Measurement of dijet production with a leading proton in proton-proton collisions at $\sqrt{s}=8\,\mathrm{TeV}$

A study of dijet production associated with a leading proton is presented. The analysis is based on a common data set collected simultaneously with the CMS and TOTEM detectors at the LHC with proton-proton collisions at \sqrt(s) = 8 TeV during a dedicated run with β∗ = 90 m, at low instantaneous luminosity. The data correspond to an integrated luminosity of 37.5 nb−1 . The analysis presents the measurement of the dijet production cross section, as a function of ξ , the proton fractional momentum loss, and as a function of t, the 4-momentum transfer squared at the proton vertex. The dijet cross section in the kinematic region defined by ξ < 0.1, 0.03 < |t| < 1 GeV2 , with at least two jets with transverse momentum pT > 40 GeV, and pseudorapidity |η | < 4.4, is measured as 21.7 ± 0.9 (stat) +3.0 (syst) ± 0.9 (lumi) nb. Both the processes pp → pX and pp → Xp, i.e. with the proton scattering to either side of the interaction, are measured, with X including a system of two jets. The results correspond to the aver- age of their cross sections. The ratio of the single-diffractive to inclusive dijet yields, normalised per unit of ξ , is presented as a function of x, the longitudinal momentum fraction of the proton carried by the struck parton. The ratio in the kinematic region defined above, for x values in the range −2.9 ≤ log10 x ≤ −1.6, was measured as pX R = σjj /∆ξ /σjj = 0.025 ± 0.001 (stat) ± 0.003 (syst). The results are compared to the predictions from models of diffractive and non-diffractive interactions.