3,072 research outputs found
Strangeness Production in Heavy-Ion Collisions at STAR
We report an overview of strangeness production in Cu+Cu and Au+Au collisions
at the energies 62.4 and 200 GeV. We show new mid-rapidly
results for the , , , particles in
Cu+Cu \sNN{62} collisions and compare to results in Au+Au \sNN{62} collisions.
We show new results for mid- ratios in Cu+Cu \sNN{62}
collisions and again compare to ratios in Au+Au \sNN{62} collisions. Finally,
we show the high- ( GeV/c) as a function
of system size in Au+Au \sNN{200} collisions and compare to .Comment: 4 pages, 3 figures - To appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse
Bulk Properties in Au+Au Collisions at = 9.2 GeV in STAR Experiment at RHIC
One of the primary goals of high-energy heavy-ion collisions is to establish
the QCD phase diagram and search for possible phase boundaries. The planned
RHIC energy scan program will explore this exciting physics topic using
heavy-ion collisions at various center of mass energies. The first test run
with Au+Au collisions at = 9.2 GeV took place in early 2008. We
present the results on identified particle ratios, azimuthal anisotropy
parameters (v1 and v2) and HBT at midrapidity using data from this run. These
results are compared to data for both lower and higher center of mass energies
at the AGS, SPS and RHIC. These new data demonstrate the capabilities of the
STAR detector for exploring the QCD phase diagram.Comment: 4 pages, 2 figures: Re-submitted to appear in proceedings for Quark
Matter 2009, March 30 - April 4, Knoxville, Tennesse
Strangeness with ALICE: from pp to Pb-Pb
We present the measurements of strange and multi-strange hadrons in high
energy pp and Pb-Pb collisions at the Large Hadron Collider (LHC) at CERN. The
data for these measurements were collected by the ALICE detector in 2010 and
2011. By comparing strangeness data where Quark-Gluon Plasma (QGP) is not
expected to be produced (pp collisions) with data where the energy-density of
the collision is sufficient to produce the QGP (central and mid-central Pb-Pb
collisions), we are able to investigate the properties of the QGP. We
characterize the matter created in the collision by presenting strange and
multi-strange particle spectra, yields, and transverse momenta in the context
of increasing strangeness number, varying collision energy, and the number of
nucleons participating in the collision (Npart).Comment: This is a proceedings for the Physics of the LHC 2012 Conference,
held in Vancouver, B
Charmonia production in ALICE
Quarkonia states are expected to provide essential information on the
properties of the high-density strongly-interacting system formed in the early
stages of high-energy heavy-ion collisions. ALICE is the LHC experiment
dedicated to the study of nucleus-nucleus collisions and can study charmonia at
forward rapidity (2.5 < y < 4) via the mu+ mu- decay channel and at mid
rapidity (|y| < 0.9) via the e+ e- decay channel. In both cases charmonia are
measured down to zero transverse momentum. The inclusive J/psi production as a
function of transverse momentum and rapidity in pp collisions at sqrt{s} = 2.76
and 7 TeV are presented. For pp collisions at sqrt{s} = 7 TeV, the inclusive
J/psi production as a function of the charged particle multiplicity, the
inclusive J/psi polarization at forward rapidity and the J/psi prompt to
non-prompt fraction are discussed. Finally, the analysis of the inclusive J/psi
production in the Pb-Pb data collected fall 2011 at a center of mass energy of
sqrt{s_{NN}} = 2.76 TeV is presented. Results on the nuclear modification
factor are then shown as a function of centrality, transverse momentum and
rapidity and compared to model predictions. First results on inclusive J/psi
elliptic flow are given.Comment: Proceedings of plenary talk at the 5th international conference on
hard and electromagnetic probes of high-energy nuclear collisions (Hard
Probes 2012), Cagliari, Italy. 8 pages, 8 figure
Measurement of electrons from heavy-flavour decays in pp and Pb-Pb collisions with ALICE at the LHC
The ALICE experiment has measured at mid-rapidity electrons from
heavy-flavour decays in pp collisions at = 2.76 and 7 TeV, and in
Pb-Pb collisions at = 2.76 TeV. In pp collisions, electrons
from charm-hadron and from beauty-hadron decays are identified by applying cuts
on displaced vertices. The relative yield of electrons from beauty-hadron
decays to those from heavy-flavour decays is extracted using electron-hadron
correlations. Results are compared to pQCD-based calculations. In Pb-Pb
collisions, the dependence of the nuclear modification factor of
electrons from heavy-flavour decays is presented in two centrality classes. The
status on the analysis of electrons from beauty-hadron decays is reported in
Pb-Pb collisions, in view of the measurement of the corresponding nuclear
modification factor.Comment: 4 page, 5 figures, proceedings for the fifth International Conference
on Hard and Electromagnetic Probes of High Energy Nuclear Collisions (Hard
Probes 2012), May 27 - June 1, Cagliari, Ital
Non-photonic electron-hadron azimuthal correlation for AuAu, CuCu and pp collisions at GeV
We present preliminary STAR results of azimuthal correlations between
non-photonic electrons and hadrons in AuAu, CuCu and pp at
GeV. Comparison of the e-h correlations from these colliding systems allows one
to study the system-size dependence of heavy quark jet-medium interactions. We
also report on the relative charm and bottom contributions to non-photonic
electrons extracted from correlations measured in pp collisions. Our results,
when combined with measurements of non-photonic electrons, constrain
the charm and bottom energy loss in the dense medium.Comment: 4 pages 3 figures - To appear in the conference proceedings for Quark
Matter 2009, March 30 - April 4, Knoxville, Tennessee. v4 has beautified
figures for the CuCu and AuAu e-h correlations, no other chang
Recent Longitudinal Spin Asymmetry Measurements for Inclusive Jet Production at STAR
We present measurements of the longitudinal spin asymmetry, , for the
inclusive jet signal at STAR. The data presented here are mid-rapidity jets in
the transverse momentum range of GeV/c and come from polarized
proton-proton collisions at center of mass energies of GeV. We
compare our measured values to predictions derived from various
parameterizations of the polarized gluon distribution function. The results are
shown to provide significant constraints for allowable gluon parameterizations
within the measurement's kinematic Bjorken-x range of .Comment: 3 pages, 4 figures, to appear in PANIC 2008 Proceedings, Nuclear
Physics A special issu
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