Search for Neutral MSSM Higgs Bosons at LEP

TL;DR

This paper reports a combined LEP search for neutral MSSM Higgs bosons using data from ALEPH, DELPHI, L3 and OPAL collected up to $\sqrt{s}=209$ GeV. It employs CP-conserving and CP-violating MSSM benchmarks (e.g., $m_h$-max, no-mixing, large-$\mu$, gluophobic, small-$\alpha_{\rm eff}$, CPX) and computes radiative corrections with $FeynHiggs$ and $SUBHPOLE$ to predict production cross-sections and decays, then derives 95% CL upper limits on topological cross-sections via CLs. The results show no significant signal, yielding large exclusions in MSSM parameter space and absolute limits on $\tan\beta$ and neutral Higgs masses in CP-conserving cases, while CP-violating CPX scenarios leave substantial allowed regions depending on $m_t$ and CP phases. The findings constrain MSSM Higgs phenomenology at LEP energies and guide expectations for higher-energy colliders.

Abstract

The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by the Minimal Supersymmetric Standard Model (MSSM). The data of the four collaborations are statistically combined and examined for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number of "benchmark" models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large exclusions in the MSSM parameter space. Absolute limits are set on the parameter tanb and, in some scenarios, on the masses of neutral Higgs bosons.

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