High mass Higgs search and combined discovery prospects at LHC

The prospective analyses for the search of the Standard Model (SM) Higgs boson decaying in to $ZZ^{\ast} \rightarrow$ 4 leptons ($4e$, $4\mu$ or $2e2\mu$) or $WW^{\ast} \rightarrow l \nu l' \nu'$ (l or l' = e or $\mu$) with the ATLAS and the CMS detectors at the CERN LHC pp collider are presented. Signal and background datasets obtained with a detailed Monte Carlo simulation of the detectors response are treated using a complete reconstruction chain. An evaluation of expected 95\% C.L. exclusion limit in early Higgs boson searches is presented. It is showed that these two channels alone should allow for excluding the SM Higgs boson in the mass range of 140-230 GeV by the time when CMS or ATLAS collect 1~fb$^{-1}$ of data at a center-of-mass collision energy of 14 TeV. An estimate of how the change of the center-of-mass energy from 14 to 10 TeV would impact the Higgs boson exclusion limits is also given.