Evidence for exclusive gamma gamma -> W (+) W (-) production and constraints on anomalous quartic gauge couplings in pp collisions at and 8 TeV
Marie-Curie program ; European Research Council ; EPLANET (European Union) ; Leventis Foundation ; A. P. Sloan Foundation ; Alexander von Humboldt Foundation ; Belgian Federal Science Policy Office ; Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium) ; Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium) ; Ministry of Education, Youth and Sports (MEYS) of the Czech Republic ; Council of Science and Industrial Research, India ; HOMING PLUS program of the Foundation for Polish Science ; European Union, Regional Development Fund ; Mobility Plus program of the Ministry of Science and Higher Education (Poland) ; OPUS program of the National Science Center (Poland) ; MIUR (Italy) ; EU-ESF ; Greek NSRF ; National Priorities Research Program by Qatar National Research Fund ; Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand) ; Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand) ; Welch Foundation ; Science and Technology Facilities Council ; MIUR (Italy): 20108T4XTM ; Welch Foundation: C-1845 ; Science and Technology Facilities Council: ST/M004775/1 ; Science and Technology Facilities Council: CMS ; Science and Technology Facilities Council: ST/M002020/1 ; Science and Technology Facilities Council: ST/K001639/1 CMS Upgrades ; Science and Technology Facilities Council: ST/L005603/1 ; Science and Technology Facilities Council: ST/J004871/1 ; Science and Technology Facilities Council: ST/K003542/1 GRIDPP ; Science and Technology Facilities Council: ST/K001256/1 ; Science and Technology Facilities Council: ST/I000305/1 ; Science and Technology Facilities Council: ST/H000925/1 ; Science and Technology Facilities Council: ST/I003622/1 ; Science and Technology Facilities Council: ST/N000242/1 ; Science and Technology Facilities Council: PP/E000479/1 ; Science and Technology Facilities Council: PP/E002803/1 ; Science and Technology Facilities Council: ST/K001531/1 ; Science and Technology Facilities Council: ST/K003542/1 ; Science and Technology Facilities Council: ST/K003224/1 CMS Upgrades ; Science and Technology Facilities Council: ST/N000250/1 ; Science and Technology Facilities Council: GRIDPP ; Science and Technology Facilities Council: ST/K001639/1 ; Science and Technology Facilities Council: ST/M004775/1 GRIDPP ; Science and Technology Facilities Council: ST/I003622/1 GRIDPP ; Science and Technology Facilities Council: ST/K003542/1 GRID PP ; Science and Technology Facilities Council: ST/J005479/1 ; Science and Technology Facilities Council: ST/H000925/2 ; Science and Technology Facilities Council: ST/N001273/1 ; A search for exclusive or quasi-exclusive gamma gamma -> W (+) W (-) production, via pp -> p ((*)) W (+) W (-) p ((*)) -> p ((*)) mu (+/-)e(a) p ((*)) at 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 (T)(mu (+/-)e(a)) > 30 GeV, and no associated charged particles detected from the same vertex. The 8 TeV results are combined with the previous 7 TeV results (obtained for 5.05 fb(-1) of 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 3.4 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 -> W (+) W (-) production. Upper limits on the anomalous quartic gauge coupling operators a (0,C) (W) (dimension-6) and f (M0,1,2,3) (dimension-8), the most stringent to date, are derived from the measured dilepton transverse momentum spectrum.