Measurement of Higgs Boson Production via Vector Boson Fusion in Decays into $W$ Bosons with the ATLAS Detector

The vector boson fusion production rate of the Standard Model Higgs boson has been measured in decays into two $W$ bosons, each subsequently decaying into an electron or muon and a neutrino, with the ATLAS detector at the Large Hadron Collider (LHC). The vector boson fusion production cross section in the Standard Model is about an order of magnitude smaller than the dominant Higgs boson production cross section from gluon fusion. Proton-proton collision data at a center-of-mass energy of 8 TeV delivered by the LHC recorded with the ATLAS detector corresponding to an integrated luminosity of 21 fb$^{-1}$ have been analyzed. Motivated by the recent discovery of a Higgs-like boson with a mass of $(125.5\pm0.6)\,\text{GeV}$ and $(125.7\pm0.4)\,\text{GeV}$ by the ATLAS and CMS collaborations at the LHC, the analysis is optimized for this mass. An excess of events, compatible with the Standard Model expectation for a Higgs Boson with $m_{\text{H}}=125\,\text{GeV}$, is observed with a significance of 2.8 standard deviations when compared to the background-only expectation. The corresponding signal strength, the observed event rate relative to the Standard Model prediction of $m_{\text{H}}=125\,\text{GeV}$ is $2.1^{+1.0}_{-0.8}$. A Higgs Boson produced via vector boson fusion is excluded with 95% confidence level in the mass range between 152 GeV and 185 GeV. When combined with measurements of other Higgs boson production and decay channels by ATLAS, evidence for vector boson fusion production with a significance of 3.3 standard deviations is observed. All measurements of Higgs boson couplings to Standard Model particles are in agreement with the predictions of the Standard Model.