Measurement of the 4-jet production at the CMS experiment

Measurements are presented of exclusive 4-jet production cross sections as a function of the transverse momentum $p_{\rm T}$, pseudorapidity $\eta$, as well as of correlations in azimuthal angle, pseudorapidity and $p_{\rm T}$ balance among the jets. The data sample was collected at a centre-of-mass energy of 7 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 36 pb$^{-1}$. The jets are reconstructed with the anti-$k_{\rm T}$ jet algorithm in a range of $|\eta| < 2.5$. The two leading jets are required to have a transverse momentum $p_{\rm T} > 50$ GeV, while the two soft jets are required to have $p_{\rm T} > 20$ GeV. The measured cross sections agree within uncertainties with the predictions of parton shower Monte Carlo event generators and with NLO calculations matched to parton showers, but several features in the data indicate the need for improvements in the matching of the latter to the former. The study of the angular correlations between the four jets provide a useful baseline for future studies to investigate possible contributions from double parton scattering.