Prospects of measuring gluon fusion and weak boson fusion cross sections at the LHC with CMS

The possibility to observe a Higgs boson having a mass between 300 and 600 GeV and to measure its couplings to vector bosons and top quark with CMS at the LHC is studied. Six different signatures are analyzed. The possibility to separate the Higgs events produced through weak boson fusion from the Higgs produced through gluon fusion using the forward going jets emitted in the weak boson fusion process is discussed for each of these different channels. The results are then used to determine the possible statistical errors on the ratio between the two Higgs decay branching fractions when it decays into Ws and into Zs and the possible statistical errors on the weak boson fusion and gluon fusion cross sections after one year of LHC running.