176 research outputs found
CGC, QCD Saturation and RHIC data (Kharzeev-Levin-McLerran-Nardi point of view)
This is the talk given at the Workshop:"Focus on Multiplicitioes", Bari,
Italy, 17-19 June,2004.. In this talk, we are going to discuss ion-ion and
deuteron - nucleus RHIC data and show that they support, if not more, the idea
of the new QCD phase: colour glass condensate with saturated parton density. .Comment: 26 pages with 33 figure
Evidence from Identified Particles for Active Quark and Gluon Degrees of Freedom
Measurements of intermediate pT (1.5 < pT < 5.0 GeV/c) identified particle
distributions in heavy ion collisions at SPS and RHIC energies display striking
dependencies on the number of constituent quarks in the corresponding hadron.
One finds that elliptic flow at intermediate pT follows a constituent quark
scaling law as predicted by models of hadron formation through coalescence. In
addition, baryon production is also found to increase with event multiplicity
much faster than meson production. The rate of increase is similar for all
baryons, and seemingly independent of mass. This indicates that the number of
constituent quarks determines the multiplicity dependence of identified hadron
production at intermediate pT. We review these measurements and interpret the
experimental findings.Comment: 8 pages, 5 figures, proceedings for SQM2006 conference in Los Angele
Perspectives of a Midrapidity Dimuon Program at RHIC: A Novel and Compact Muon Telescope Detector
We propose a large-area, cost-effective Muon Telescope Detector (MTD) for the
Solenoidal Tracker at RHIC (STAR) at mid-rapidity and for the next generation
of detectors at a possible electron-ion collider. We utilize Multi-gap
Resistive Plate Chambers with large modules and long readout strips (Long-MRPC)
in the detector design. The results from cosmic ray and beam tests show the
intrinsic timing and spatial resolution for a Long-MRPC are 60-70 ps and
cm, respectively. The prototype performance of such a novel muon
telescope detector at STAR indicates that muon identification at the transverse
momentum of a few GeV/ can be achieved through the combined information of
track matching with the MTD, ionization energy loss in the Time Projection
Chamber, and time-of-flight measurements. A primary muon over secondary muon
ratio of better than 1/3 can be achieved. This provides a promising device for
future quarkonium programs and primordial dilepton measurements at RHIC.
Simulations of the muon efficiency, the signal-to-background ratio of ,
the separation of 1S from 2S+3S states, and the electron-muon
correlation from charm pair production in the RHIC environment are presented.Comment: 18 pages, 10 figures, add more references, accepted by Journal of
Physics
meson production and partonic collectivity at RHIC
New results on -meson production and elliptic flow measurements
from RHIC 2004 run (Run-IV) have been reviewed. In addition, the di-hadron
correlation function between the trigged and and the associated
soft particles was simulated. Knowledge about these results are discussed.Comment: 8 pages, 7 figures; Invited talk in International Conference on
Strangess in Quark Matter (SQM2006), UCLA, California, USA, March 26-31,
2006; to be publsihed in the Proceeding isuue of J. Phys.
Production Ratios of Strange Baryons from QGP with Diquarks
Assuming that vector and scalar diquarks exist in the Quark-Gluon Plasma near
the critical temporature , baryons can be produced through the processes
of quarks and diquarks forming baryon states. Ratios of different
baryons can be estimated through this method, if such kind of QGP with diquarks
can exists.Comment: Correct some expressions of equation
Relevance of baseline hard proton-proton spectra for high-energy nucleus-nucleus physics
We discuss three different cases of hard inclusive spectra in proton-proton
collisions: high single hadron production at 20 GeV and
at = 62.4 GeV, and direct photon production at = 200 GeV;
with regard to their relevance for the search of Quark Gluon Plasma signals in
A+A collisions at SPS and RHIC energies.Comment: Proceeds. Hot Quarks 2004 Int. Workshop on the Physics of
Ultrarelativistic Nucleus-Nucleus Collisions. 26 pages. 26 figs. [minor
corrs., refs. added
Anisotropic flow at RHIC: How unique is the number-of-constituent-quark scaling?
The transverse momentum dependence of the anisotropic flow for ,
, nucleon, , and is studied for Au+Au collisions at
GeV within two independent string-hadron transport
approaches (RQMD and UrQMD). Although both models reach only 60% of the
absolute magnitude of the measured , they both predict the particle type
dependence of , as observed by the RHIC experiments: exhibits a
hadron-mass hierarchy (HMH) in the low region and a
number-of-constituent-quark (NCQ) dependence in the intermediate region.
The failure of the hadronic models to reproduce the absolute magnitude of the
observed indicates that transport calculations of heavy ion collisions at
RHIC must incorporate interactions among quarks and gluons in the early, hot
and dense phase. The presence of an NCQ scaling in the string-hadron model
results suggests that the particle-type dependencies observed in heavy-ion
collisions at intermediate might be related to the hadronic cross
sections in vacuum rather than to the hadronization process itself.Comment: 10 pages, 5 figures; A new author (H. Petersen) is added; A new
figure (fig.1) on time evolution of elliptic flow and number of collisions is
added; Version accepted for publication in J. Phys.
Hydrodynamics and Flow
In this lecture note, we present several topics on relativistic hydrodynamics
and its application to relativistic heavy ion collisions. In the first part we
give a brief introduction to relativistic hydrodynamics in the context of heavy
ion collisions. In the second part we present the formalism and some
fundamental aspects of relativistic ideal and viscous hydrodynamics. In the
third part, we start with some basic checks of the fundamental observables
followed by discussion of collective flow, in particular elliptic flow, which
is one of the most exciting phenomenon in heavy ion collisions at relativistic
energies. Next we discuss how to formulate the hydrodynamic model to describe
dynamics of heavy ion collisions. Finally, we conclude the third part of the
lecture note by showing some results from ideal hydrodynamic calculations and
by comparing them with the experimental data.Comment: 40 pages, 35 figures; lecture given at the QGP Winter School, Jaipur,
India, Feb.1-3, 2008; to appear in Springer Lecture Notes in Physic
Thermal Dileptons at LHC
We predict dilepton invariant-mass spectra for central 5.5 ATeV Pb-Pb
collisions at LHC. Hadronic emission in the low-mass region is calculated using
in-medium spectral functions of light vector mesons within hadronic many-body
theory. In the intermediate-mass region thermal radiation from the Quark-Gluon
Plasma, evaluated perturbatively with hard-thermal loop corrections, takes
over. An important source over the entire mass range are decays of correlated
open-charm hadrons, rendering the nuclear modification of charm and bottom
spectra a critical ingredient.Comment: 2 pages, 2 figures, contributed to Workshop on Heavy Ion Collisions
at the LHC: Last Call for Predictions, Geneva, Switzerland, 14 May - 8 Jun
2007 v2: acknowledgment include
Identification of High Particles with the STAR-RICH Detector
The STAR-RICH detector extends the particle identification capapbilities of
the STAR experiment for charged hadrons at mid-rapidity. This detector
represents the first use of a proximity-focusing CsI-based RICH detector in a
collider experiment. It provides identification of pions and kaons up to 3
GeV/c and protons up to 5 GeV/c. The characteristics and performance of the
device in the inaugural RHIC run are described.Comment: 6 pages, 6 figure
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