532 research outputs found
v4 for identified particles at RHIC from viscous hydrodynamics
Using ideal and viscous hydrodynamics, the ratio of azimuthal moments
v4/(v2)^2 is calculated for pions, protons, and kaons in sqrt{s}=200 A*GeV
Au+Au collisions. For any value of viscosity here is little dependence on
particle species. Ideal hydrodynamics and data show a flat curve as a function
of pt. Adding viscosity in the standard way destroys this flatness. However, it
can be restored by replacing the standard quadratic ansatz for delta f (the
viscous correction to the distribution function at freeze-out) with a weaker
momentum dependence.Comment: Proceedings of Hot Quarks 2010, 21-26 June 2010 La Londe Les Maures,
4 pages, 2 figure
Event anisotropy of identified , photon and electron compared to charged , , and deuteron in = 200 GeV Au+Au at PHENIX
We report the recent results of event anisotropy analysis focused on in
= 200 GeV Au+Au collisions at PHENIX.Comment: 4 pages, 3 figures, contribution to the proceedings of the 17th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions
(Quark Matter, Oakland, January 11-17, 2004). To appear in the proceedings
(Journal of Physics G
Excitation functions of baryon anomaly and freeze-out properties at RHIC-PHENIX
The intermediate region (2 - 5 GeV/) in central Au+Au collisions at
RHIC has a rich physics content. The (anti)proton to pion ratio at the
intermediate gives us a powerful tool to investigate the bulk properties
of the hot and dense matter created at RHIC and their hadronization processes.
We present the preliminary results of identified charged hadron spectra at the
lower beam energies at RHIC. The excitation function of (anti)proton to pion
ratios from SPS to RHIC are shown. We also discuss the onset of the baryon
enhancement at the high energy heavy ion collisions.Comment: 4 pages, 3 figures, Quark Matter 2006 conference proceeding
PHENIX Studies of the Scaling Properties of Elliptic Flow at RHIC
Recent PHENIX elliptic flow () measurements for identified particles
produced in Au+Au and Cu+Cu collisions at GeV are presented
and compared to other RHIC measurements. They indicate universal scaling of
compatible with partonic collectivity leading to the flow of light,
strange and heavy quarks with a common expansion velocity field.Comment: Proceedings, Quark Matter 2006, Shanghai, Chin
Recent PHENIX Results on Open Heavy Flavor
Throughout the history of the RHIC physics program, questions concerning the
dynamics of heavy quarks have generated much experimental and theoretical
investigation. A major focus of the PHENIX experiment is the measurement of
these quarks through their semi-leptonic decay channels at mid and forward
rapidity. Heavy quark measurements in collisions give information on the
production of heavy flavor, without complications from medium effects. New
measurements in Au and Cu+Cu indicate surprising cold nuclear matter
effects on these quarks at midrapidity, and provide a new baseline for
interpretation of the observed suppression in Au+Au collisions. When considered
all together, these measurements present a detailed study of nuclear matter
across a wide range of system size and temperature. Here we present preliminary
PHENIX measurements of non-photonic electron spectra and their centrality
dependence in +Au and Cu+Cu, and discuss their implications on the current
understanding of parton energy loss in the nuclear medium.Comment: 4 pages, 3 figures, to appear in the proceedings of Quark Matter 201
Characteristics of Parton Energy Loss Studied with High-p_T Particle Spectra from PHENIX
In the first three years of the physics program at the Relativistic Heavy Ion
Collider (RHIC) a picture was established in which the suppression of hadrons
at high transverse momenta (p_T) in central Au+Au collisions is explained by
energy loss of quark and gluon jets in a medium of high color-charge density.
Measurements of single particle spectra for a smaller nucleus (Cu), for
different center-of-mass energies and with higher statistics were performed in
the subsequent years and are used to test predictions and assumptions of jet
quenching models in more detail. The measurements presented here are consistent
with a parton energy loss scenario so that these models can be used to relate
the observed suppression to properties of the created medium.Comment: To appear in the proceedings of 20th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008),
Jaipur, India, 04-10 Feb 200
Hadron Production at Intermediate at RHIC
Large proton and antiproton enhancement with respect to pions has been
observed at intermediate transverse momentum 2-5 GeV/ in Au+Au
collisions at RHIC. To investigate the possible source of this anomaly, the
production of mesons and two particle angular correlations triggered by
mid- baryons or mesons are studied. We also present the first measurement
of proton and antiproton production at GeV in Au+Au
collisions, which aims to study the energy dependence of the observed baryon
enhancement.Comment: 7 pages, 5 figures, proceedings of Hot Quarks 2004 workshop, Taos
Valley, New Mexico, 18-24 Jul 2004,, to be published in J. Phys.
Quarkonium production in ultra-relativistic nuclear collisions: suppression vs. enhancement
After a brief review of the various scenarios for quarkonium production in
ultra-relativistic nucleus-nucleus collisions we focus on the ingredients and
assumptions underlying the statistical hadronization model. We then confront
model predictions for J/ phase space distributions with the most recent
data from the RHIC accelerator. Analysis of the rapidity dependence of the
J/ nuclear modification factor yields first evidence for the production
of J/ mesons at the phase boundary. We conclude with predictions for
charmonium production at the LHC.Comment: 8 pages, 6 figures, invited paper, Quark Matter 2006 conference,
Shanghai, submitted to J. Phys.
Highlights from PHENIX - II
This contribution highlights recent results from the PHENIX Collaboration at
RHIC with emphasis on those obtained through lepton and photon measurements in
PHENIX.Comment: 9 pages, 13 figures, presented at the 20th International Conference
on Ultra-Relativistic Nucleus-Nucleus Collisions - "Quark Matter 2008",
Jaipur, India, February 4-10, 200
J/ production in In-In and p-A collisions
The NA60 experiment studies dimuon production in In-In and p-A collisions at
the CERN SPS. We report recent results on \jpsi production, measured through
its muon pair decay. As a function of centrality, we show that in In-In the
\jpsi yield is suppressed beyond expectations from nuclear absorption. We
present also for the first time results on \jpsi production in p-A collisions
at 158 GeV, the same energy of the nucleus-nucleus data. For both p-A and In-In
we show preliminary results on \psip suppression. Finally, we have studied the
kinematical distributions of the \jpsi produced in In-In collisions. We present
results on transverse momentum and rapidity, as well as on the angular
distribution of the \jpsi decay products.Comment: 8 pages, Quark Matter 2006 conference proceeding
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