Measurement of the cross section ratio sigma(t t-bar b b-bar) / sigma(t t-bar jj) in pp collisions at sqrt(s) = 8 TeV

• Published in: Physics letters. B Vol. 746; pp. 132 - 153
• Main Authors: Khachatryan, V., Besancon, M., Couderc, F., Dejardin, M., Denegri, D., Fabbro, B., Faure, J.L., Favaro, C., Ferri, F., Ganjour, S., Givernaud, A., Gras, P., Monchenault, G. Hamel De, Jarry, P., Locci, E., Malcles, J., Rander, J., Rosowsky, A., Baffioni, M. Titov S., Beaudette, F., Busson, P., Charlot, C., Dahms, T., Dalchenko, M., Dobrzynski, L., Filipovic, N., Florent, A., Granier de Cassagnac, R., Mastrolorenzo, L., Mine, P., Mironov, C., Naranjo, I.N., Nguyen, M., Ochando, C., Paganini, P., Regnard, S., Salerno, R., Sauvan, J.B., Sirois, Y., Veelken, C., Yilmaz, Y., Agram, A. Zabi J.-L., Andrea, J., Aubin, A., Bloch, D., Brom, J.-M., Chabert, E.C., Collard, C., Conte, E., Fontaine, J.-C., Gele, D., Goerlach, U., Goetzmann, C., Bihan, A.-C. Le, Xiao, H., Viret, S., van Hove, P., Chierici, R., Verdier, P., Beauceron, S., Beaupere, N., Boudoul, G., Bouvier, E., Brochet, S., Montoya, C.A. Carrillo, Chasserat, J., Gadrat, S., Contardo, D., Depasse, P., Mamouni, H. El, Fan, J., Fay, J., Gascon, S., Gouzevitch, M., Ille, B., Kurca, T., Lethuillier, M., Mirabito, L., Perries, S., Alvarez, J.D. Ruiz, Sabes, D., Sgandurra, L., Sordini, V., Donckt, M. Vander
• Format: Journal Article
• Language: English
• Published: Elsevier 2015
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 0370-2693
• DOI: 10.1016/j.physletb.2015.04.060

The first measurement of the cross section ratio sigma(t t-bar b b-bar) / sigma(t t-bar jj) is presented using a data sample corresponding to an integrated luminosity of 19.6 inverse femtobarns collected in pp collisions at sqrt(s) = 8 TeV with the CMS detector at the LHC. Events with two leptons (e or mu) and four reconstructed jets, including two identified as b quark jets, in the final state are selected. The ratio is determined for a minimum jet transverse momentum pt of both 20 and 40 GeV. The measured ratio is 0.022 +/- 0.003 (stat) +/- 0.005 (syst) for pt > 20 GeV. The absolute cross sections sigma(t t-bar b b-bar) and sigma(t t-bar jj) are also measured. The measured ratio for pt > 40 GeV is compatible with a theoretical quantum chromodynamics calculation at next-to-leading order.