Search for exclusive two-photon production of $W^{+}W^{-}$ pairs in $pp$ collisions at 7~TeV

A search for exclusive or quasi-exclusive $W^{+}W^{-}$ production by two-photon exchange, $pp \rightarrow p^{(*)}W^{+}W^{-}p^{(*)}$, at $\sqrt{s}$~=~7~TeV is reported using data collected by the CMS detector corresponding to an integrated luminosity of 5.05~fb$^{-1}$. Events are selected by requiring a $\mu^{\pm}e^{\mp}$ vertex with no associated charged tracks, and dilepton transverse momentum $\pt(\mu^{\pm}e^{\mp})>$~30~GeV. Two events passing all selection requirements are observed in the data, compared to a Standard Model expectation of $2.2 \pm 0.5$ signal events with $0.84 \pm 0.13$ background. The tail of the dilepton transverse momentum distribution, with $\pt(\mu^{\pm}e^{\mp})>$~100~GeV, is studied for deviations from the Standard Model. No events are observed in this region, and the resulting upper limits are compared to predictions involving anomalous quartic gauge couplings.