Measurement of associated production of vector bosons and t t-bar at sqrt(s)= 7 TeV
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S. Chatrchyan
- Function : Author
S. Baffioni
- Function : Author
- PersonId : 20331
- IdHAL : stephanie-barrillon
- ORCID : 0000-0002-7075-1673
Pierre Busson
- Function : Author
- PersonId : 742252
- IdHAL : pierre-busson-cnrsgr
- ORCID : 0000-0003-1027-3400
- IdRef : 096371706
R. Granier de Cassagnac
- Function : Author
- PersonId : 739189
- IdHAL : raphgrandecass
- ORCID : 0000-0002-1275-7292
- IdRef : 132136651
C. Mironov
- Function : Author
- PersonId : 1196248
- IdHAL : camelia-mironov
P. Paganini
- Function : Author
- PersonId : 739173
- IdHAL : pascal-paganini
- ORCID : 0000-0001-9580-683X
- IdRef : 183219406
C. Collard
- Function : Author
- PersonId : 753602
- IdHAL : caroline-collard
- ORCID : 0000-0002-5230-8387
- IdRef : 223465992
P. van Hove
- Function : Author
- PersonId : 742701
- IdHAL : pierre-van-hove
- ORCID : 0000-0002-2431-3381
- IdRef : 264250834
M. Gouzevitch
- Function : Author
- PersonId : 741096
- IdHAL : maxime-gouzevitch
- ORCID : 0000-0002-5524-880X
- IdRef : 13627160X
M. Lethuillier
- Function : Author
- PersonId : 740178
- IdHAL : morgan-lethuillier
- ORCID : 0000-0001-6185-2045
- IdRef : 090177835
V. Sordini
- Function : Author
- PersonId : 739810
- IdHAL : viola-sordini
- ORCID : 0000-0003-0885-824X
- IdRef : 128184035
Abstract
The first measurement of vector-boson production associated with a top quark-antiquark pair in proton-proton collisions at sqrt(s) = 7 TeV is presented. The results are based on a dataset corresponding to an integrated luminosity of 5.0 inverse femtobarns, recorded by the CMS detector at the LHC in 2011. The measurement is performed in two independent channels through a trilepton analysis of t t-bar Z events and a same-sign dilepton analysis of t t-bar V (V= W or Z) events. In the trilepton channel a direct measurement of the t t-bar Z cross section sigma(t t-bar Z) = 0.28 +0.14/-0.11 (stat) +0.06/-0.03 (syst) pb is obtained. In the dilepton channel a measurement of the t t-bar V cross section yields sigma(t t-bar V) = 0.43 +0.17/-0.15 (stat) +0.09/-0.07 (syst) pb. These measurements have a significance, respectively, of 3.3 and 3.0 standard deviations from the background hypotheses and are compatible, within uncertainties, with the corresponding NLO predictions of 0.137 +0.012/-0.016 and 0.306 +0.031/-0.053 pb.