected at the Z^0 resonance to set limits on m_h and m_A in general models with two scalar field doublets and in the MSSM. For example, in the MSSM, for tan(beta) > 1, minimal and maximal scalar top quark mixing and soft SUSY-breaking masses of 1 TeV, the 95% confidence level limits m_h > 59.0 GeV and m_A > 59.5 GeV are obtained. For the first time, the MSSM parameter space is explored in a detailed scan.