Search for Higgs Boson in $WW^{(*)}$ Decays

The process $H \rightarrow WW^{(*)} \rightarrow \ell^+ \ell^- \,(\ell = e, \mu)$ is studied in $p\bar{p}$ collisions at the center of mass energy $\sqrt{s} = 1.96$ TeV with the upgraded D\O\ detector at the Fermilab Tevatron accelerator. A Higgs particle with a mass greater than 140 GeV primarily decays into a of W-bosons and the semi-leptonic decay channels of the W provide a clear signature. Apart from the Standard Model Higgs, for which a discovery will only be possible at highest integrated luminosities, exotic models with enhanced cross sections may be probed already with data corresponding to integrated luminosities of a few hundred pb$^{-1}$.