98 research outputs found
Recent high pT measurements in STAR
After five years of data taking, the STAR experiment at the Relativistic
Heavy Ion Collider (RHIC) at Brookhaven National Laboratory provides precise
measurements of particle production at high transverse momentum in p-p, d-Au,
and Au-Au collisions at sqrt(s) = 200 GeV. We review recent results on the
flavor dependence of high pT particle suppression and hadron particle spectra
at sqrt(s) = 62.4 GeV. New results on two-particle angular correlations for
identified trigger particles and for low momentum associated charged hadrons in
p-p and Au-Au as well as near-side correlations will be presented
and discussed.Comment: 5th International Conference on Physics and Astrophysics of Quark
Gluon Plasma, Calcutta. 8 pages, 10 figures, submitted to J. Phys. G: Nucl.
Part. Phy
K0s and \Lambda\ production in Pb--Pb collisions with the ALICE experiment
We present the study of K0s and Lambda production performed with the ALICE
experiment at the LHC in Pb--Pb collisions at \sqrt{s_NN}=2.76 TeV and pp
collisions at \sqrt{s}=0.9 and 7 TeV. The K0s and Lambda particles are
reconstructed via their V0 decay topology allowing their identification up to
high transverse momenta. The corresponding baryon/meson ratios as a function of
transverse momentum are extracted for Pb--Pb collisions in centrality bins and
in the transverse momentum range from 1 to 6 GeV/c. They are also compared with
those measured in pp events at the LHC energies of 0.9 and 7 TeV as well as in
Au--Au collisions at \sqrt{s_NN} = 62.4 and 200 GeV from RHIC.Comment: 4 pages, 4 figures, proceedings of Quark Matter 2011 (May 23rd-28th
2011, Annecy, France
High pT correlations with strange particles in STAR
We present the highlights of the current identified strange particles
DeltaPhi and DeltaEta correlations analyses, including system-size and
trigger-pT of the jet and ridge, jet, ridge and away-side meson/baryon ratios,
and the current state of the multi-strange baryon analysis. We see clear
azimuthal peaks of comparable strength for all strange baryons and K0-short
mesons. We see no observable species dependence on the same-side jet or ridge
yields as a function of pT. However, while the away side and the ridge have
Lambda to K0-short ratio similar to that of the bulk, the jet-only ratio is
similar to that in . The implications of these findings on current
in-medium jet theoretical explanations are discussed.Comment: Proceedings for the Strangeness in Quark Matter 2007 Conference in
Levoca, Slovaki
Recent Results on Strangeness Production at RHIC
Due to its large acceptance, the STAR experiment has acquired a wealth of
data on strangeness production for a variety of collisions systems and
energies, from p+p to Au+Au. By using the yields and spectra, we address the
evolution of the bulk system, including strangeness enhancement and the flavour
dependence of radial and elliptic flow. Utilising the fact that we can identify
strange baryons and mesons, we investigate different hadronization mechanisms
in the intermediate and high p regions. The ratios of the particle
yields, measured to high p, are used to further investigate the range and
applicability of the previously reported anomalous baryon production. We also
study two-particle azimuthal correlations of identified particles in order to
investigate any flavour dependence of jet fragmentation in the available
p range. Data was presented for a number of different collision systems
and energies.Comment: Proceedings of SQM'06 Conference, LA, 2006 (submitted to J. Phys. G
Strange hadrons as dense matter probes
The spectra of strange hadrons have been measured in detail as a function of
centrality for a variety of collision systems and energies at RHIC. Recent
results are presented and compared to those measured at the SPS. The effects of
the system size on strange particle production and kinematics are examined. I
place specific emphasis on comparing A-A to pp production and discuss how
strangeness can be used to probe the dense matter produced in heavy-ion
collisions.Comment: Proceedings of the Strange Quark Matter Conference 200
Overview of Strangeness Production at the STAR Experiment
We present an overview of recent STAR results on strangeness production in
p+p and heavy-ion collisions at RHIC. In both Cu+Cu and Au+Au collisions we
show the centrality dependencies of bulk yield and mid- spectrum
measurements with new comparisons to theory. The latest results for
strange particles are presented and prospects for strangeness production in the
low energy scan program will be outlined. Finally, we report new measurements
of strangeness fragmentation functions for jets in p+p collisions.Comment: 8 pages, 7 figures, proceedings for SQM 200
Jets as a Probe of Dense Matter at RHIC
Jet quenching in the matter created in high energy nucleus-nucleus collisions
provides a tomographic tool to probe the medium properties. Recent experimental
results on jet production at the Relativistic Heavy-Ion Collider (RHIC) are
reviewed. Jet properties in p+p and d+Au collisions have been measured,
establishing the baseline for studying jet modification in heavy-ion
collisions. Current progress on detailed studies of high transverse momentum
production in Au+Au collisions is discussed, with an emphasis on dihadron
correlation measurements.Comment: 8 pages, 9 figures. Plenary talk given at 17th International
Conference on Ultra Relativistic Nucleus-Nucleus Collisions (Quark Matter
2004), Oakland, California, 11-17 Jan 2004. Submitted to J.Phys.
