Searches for Invisible Higgs bosons: Preliminary combined results using LEP data collected at energies up to 209 GeV

TL;DR

This paper reports a combined analysis of LEP data up to 209 GeV, searching for invisible Higgs bosons, setting a lower mass limit of 114.4 GeV due to no observed excess over background.

Contribution

It provides the first combined LEP results for invisible Higgs boson searches using data up to 209 GeV, establishing new mass bounds.

Findings

No significant excess observed over background

Lower mass limit for invisible Higgs set at 114.4 GeV

Combined data enhances search sensitivity

Abstract

In the year 2000 the four LEP experiments have collected data at energies between 200 and 209 GeV, for approximately 868 pb-1 integrated luminosity. The LEP working group for Higgs boson searches has combined these data with earlier data sets collected at lower centre-of-mass energies to search for a neutral CP-even Higgs boson, produced at the Standard Model rate, decaying into "invisible" particles. No statistically significant excess has been observed when compared to the Standard Model background prediction, and assuming that the Higgs boson decays only into such states a lower bound has been set on its mass at 95% confidence level of 114.4 GeV.