7  [GeV/c] T top quark p 0 50 100 150 200 250 300 350 400 ] -1  [pb/GeVc T  / dp d 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16  -1 DØ data, 1 fb NLO pQCD Approx. NNLO pQCD MC@NLO PYTHIA ALPGEN  [GeV/c] T top quark p 0 50 100 150 200 250 300 350 400 Ratio to NLO pQCD 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0  -1 DØ data, 1 fb NLO pQCD scale uncertainty Approx. NNLO pQCD MC@NLO PYTHIA ALPGEN FIG. 4: Inclusive d σ/ d p T for t ¯ t production (two entries per event) in data (points) compared with expectations from NLO pQCD (solid lines), from an approximate NNLO pQCD cal- culation, and for several event generators (dashed and dot- dashed lines). The gray band encompasses uncertainties on the pQCD scale and parton distribution functions. Inner and outer error bars represent the statistical and total (statistical and systematic added in quadrature) uncertainties, respec- tively. FIG. 5: Ratio of d σ/ d p T for top quarks in t ¯ t production (two entries per event) to the expectation from NLO pQCD. The gray band encompasses uncertainties on the scale of pQCD and parton distribution functions. Also shown are ratios rel- ative to NLO pQCD for an approximate NNLO pQCD calcu- lation and of predictions for several event generators. Inner and outer error bars represent statistical and total (statistical and systematic added in quadrature) uncertainties, respec- tively. many); SFI (Ireland); The Swedish Research Council (Sweden); and CAS and CNSF (China). FAPERJ, FAPESP and FUNDUNESP (Brazil); DAE and DST (India); Colciencias (Colombia); CONACyT (Mexico); KRF and KOSEF (Korea); CONICET and UBACyT (Argentina); FOM (The Netherlands); STFC and the Royal Society (United Kingdom); MSMT and GACR (Czech Republic); CRC Program, CFI, NSERC and WestGrid Project (Canada); BMBF and DFG (Ger- [a] Visitor from Augustana College, Sioux Falls, SD, USA. [b] Visitor from The University of Liverpool, Liverpool, UK. [c] Visitor from SLAC, Menlo Park, CA, USA. [d] Visitor from ICREA/IFAE, Barcelona, Spain. [e] Visitor from Centro de Investigacion en Computacion - IPN, Mexico City, Mexico. [f] Visitor from ECFM, Universidad Autonoma de Sinaloa, Prediction Absolute Shape χ $^{2}$/ NDF prob. χ $^{2}$/ NDF prob. NLO pQCD 0.695 0.653 0.315 0.904 Approx. NNLO pQCD 0.521 0.793 0.497 0.779 mc@nlo 1.22 0.295 0.777 0.566 pythia 2.61 0.0157 0.352 0.881 alpgen 5.04 3.54 10 − 5 0.204 0.961 p T 〈 p T 〉 Cross Stat. Shape Sys. NLO Section Unc. Unc. pQCD (GeV /c ) (GeV /c ) (fb/GeV) (fb/GeV) (fb/GeV) (fb/GeV) 0 − 45 29 70 11 5 59 . 6 45 90 68 130 20 10 116 90 − 140 113 89 13 6 83 . 8 140 200 165 37 6 3 35 . 6 200 − 300 233 8 . 7 1 . 7 0 . 7 7 . 72 300 400 329 1 . 1 0 . 3 0 . 1 0 . 814 σ t ¯ t (pb) 8 . 31 1 . 28 7 . 54 TABLE IV: The χ $^{2}$/ NDF and χ 2 probability for comparisons between the measured data and predictions using correlated (uncorrelated) uncertainties for the absolute (shape) compar- ison. TABLE III: Inclusive differential cross section d σ/ d p T for t ¯ t production at √$_{s}$ = 1 . 96 TeV and m t = 170 GeV /c $^{2}$. There are two entries per event, with the total normalized to the t ¯ t production cross section. In addition to total systematic uncertainties on the shape in p T in each bin, there is a p T - independent systematic uncertainty of 9 . 6% that is not in- cluded in the table.