A study of dijet production in proton-proton collisions was performed at \sqrt{s}=7 TeV for jets with pT > 35 GeV and |y|<4.7 using data collected with the CMS detector at the LHC in 2010. Events with at least one pair of jets are denoted as ``inclusive''. Events with exactly one pair of jets are called ``exclusive''. The ratio of the cross section of all pairwise combinations of jets to the exclusive dijet cross section as a function of the rapidity difference between jets DeltaY is measured for the first time up to DeltaY =9.2. The ratio of the cross section for the pair consisting of the most forward and the most backward jet from the inclusive sample to the exclusive dijet cross section is also presented. The predictions of the Monte Carlo event generators PYTHIA6 and PYTHIA8 agree with the measurements. In both ratios the HERWIG++ generator exhibits a more pronounced rise versus DeltaY than observed in the data. The BFKL-motivated generators CASCADE and HEJ+ARIADNE predict for these ratios a significantly stronger rise than observed.

Published plots in png format

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Ratios of the inclusive to exclusive dijet cross sections as a function of the rapidity separation DeltaY between the two jets, R^{incl} (left panel) and R^{MN} (right panel), compared to the predictions of the DGLAP-based MC generators PYTHIA6, PYTHIA8 and HERWIG++, as well as of CASCADE and HEJ+ARIADNE, which incorporate elements of the BFKL approach. The shaded band indicates the size of the total systematic uncertainty of the data. Statistical uncertainties are smaller than the symbol sizes. Because of limitations in the CASCADE generator, it was not possible to obtain a reliable prediction for DeltaY > 8.

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Predictions for R^{incl} (left) and R^{MN} (right) from DGLAP-based MC generators presented as ratio to data corrected for detector effects. Both BFKL-motivated generators CASCADE and HEJ+ARIADNE (not shown) lead to a MC/data ratio well above unity. The shaded band indicates the size of the total systematic uncertainty of the data while statistical uncertainties are shown as bars.