Mueller–Navelet jets at LHC: BFKL versus high-energy DGLAP

F G Celiberto,A Papa,B Murdaca,D Yu Ivanov

doi:10.1140/epjc/s10052-015-3522-6

Abstract

The production of forward jets separated by a large rapidity gap at LHC, the so-called Mueller–Navelet jets, is a fundamental testfield for perturbative QCD in the high-energy limit. Several analyses have already provided us with evidence about the compatibility of theoretical predictions, based on collinear factorization and BFKL resummation of energy logarithms in the next-to-leading approximation, with the CMS experimental data at 7 TeV of center-of-mass energy. However, the question if the same data can be described also by fixed-order perturbative approaches has not yet been fully answered. In this paper we provide numerical evidence that the mere use of partially asymmetric cuts in the transverse momenta of the detected jets allows for a clear separation between BFKL-resummed and fixed-order predictions in some observables related with the Mueller–Navelet jet production process.

Highlights

It is widely believed that the inclusive hadroproduction of two jets featuring transverse momenta of the same order and much larger than the typical hadronic masses and being separated by a large rapidity gap Y, the so-called Mueller– Navelet jets [1], is a fundamental testfield for perturbative QCD in the high-energy limit, the jet transverse momenta providing us with the hard scales of the process.The other resummation mech√anism at work, justified by the large center-of-mass energy s available at LHC, is the BFKL resummation of energy logarithms, which are so large as to compensate the small QCD coupling and must be accounted for to all orders of perturbation
These energy logarithms are related with the emission of undetected partons between the two jets, which lead to a reduced azimuthal correlation between the two detected forward jets, in comparison to the fixed-order DGLAP calculation, where jets are emitted almost back-to-back
In this paper we have considered the Mueller–Navelet jet production process at LHC at the center-of-mass energy of 7 TeV and have compared predictions for several azimuthal correlations and ratios between them, both in full next-to-leading logarithmic approximation (NLA) BFKL approach and in fixed-order next-to-leading order (NLO) DGLAP

Summary

Introduction

It is widely believed that the inclusive hadroproduction of two jets featuring transverse momenta of the same order and much larger than the typical hadronic masses and being separated by a large rapidity gap Y , the so-called Mueller– Navelet jets [1], is a fundamental testfield for perturbative QCD in the high-energy limit, the jet transverse momenta providing us with the hard scales of the process. For this purpose, we compare predictions for several azimuthal correlations and their ratios obtained, on one side, by a fixed-order DGLAP calculation at the NLO and, on the other side, by BFKL resummation in the NLA. The paper is organized as follows: we give the kinematics and the basic formulas for the Mueller– Navelet jet process cross section; in Sect. 3 we present our results; in Sect. 4 we draw our conclusions

Theoretical setup

Results

Used tools

Uncertainty estimation

Conclusions