Search for flavor-changing neutral currents in top-quark decays t to Zq in pp collisions at sqrt(s)=8 TeV
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S. Chatrchyan
- Function : Author
S. Baffioni
- Function : Author
- PersonId : 20331
- IdHAL : stephanie-barrillon
- ORCID : 0000-0002-7075-1673
P. Busson
- Function : Author
- PersonId : 741166
- IdHAL : phbusson
- ORCID : 0000-0001-6027-4511
- IdRef : 033562466
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
A search for flavor-changing neutral currents in top-quark decays t to Zq is performed in events produced from the decay chain t t-bar to Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A dataset collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus no evidence for flavor-changing neutral currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t to Zq branching fraction greater than 0.05% at the 95% confidence level.