Tracing the path from Tevatron to LHC
In November 2015 the LHC delivered proton-proton collisions at 5.02 TeV, with CMS having being fully efficient and having managed to collect 27.4pb-1 of low pileup proton-proton collision data. The fraction of tt events initiated by gluon-gluon collisions grows monotonically with center-of-mass energy, rendering this 'peculiar' data set partially complementary to the higher energy samples. This study exploited candidate events with at at least one charge lepton (muon or electron), accompanied by the presence of at least two jets (from the hadronization of the b quarks). The cross section is separately extracted with an elaborate distribution fit (l+jets channel) and a simpler, but robust, event-counting experiment approach (dilepton channel), and found in agreement with the SM expectation (CMS-PAS-TOP-16-023). The final uncertainty of the measurement is now measured 12%, the latter almost equally dominated by the statistical precision and systematic considerations.
The CP3 members Georgios Krintiras and Andrea Giammanco were involved in this measurement.
Reference url: http://cds.cern.ch/record/2258177