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Title: Triangularity and dipole asymmetry in relativistic heavy ion collisions

Abstract

We introduce a cumulant expansion to parametrize possible initial conditions in relativistic heavy ion collisions. We show that the cumulant expansion converges and that it can systematically reproduce the results of Glauber type initial conditions. At third order in the gradient expansion the cumulants characterize the triangularity <r{sup 3}cos3({phi}-{psi}{sub 3,3})> and the dipole asymmetry <r{sup 3}cos({phi}-{psi}{sub 1,3})> of the initial entropy distribution. We show that for midperipheral collisions the orientation angle of the dipole asymmetry {psi}{sub 1,3} has a 20% preference out of plane. This leads to a small net v{sub 1} out of plane. In peripheral and midcentral collisions the orientation angles {psi}{sub 1,3} and {psi}{sub 3,3} are strongly correlated, but this correlation disappears towards central collisions. We study the ideal hydrodynamic response to these cumulants and determine the associated v{sub 1}/{epsilon}{sub 1} and v{sub 3}/{epsilon}{sub 3} for a massless ideal gas equation of state. The space time development of v{sub 1} and v{sub 3} is clarified with figures. These figures show that v{sub 1} and v{sub 3} develop toward the edge of the nucleus, and consequently the final spectra are more sensitive to the viscous dynamics of freezeout. The hydrodynamic calculations for v{sub 3} are provisionally compared tomore » Alver and Roland fit of STAR inclusive two-particle correlation functions. Finally, we propose to measure the v{sub 1} associated with the dipole asymmetry and the correlations between {psi}{sub 1,3} and {psi}{sub 3,3} by measuring a two-particle correlation with respect to the participant plane <cos({phi}{sub {alpha}{sup -}}3{phi}{sub {beta}{sup +}}2{Psi}{sub PP})>. The hydrodynamic prediction for this correlation function is several times larger than a correlation currently measured by the STAR collaboration <cos({phi}{sub {alpha}{sup +}}{phi}{sub {beta}{sup -}}2{Psi}{sub PP})>. This experimental measurement would provide convincing evidence for the hydrodynamic and geometric interpretation of two-particle correlations at RHIC.« less

Authors:
;  [1]
  1. Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800 (United States)
Publication Date:
OSTI Identifier:
21502808
Resource Type:
Journal Article
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 83; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevC.83.064904; (c) 2011 American Institute of Physics; Journal ID: ISSN 0556-2813
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ASYMMETRY; BROOKHAVEN RHIC; COLLISIONS; CORRELATION FUNCTIONS; CORRELATIONS; DIPOLES; DISTRIBUTION; ENTROPY; EQUATIONS OF STATE; EXPANSION; FORECASTING; HEAVY ION REACTIONS; NUCLEI; PARTICLES; RELATIVISTIC RANGE; SPACE-TIME; SPECTRA; ACCELERATORS; ENERGY RANGE; EQUATIONS; FUNCTIONS; HEAVY ION ACCELERATORS; MULTIPOLES; NUCLEAR REACTIONS; PHYSICAL PROPERTIES; STORAGE RINGS; THERMODYNAMIC PROPERTIES

Citation Formats

Teaney, Derek, and Li, Yan. Triangularity and dipole asymmetry in relativistic heavy ion collisions. United States: N. p., 2011. Web. doi:10.1103/PHYSREVC.83.064904.
Teaney, Derek, & Li, Yan. Triangularity and dipole asymmetry in relativistic heavy ion collisions. United States. https://doi.org/10.1103/PHYSREVC.83.064904
Teaney, Derek, and Li, Yan. 2011. "Triangularity and dipole asymmetry in relativistic heavy ion collisions". United States. https://doi.org/10.1103/PHYSREVC.83.064904.
@article{osti_21502808,
title = {Triangularity and dipole asymmetry in relativistic heavy ion collisions},
author = {Teaney, Derek and Li, Yan},
abstractNote = {We introduce a cumulant expansion to parametrize possible initial conditions in relativistic heavy ion collisions. We show that the cumulant expansion converges and that it can systematically reproduce the results of Glauber type initial conditions. At third order in the gradient expansion the cumulants characterize the triangularity <r{sup 3}cos3({phi}-{psi}{sub 3,3})> and the dipole asymmetry <r{sup 3}cos({phi}-{psi}{sub 1,3})> of the initial entropy distribution. We show that for midperipheral collisions the orientation angle of the dipole asymmetry {psi}{sub 1,3} has a 20% preference out of plane. This leads to a small net v{sub 1} out of plane. In peripheral and midcentral collisions the orientation angles {psi}{sub 1,3} and {psi}{sub 3,3} are strongly correlated, but this correlation disappears towards central collisions. We study the ideal hydrodynamic response to these cumulants and determine the associated v{sub 1}/{epsilon}{sub 1} and v{sub 3}/{epsilon}{sub 3} for a massless ideal gas equation of state. The space time development of v{sub 1} and v{sub 3} is clarified with figures. These figures show that v{sub 1} and v{sub 3} develop toward the edge of the nucleus, and consequently the final spectra are more sensitive to the viscous dynamics of freezeout. The hydrodynamic calculations for v{sub 3} are provisionally compared to Alver and Roland fit of STAR inclusive two-particle correlation functions. Finally, we propose to measure the v{sub 1} associated with the dipole asymmetry and the correlations between {psi}{sub 1,3} and {psi}{sub 3,3} by measuring a two-particle correlation with respect to the participant plane <cos({phi}{sub {alpha}{sup -}}3{phi}{sub {beta}{sup +}}2{Psi}{sub PP})>. The hydrodynamic prediction for this correlation function is several times larger than a correlation currently measured by the STAR collaboration <cos({phi}{sub {alpha}{sup +}}{phi}{sub {beta}{sup -}}2{Psi}{sub PP})>. This experimental measurement would provide convincing evidence for the hydrodynamic and geometric interpretation of two-particle correlations at RHIC.},
doi = {10.1103/PHYSREVC.83.064904},
url = {https://www.osti.gov/biblio/21502808}, journal = {Physical Review. C, Nuclear Physics},
issn = {0556-2813},
number = 6,
volume = 83,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2011},
month = {Wed Jun 15 00:00:00 EDT 2011}
}