Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC

P. Kotko, K. Kutak, S. Sapeta, A. M. Stasto, M. Strikman

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Using the framework that interpolates between the leading power limit of the color glass condensate and the high energy (or kT) factorization we calculate the direct component of the forward dijet production in ultra-peripheral Pb –Pb collisions at CM energy 5.1TeV per nucleon pair. The formalism is applicable when the average transverse momentum of the dijet system PT is much bigger than the saturation scale Qs, PT≫ Qs, while the imbalance of the dijet system can be arbitrary. The cross section is uniquely sensitive to the Weizsäcker–Williams (WW) unintegrated gluon distribution, which is far less known from experimental data than the most common dipole gluon distribution appearing in inclusive small-x processes. We have calculated cross sections and nuclear modification ratios using WW gluon distribution obtained from the dipole gluon density through the Gaussian approximation. The dipole gluon distribution used to get WW was fitted to the inclusive HERA data with the nonlinear extension of unified BFKL + DGLAP evolution equation. The saturation effects are visible but rather weak for realistic pT cut on the dijet system, reaching about 20% with the cut as low as 6GeV. We find that the LO collinear factorization with nuclear leading-twist shadowing predicts quite similar effects.

Original languageEnglish (US)
Article number353
JournalEuropean Physical Journal C
Volume77
Issue number5
DOIs
StatePublished - May 1 2017

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Factorization
Heavy ions
ionic collisions
estimating
dipoles
factorization
Momentum
Color
saturation
Glass
cross sections
transverse momentum
condensates
formalism
color
collisions
energy
glass
approximation

All Science Journal Classification (ASJC) codes

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)

Cite this

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abstract = "Using the framework that interpolates between the leading power limit of the color glass condensate and the high energy (or kT) factorization we calculate the direct component of the forward dijet production in ultra-peripheral Pb –Pb collisions at CM energy 5.1TeV per nucleon pair. The formalism is applicable when the average transverse momentum of the dijet system PT is much bigger than the saturation scale Qs, PT≫ Qs, while the imbalance of the dijet system can be arbitrary. The cross section is uniquely sensitive to the Weizs{\"a}cker–Williams (WW) unintegrated gluon distribution, which is far less known from experimental data than the most common dipole gluon distribution appearing in inclusive small-x processes. We have calculated cross sections and nuclear modification ratios using WW gluon distribution obtained from the dipole gluon density through the Gaussian approximation. The dipole gluon distribution used to get WW was fitted to the inclusive HERA data with the nonlinear extension of unified BFKL + DGLAP evolution equation. The saturation effects are visible but rather weak for realistic pT cut on the dijet system, reaching about 20{\%} with the cut as low as 6GeV. We find that the LO collinear factorization with nuclear leading-twist shadowing predicts quite similar effects.",
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Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC. / Kotko, P.; Kutak, K.; Sapeta, S.; Stasto, A. M.; Strikman, M.

In: European Physical Journal C, Vol. 77, No. 5, 353, 01.05.2017.

Research output: Contribution to journalArticle

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