a r X i v : 1 2 0 7 . 7 2 1 4 v 2 [ h e p e x ] 3 1 A u g 2 0 1 2 EUROPEAN ORGANI SA TI ON FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP-2012-218 Accept ed by : Ph ys ic s Letters B Observation of a New Particle in the Search for the Standard Model Higgs Boson with the ATLAS Detector at the LHC The A TLAS Coll abor ation This paper is dedicated to the memory of our A TL AS colleagues who did not li ve to see th e full impact and signi ficance of their contributions to the experimen t. Abstract A search for the Standard Model Hi ggs boson in proton-proton collisions wi th the A TLAS detector at th e LHC is presented. The data sets used corre sp ond to integ rat ed lu mi nosi ti es of approxi matel y 4.8 fb −1 collected at √ s = 7 TeV in 2011 and 5.8 fb −1 at √ s =8 TeV in 2012. Indi vi dual sear ches in the channels H→ZZ(∗) → 4ℓ , H→ γγ and H→ WW(∗) → eνµν in the 8 T eV data are combined with previ ousl y publi shed res ul ts of se ar ch es f or H→ZZ(∗) , WW(∗) , b ¯ b and τ + τ − inthe 7 T eV data and results from impr oved ana lyses of theH→ZZ(∗) → 4ℓ andH→ γγ channelsin the7 T eV data. Clear evidence f or the pr oduction of a neutral boson wi th a measured mass of 126.0 ± 0.4 (stat) ± 0.4 (sys) GeV is presented. This obs ervat ion , which has a si gni ficance of 5. 9 st and ar d de vi at ion s, correspon din g to a back gr oun d fluc tuat ion probabilit y of 1.7 × 10 −9 , is compatible with the produc ti on and deca y of the Standard Model Hi ggs bos on.
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