Observation of an Excess of Events in the Search for the Standard Model Higgs Boson in the $H\to WW^{(\ast)}\to \ell\nu\ell\nu$ Channel with the ATLAS Detector

A Standard Model Higgs boson search in the $H \to WW^{(*)} \to e\nu\mu\nu$ decay mode has been performed using proton-proton collision data corresponding to an integrated luminosity of 5.8 fb$^{-1}$ at a centre-of-mass energy of 8 TeV collected during 2012 with the ATLAS detector at the Large Hadron Collider. The search focuses on the mass region around 125 GeV, not previously excluded, where an excess of events over the expected background is observed corresponding to a local $p_0$-value of $6.0 \times 10^{-4}$, or 3.2 standard deviations. In a combined analysis of the 2012 data with the 4.7 fb$^{-1}$ of data acquired at $\sqrt{s} = 7$ TeV in 2011, the observed excess corresponds to a minimum local $p_0$ of $3 \times 10^{-3}$ or 2.8 standard deviations.