Dijet Azimuthal Decorrelations in pp Collisions at sqrt(s) = 7 TeV

Abstract

Measurements of dijet azimuthal decorrelations in pp collisions at sqrt(s) = 7 TeV using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding to an integrated luminosity of 2.9 inverse picobarns. The results are compared to predictions from perturbative QCD calculations and various Monte Carlo event generators. The dijet azimuthal distributions are found to be sensitive to initial-state gluon radiation.

Figures (4)

• Figure 1: Normalized $\Delta \varphi_\text{dijet}$ distributions in several $p_{T}$$^\text{max}$ regions, scaled by the multiplicative factors given in the figure for easier presentation. The curves represent predictions from pythia6, pythia8, herwig++, and madgraph. The error bars on the data points include statistical and systematic uncertainties.
• Figure 2: Ratios of measured normalized $\Delta \varphi_\text{dijet}$ distributions to pythia6, pythia8, herwig++, and madgraph predictions in several $p_{T}$$^\text{max}$ regions. The shaded bands indicate the total systematic uncertainty.
• Figure 3: Ratios of measured normalized $\Delta \varphi_\text{dijet}$ distributions to NLO pQCD predictions with non-perturbative corrections in several $p_{T}$$^\text{max}$ regions. The error bars on the data points include statistical and systematic uncertainties. The effect on the NLO pQCD predictions due to $\mu_r$ and $\mu_f$ scale variations and PDF uncertainties, as well as the uncertainties from the non-perturbative corrections are shown.
• Figure 4: Ratios of measured normalized $\Delta \varphi_\text{dijet}$ distributions to pythia6 tune D6T with various values of $k_{\text{ISR}}$ in several $p_{T}$$^\text{max}$ regions. The shaded bands indicate the total systematic uncertainty.