Triangularity and Dipole Asymmetry in Heavy Ion Collisions
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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 and the dipole asymmetry 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 . The hydrodynamic prediction for this correlation function is several times larger than a correlation currently measured by the STAR collaboration . This experimental measurement would provide convincing evidence for the hydrodynamic and geometric interpretation of two-particle correlations at RHIC.« less
Subfields: Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/1431539a7c0f5b7a058ec6d6f49bb32454789587
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In Nuclear and High Energy Physics
Citations in the corpus
- Non linearities in the harmonic spectrum of heavy ion collisions with ideal and viscous hydrodynamics (2012, methodology): “Motivated by Fourier analysis [9], we replace the general distribution ρ(x) with a Gaussian, eq.”
- Conformal hydrodynamics in Minkowski and de Sitter spacetimes (2010, methodology): “3 how the natural treatment of initial conditions based on conformal symmetry compares to the cumulant expansion of [8].”
- Improved Monte Carlo Glauber predictions at present and future nuclear colliders (2017, positive): “The second moment, also called eccentricity [20], the third moment, also called triangularity [21], and higher moments [22] of the collision region at impact parameter b, which are used to characterize the initial geometrical shape, are given by”
- Relativistic Fluid Dynamics in and out of Equilibrium (2017, background): “To characterize the properties of these lumpy energy-density profiles, it is customary to consider the so-called initial state eccentricities en and participant plane angles Φn defined as [34, 285, 286]”
- Strongly correlated quantum fluids: ultracold quantum gases, quantum chromodynamic plasmas and holographic duality (2012, background): “Odd Fourier moments such as v1 and v3 arise mainly from fluctuations in the initial state [260, 261].”