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Title: Scaling Properties of Azimuthal Anisotropy in Au+Au and Cu+Cu Collisions at {radical}(s{sub NN})=200 GeV

Abstract

Differential measurements of elliptic flow (v{sub 2}) for Au+Au and Cu+Cu collisions at {radical}(s{sub NN})=200 GeV are used to test and validate predictions from perfect fluid hydrodynamics for scaling of v{sub 2} with eccentricity, system size, and transverse kinetic energy (KE{sub T}). For KE{sub T}{identical_to}m{sub T}-m up to {approx}1 GeV the scaling is compatible with hydrodynamic expansion of a thermalized fluid. For large values of KE{sub T} mesons and baryons scale separately. Quark number scaling reveals a universal scaling of v{sub 2} for both mesons and baryons over the full KE{sub T} range for Au+Au. For Au+Au and Cu+Cu the scaling is more pronounced in terms of KE{sub T}, rather than transverse momentum.

Authors:
; ; ; ; ; ; ;  [1]; ; ; ; ; ; ;  [2]; ; ; ; ;  [3]
  1. University of Colorado, Boulder, Colorado 80309 (United States)
  2. Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)
  3. Columbia University, New York, New York 10027 (United States) and Nevis Laboratories, Irvington, New York 10533 (US) (and others)
Publication Date:
OSTI Identifier:
20951251
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 98; Journal Issue: 16; Other Information: DOI: 10.1103/PhysRevLett.98.162301; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANISOTROPY; BARYONS; COLLIDING BEAMS; COPPER 63 BEAMS; COPPER 63 REACTIONS; COPPER 63 TARGET; GEV RANGE 100-1000; GOLD 197 BEAMS; GOLD 197 REACTIONS; GOLD 197 TARGET; KINETIC ENERGY; MESONS; QUARKS; TRANSVERSE MOMENTUM

