W pair Production
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Measurement of the $W^+W^-$ Production Cross Section and Search for Anomalous $WW\gamma$ and $WWZ$ Couplings in $p \bar p$ Collisions at $\sqrt{s} = 1.96$ TeV

The CDF collaboration Aaltonen, T. ; Adelman, J. ; Alvarez Gonzalez, B. ; et al.
Phys.Rev.Lett. 104 (2010) 201801, 2010.
Inspire Record 841021 DOI 10.17182/hepdata.54291

This Letter describes the current most precise measurement of the $W$ boson pair production cross section and most sensitive test of anomalous $WW\gamma$ and $WWZ$ couplings in $p \bar p$ collisions at a center-of-mass energy of 1.96 TeV. The $WW$ candidates are reconstructed from decays containing two charged leptons and two neutrinos, where the charged leptons are either electrons or muons. Using data collected by the CDF II detector from 3.6 fb$^{-1}$ of integrated luminosity, a total of 654 candidate events are observed with an expected background contribution of $320 \pm 47$ events. The measured total cross section is $\sigma (p \bar p \to W^+ W^- + X) = 12.1 \pm 0.9 \textrm{(stat)} ^{+1.6}_{-1.4} \textrm{(syst)}$ pb, which is in good agreement with the standard model prediction. The same data sample is used to place constraints on anomalous $WW\gamma$ and $WWZ$ couplings.

1 data table
Table 1

Measured cross section for inclusive W+ W- production.


Measurement of the WW+WZ Production Cross Section Using the Lepton+Jets Final State at CDF II

The CDF collaboration Aaltonen, T. ; Adelman, J. ; Alvarez Gonzalez, B. ; et al.
Phys.Rev.Lett. 104 (2010) 101801, 2010.
Inspire Record 837610 DOI 10.17182/hepdata.54292

We report two complementary measurements of the WW+WZ cross section in the final state consisting of an electron or muon, missing transverse energy, and jets, performed using p\bar{p} collision data at sqrt{s} = 1.96 TeV collected by the CDF II detector. The first method uses the dijet invariant mass distribution while the second more sensitive method uses matrix-element calculations. The result from the second method has a signal significance of 5.4 sigma and is the first observation of WW+WZ production using this signature. Combining the results gives sigma_{WW+WZ} = 16.0 +/- 3.3 pb, in agreement with the standard model prediction.

3 data tables
Table 1

Cross section from the combined analysis.. Error is combined statistics and systematics.

Table 2

Cross section from method one.

Table 3

Cross section from method two.


Model-independent measurement of the W boson helicity in top quark decays at D0

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Rev.Lett. 100 (2008) 062004, 2008.
Inspire Record 767094 DOI 10.17182/hepdata.47072

We present the first model-independent measurement of the helicity of $W$ bosons produced in top quark decays, based on a 1 fb$^{-1}$ sample of candidate $t\bar{t}$ events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider. We reconstruct the angle $\theta^*$ between the momenta of the down-type fermion and the top quark in the $W$ boson rest frame for each top quark decay. A fit of the resulting \costheta distribution finds that the fraction of longitudinal $W$ bosons $f_0 = 0.425 \pm 0.166 \hbox{(stat.)} \pm 0.102 \hbox{(syst.)}$ and the fraction of right-handed $W$ bosons $f_+ = 0.119 \pm 0.090 \hbox{(stat.)} \pm 0.053 \hbox{(syst.)}$, which is consistent at the 30% C.L. with the standard model.

6 data tables
Table 1

COS(THETA*) distribution for leptonic W decay in lepton+jets events.. Data are read from plots and errors are statistcial (sqrt(N)).

Table 2

COS(THETA*) distribution for hadronic W decay in lepton+jets events.. Data are read from plots and errors are statistcial (sqrt(N)).

Table 3

COS(THETA*) distribution for W decay in dilepton events.. Data are read from plots and errors are statistcial (sqrt(N)).

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