Measurement of the sum of WW and WZ production with W+dijet events in pp collisions at sqrt(s) = 7 TeV

Abstract

A measurement of the inclusive WW+WZ diboson production cross section in proton-proton collisions is reported, based on events containing a leptonically decaying W boson and exactly two jets. The data sample, collected at sqrt(s) = 7 TeV with the CMS detector at the LHC, corresponds to an integrated luminosity of 5.0 inverse femtobarns. The measured value of the sum of the inclusive WW and WZ cross sections is sigma(pp to WW+WZ) = 68.9 +/- 8.7 (stat.) +/- 9.7 (syst.) +/- 1.5 (lum.) pb, consistent with the standard model prediction of 65.6 +/- 2.2 pb. This is the first measurement of WW+WZ production in pp collisions using this signature. No evidence for anomalous triple gauge couplings is found and upper limits are set on their magnitudes.

Figures (3)

• Figure 1: (a) Distribution of the dijet invariant mass in data, with the binning chosen based on the resolution and fit projections of the relevant components overlaid. (b) The dijet invariant mass after subtraction of all components except the electroweak WW+WZ processes. The error bars represent the statistical uncertainties and the hatched bands represent the systematic uncertainties. (c) The normalized residual or pull: $(\text{data} - \text{fit})/(\text{fit~uncertainty})$.
• Figure 2: Dijet $p_{\mathrm{T}}$ distributions for (a) the muon and (b) the electron channels after full selection and with the requirement $75\,\text{Ge\spaceV}\xspace < m_{jj}\xspace < 95\,\text{Ge\spaceV}\xspace$. The stacked histogram shapes are taken from simulation or, where applicable, from data-driven estimates. They are normalized according to the fit to the observed $m_{jj}$ spectrum in data. Below we show the Data/MC ratio with the (dashed) red lines corresponding to the shape uncertainty. The last bin includes the overflow.
• Figure 3: Observed (solid) and expected (dashed) exclusion limits at 95% CL for anomalous triple gauge couplings. The dark green and light yellow bands correspond to the one and two sigma intervals, respectively, in the expected limit distribution. The SM expectation is shown by the solid dot.