9,194 research outputs found
Spin physics with STAR
The STAR collaboration aims to study polarized proton-proton collisions at
RHIC. The emphasis of the spin run this year is on transverse single spin
asymmetries. Beyond 2001, we aim to determine directly and precisely the gluon
polarization, as well as the polarizations of the u, , d and
quarks in the proton by measuring in addition longitudinal and double spin
asymmetries. Furthermore, we aim to measure for the first time the quark
transversity distributions. These measurements will improve substantially the
knowledge and understanding of the spin structure of the nucleon.Comment: 9 pages, 3 figures. Talk presented at The 3rd Circum-Pan-Pacific
Symposium on "High Energy Spin Physics" October 8-13 2001, Beijing, Chin
Azimuthal and pseudo-rapidity correlations with strange particles at intermediate-p at RHIC
We present results on two-particle azimuthal correlations with strange
trigger particles (, , , ) associated with
unidentified charged particles %at intermediate in d+Au and Au+Au
collisions at = 200 GeV. We investigate, in detail, the
near-side associated yield as a function of centrality, and strangeness
content in the trigger particle to look for possible flavor and baryon/meson
differences. We compare our results to a fragmentation and recombination model,
where the study of -triggered correlations is used as a critical test
of the validity of the recombination picture.Comment: 4 pages, 3 figures, presented at the 19th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions, "Quark Matter 2006", Shanghai,
China, November 14-20, 200
Intra-jet correlations of high- hadrons from STAR
Systematic measurements of pseudorapidity () and azimuthal
() correlations between high- charged hadrons in
=200 GeV Au+Au collisions are presented. An enhancement of
correlated yield at large on the near-side is observed. This
effect persists up to trigger 9 GeV/c, indicating that it
is associated with jet production. More detailed analysis suggests distinct
short-range and long-range components in the correlation.Comment: 4 pages, 5 figures, presented at the 19th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions, "Quark Matter 2006", Shanghai,
China, November 14-20, 200
Detecting gravitational radiation from neutron stars using a six-parameter adaptive MCMC method
We present a Markov chain Monte Carlo technique for detecting gravitational
radiation from a neutron star in laser interferometer data. The algorithm can
estimate up to six unknown parameters of the target, including the rotation
frequency and frequency derivative, using reparametrization, delayed rejection
and simulated annealing. We highlight how a simple extension of the method,
distributed over multiple computer processors, will allow for a search over a
narrow frequency band. The ultimate goal of this research is to search for
sources at a known locations, but uncertain spin parameters, such as may be
found in SN1987A.Comment: Submitted to Classical and Quantum Gravity for GWDAW-8 proceeding
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
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
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.
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