Searches for the Neutral Higgs Bosons of the MSSM: Preliminary Combined Results Using LEP Data Collected at Energies up to 209 GeV
ALEPH Collaboration, DELPHI Collaboration, L3 Collaboration, OPAL Collaboration, the LEP Higgs Working Group
TL;DR
This paper presents a preliminary combined search for neutral MSSM Higgs bosons using LEP data up to 209 GeV from the four experiments. It interprets the data within three benchmark MSSM scenarios, employing h^0 Z^0 and h^0 A^0 production channels and flavour-independent hadronic searches to derive stringent limits on $m_{h^0}$, $m_{A^0}$, and $ aneta$, with 95% CL exclusions across the parameter spaces. The results yield lower bounds $m_{h^0}>91.0$ GeV and $m_{A^0}>91.9$ GeV in the canonical scans, while excluding the large-$ extmu$ scenario entirely; mild 2σ excesses are observed at certain mass points but not confirmed. The study demonstrates the power of combining LEP data to constrain MSSM Higgs sectors and provides coupling-strength limits for reduced cross-sections or branching ratios.
Abstract
In the year 2000 the four LEP experiments collected data at centre-of-mass energies between 200 and 209 GeV, integrating approximately 870 pb-1 of luminosity, with about 510 pb-1 above 206 GeV. The LEP working group for Higgs boson searches has combined these data with data sets collected previously at lower energies. In representative scans of the parameters of the Minimal Supersymmetric Standard Model (MSSM), the mass limits mh>91.0 GeV and mA>91.9 GeV are obtained for the light CP-even and the CP-odd neutral Higgs boson, respectively. For a top quark mass less than or equal to 174.3 GeV, assuming that the stop quark mixing is maximal, and choosing conservative values for other SUSY parameters affecting the Higgs sector, the range 0.5<tanbeta<2.4 is excluded. Additionally, the results of flavour-independent searches for hadronically decaying Higgs bosons are included, allowing exclusion of MSSM models with suppressed decays of the Higgs bosons to pairs of b quarks.