Searches for exclusively produced W boson pairs in the process pp(γγ) → pW+W− p and exclusively produced Higgs boson in the process pp(gg) → pHp have been performed using e ±µ ∓ final states. These measurements use 20.2 fb−1 of pp collisions collected by the ATLAS experiment at a center-of-mass energy √ s = 8 TeV at the LHC. Exclusive production of W+W− consistent with the Standard Model prediction is found with 3.0σ significance. The exclusive W+W− production cross-section is determined to be σ(γγ → W+W− → e ±µ ∓X) = 6.9 ± 2.2(stat.) ± 1.4(sys.) fb, in agreement with the Standard Model prediction. Limits on anomalous quartic gauge couplings are set at 95% confidence-level as −1.7×10−6 < aW0 /Λ2 < 1.7×10−6 GeV−2 and −6.4×10−6 < aWC /Λ2 < 6.3×10−6 GeV−2 . A 95% confidence-level upper limit on the total production cross-section for exclusive Higgs boson is set to 1.2 pb.
Bibliographical note31 pages + author list (48 pages total), 15 figures, 12 tables, published in Phys. Rev. D, all figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2015-10/