Measurement of exclusive γγ → W⁺W⁻ production and search for exclusive Higgs boson production in pp collisions at √ s = 8 TeV using the ATLAS detector

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 < a^W₀ /Λ² < 1.7×10⁻⁶ GeV⁻² and −6.4×10⁻⁶ < a^W_C /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.