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 an 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 an exclusive Higgs boson is set to 1.2 pb.