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 $pp(\\gamma\\gamma) \\rightarrow pW^+W^-p$ and exclusively produced Higgs boson in the process $pp(gg) \\rightarrow pHp$ have been performed using $e^{\\pm}\\mu^{\\mp}$ final states. These measurements use 20.2 fb$^{-1}$ of $pp$ collisions collected by the ATLAS experiment at a center-of-mass energy $\\sqrt{s}=8$ TeV at the LHC. Exclusive production of $W^+W^-$ consistent with the Standard Model prediction is found with 3.0$\\sigma$ significance. The exclusive $W^+W^-$ production cross-section is determined to be $\\sigma (\\gamma\\gamma\\rightarrow W^{+}W^{-}\\rightarrow e^{\\pm}\\mu^{\\mp} X) = 6.9 \\pm 2.2 (\\mathrm{stat.}) \\pm 1.4 (\\mathrm{sys.})$ fb, in agreement with the Standard Model prediction. Limits on anomalous quartic gauge couplings are set at 95\\% confidence-level as $-1.7 \\times 10^{-6} < a_0^W/\\Lambda^2 < 1.7 \\times 10^{-6}$ GeV$^{-2}$and $-6.4 \\times 10^{-6} < a_C^W/\\Lambda^2 < 6.3 \\times 10^{-6}$ GeV$^{-2}$. A 95\\% confidence-level upper limit on the total production cross-section for exclusive Higgs boson is set to 1.2 pb.