Measurement of the top-quark mass in $$ t\overline{t} $$ + 1-jet events collected with the ATLAS detector in pp collisions at $$ \sqrt{s} $$ = 8 TeV

Abstract

A determination of the top-quark mass is presented using 20.2 fb −1 of 8 TeV proton-proton collision data produced by the Large Hadron Collider and collected by the ATLAS experiment. The normalised differential cross section of top-quark pair production in association with an energetic jet is measured in the lepton+jets final state and unfolded to parton and particle levels. The unfolded distribution at parton level can be described using next-to-leading-order QCD predictions in terms of either the top-quark pole mass or the running mass as defined in the (modified) minimal subtraction scheme. A comparison between the experimental distribution and the theoretical prediction allows the top-quark mass to be extracted in the two schemes. The value obtained for the pole-mass scheme is: m pole t = 171.1 ± 0.4 (stat) ± 0.9 (syst) +0.7 −0.3 (theo) GeV. The extracted value in the running-mass scheme is: m t (m t) = 162.9 ± 0.5 (stat) ± 1.0 (syst) +2.1 −1.2 (theo) GeV. The results for the top-quark mass using the two schemes are consistent, when translated from one scheme to the other.

Top quark pair production in the exclusive processes at the LHC

“…Good prospects for observing the exclusive signal over a mixture of inclusive and combinatorial background are achieved for all luminosity scenarios, although a good separation between the two is observed for rather low amounts of pileup, typically lower than hμi of 50. Statistical significances evaluated from estimated numbers of signal and background events are around 3 for the highest luminosity scenario ðhμi; L½fb −1 Þ ¼ ð50; 300Þ, about 6 for the (10,30) and 11 for the (5,10) scenarios. From a simple statistical analysis, we find that these significances are still not sufficient for a determination of the top quark mass that would be competitive with inclusive methods.…”

“…This expectation is directly related to the fact that the top quark couples to all gauge bosons and the Higgs boson, which implies that the top production is very sensitive to the presence of BSM phenomena. In addition, recent experimental results for the inclusive top pair production have demonstrated that this process can be used to measure the top mass in a well-defined scheme with high accuracy [5][6][7][8][9][10]. These results provide motivation for the study of the top pair production in diffractive processes, where the final state is cleaner than the typical inclusive one, where both incident protons fragment and a large number of particles are produced in addition to the top pair (for a review on diffraction see, e.g., Ref.…”

Top quark pair production near threshold: single/double distributions and mass determination

“…Precision theoretical predictions for this observable, especially in the threshold region, are therefore highly demanded to achieve the goal of extracting the top quark mass. A closely related observable ρ s (and similar ones) in tt + jet production was employed in [17][18][19][20][21], where ρ s is defined as…”

Associated Production of W + Charm in 13 TeV Proton-Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton

“…The recent measurements of the pole and MS mass of the top quark in proton-proton collisions are presented in Refs. [29,30].…”