36 research outputs found
Study of Cronin effect and nuclear modification of strange particles in d-Au and Au-Au collisions at 200 GeV in PHENIX
Effects of strangeness on nuclear modification in d-Au and Au-Au collisions
at 200 GeV are studied, in order to quantify the effects of quark content and
mass. Measurements of ratios of the yields in central collisions to the yields
in peripheral collisions are performed for lambda baryon and phi meson. Found
results show little dependence of particle suppression or enhancement on mass
and strange content, but rather prominent difference in nuclear modification
between mesons and baryons.Comment: 4 pages, 4 figures, proceedings of the Seventeenth International
Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter
2004
Stopping and Baryon Transport in Heavy Ion Reactions
In this report I will give an experimental overview on nuclear stopping in
hadron collisions, and relate observations to understanding of baryon
transport. Baryon number transport is not only evidenced via net-proton
distributions but also by the enhancement of strange baryons near mid-rapidity.
Although the focus is on high-energy data obtained from pp and heavy ions from
RHIC, relevant data from SPS and ISR will be considered. A discussion how the
available data at higher energy relates and gives information on baryon
junction, quark-diquark breaking will be made.Comment: 8 pages, 7 figures. Invited plenary talk for the 5'th international
conference on Physics and Astrophysics of Quark Gluon Plasma, February 8-12,
2005, Salt Lake City, Kolkata, Indi
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
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.
Baryonic Effect on chi_cJ Suppression in Au+Au Collisions at RHIC Energies
We predict that initially produced chi_cJ mesons at low transverse momentum
in the central rapidity region are almost dissociated by nucleons and
antinucleons in hadronic matter produced in central Au+Au collisions at RHIC
energies sqrt {s_{NN}}= 130 and 200 GeV. In calculations the nucleon and
antinucleon distributions in hadronic matter are results of evolution from
their freeze-out distributions which well fit the experimental p_T spectra of
proton and antiproton. Any measured chi_cJ mesons at low p_T are generated from
deconfined matter and give an explicit proof of regeneration mechanism
(recombination mechanism).Comment: 10 pages, 3 figures, Latex, a discussion added to the referenc
meson production in d + Au collisions at = 200 GeV
We present the preliminary results on meson production in the and decay channels measured at
mid-rapidity in = 200 GeV d + Au collisions at RHIC by the PHENIX
experiment. The transverse mass spectra were obtained in both channels. The
extracted yields are found to be consistent with each other. The results
are compared to the measurements in Au + Au collisions at the same center of
mass energy.Comment: To appear in the proceedings of 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. Submitted to J.Phys.
Centrality and dE_{T}/d\etadN_{ch}/d\eta$ in Heavy Ion Collisions at Mid-Rapidity
The PHENIX experiment at RHIC has measured transverse energy and charged
particle multiplicity at mid-rapidity in Au + Au collisions at
= 19.6, 130, 62.4 and 200 GeV as a function of centrality. The presented
results are compared to measurements from other RHIC experiments, and
experiments at lower energies. The dependence of
and per pair of participants is consistent with logarithmic
scaling for the most central events. The centrality dependence of
and is similar at all measured incident
energies. At RHIC energies the ratio of transverse energy per charged particle
was found independent of centrality and growing slowly with . A
survey of comparisons between the data and available theoretical models is also
presented.Comment: Proccedings of the Workshop: Focus on Multiplcity at Bari, Italy,
June 17-19,2004. To be submitted to the Jornal of Physics, "Conference
series". Includes: 20 Pages, 15 figures, 3 Tables, 80 Referencie
phi meson production in Au + Au collisions at sqrt{s_{NN} = 200 GeV
We present the results on the mid-rapidity phi meson production in the
K^{+}K^{-} decay channel in Au + Au collisions at sqrt(s_NN) = 200 GeV measured
by the PHENIX experiment at RHIC. The spectral shape of the phi resonance,
studied at different collision centralities, is consistent with the particle
data book. The transverse mass spectra are measured in four centrality bins.
The inverse slopes (T), yields (dN/dy) and particle ratios are studied as a
function of centrality. The nuclear modification factor is measured through the
ratio, R_{CP}, of central to peripheral yields normalized to the number of
nucleon-nucleon collisions. The R_{CP} of the phi mesons is less than unity and
is comparable to that of pions rather than R_{CP} ~ 1 observed for protons and
anti-protons
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
Hadronization in heavy ion collisions: recombination or fragmentation?
We show that hadron production in relativistic heavy ion collisions at
transverse momenta larger than 2 GeV/c can be explained by the competition of
two different hadronization mechanisms. Above 5 GeV/c hadron production can be
described by fragmentation of partons that are created perturbatively. Below 5
GeV/c recombination of partons from the dense and hot fireball dominates. This
can explain some of the surprising features of RHIC data like the constant
baryon-to-meson ratio of about one and the small nuclear suppression for
baryons between 2 to 4 GeV/c.Comment: Contribution to the 7th Conference on Strange Quark Matter (SQM
2003), submitted to J.Phys.G; 6 pages LaTeX, 4 eps figures, uses iopart.cl