2,092 research outputs found
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
Low- and Intermediate-p Di-hadron Distributions in Au+Au Collisions at GeV from STAR
We present a study of low- and intermediate-p correlated azimuthal
angular distributions in Au+Au collisions at from
STAR. The near-side associated yields in Au+Au collisions are found to be
strongly enhanced, due to contributions from large . The
enhancement is reduced for high \pTtrig. We show a strong broadening and
enhancement of the away-side yield. The evolution of the away-side shape may be
explained as the sum of a broad structure from bulk response and a narrow peak
from jet fragmentation.Comment: 4 pages, 3 figure
Jet Studies in STAR via 2+1 Correlations
This paper reports analysis on jet-medium interactions and di-jet surface
emission bias at RHIC, based on a new multi-hadron correlation technique called
\texttt{2+1} where back-to-back high hadron triggers work as proxy of
di-jets. In contrast with traditional correlations with single triggers, the
associated hadron distributions and spectra at both trigger sides show no
evident modification from d+Au to central Au+Au collisions. This observation
stands for both cases when triggers pairs are symmetric(5GeV/ vs.
4GeV/) or asymmetric(10GeV/ vs. 4GeV/).Comment: DIS 2011 conference proceeding
Jet-hadron correlations in STAR
Advancements in full jet reconstruction have made it possible to use jets as
triggers in azimuthal angular correlations to study the modification of
hard-scattered partons in the medium created in ultrarelativistic heavy-ion
collisions. This increases the range of parton energies accessible in these
analyses and improves the signal-to-background ratio compared to dihadron
correlations. Results of a systematic study of jet-hadron correlations in
central Au-Au collisions at sqrt(s_NN) = 200 GeV are indicative of a broadening
and softening of jets which interact with the medium. Furthermore, jet-hadron
correlations suggest that the suppression of the associated hadron yield at
high-pT is balanced in large part by low-pT enhancement.Comment: 4 pages, 2 figures, proceedings for Quark Matter 201
Viscosity and the Soft Ridge at RHIC
Correlation studies exhibit a ridge-like feature in rapidity and azimuthal
angle, with and without a jet trigger. We ask whether the feature in
untriggered correlations can be a consequence of transverse flow and viscous
diffusion.Comment: Proc. Quark Matter 2008, Jaipur, Indi
Energy and system dependence of high- triggered two-particle near-side correlations
Previous studies have indicated that the near-side peak of high-
triggered correlations can be decomposed into two parts, the \textit{Jet} and
the \textit{Ridge}. We present data on the yield per trigger of the
\textit{Jet} and the \textit{Ridge} from , and collisions
at = 62.4 GeV and 200 GeV and compare data on the \textit{Jet}
to PYTHIA 8.1 simulations for . PYTHIA describes the \textit{Jet}
component up to a scaling factor, meaning that PYTHIA can provide a better
understanding of the \textit{Ridge} by giving insight into the effects of the
kinematic cuts. We present collision energy and system dependence of the
\textit{Ridge} yield, which should help distinguish models for the production
mechanism of the \textit{Ridge}.Comment: 4 pages, 6 figures, proceedings for Hot Quarks in Estes Park,
Colorad
STAR Results on High Transverse Momentum, Heavy Flavor and Electromagnetic Probes
We summarize here recent results from the STAR collaboration focusing on
processes involving large momentum transfers. Measurements of angular
correlations of di-hadrons are explored in both the pseudorapidity (eta) and
azimuthal (phi) projections. In central Au+Au, an elongated structure is found
in the eta projection which persists up to the highest measured pT. After
quantifying the particle yield in this structure and subtracting it from the
near-side yield, we observe that the remainder exhibits a behavior strikingly
similar to that of the near-side yield in d+Au. For heavy flavor production,
using electron-hadron correlations in p+p collisions, we obtain an estimate of
the b-quark contribution to the non-photonic electrons in the pT region 3-6
GeV/c, and find it consistent with FONLL calculations. Together with the
observed suppression of non-photonic electrons in Au+Au, this strongly suggests
suppression of b-quark production in Au+Au collisions. We discuss results on
the mid-rapidity Upsilon cross-section in p+p collisions. Finally, we present a
proof-of-principle measurement of photon-hadron correlations in p+p collisions,
paving the way for the tomographic study of the matter produced in central
Au+Au via gamma-jet measurements.Comment: 8 pages, 4 figures. Proceedings of "Quark Matter 2006", 19th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collision
Understanding jet quenching and medium response with di-hadron correlation
A brief review of the dependence of the dihadron correlations from RHIC
is presented. We attempt to construct a consistent picture that can describe
the data as a whole, focusing on the following important aspects, 1) the
relation between jet fragmentation of survived jet and medium response to
quenched jets, 2) the possible origin of the medium response and its relation
to intermediate physics for single hadron production, 3) the connection
between the near-side ridge and away-side cone, 4) and their relations to low
energy results.Comment: 8 pages, 8 figures, presented at the 20th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions, "Quark Matter 2008", Jaipur,
India, February 4-10, 2008. Updated with the published versio
QGP collective effects and jet transport
We present numerical simulations of the SU(2) Boltzmann-Vlasov equation
including both hard elastic particle collisions and soft interactions mediated
by classical Yang-Mills fields. We provide an estimate of the coupling of jets
to a hot isotropic plasma, which is independent of infrared cutoffs. In
addition, we investigate jet propagation in anisotropic plasmas, as created in
heavy-ion collisions. The broadening of jets is found to be stronger along the
beam line than in azimuth due to the creation of field configurations with
B_t>E_t and E_z>B_z via plasma instabilities.Comment: 4 pages, 5 figures. Presented at the 20th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008),
Jaipur, India, 4-10 Feb 200
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