Preliminary Results

The dijet cross sections were measured using a data sample of 5.4 pb-1 in proton-proton collisions at 200 GeV. The cross sections were measured at the mid-rapidity |η| ≤ 0.8 as a function of dijet mass Mjj.

The dijet cross sections were estimated with the formula:

\displaystyle \frac{\text{d}^3\sigma}{\text{d}M_{\text{jj}}\text{d}\eta_3\text{d}\eta_4}=\frac{1}{\int {\cal
L}\text{d}t}\cdot\frac{1}{\Delta M_{\text{jj}}\Delta\eta_3\Delta\eta_4}\cdot\frac{1}{{\cal C}}\cdot J.

J is the dijet yields at the detector level. C is the correction factors which correct the dijet yields to the hadron level. The correction factors C are estimated from the MC events as bin-by-bin ratios of the dijet yields at the detector level and at the hadron level. ΔMjjΔη3Δη4 normalizes the cross sections to per unit space volume.

The major systematic uncertainty was due to the uncertainty on the jet energy scale (JES). Because the Mjj dependence is steeply decreasing, the uncertainty of the cross section is very sensitive to systematic uncertainty on the JES.

The dijet cross sections compared to theoretical predictions. The systematic uncertainty does not include 7.68% of uncertainly due to the uncertainly on the integrated luminosity.
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The ratios: (data - theory)/theory. The theory includes the NLO pQCD predictions and the corrections for the effects of hadronization and underlying events. The ratios are taken bin by bin.
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The figures show the preliminary results of the dijet cross section measurements. The measured dijet cross sections are well described by the theory. This indicates that measured ALL as well can be interpreted in the same theory and suggests ways to constrain the polarized gluon distributions from dijet ALL.