A measurement of the cross section for the production of top quark-antiquark pairs (t (t) over bar) in association with a vector boson V (W or Z) in proton-proton collisions at root s = 8 TeV is presented. The results are based on a dataset corresponding to an integrated luminosity of 19.5 fb(-1) recorded with the CMS detector at the LHC. The measurement is performed in three leptonic (e and mu) channels: a same-sign dilepton analysis targeting t (t) over barW events, and trilepton and four-lepton analyses designed for t (t) over barZ events. In the same-sign dilepton channel, the t (t) over barW cross section is measured as sigma(t (t) over barW) = 170(-80)(+90) (stat) +/- 70 (syst) fb, corresponding to a significance of 1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the t (t) over barZ cross section, sigma(t (t) over barZ) = 200(-70)(+80) (stat)(-30)(+40) (syst)fb(-1), is obtained with a significance of 3.1 standard deviations. The measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive t (t) over barV process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.

Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at root s=8 TeV / Chatrchyan, S., Khachatryan, V., Sirunyan, A.M., Tumasyan, A., Adam, W., Bergauer, T., Dragicevic, M., Erö, J., Fabjan, C., Friedl, M., Frühwirth, R., Ghete, V.M., Hartl, C., Hörmann, N., Hrubec, J., Jeitler, M., Kiesenhofer, W., Knünz, V., Krammer, M., Krätschmer, I., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - STAMPA. - 74:9(2014). [10.1140/epjc/s10052-014-3060-7]

Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at root s=8 TeV

D. Creanza;N. De Filippis;G. Iaselli;G. Maggi;G. Pugliese;
2014

Abstract

A measurement of the cross section for the production of top quark-antiquark pairs (t (t) over bar) in association with a vector boson V (W or Z) in proton-proton collisions at root s = 8 TeV is presented. The results are based on a dataset corresponding to an integrated luminosity of 19.5 fb(-1) recorded with the CMS detector at the LHC. The measurement is performed in three leptonic (e and mu) channels: a same-sign dilepton analysis targeting t (t) over barW events, and trilepton and four-lepton analyses designed for t (t) over barZ events. In the same-sign dilepton channel, the t (t) over barW cross section is measured as sigma(t (t) over barW) = 170(-80)(+90) (stat) +/- 70 (syst) fb, corresponding to a significance of 1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the t (t) over barZ cross section, sigma(t (t) over barZ) = 200(-70)(+80) (stat)(-30)(+40) (syst)fb(-1), is obtained with a significance of 3.1 standard deviations. The measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive t (t) over barV process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.
2014
Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at root s=8 TeV / Chatrchyan, S., Khachatryan, V., Sirunyan, A.M., Tumasyan, A., Adam, W., Bergauer, T., Dragicevic, M., Erö, J., Fabjan, C., Friedl, M., Frühwirth, R., Ghete, V.M., Hartl, C., Hörmann, N., Hrubec, J., Jeitler, M., Kiesenhofer, W., Knünz, V., Krammer, M., Krätschmer, I., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - STAMPA. - 74:9(2014). [10.1140/epjc/s10052-014-3060-7]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11589/77192
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