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

Abstract

Using the framework that interpolates between the leading power limit of the color glass condensate and the high energy (or k T ) factorization we calculate the direct component of the forward dijet production in ultra-peripheral Pb–Pb collisions atCMenergy 5.1 TeV per nucleon pair. The formalism is applicablewhen the average transversemomentum of the dijet system P T is much bigger than the saturation scale Q s , P T >> Qs , while the imbalance of the dijet system can be arbitrary. The cross section is uniquely sensitive to theWeizsäcker–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 also 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 p T cut on the dijet system, reaching about 20% with the cut as low as 6 GeV. Finally, we find that the LO collinear factorization with nuclear leading-twistmore » shadowing predicts quite similar effects.« less

Authors:
 [1];  [2];  [2];  [1];  [1]
  1. Pennsylvania State Univ., University Park, PA (United States). Dept. of Physics
  2. Polish Academy of Sciences, Krakow (Poland). Inst. of Nuclear Physics
Publication Date:
Research Org.:
Pennsylvania State Univ., University Park, PA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1361943
Alternate Identifier(s):
OSTI ID: 1389276
Grant/Contract Number:
FG02-93ER20097; SC0002145; FG02-93ER40771; 2015/17/B/ST2/01838; 2013/10/E/ST2/00656
Resource Type:
Journal Article: Published Article
Journal Name:
European Physical Journal. C, Particles and Fields
Additional Journal Information:
Journal Volume: 77; Journal Issue: 5; Journal ID: ISSN 1434-6044
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS

Citation Formats

Kotko, P., Kutak, K., Sapeta, S., Stasto, A. M., and Strikman, M. Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC. United States: N. p., 2017. Web. doi:10.1140/epjc/s10052-017-4906-6.
Kotko, P., Kutak, K., Sapeta, S., Stasto, A. M., & Strikman, M. Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC. United States. doi:10.1140/epjc/s10052-017-4906-6.
Kotko, P., Kutak, K., Sapeta, S., Stasto, A. M., and Strikman, M. Sat . "Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC". United States. doi:10.1140/epjc/s10052-017-4906-6.
@article{osti_1361943,
title = {Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC},
author = {Kotko, P. and Kutak, K. and Sapeta, S. and Stasto, A. M. and Strikman, M.},
abstractNote = {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 atCMenergy 5.1 TeV per nucleon pair. The formalism is applicablewhen the average transversemomentum 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 theWeizsäcker–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 also 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 6 GeV. Finally, we find that the LO collinear factorization with nuclear leading-twist shadowing predicts quite similar effects.},
doi = {10.1140/epjc/s10052-017-4906-6},
journal = {European Physical Journal. C, Particles and Fields},
number = 5,
volume = 77,
place = {United States},
year = {Sat May 27 00:00:00 EDT 2017},
month = {Sat May 27 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1140/epjc/s10052-017-4906-6

Citation Metrics:
Cited by: 1work
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  • Using the framework that interpolates between the leading power limit of the color glass condensate and the high energy (or k T ) factorization we calculate the direct component of the forward dijet production in ultra-peripheral Pb–Pb collisions atCMenergy 5.1 TeV per nucleon pair. The formalism is applicablewhen the average transversemomentum of the dijet system P T is much bigger than the saturation scale Q s , P T >> Qs , while the imbalance of the dijet system can be arbitrary. The cross section is uniquely sensitive to theWeizsäcker–Williams (WW) unintegrated gluon distribution, which is far less known frommore » experimental data than the most common dipole gluon distribution appearing in inclusive small-x processes. We also 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 p T cut on the dijet system, reaching about 20% with the cut as low as 6 GeV. Finally, we find that the LO collinear factorization with nuclear leading-twist shadowing predicts quite similar effects.« less
  • No abstract prepared.
  • No abstract prepared.
  • We present the first data on e{sup +}e{sup -} pair production accompanied by nuclear breakup in ultra-peripheral gold-gold collisions at a center of mass energy of 200 GeV per nucleon pair. The nuclear breakup requirement selects events at small impact parameters, where higher-order corrections to the pair production cross section should be enhanced. We compare the pair kinematic distributions with two calculations: one based on the equivalent photon approximation, and the other using lowest-order quantum electrodynamics (QED); the latter includes the photon virtuality. The cross section, pair mass, rapidity and angular distributions are in good agreement with both calculations. Themore » pair transverse momentum, p{sub T}, spectrum agrees with the QED calculation, but not with the equivalent photon approach. We set limits on higher-order contributions to the cross section. The e{sup +} and e{sup -} p{sub T} spectra are similar, with no evidence for interference effects due to higher-order diagrams.« less
  • No abstract prepared.