Azimuthal decorrelation of jets widely separated in rapidity in pp collisions at $\sqrt{s} =$ 7 TeV

Abstract

The decorrelation in the azimuthal angle between the most forward and the most backward jets (Mueller-Navelet jets) is measured in data collected in pp collisions with the CMS detector at the LHC at $\sqrt{s} =$ 7 TeV. The measurement is presented in the form of distributions of azimuthal-angle differences, $\Delta\phi$, between the Mueller-Navelet jets, the average cosines of $(\pi-\Delta\phi)$, $2(\pi-\Delta\phi)$, and $3(\pi-\Delta\phi)$, and ratios of these cosines. The jets are required to have transverse momenta, $p_{\mathrm{T}}$, in excess of 35 GeV and rapidities, $| y |$, of less than 4.7. The results are presented as a function of the rapidity separation, $\Delta{y}$, between the Mueller-Navelet jets, reaching $\Delta{y}$ up to 9.4 for the first time. The results are compared to predictions of various Monte Carlo event generators and to analytical predictions based on the DGLAP and BFKL parton evolution schemes