@article{10902/14050,
year = {2014},
month = {9},
url = {http://hdl.handle.net/10902/14050},
abstract = {A measurement of the cross section for the production of top quark–antiquark pairs (tt¯) in association with a vector boson V (W or Z) in proton-proton collisions at vs = 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 µ) channels: a same-sign dilepton analysis targeting  tt¯Wtt¯W  events, and trilepton and four-lepton analyses designed for tt¯Z events. In the same-sign dilepton channel, the tt¯W cross section is measured as stt¯W=170+90-80(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 tt¯Z cross section, stt¯Z=200+80-70(stat)+40-30(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 tt¯V process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.},
publisher = {Springer New York LLC},
publisher = {European Physical Journal C, Vol. 74, Num. 9, Art. Num. 3060, (2014)},
title = {Measurement of top quark–antiquark pair production in association with a W or Z boson in pp collisions at √s = 8TeV},
author = {Khachatryan, Vladimir and Brochero Cifuentes, Javier Andrés and Cabrillo Bartolomé, José Iban and Calderón Tazón, Alicia and Duarte Campderros, Jorge and Fernández García, Marcos and Gómez Gramuglio, Gervasio and Graziano, Alberto and López Virto, María Amparo and Marco de Lucas, Jesús and Marco de Lucas, Rafael José and Martínez Rivero, Celso and Matorras Weinig, Francisco and Muñoz Sánchez, Francisca Javiela and Piedra Gómez, Jonatan and Rodrigo Anoro, Teresa and Rodríguez Marrero, Ana Yaiza and Ruiz Jimeno, Alberto and Scodellaro, Luca and Vila Álvarez, Iván  and Vilar Cortabitarte, Rocío},
}