In this thesis we study the prospects for observing the invisibly decaying
Higgs boson in the associated ttΛH production at the LHC. The results of
the Monte Carlo simulations of signal and background processes show that there
is a possibility of observing the statistically significant number of signal
events required for the discovery. Moreover, the analysis can be further
improved to reduce the number of false reconstructions of the W boson.
The analysis of the ttΛH production is independent of the model in
which the Higgs boson decays into the invisible channel. There are several
possibilities for models where Hβinvisible can be of interest. For this
thesis, we have studied the simplest supersymmetric model, called mSUGRA. The
results of the scans of the mSUGRA model parameter space show that the regions,
where the branching ratio of the lightest neutral Higgs boson to the lightest
neutralino pair is high, are excluded by current experimental constraints. The
hβbbΛ channel dominates, and the possibility for discovery in this c
hannel will not be suppressed by the invisible decays. This result does not
disqualify invisible channel as possible signature in other models.
Chapter 4 of this thesis is based on the published paper: B.P. Kersevan,
\underline{M. Malawski}, E. Richter-Was: {\em Prospects for observing an
invisibly decaying Higgs boson in the ttΛH production at the LHC}, The
European Physical Journal C - Particles and Fields, 2003, vol. 29, no. 4, pp.
541 - 548.Comment: Master of Science Thesi