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 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.
- Authors:
-
[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:
- 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. https://doi.org/10.1016/j.nuclphysa.2018.08.003
Vogt, R. Tue .
"Quarkonium Production and Polarization in an Improved Color Evaporation Model". United States. https://doi.org/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},
number = C,
volume = 982,
place = {United States},
year = {Tue Jan 22 00:00:00 EST 2019},
month = {Tue Jan 22 00:00:00 EST 2019}
}
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Figures / Tables:
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 »