High pT hadron spectra at RHIC: an overview
Recent results on high transverse momentum (pT) hadron production in p+p,
d+Au and Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) are
reviewed. Comparison of the nuclear modification factors, and
, demonstrates that the large suppression in central Au+Au
collisions is due to strong final-state effects. Theoretical models which
incorporate jet quenching via gluon Bremsstrahlung in the dense partonic medium
that is expected in central Au+Au collisions at ultra-relativistic energies are
shown to reproduce the shape and magnitude of the observed suppression over the
range of collision energies so far studied at RHIC.Comment: 12 pages, 10 figures, Talk given at Hot Quarks 2004: Workshop for
Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus
Collisions (HQ'04), Taos Valley, New Mexico, 18-24 Jul 2004, to be published
in J. Phys.
Azimuthal anisotropy in Au+Au collisions at sqrtsNN = 200 GeV
The results from the STAR Collaboration on directed flow (v_1), elliptic flow
(v_2), and the fourth harmonic (v_4) in the anisotropic azimuthal distribution
of particles from Au+Au collisions at sqrtsNN = 200 GeV are summarized and
compared with results from other experiments and theoretical models. Results
for identified particles are presented and fit with a Blast Wave model.
Different anisotropic flow analysis methods are compared and nonflow effects
are extracted from the data. For v_2, scaling with the number of constituent
quarks and parton coalescence is discussed. For v_4, scaling with v_2^2 and
quark coalescence is discussed.Comment: 26 pages. As accepted by Phys. Rev. C. Text rearranged, figures
modified, but data the same. However, in Fig. 35 the hydro calculations are
corrected in this version. The data tables are available at
http://www.star.bnl.gov/central/publications/ by searching for "flow" and
then this pape
Measurements of meson production in relativistic heavy-ion collisions at RHIC
We present results for the measurement of meson production via its
charged kaon decay channel in Au+Au collisions at
, 130, and 200 GeV, and in and +Au collisions
at GeV from the STAR experiment at the BNL Relativistic
Heavy Ion Collider (RHIC). The midrapidity () meson transverse
momentum () spectra in central Au+Au collisions are found to be well
described by a single exponential distribution. On the other hand, the
spectra from , +Au and peripheral Au+Au collisions show power-law tails
at intermediate and high and are described better by Levy
distributions. The constant yield ratio vs beam species, collision
centrality and colliding energy is in contradiction with expectations from
models having kaon coalescence as the dominant mechanism for production
at RHIC. The yield ratio as a function of is consistent
with a model based on the recombination of thermal quarks up to GeV/, but disagrees at higher transverse momenta. The measured nuclear
modification factor, , for the meson increases above unity at
intermediate , similar to that for pions and protons, while is
suppressed due to the energy loss effect in central Au+Au collisions. Number of
constituent quark scaling of both and for the meson
with respect to other hadrons in Au+Au collisions at =200 GeV
at intermediate is observed. These observations support quark
coalescence as being the dominant mechanism of hadronization in the
intermediate region at RHIC.Comment: 22 pages, 21 figures, 4 table
- …