Testing the parton evolution with the use of two-body final states

H. Jung,A. V. Lipatov,S. P. Baranov,M. A. Malyshev

doi:10.1140/epjc/s10052-016-4562-2

Abstract

We consider the production of b{bar{b}} quarks and Drell–Yan lepton pairs under LHC conditions focusing attention on the total transverse momentum of the produced pair and on the azimuthal angle between the momenta of the outgoing particles. Plotting the corresponding distributions in bins of the final-state invariant mass, one can reconstruct the full map of the transverse momentum dependent parton densities in a proton. We give examples of how these distributions can look like at the LHC energies.

Highlights

Drell–Yan lepton pairs under LHC conditions focusing attention on the total transverse momentum of the produced pair and on the azimuthal angle between the momenta of the outgoing particles
Experiments of new generation running at the LHC yield plenty of high precision data
In order to properly interpret these data we need the parton distribution functions to be known with adequately good accuracy

Summary

We consider the production of bbquarks and

Drell–Yan lepton pairs under LHC conditions focusing attention on the total transverse momentum of the produced pair and on the azimuthal angle between the momenta of the outgoing particles. Plotting the corresponding distributions in bins of the final-state invariant mass, one can reconstruct the full map of the transverse momentum dependent parton densities in a proton. We do not consider here higher-order corrections q + q → l + + l − + g since they are already taken into account in the k T -factorization approach [3,4,5,6,7] as a part of the evolution of TMD quark densities. The final states of the processes (1) and (2) are represented by two-body systems with fully reconstructible kinematics where the transverse momentum pT of the bbor lepton pair measures the net transverse momentum of the initial gluons or quarks, the invariant mass of the pair measures the product of longitudinal momentum fractions, M 2 = x1 x2 s, and the rapidity of the pairs measures the ratio of the momentum fractions, y = (1/2) ln(x1 /x2 ). Comparing the pT and φ spectra at varying gluon momentum fraction x we watch the evolution of parton distributions

To simulate the bbpair production we used the latest

This research was supported in part by RFBR