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Abstract The Precision Proton Spectrometer (PPS) of the CMS and TOTEM experiments collected 107.7 fb -1 in proton-proton (pp) collisions at the LHC at 13 TeV (Run 2). This paper describes the key features of the PPS alignment and optics calibrations, the proton reconstruction procedure, as well as the detector efficiency and the performance of the PPS simulation. The reconstruction and simulation are validated using a sample of (semi)exclusive dilepton events. The performance of PPS has proven the feasibility of continuously operating a near-beam proton spectrometer at a high luminosity hadron collider. 

Abstract The production of Z bosons associated with jets is measured in $$\text {p}\text {p}$$ pp collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$ s = 13 Te V with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3 $$\,\text {fb}^{-1}$$ fb - 1 . The multiplicity of jets with transverse momentum $$p_{\textrm{T}} > 30\,\text {Ge}\hspace{-.08em}\text {V} $$ p T > 30 Ge V is measured for different regions of the Z boson’s $$p_{\textrm{T}} (\text {Z })$$ p T ( Z ) , from lower than 10 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ Ge V to higher than 100 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ Ge V . The azimuthal correlation $$\varDelta \phi $$ Δ ϕ between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of $$p_{\textrm{T}} (\text {Z })$$ p T ( Z ) . The measurements are compared with several predictions at leading and next-to-leading orders, interfaced with parton showers. Predictions based on transverse-momentum dependent parton distributions and corresponding parton showers give a good description of the measurement in the regions where multiple parton interactions and higher jet multiplicities are not important. The effects of multiple parton interactions are shown to be important to correctly describe the measured spectra in the low $$p_{\textrm{T}} (\text {Z })$$ p T ( Z ) regions. 

Abstract Multijet events at large transverse momentum ( $$p_{\textrm{T}}$$ p T ) are measured at $$\sqrt{s}=13\,\text {TeV} $$ s = 13 TeV using data recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of $$36.3{\,\text {fb}^{-1}} $$ 36.3 fb - 1 . The multiplicity of jets with $$p_{\textrm{T}} >50\,\text {GeV} $$ p T > 50 GeV that are produced in association with a high- $$p_{\textrm{T}}$$ p T dijet system is measured in various ranges of the $$p_{\textrm{T}}$$ p T of the jet with the highest transverse momentum and as a function of the azimuthal angle difference $$\varDelta \phi _{1,2}$$ Δ ϕ 1 , 2 between the two highest $$p_{\textrm{T}}$$ p T jets in the dijet system. The differential production cross sections are measured as a function of the transverse momenta of the four highest $$p_{\textrm{T}}$$ p T jets. The measurements are compared with leading and next-to-leading order matrix element calculations supplemented with simulations of parton shower, hadronization, and multiparton interactions. In addition, the measurements are compared with next-to-leading order matrix element calculations combined with transverse-momentum dependent parton densities and transverse-momentum dependent parton shower.