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Semihard Scattering Unraveled from Collective Dynamics by Two-Pion Azimuthal Correlations in158A GeV/cPb+AuCollisions

Authors :
C. Weber
P. Glässel
C. Fuchs
H. Tilsner
I. Ravinovich
C. Voigt
N. Saveljic
H. Appelshäuser
S. Razin
P. Braun-Munzinger
P. Rehak
J. Bielcikova
S. Shimansky
O. Nix
A. Drees
R. Baur
A. Marín
S. Voloshin
W. Schmitz
G. Hering
H. Sako
G. Agakichiev
S. Specht
B. Lenkeit
D. Mikowiec
F. Messer
A. Pfeiffer
J.P. Wessels
M. Messer
E. Socol
J.P. Wurm
S.I. Esumi
Z. Fraenkel
I. Tserruya
V. Petráek
V. Yurevich
A. Cherlin
J. Stachel
Y. Panebrattsev
P. Huovinen
Jovan Milosevic
K. Filimonov
J. Rak
Source :
Physical Review Letters. 92
Publication Year :
2004
Publisher :
American Physical Society (APS), 2004.

Abstract

Elliptic flow and two-particle azimuthal correlations of charged hadrons and high-${p}_{T}$ pions (${p}_{T}g1\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$) have been measured close to midrapidity in $158A\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$ $\mathrm{P}\mathrm{b}+\mathrm{A}\mathrm{u}$ collisions by the CERES experiment. Elliptic flow (${v}_{2}$) rises linearly with ${p}_{T}$ to a value of about $10%$ at $2\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$. Beyond ${p}_{T}\ensuremath{\approx}1.5\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$, the slope decreases considerably, possibly indicating a saturation of ${v}_{2}$ at high ${p}_{T}$. Two-pion azimuthal anisotropies for ${p}_{T}g1.2\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$ exceed the elliptic flow values by about $60%$ in midcentral collisions. These nonflow contributions are attributed to nearside and back-to-back jetlike correlations, the latter exhibiting centrality dependent broadening.

Details

ISSN :
10797114 and 00319007
Volume :
92
Database :
OpenAIRE
Journal :
Physical Review Letters
Accession number :
edsair.doi...........1dfd4d9d9832f4340c9524cf3b4908cf