skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Quarkonium Production and Polarization in an Improved Color Evaporation Model

Abstract

An improved version of the color evaporation model (ICEM) has been introduced to describe heavy quarkonium production. In contrast to the traditional color evaporation model, the constraint was imposed that the invariant mass of the intermediate heavy quark-antiquark pair must be larger than the mass of produced quarkonium. A momentum shift between heavy quark-antiquark pair and the quarkonium was also introduced. Calculations show that the model can describe the charmonium yields as well as ratio of $$\psi$$' over $J$/$$\psi$$ better than the traditional color evaporation model. The ICEM has been extended to calculate the polarization of prompt $J$/$$\psi$$ and $Υ$($1S$) production for the first time in the color evaporation approach. The first calculations were made at leading order. The polarization parameter λ$$_\vartheta$$ was calculated as a function of center of mass energy and rapidity in p + p collisions. The x F dependence of the polarization was also calculated and compred to experimental results in p+Cu and π+W collisions. The next step of calculating the p T dependence of the polarization has been taken, with a calculation in the k T-factorization approach. We compare the unpolarized p T distributions for the $J$/$$\psi$$ and $$\psi$$, as well as the $$\psi$$ to $J$/$$\psi$$ ratio, in p + p collisions at RHIC and the LHC for several energies. We also present the polarization results and make comparison to polarization data.

Authors:
ORCiD logo [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Nuclear and Chemical Sciences Division; Univ. of California, Davis, CA (United States). Physics Dept.
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1513116
Report Number(s):
LLNL-JRNL-753547
Journal ID: ISSN 0375-9474; 940193
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Physics. A
Additional Journal Information:
Journal Volume: 982; Journal Issue: C; Journal ID: ISSN 0375-9474
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; quarkonium; polarization

Citation Formats

Vogt, R. Quarkonium Production and Polarization in an Improved Color Evaporation Model. United States: N. p., 2019. Web. doi:10.1016/j.nuclphysa.2018.08.003.
Vogt, R. Quarkonium Production and Polarization in an Improved Color Evaporation Model. United States. doi:10.1016/j.nuclphysa.2018.08.003.
Vogt, R. Tue . "Quarkonium Production and Polarization in an Improved Color Evaporation Model". United States. doi:10.1016/j.nuclphysa.2018.08.003. https://www.osti.gov/servlets/purl/1513116.
@article{osti_1513116,
title = {Quarkonium Production and Polarization in an Improved Color Evaporation Model},
author = {Vogt, R.},
abstractNote = {An improved version of the color evaporation model (ICEM) has been introduced to describe heavy quarkonium production. In contrast to the traditional color evaporation model, the constraint was imposed that the invariant mass of the intermediate heavy quark-antiquark pair must be larger than the mass of produced quarkonium. A momentum shift between heavy quark-antiquark pair and the quarkonium was also introduced. Calculations show that the model can describe the charmonium yields as well as ratio of $\psi$' over $J$/$\psi$ better than the traditional color evaporation model. The ICEM has been extended to calculate the polarization of prompt $J$/$\psi$ and $Υ$($1S$) production for the first time in the color evaporation approach. The first calculations were made at leading order. The polarization parameter λ$_\vartheta$ was calculated as a function of center of mass energy and rapidity in p + p collisions. The xF dependence of the polarization was also calculated and compred to experimental results in p+Cu and π+W collisions. The next step of calculating the pT dependence of the polarization has been taken, with a calculation in the kT-factorization approach. We compare the unpolarized pT distributions for the $J$/$\psi$ and $\psi$, as well as the $\psi$ to $J$/$\psi$ ratio, in p + p collisions at RHIC and the LHC for several energies. We also present the polarization results and make comparison to polarization data.},
doi = {10.1016/j.nuclphysa.2018.08.003},
journal = {Nuclear Physics. A},
issn = {0375-9474},
number = C,
volume = 982,
place = {United States},
year = {2019},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Figures / Tables:

Fig. 1 Fig. 1: Results from the ICEM for J/ψ (left) and ψ' (center) production as well as the ψ' to J/ψ ratio (right) at √s = 7 TeV in the LHCb forward acceptance, 2.5 < y < 5. The LHCb J/ψ data are taken from Ref. [17] while the ψ' datamore » as well as the ratio are from Ref. [18]. From Ref. [12].« less

Save / Share:

Figures / Tables found in this record:

    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.