Measurement of the cross section for top quark pair production in association with a W or Z boson in proton-proton collisions at √s = 13 TeV
Date
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
A measurement is performed of the cross section of top quark pair production in association with a W or Z boson using proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb⁻¹, collected by the CMS experiment in 2016. The measurement is performed in the same-sign dilepton, three- and four-lepton final states. The production cross sections are measured to be (\sigma \left(t\overline{t}W\right)={0.77}{-0.11}^{+0.12}{\left(\mathrm{stat}\right)}{-0.12}^{+0.13}\left(\mathrm{syst}\right)pb) and (\sigma \left(t\overline{t}Z\right)={0.99}{-0.08}^{+0.09}{\left(\mathrm{stat}\right)}{-0.10}^{+0.12}\left(\mathrm{syst}\right)pb). The expected (observed) signal significance for the (t\overline{t}W) production in same-sign dilepton channel is found to be 4.5 (5.3) standard deviations, while for the (t\overline{t}Z) production in three- and four-lepton channels both the expected and the observed significances are found to be in excess of 5 standard deviations. The results are in agreement with the standard model predictions and are used to constrain the Wilson coefficients for eight dimension-six operators describing new interactions that would modify (t\overline{t}W) and (t\overline{t}Z) production.