CMS-PAS-FSQ-12-033

CMS-PAS-FSQ-12-033
Measurement of dijet production with a leading proton in proton-proton collisions at $\sqrt{s}=$ 8 TeV
CMS Collaboration
September 2018

Abstract: 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 $\beta^{*}=$ 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 $\xi$ , 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 $\xi <$ 0.1, 0.03 $< \| t \| <$ 1 GeV $^2$ , with at least two jets with transverse momentum $p_{\mathrm{T}} >$ 40 GEV, and pseudorapidity $\| \eta \| <$ 4.4, is measured as 21.7 $\pm$ 0.9 (stat) $^{+3.0}_{-3.3}$ (syst) $\pm$ 0.9 (lumi) nb. Both the processes $\mathrm{pp} \to \mathrm{pX}$ and $\mathrm{pp} \to \mathrm{Xp}$ , 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 average of their cross sections. The ratio of the single-diffractive to inclusive dijet yields, normalised per unit of $\xi$ , 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 $-2.9 \leq \log_{10} x \leq -1.6$ , was measured as $R = (\sigma^{\mathrm{pX}}_{\mathrm{jj}}/\Delta\xi )/\sigma_{\mathrm{jj}} =$ 0.025 $\pm$ 0.001 (stat) $\pm$ 0.003 (syst). The results are compared to the predictions from models of diffractive and non-diffractive interactions.
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; These preliminary results are superseded in this paper, EPJC 80, 1164 (2020). The superseded preliminary plots can be found here.

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