The Higgs boson decay into WW(∗) is an interesting channel in a wide Higgs mass (mH) range. In particular the high Branching Ratio (BR) allows H → WW(∗) to be one of the most important channels for all the studies related to the Higgs boson properties. The fully leptonic final state of this channel provides a clear signature and allowed the observation of a Higgs boson with mH ∼ 125GeV in the data collected by ATLAS until 2012
