Study of double-parton scattering in the inclusive production of four jets with low transverse momentum in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A study of inclusive four-jet production in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. The transverse momentum of jets within $|\eta| < 4.7$ reaches down to 35, 30, 25, and 20 GeV for the first, second, third, and fourth leading jet, respectively. Differential cross sections are measured as a function of the jet transverse momentum and pseudorapidity, and of several other observables that exploit angular correlations between the jets. It is found that the measured distributions show sensitivity to different aspects of the underlying event, parton shower, and matrix element calculations. In particular, the interplay between decorrelations caused by parton shower and double-parton scattering contributions is shown to be important. The double-parton scattering contribution is extracted by means of a template fit of distributions for single-parton scattering obtained from Monte Carlo event generators and a double-parton scattering distribution constructed from inclusive single-jet events in data. Values of the effective cross section are calculated and discussed in view of earlier measurements and of their dependence on the models used for the single-parton scattering background.