Evidence for exclusive γγ → W+W− production and constraints on anomalous quartic gauge couplings in pp collisions at s=7 and 8 TeV

• Published in: The journal of high energy physics 2016-08, Vol.2016 (8)
• Main Authors: Rahbaran, B., Schieck, J., Tavernier, S., Brun, H., Caillol, C., Clerbaux, B., Karapostoli, G., Perniè, L., Forthomme, L., Popov, A., Beliy, N., Da Costa, E. M., Tonelli Manganote, E. J., Petkov, P., Li, Q., Florez, C., Gomez, J. P., Nicolaou, C., Finger, M., Strebler, T., Ruiz Alvarez, J. D., Radziej, M., Nugent, I. M., Asin, I., Dooling, S., Lobanov, A., Colombo, F., Mandal, K., Sarkar, S., Shukla, P., Paktinat Mehdiabadi, S., Abbrescia, M., Radogna, R., Ranieri, A., Campanini, R., Marcellini, S., Giordano, F., Sguazzoni, G., Monge, M. R., Gennai, S., Gonella, F., Pozzobon, N., Ronchese, P., Biino, C., Cossutti, F., Son, D. C., Mohamad Idris, F., Sanchez-Hernandez, A., Bluj, M., Skatchkov, N., Dermenev, A., Obraztsov, S., Azhgirey, I., Escalante Del Valle, A., Fouz, M. C., Gonzalez Caballero, I., Castello, R., Cepeda, M., du Pree, T., Duggan, D., Gigi, D., Kirschenmann, H., Simon, M., Musella, P., Pandolfi, F., Pauss, F., Perrozzi, L., Galloni, C., Hreus, T., Onengut, G., Ball, F., Dunne, P., Pela, J., Richards, A., Uchida, K., Funk, G., Stuart, D., Anderson, D., Chaves, J., Lykken, J., Strobbe, N., Yelton, J., Adams, T., Prosper, H., Varelas, N., Wu, Z., Clarida, W., Gandrajula, R. P., Nachtman, J., Fehling, D., Baringer, P., George, J., Hahn, K. A., Valls, N., Woodard, A., Hebda, P., Garcia-Bellido, A., Dragoiu, C., Kunori, S., Herndon, M.
• Format: Article
• Language: English
• Subjects: Classical and Quantum Gravitation; Elementary Particles; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Experimental Physics; Relativity Theory; String Theory
• ISSN: 1029-8479
• DOI: 10.1007/JHEP08(2016)119

A bstract A search for exclusive or quasi-exclusive γγ → W + W − production, via pp → p (*) W + W − p (*) → p (*) μ ± e ∓ p (*) at 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 T ( μ ± e ∓ ) > 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 3.4σ 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 a 0, C W (dimension-6) and f M 0,1,2,3 (dimension-8), the most stringent to date, are derived from the measured dilepton transverse momentum spectrum.