Abstract

A study of dijet production in proton-proton collisions was performed at sqrt(s) = 7 TeV for jets with pt > 35 GeV and abs(y) < 4.7 using data collected with the CMS detector at the LHC in 2010. Events with at least one pair of jets are denoted as "inclusive". Events with exactly one pair of jets are called "exclusive". The ratio of the cross section of all pairwise combinations of jets to the exclusive dijet cross section as a function of the rapidity difference between jets abs(Delta(y)) is measured for the first time up to abs(Delta(y)) = 9.2. The ratio of the cross section for the pair consisting of the most forward and the most backward jet from the inclusive sample to the exclusive dijet cross section is also presented. The predictions of the Monte Carlo event generators PYTHIA6 and PYTHIA8 agree with the measurements. In both ratios the HERWIG++ generator exhibits a more pronounced rise versus abs(Delta(y)) than observed in the data. The BFKL-motivated generators CASCADE and HEJ+ARIADNE predict for these ratios a significantly stronger rise than observed.

Highlights

  • The measurement of inclusive jet production in pp collisions provides an important testing ground for the Standard Model

  • Inclusive jet production is well described at LHC energies, over a wide range in jet transverse momentum and rapidity [1, 2], by calculations at next-to-leading-order (NLO) in perturbative quantum chromodynamics (QCD) using the Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) approach [3,4,5,6,7] and collinear factorization

  • Mueller–Navelet jet pairs [17] are a subset of the inclusive dijet class

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Summary

Introduction

The ratio of the dijet production cross section in “inclusive” events to that in “exclusive” events, Rincl = σ incl/σ excl, as a function of the rapidity separation | y| between two jets, is a sensitive probe of effects beyond collinear factorization [16]. This allowed to collect a number of dijet events at high | y| values more than 100 times larger than with the single-jet trigger. The exclusive dijet sample is a subset of the inclusive and Mueller–Navelet samples, and consists of events where exactly one pair of jets is found.

Results
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