First Observation of Top Quark Production in the Forward Region

Abstract

Top quark production in the forward region in proton-proton collisions is observed for the first time. The W + b final state with W → μ ν is reconstructed using muons with a transverse momentum, p T , larger than 25 GeV in the pseudorapidity range 2.0 < η < 4.5 . The b jets are required to have 50 < p T < 100 GeV and 2.2 < η < 4.2 , while the transverse component of the sum of the muon and b -jet momenta must satisfy p T > 20 GeV . The results are based on data corresponding to integrated luminosities of 1.0 and 2.0 fb − 1 collected at center-of-mass energies of 7 and 8 TeV by LHCb. The inclusive top quark production cross sections in the fiducial region are σ ( top ) [ 7 TeV ] = 239 ± 53 ( stat ) ± 33 ( syst ) ± 24 ( theory ) fb , σ ( top ) [ 8 TeV ] = 289 ± 43 ( stat ) ± 40 ( syst ) ± 29 ( theory ) fb . These results, along with the observed differential yields and charge asymmetries, are in agreement with next-to-leading order standard model predictions.