A search for exclusive or quasi-exclusive γγ → W+W- production, via pp → p(∗)W+W-p(∗) → p(∗)μ±e±p(∗) at √s = 8TeV, 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 pT(μ±e±) > 30 GeV, and no associated charged particles detected from the same vertex. The 8TeV results are combined with the previous 7TeV results (obtained for 5.05 fb-1of data). In the signal region, 13(2) events are observed over an expected background of 3.9 ± 0.6 (0.84 ± 0.15) events for 8 (7) TeV, resulting in a combined excess of 3.4σ over the background-only hypothesis. The observed yields and kinematic distributions are compatible with the standard model prediction for exclusive and quasi-exclusive γγ → W+W- production. Upper limits on the anomalous quartic gauge coupling operators aW0,C (dimension-6) and fM0,1,2,3 (dimension-8), the most stringent to date, are derived from the measured dilepton transverse momentum spectrum.
- Forward physics
- Hadron-Hadron scattering (experiments)