Study on the azimuthal angle correlation between two jets in the top quark pair production

An azimuthal angle correlation between the two hardest jets is studied in the ttbar production process at the 14 TeV LHC. The event samples are generated by merging the tree level matrix elements for the ttbar plus up to 2 or 3 partons with parton showers. The generated event samples show a strong correlation in the azimuthal angle difference between the two hardest jets, as predicted in the analysis based on the tree level matrix elements for the ttbar+2 partons. The effects of merging the matrix elements for the ttbar+3 partons on the correlation are studied in detail. It is found that they play important roles in improving the prediction of the correlation.