Search for associated production of the Higgs boson in the WH→ WWW(∗)→ lνlνlν and ZH→ ZWW(∗)→ lllνlν channels with the ATLAS detector at the LHC

A search for the Higgs boson in the WH and ZH associated production modes, with H→ WW(∗) and all vector bosons decaying to electrons or muons, is performed using 20.7 fb−1 of proton-proton collision data at a centre-of-mass energy of 8 TeV collected in 2012 with the ATLAS detector at the CERN Large Hadron Collider. The 2012 result is combined with an earlier search for WH→ WWW(∗)→ lνlνlν with 4.7 fb−1 of data recorded at a centre-of- mass energy of 7 TeV. No significant excess is observed over the Standard Model expecta- tions, with or without a mH = 125 GeV Higgs boson. Limits at 95% confidence level on the cross section ratio to the Standard Model prediction are set for the mass interval 110 GeV ≤ mH ≤ 200 GeV. The observed (expected) limits are determined to be 7.2 (3.6) times the Standard Model cross section for a Higgs boson of mass mH=125 GeV.