Research output: Contribution to Journal/Magazine › Journal article › peer-review
<mark>Journal publication date</mark> | 01/2007 |
---|---|
<mark>Journal</mark> | European Physical Journal C: Particles and Fields |
Issue number | 2 |
Volume | 49 |
Number of pages | 16 |
Pages (from-to) | 457-472 |
Publication Status | Published |
<mark>Original language</mark> | English |
This paper describes a topological search for an invisibly decaying Higgs boson, H, produced via the Bjorken process (e(+)e(-)-> HZ). The analysis is based on data recorded using the OPAL detector at LEP at centre-of-mass energies from 183 to 209 GeV corresponding to a total integrated luminosity of 629 pb(-1). In the analysis only hadronic decays of the Z boson are considered. A scan over Higgs boson masses from 1 to 120 GeV and decay widths from 1 to 3000 GeV revealed no indication for a signal in the data. From a likelihood ratio of expected signal and standard model background we determine upper limits on cross-section times branching ratio to an invisible final state. For moderate Higgs boson decay widths, these range from about 0.07 pb (M-H=60 GeV) to 0.57 pb (M-H=114 GeV). For decay widths above 200 GeV the upper limits are of the order of 0.15 pb. The results can be interpreted in general scenarios predicting a large invisible decay width of the Higgs boson. As an example we interpret the results in the so-called stealthy Higgs scenario. The limits from this analysis exclude a large part of the parameter range of this scenario experimentally accessible at LEP 2.