5,181 research outputs found
Jet-like correlations between Forward- and Mid- rapidity in p+p, d+Au and Au+Au collisions from STAR at 200 GeV
In this proceedings we present STAR measurements of two particle azimuthal
correlations between trigger particles at mid-rapidity ( 1) and
associated particles at forward rapidities (2.7 3.9) in p+p, d+Au
and Au+Au collisions at = 200 GeV. Two particle azimuthal
correlations between a mid-rapidity trigger particle and forward-rapidity
associated particles preferably probe large-x quarks scattered off small-x
gluons in RHIC collisions. Comparison of the separate d- and Au-side
measurements in d+Au collisions may potentially probe gluon saturation and the
presence of Color Glass Condensate. In Au+Au collisions quark energy loss can
be probed at large rapidities, which may be different from gluon energy loss
measured at mid-rapidity.Comment: Quark Matter 06 Conference proceedings, submitted to Journal of Phys.
Centrality dependence of the ratios and - a test of thermalization in Au+Au collisions at RHIC
We present the centrality dependence of the ratios and
measured in Au+Au collisions at GeV by the
STAR experiment at RHIC. The results are compared to measurements of other
identified particles and recombination model expectations in order to gain
insight into the partonic collectivity and possible thermalization of the
produced medium.Comment: 4 pages, 2 figures, Quark Matter 2006 conference proceeding
Upsilon cross section in p+p collisions at STAR
The main focus of the heavy flavor program at RHIC is to investigate the
properties of the dense matter produced in heavy-ion collisions by studying its
effect on open heavy flavor and quarkonia production. This in turn requires a
detailed understanding of their production in elementary p+p collisions so that
the dense matter effects can be later unfolded. In this paper, we present the
first mid-rapidity cross section measurement of bottomonium at
GeV with the STAR experiment. We compare our results with perturbative QCD
calculations. A brief status on the study of charmonium in STAR is given.Comment: 4 pages, 4 figures. To appear in the proceedings of Quark Matter 2006
as a special issue of Journal of Physics G: Nuclear and Particle Physic
The first measurement of meson semi-leptonic decay contribution to non-photonic electrons at RHIC
We present the first measurement for the meson semi-leptonic decay
contribution to non-photonic electrons at RHIC using non-photonic electron
azimuthal correlations with charged hadrons in p+p collisions at GeV from STAR.Comment: 4 pages, 3 figures, Quark Matter 2006 Proceedings, to appear in J.
Phys.
Centrality Dependence of Azimuthal Anisotropy of Strange Hadrons in 200 GeV Au+Au Collisions
Measurements of azimuthal anisotropy for strange and multi-strange hadrons
are presented for the first time in their centrality dependence. The high
statistics results of v2(pT) allow for a more detailed comparison to
hydrodynamical model calculations. Number-of-constituent-quark scaling was
tested for different centrality classes separately. Higher order anisotropies
like v4(pT) are measured for multi-strange hadrons. While we observe agreement
between measured data and models a deeper understanding and refinement of the
models seem to be necessary in order to fully understand the details of the
data.Comment: 4 pages, 2 figures; Strange Quark Matter 2006 conference proceedings,
to appear in J. Phys.
First Results from Photon Multiplicity Detector at RHIC
We present the first measurement of multiplicity and pseudorapidity
distributions of photons in the pseudorapidity region 2.3 < eta < 3.7 for
different centralities in Au + Au collisions at sqrt{s_NN} = 62.4 GeV. The
pseudorapidity distribution of photons, dominated by neutral pion decays, has
been compared to those of identified charged pions, photons, and inclusive
charged particles from heavy ion and nucleon-nucleon collisions at various
energies. Scaling of photon yield with number of participating nucleons and
limiting fragmentation scenario for inclusive photon production has been
studied.Comment: Talk given at 5th International Conference on Physics and
Astrophysics of Quark Gluon Plasma (February 8 - 12, 2005); 4 pages and 6
figure
Physics with Identified Particles at STAR
New physics results with identified particles at STAR are presented.
Measurements at low address bulk properties of the collision, while those
at high address jet energy loss in the bulk matter produced. Between
these extremes, measurements at intermediate address the interplay
between jets and the bulk. We highlight: measurements of fluctuations as
a new, sensitive probe of the initial conditions and the equation of state;
correlations involving multi-strange particles, along with ratios of identified
particles to test coalescence as a mechanism of particle production at
intermediate ; three particle azimuthal correlation to search for conical
emission; and the energy and particle-type dependence of hadron production at
high to study quark and gluon jet energy loss.Comment: 9 pages, 7 figures. To appear in the proceedings of the 19th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions
(Quark Matter 2006), Shanghai, China, November 14-20, 200
Event Structure at RHIC from p-p to Au-Au
Several correlation analysis techniques are applied to p-p and Au-Au
collisions at RHIC. Strong large-momentum-scale correlations are observed which
can be related to local charge and momentum conservation during hadronization
and to minijet (minimum-bias parton fragment) correlations.Comment: 6 pages, 6 figures, 20th Winter Workshop on Nuclear Dynamics,
Trelawny Beach, Jamaica, March 15-20, 200
- …