Study of dijet events with a large rapidity gap between the two leading jets in pp collisions at s = 7 TeV

Abstract

Events with no charged particles produced between the two leading jets are studied in proton-proton collisions at $\sqrt{s}=7$ $\text{TeV}$ . The jets were required to have transverse momentum $p_T^{\text{jet}}>40$ $\text{GeV}$ and pseudorapidity $1.5<|{\eta }^{\text{jet}}|<4.7$ , and to have values of ${\eta }^{\text{jet}}$ with opposite signs. The data used for this study were collected with the CMS detector during low-luminosity running at the LHC, and correspond to an integrated luminosity of 8 ${\text{pb}}^{-1}$ . Events with no charged particles with $p_T>0.2$ $\text{GeV}$ in the interval $-1<\eta <1$ between the jets are observed in excess of calculations that assume no color-singlet exchange. The fraction of events with such a rapidity gap, amounting to 0.5-1% of the selected dijet sample, is measured as a function of the $p_T$ of the second-leading jet and of the rapidity separation between the jets. The data are compared to previous measurements at the Tevatron, and to perturbative quantum chromodynamics calculations based on the Balitsky-Fadin-Kuraev-Lipatov evolution equations, including different models of the non-perturbative gap survival probability.

Keywords: CMS; Diffraction; Physics; QCD.