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Search for Neutral Higgs Boson in CP-Conserving and CP-Violating MSSM Scenarios

The OPAL collaboration, G. Abbiendi

TL;DR

OPAL's final LEP results search for neutral MSSM Higgs bosons across CP-conserving and CP-violating scenarios using data up to $\sqrt{s}=209$ GeV. The study interprets results in benchmark scenarios such as $m_h$-max and CPX, employing both Higgsstrahlung and pair-production topologies, including cascade decays and flavor-independent channels. No significant excess is observed; the paper provides model-independent cross-section limits and comprehensive MSSM parameter-space exclusions, illustrating strong sensitivity even in difficult regions. These findings guide future collider explorations and refine expectations for Higgs-sector phenomenology in the MSSM.

Abstract

This report summarizes the final results from the OPAL collaboration on searches for neutral Higgs bosons predicted by the Minimal Supersymmetric Standard Model (MSSM). CP-conserving and for the first time at LEP CP-violating scenarios are studied. New scenarios are also included, which aim to set the stage for Higgs searches at future colliders. The results are based on the data collected with the OPAL detector at e+e- centre-of-mass energies up to 209 GeV. The data are consistent with the prediction of the Standard Model with no Higgs boson produced. Model-independent limits are derived for the cross-section of a number of events topologies motivated by prediction of the MSSM. Limits on Higgs boson masses and other MSSM parameters are obtained for a number of representative MSSM benchmark scenarios. For example, in the CP-conserving scenario mh-max where the MSSM parameters are adjusted to predict the largest range of values for mh at each tan beta, and for a top quark mass of 174.3 GeV, the domain 0.7<tan beta<1.9 is excluded at the 95% confidence level and Higgs boson mass limits of mh>84.5 GeV and ma>85.0 GeV are obtained. For the CP-violating benchmark scenario CPX which, by construction, enhances the CP-violating effects in the Higgs sector, the domain tan beta<2.8 is excluded but no universal limit can be set on the Higgs boson masses.

Search for Neutral Higgs Boson in CP-Conserving and CP-Violating MSSM Scenarios

TL;DR

OPAL's final LEP results search for neutral MSSM Higgs bosons across CP-conserving and CP-violating scenarios using data up to GeV. The study interprets results in benchmark scenarios such as -max and CPX, employing both Higgsstrahlung and pair-production topologies, including cascade decays and flavor-independent channels. No significant excess is observed; the paper provides model-independent cross-section limits and comprehensive MSSM parameter-space exclusions, illustrating strong sensitivity even in difficult regions. These findings guide future collider explorations and refine expectations for Higgs-sector phenomenology in the MSSM.

Abstract

This report summarizes the final results from the OPAL collaboration on searches for neutral Higgs bosons predicted by the Minimal Supersymmetric Standard Model (MSSM). CP-conserving and for the first time at LEP CP-violating scenarios are studied. New scenarios are also included, which aim to set the stage for Higgs searches at future colliders. The results are based on the data collected with the OPAL detector at e+e- centre-of-mass energies up to 209 GeV. The data are consistent with the prediction of the Standard Model with no Higgs boson produced. Model-independent limits are derived for the cross-section of a number of events topologies motivated by prediction of the MSSM. Limits on Higgs boson masses and other MSSM parameters are obtained for a number of representative MSSM benchmark scenarios. For example, in the CP-conserving scenario mh-max where the MSSM parameters are adjusted to predict the largest range of values for mh at each tan beta, and for a top quark mass of 174.3 GeV, the domain 0.7<tan beta<1.9 is excluded at the 95% confidence level and Higgs boson mass limits of mh>84.5 GeV and ma>85.0 GeV are obtained. For the CP-violating benchmark scenario CPX which, by construction, enhances the CP-violating effects in the Higgs sector, the domain tan beta<2.8 is excluded but no universal limit can be set on the Higgs boson masses.

Paper Structure

This paper contains 22 sections, 12 equations, 1 figure, 15 tables.

Table of Contents

  1. Introduction
  2. Introduction
  3. OPAL detector and Monte Carlo samples
  4. Higgs boson production processes
  5. Signal topologies and experimental searches
  6. Searches for Higgsstrahlung processes
  7. Modification of the search in the four-jet channel
  8. Modification of the search in the missing energy channel
  9. Searches for pair production processes
  10. Search for $\hbox{${\mathrm{e}}^+ {\mathrm{e}}^-$}\hbox{$\rightarrow$}{{\cal H}_1}{{\cal H}_2}\hbox{$\rightarrow$}\mathrm{b}\bar{\mathrm{b}}\mathrm{b}\bar{\mathrm{b}}$ optimized for high $m_{{\cal H}_1}$
  11. Search for $\hbox{${\mathrm{e}}^+ {\mathrm{e}}^-$}\hbox{$\rightarrow$}{{\cal H}_1}{{\cal H}_2}\hbox{$\rightarrow$}\mathrm{b}\bar{\mathrm{b}}\mathrm{b}\bar{\mathrm{b}}$ for low $m_{{\cal H}_1}$
  12. Search for $\hbox{${\mathrm{e}}^+ {\mathrm{e}}^-$}\hbox{$\rightarrow$}{{\cal H}_1}{{\cal H}_2}\hbox{$\rightarrow$}{{\cal H}_1}{{\cal H}_1}{{\cal H}_1}\hbox{$\rightarrow$}\mathrm{b}\bar{\mathrm{b}}\mathrm{b}\bar{\mathrm{b}}\mathrm{b}\bar{\mathrm{b}}$
  13. Search for the process $\hbox{${\mathrm{e}}^+ {\mathrm{e}}^-$}\hbox{$\rightarrow$}{{\cal H}_1}{{\cal H}_2}\hbox{$\rightarrow$}\mathrm{b}\bar{\mathrm{b}}\,\tau^+\tau^-$ and $\tau^+\tau^-\mathrm{b}\bar{\mathrm{b}}$
  14. Comparison of Data and Expected Background Monte Carlo
  15. Combination of search channels and hypothesis testing
  16. ...and 7 more sections

Figures (1)

  • Figure :