2011 QCD and High Energy Interactions - Rencontres de Moriond ...

Figure 3: Leading jet pT in Z/γ ∗ → µ + µ − (left) and Z/γ ∗ → e + e − (right) + jets events. The Z + b-jet
contribution used to measure the σ(Z+b)
cross section ratio is shown in red color.
σ(Z+jet)
Events that are consistent with the electronic and muonic W boson decay and contain one or two
jets with ET 20GeV and |η| 2.0 are selected. The b-jet flavor composition is determined
through a fit to the distribution of the secondary vertex mass in the data. The measured
cross section is σ(W + b-jets) × BR(W → lν) = 2.74 ± 0.27 ± 0.42 pb. This result cannot be
accommodated by different available theoretical predictions. The Pythia prediction is 1.10 pb,
while Alpgen predicts 0.78 pb, and a recent MCFM NLO calculation of 1.22 ± 0.14 pb is also
signicantly lower than the measurement.
Summary
New results at the Tevatron of Z/W + jets and Z/W + heavy flavor production are in general
good agreement with the NLO predictions, even if with large uncertainties in some cases. There
are prospects for more precise measurements of W/Z + HF production, and for the combination
of the electron and muon channels in the Z+jets production.
References
1. D.J. Gross and F. Wilczek, Phys. Rev. D 8, 3633 (1973).
2. J.Campbell and R.K. Ellis, Phys. Rev. D 65, 113007 (2002).
3. CDF Collaboration, CDF Conference Note 10216
http://www-cdf.fnal.gov/physics/new/qcd/abstracts/zjets 10.html
4. CDF Collaboration, CDF Conference Note 10423
http://www-cdf.fnal.gov/physics/new/qcd/abstracts/zjets 10.html
5. A. Abulencia et al. (CDF Collaboration), Phys. Rev. D 74, 071103(R) (2006).
6. T. Aaltonen et al. (CDF Collaboration), Phys. Rev. Lett. 100, 102001 (2008).
7. D0 Collaboration Phys. Lett. B 682, 370 (2010)
8. CDF Collaboration Phys. Rev. D 79, 052008 (2009)
9. D0 Collaboration Phys. Rev. D 83, 031105 (2011)
10. CDF Collaboration Phys. Rev. Lett. 104, 131801 (2010)