CERN-LHC. Measurement of the differential cross-section for pair production of top quarks with high transverse momentum ($p_T$), with respect to the transverse momentum of the top quark, obtained using the lepton+jets channel. The hadronically decaying top quark is reconstructed as an anti-kt jet with radius parameter R=1.0 and identified with jet substructure techniques. The measurement is obtained using 20.3 fb-1 of proton--proton collisions at a center-of-mass energy of 8 TeV and is corrected at both particle-level, in a fiducial region close to the event selection, and at parton-level, for events with top quarks with $p_T$ > 300 GeV.
The fiducial region is defined as (see also Table 1 of the paper):
- Exactly one lepton (e or mu)
- p_T(lepton) > 25 GeV and |eta(lepton)| < 2.5
- p_T(anti-kt R=0.4 jets) > 25 GeV and |eta(anti-kt R=0.4 jets)| < 2.5
- MET > 20 GeV and MET+MTW > 60 GeV (MTW is the transverse mass between the lepton and the MET)
- at least one anti-kt R=0.4 jets within Delta-R < 1.5 from the lepton
- at least one anti-kt R=1.0 jets with p_T > 300 GeV, mass > 100 GeV, sqrt(d_12) > 40 GeV (sqrt(d_12) is the first splitting scale)
- $\Delta R$(anti-kt R=1.0 jet, anti-kt R=0.4 jet) > 1.5 and $\Delta \phi$(anti-kt R=1.0 jet, lepton) > 2.3
- At least one of the anti-kt R=0.4 jets is b-tagged among: (a) the leading jet within $\Delta R$ < 1.5 from the lepton; (b) one jet within $\Delta R$ < 1.0 from anti-kt R=1.0 jet axis.
