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

The measurement of a 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 √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 μ) channels: a same-sign dilepton analysis targeting tt¯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 σ tt¯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, σ tt¯Z=200 +80 -70(stat) +40 -30(syst)fb -1, is obtained with a significance of 3.1 standard deviations. Finally, 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.
Authors:
 [1]
  1. Yerevan Physics Inst. (YerPhI) (Armenia). et al.
Publication Date:
Report Number(s):
FERMILAB-PUB-14-213-CMS; CERN-PH-EP-2014-136; CMS-TOP-12-036
Journal ID: ISSN 1434-6052; arXiv eprint number arXiv:1406.7830
Grant/Contract Number:
AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
European Physical Journal. C, Particles and Fields (Online)
Additional Journal Information:
Journal Name: European Physical Journal. C, Particles and Fields (Online); Journal Volume: 74; Journal Issue: 9; Journal ID: ISSN 1434-6052
Publisher:
Springer
Research Org:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
CMS Collaboration
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1234838

Khachatryan, Vardan. Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at √s=8 TeV. United States: N. p., Web. doi:10.1140/epjc/s10052-014-3060-7.
Khachatryan, Vardan. Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at √s=8 TeV. United States. doi:10.1140/epjc/s10052-014-3060-7.
Khachatryan, Vardan. 2014. "Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at √s=8 TeV". United States. doi:10.1140/epjc/s10052-014-3060-7. https://www.osti.gov/servlets/purl/1234838.
@article{osti_1234838,
title = {Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at √s=8 TeV},
author = {Khachatryan, Vardan},
abstractNote = {The measurement of a 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 √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 μ) channels: a same-sign dilepton analysis targeting tt¯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 σtt¯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, σtt¯Z=200+80-70(stat)+40-30(syst)fb-1, is obtained with a significance of 3.1 standard deviations. Finally, 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.},
doi = {10.1140/epjc/s10052-014-3060-7},
journal = {European Physical Journal. C, Particles and Fields (Online)},
number = 9,
volume = 74,
place = {United States},
year = {2014},
month = {9}
}