185 research outputs found
Elliptic flow of electrons from heavy-flavor hadron decays in Au+Au collisions at 200, 62.4, and 39 GeV
We present measurements of elliptic flow () of electrons from the decays
of heavy-flavor hadrons () by the STAR experiment. For Au+Au collisions
at 200 GeV we report , for transverse momentum
() between 0.2 and 7 GeV/c using three methods: the event plane method
({EP}), two-particle correlations ({2}), and four-particle
correlations ({4}). For Au+Au collisions at = 62.4 and
39 GeV we report {2} for GeV/c. {2} and {4} are
non-zero at low and intermediate at 200 GeV, and {2} is consistent
with zero at low at other energies. The {2} at the two lower beam
energies is systematically lower than at 200 GeV for
GeV/c. This difference may suggest that charm quarks interact less
strongly with the surrounding nuclear matter at those two lower energies
compared to GeV.Comment: Version accepted by PR
Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC
We present results from a harmonic decomposition of two-particle azimuthal
correlations measured with the STAR detector in Au+Au collisions for energies
ranging from GeV to 200 GeV. The third harmonic
, where is the
angular difference in azimuth, is studied as a function of the pseudorapidity
difference between particle pairs . Non-zero
{\vthree} is directly related to the previously observed large-
narrow- ridge correlations and has been shown in models to be
sensitive to the existence of a low viscosity Quark Gluon Plasma (QGP) phase.
For sufficiently central collisions, persist down to an energy of
7.7 GeV suggesting that QGP may be created even in these low energy collisions.
In peripheral collisions at these low energies however, is
consistent with zero. When scaled by pseudorapidity density of charged particle
multiplicity per participating nucleon pair, for central
collisions shows a minimum near {\snn} GeV.Comment: 7 pages, 4 figures, for submission to Phys. Rev. Let
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