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Compact Muon Solenoid
LHC, CERN

CMS-PAS-FSQ-13-008
Evidence for exclusive gamma-gamma to $\mathrm{W^+ W^-}$ production and constraints on Anomalous Quartic Gauge Couplings at $ \sqrt{s} =$ 8 TeV
Abstract: A search for exclusive or quasi-exclusive $\gamma\gamma \rightarrow \mathrm{ W^{+}W^{-} }$ production, $ \mathrm{pp \rightarrow p^{(*)} W^{+}W^{-} p^{(*)} \to p^{(*)} \mu^{\pm} e^{\mp} p^{(*)} } $, at $\sqrt{s} =$ 8 TeV is reported using data corresponding to an integrated luminosity of 19.7 fb$^{-1}$. Events are selected by requiring the presence of an electron-muon pair with large transverse momentum $p_{\mathrm{T}}(\mu^{\pm} \mathrm{e}^{\mp})> $ 30 GeV and no associated charged particles detected from the same vertex. In the signal region 13 events are observed over an expected background of 3.5 $\pm$ 0.5 events, corresponding to an excess of 3.6$\sigma$ over the background-only hypothesis. The observed yields and kinematic distributions are compatible with the Standard Model prediction for exclusive and quasi-exclusive $\gamma\gamma \rightarrow \mathrm{ W^{+}W^{-} } $ production. The dilepton transverse momentum spectrum is studied for deviations from the Standard Model, and the resulting upper limits are compared to predictions assuming anomalous quartic gauge couplings.
CMS Publications
Compact Muon Solenoid
LHC, CERN