Measurement of W → l ν + jets Differential Cross Section with 9.0 fb-1

Authors: A. Driutti, G. Pauletta, V. Rusu, M. Trovato
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Public note: CDF11167





Preliminary results for the production of a W boson in association with jets, in pp collisions at √s= 1.96 TeV center mass energy are presented. The measurement is based on the whole data set collected by CDF during Run II, which corresponds to an integrated luminosity of 9.0 fb-1. Cross section for the inclusive production of jets with ET jet > 25 GeV and |η jet| <2, in conjunction with a W boson which decays into an electron-neutrino or muon-neutrino pair, are presented as a function of ET jet and inclusive jet multiplicity.




Background Modeling & Validation


ele_b_jet1_et.gif muo_b_jet1_et.gif

Fig. 1: The leading jet ET distribution for the W (→ eν) + ≥ 1 jets sample (a) and W (→ μν) + ≥ 1 jets sample (b) in the control region. The lower figures illustrate the ratio between data distributions and predictions (see text).


Estimated and Observed Number of Events


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Tab. 1: Estimated number of background events in 9.0 fb-1 for W (→ eν) + ≥ 1, 2, 3 and 4 jets and data yields.


muoEV.png

Tab. 2: Estimated number of background events in 9.0 fb-1 for W (→ μν) + ≥ 1, 2, 3 and 4 jets and data yields.


eleN.gif muN.gif

Fig. 2: Data and background jet multiplicities in the W → eν channel (a) and in the W → μν channel (b). The LO×K-factor ALPGEN+PYTHIA theoretical prediction is also shown.


Systematic Uncertanties


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Fig. 3: Total systematic uncertainties vs inclusive jet multiplicity in the W → eν channel (a) and in the W → μν channel (b).


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Fig. 4: Total systematic uncertainties vs leading jet ET in the W → eν channel (a) and in the W → μν channel (b).


Channel Combination


AIBN_wL.gif AIBJ_wL.gif

Fig. 5: Measured cross section in the W (→ eν) + jets (blue dots) and W (→ μν) + jets (red squares) decay channels as a function of inclusive number of jets (a) and leading jet ET (b) in events with ≥ 1 jet. The lower figures illustrate the ratio between measured cross sections and combination with the total systematic uncertainty (all correlations are properly accounted for).


Results


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Fig. 6: Measured inclusive jet differential cross section (black dots) as a function of the inclusive jet multiplicity (a) and leading jet ET (b) compared to LO calculations corrected by K-factor pQCD predictions (open squares). The shaded bands show the total systematic uncertainty, except for the 6% luminosity uncertainty. The dashed and the plain lines indicate the PDF uncertainty and the variation of the renormalization scale μ0, respectively.


tabfN.png

Tab. 3: Unfolded W (→ lν)+jets cross section mesurements for inclusive jet multiplicities up to 4 jets together with statistical, systematic and luminosity uncertainties. The kinematic region in which the measurements are performed is ETl > 25 GeV and |ηl| <1, ET jet > 25 GeV and |η jet| <2 and mTW > 40 GeV/c2.