Citation Formats

Adare, A., Bickley, A. A., Ellinghaus, F., Kelly, S., Kinney, E., Nagle, J. L., Seele, J., Wysocki, M., Afanasiev, S., Isupov, A., Litvinenko, A., Malakhov, A., Peresedov, V., Rukoyatkin, P., Zolin, L., Aidala, C., Bjorndal, M. T., Chi, C. Y., Cole, B. A., and D'Enterria, D.. Scaling Properties of Azimuthal Anisotropy in Au+Au and Cu+Cu Collisions at {radical}(s{sub NN})=200 GeV. United States: N. p., 2007. Web. doi:10.1103/PHYSREVLETT.98.162301.
Adare, A., Bickley, A. A., Ellinghaus, F., Kelly, S., Kinney, E., Nagle, J. L., Seele, J., Wysocki, M., Afanasiev, S., Isupov, A., Litvinenko, A., Malakhov, A., Peresedov, V., Rukoyatkin, P., Zolin, L., Aidala, C., Bjorndal, M. T., Chi, C. Y., Cole, B. A., & D'Enterria, D.. Scaling Properties of Azimuthal Anisotropy in Au+Au and Cu+Cu Collisions at {radical}(s{sub NN})=200 GeV. United States. doi:10.1103/PHYSREVLETT.98.162301.
Adare, A., Bickley, A. A., Ellinghaus, F., Kelly, S., Kinney, E., Nagle, J. L., Seele, J., Wysocki, M., Afanasiev, S., Isupov, A., Litvinenko, A., Malakhov, A., Peresedov, V., Rukoyatkin, P., Zolin, L., Aidala, C., Bjorndal, M. T., Chi, C. Y., Cole, B. A., and D'Enterria, D.. Fri . "Scaling Properties of Azimuthal Anisotropy in Au+Au and Cu+Cu Collisions at {radical}(s{sub NN})=200 GeV". United States. doi:10.1103/PHYSREVLETT.98.162301.
@article{osti_20951251,
title = {Scaling Properties of Azimuthal Anisotropy in Au+Au and Cu+Cu Collisions at {radical}(s{sub NN})=200 GeV},
author = {Adare, A. and Bickley, A. A. and Ellinghaus, F. and Kelly, S. and Kinney, E. and Nagle, J. L. and Seele, J. and Wysocki, M. and Afanasiev, S. and Isupov, A. and Litvinenko, A. and Malakhov, A. and Peresedov, V. and Rukoyatkin, P. and Zolin, L. and Aidala, C. and Bjorndal, M. T. and Chi, C. Y. and Cole, B. A. and D'Enterria, D.},
abstractNote = {Differential measurements of elliptic flow (v{sub 2}) for Au+Au and Cu+Cu collisions at {radical}(s{sub NN})=200 GeV are used to test and validate predictions from perfect fluid hydrodynamics for scaling of v{sub 2} with eccentricity, system size, and transverse kinetic energy (KE{sub T}). For KE{sub T}{identical_to}m{sub T}-m up to {approx}1 GeV the scaling is compatible with hydrodynamic expansion of a thermalized fluid. For large values of KE{sub T} mesons and baryons scale separately. Quark number scaling reveals a universal scaling of v{sub 2} for both mesons and baryons over the full KE{sub T} range for Au+Au. For Au+Au and Cu+Cu the scaling is more pronounced in terms of KE{sub T}, rather than transverse momentum.},
doi = {10.1103/PHYSREVLETT.98.162301},
journal = {Physical Review Letters},
number = 16,
volume = 98,
place = {United States},
year = {Fri Apr 20 00:00:00 EDT 2007},
month = {Fri Apr 20 00:00:00 EDT 2007}
}
  • Measurements of neutral pion ({pi}{sup 0}) production at midrapidity in {radical}(s{sub NN})=200 GeV Au+Au collisions as a function of transverse momentum, p{sub T}, collision centrality, and angle with respect to reaction plane are presented. The data represent the final {pi}{sup 0} results from the PHENIX experiment for the first RHIC Au+Au run at design center-of-mass energy. They include additional data obtained using the PHENIX Level-2 trigger with more than a factor of 3 increase in statistics over previously published results for p{sub T}>6 GeV/c. We evaluate the suppression in the yield of high-p{sub T} {pi}{sup 0}'s relative to pointlike scalingmore » expectations using the nuclear modification factor R{sub AA}. We present the p{sub T} dependence of R{sub AA} for nine bins in collision centrality. We separately integrate R{sub AA} over larger p{sub T} bins to show more precisely the centrality dependence of the high-p{sub T} suppression. We then evaluate the dependence of the high-p{sub T} suppression on the emission angle {delta}{phi} of the pions with respect to event reaction plane for seven bins in collision centrality. We show that the yields of high-p{sub T} {pi}{sup 0}'s vary strongly with {delta}{phi}, consistent with prior measurements 1,2. We show that this variation persists in the most peripheral bin accessible in this analysis. For the peripheral bins we observe no suppression for neutral pions produced aligned with the reaction plane, whereas the yield of {pi}{sup 0}'s produced perpendicular to the reaction plane is suppressed by a factor of {approx}2. We analyze the combined centrality and {delta}{phi} dependence of the {pi}{sup 0} suppression in different p{sub T} bins using different possible descriptions of parton energy loss dependence on jet path-length averages to determine whether a single geometric picture can explain the observed suppression pattern.« less
  • We have studied the dependence of azimuthal anisotropy v 2 for inclusive and identified charged hadrons in Au+Au and Cu+Cu collisions on collision energy, species, and centrality. The values of v 2 as a function of transverse momentum pT and centrality in Au+Au collisions at √s NN=200 and 62.4 GeV are the same within uncertainties. However, in Cu+Cu collisions we observe a decrease in v 2 values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au+Au and Cu+Cu collisions we find that v 2 dependsmore » both on eccentricity and the number of participants, N part. We observe that v 2 divided by eccentricity (ε) monotonically increases with N part and scales as N 1/3 part. Thus, the Cu+Cu data at 62.4 GeV falls below the other scaled v 2 data. For identified hadrons, v 2 divided by the number of constituent quarks nq is independent of hadron species as a function of transverse kinetic energy KE T=m T–m between 0.1T/n q<1 GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the Cu+Cu data at 62.4 GeV, of v 2/(n q∙ε∙N 1/3 part) vs KE T/n q for all measured particles.« less
  • No abstract prepared.
  • New measurements are presented for charged hadron azimuthal correlations at midrapidity in Au+Au collisions at {radical}(s{sub NN})=62.4 and 200 GeV. They are compared to earlier measurements obtained at {radical}(s{sub NN})=130 GeV and in Pb+Pb collisions at {radical}(s{sub NN})=17.2 GeV. Sizeable anisotropies are observed with centrality and transverse momentum (p{sub T}) dependence characteristic of elliptic flow (v{sub 2}). For a broad range of centralities, the observed magnitudes and trends of the differential anisotropy, v{sub 2}(p{sub T}), change very little over the collision energy range {radical}(s{sub NN})=62-200 GeV, indicating saturation of the excitation function for v{sub 2} at these energies. Such amore » saturation may be indicative of the dominance of a very soft equation of state for {radical}(s{sub NN}){approx}60-200 GeV.« less