Evidence for exclusive ?? ? W+W? production and constraints on anomalous quartic gauge couplings in ppcollisions at s?=7s=7 and 8 TeV


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.


Citation: Khachatryan, V., Sirunyan, A. M., Tumasyan, A., Adam, W., Asilar, E., Bergauer, T., . . . Collaboration, C. M. S. (2016). Evidence for exclusive gamma gamma -> W (+) W (-) production and constraints on anomalous quartic gauge couplings in pp collisions at and 8 TeV. Journal of High Energy Physics(8), 47. doi:10.1007/jhep08(2016)119


Forward Physics, Hadron-Hadron Scattering (Experiments), Cross-Section, Hadron Colliders, Boson Couplings, High-Energies