2,500 research outputs found
The Study of Noncollectivity by the Forward-Backward Multiplicity Correlation Function
We propose a forward-backward multiplicity correlation function ,
which is experimentally accessible, to measure the noncollectivity
contribution. We find that is sensitive to the jet contribution for
the particle-rich case. Surprisingly, it will automatically decrease for the
particle-rare case. Our study indicates that similar decreasing trend observed
previously is mainly driven by particle scarcity instead of jets. The function
is studied in Au+Au collision at GeV with a multiphase
transport model (AMPT). We find that the jet fraction is about 10% at
transverse momentum () around 2.5 GeV/ and reaches up to 30% at 3.5
GeV/. The implication of this study in the investigation of the
noncollectivity contribution in elliptic anisotropy parameter is also
discussed.Comment: 5 pages, 4 figure
Transverse Pressure and Strangeness Dynamics in Relativistic Heavy Ion Reactions
Transverse hadron spectra from proton-proton, proton-nucleus and
nucleus-nucleus collisions from 2 AGeV to 21.3 ATeV are investigated within two
independent transport approaches (HSD and UrQMD). For central Au+Au (Pb+Pb)
collisions at energies above 5 AGeV, the measured
transverse mass spectra have a larger inverse slope parameter than expected
from the default calculations. The additional pressure - as suggested by
lattice QCD calculations at finite quark chemical potential and
temperature - might be generated by strong interactions in the early
pre-hadronic/partonic phase of central Au+Au (Pb+Pb) collisions. This is
supported by a non-monotonic energy dependence of in the present
transport model.Comment: Proceedings of Strange Quark Matter 200
Elliptic Flow Analysis at RHIC with the Lee-Yang Zeroes Method in a Relativistic Transport Approach
The Lee-Yang zeroes method is applied to study elliptic flow () in Au+Au
collisions at ~GeV, with the UrQMD model. In this transport
approach, the true event plane is known and both the nonflow effects and
event-by-event fluctuations exist. Although the low resolutions prohibit
the application of the method for most central and peripheral collisions, the
integral and differential elliptic flow from the Lee-Yang zeroes method agrees
with the exact values very well for semi-central collisions.Comment: 4 pages, 4 figure
Sensitivity of Azimuthal Jet Tomography to Early Time Energy-Loss at RHIC and LHC
We compute the jet path-length dependence of energy-loss for higher azimuthal
harmonics of jet-fragments in a generalized model of energy-loss that can
interpolate between pQCD and AdS/CFT limits and compare results with Glauber
and CGC/KLN initial conditions. We find, however, that even the high-pT second
moment is most sensitive to the poorly known early-time evolution during the
first fm/c. Moreover, we demonstrate that quite generally the energy and
density-dependence leads to an overquenching jet fragments relative to the
first LHC -data, once the parameters of the energy-loss model are fixed
from -data at RHIC.Comment: 4 pages, 2 figures, version accepted for publication in J. Phys. G:
Nucl. Part. Phys. as conference proceedings for Quark Matter 2011, May 23 -
May 28, Annecy, Franc
Flow fluctuations and long-range correlations: elliptic flow and beyond
These proceedings consist of a brief overview of the current understanding of
collective behavior in relativistic heavy-ion collisions. In particular, recent
progress in understanding the implications of event-by-event fluctuations have
solved important puzzles in existing data -- the "ridge" and "shoulder"
phenomena of long-range two-particle correlations -- and have created an
exciting opportunity to tightly constrain theoretical models with many new
observables.Comment: 10 pages, 2 figures, Proceedings for the 22nd International
Conference On Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter
2011), Annecy, France, May 23 - 28, 2011; includes Fig. 2 which was omitted
from journal submission for lack of spac
Enhanced Event-by-Event Fluctuations in Pion Multiplicity as a Signal of Disoriented Chiral Condensates at RHIC
The factorial moments of the pion multiplicity distributions are calculated
with HIJING and UrQMD and found to be independent of the pT range included, in
contrast to recent simulations with the linear sigma model which leads to large
enhancements for pions with transverse kinetic energies below 200 MeV. This
supports the use of the ratio of the factorial moments of low and high pT pions
as a signal of ``new'' physics at low momentum scales, such as the formation of
disoriented chiral condensates.Comment: 4 pages total, incl 4 eps figures ([email protected]
First language and second language writing: the role of linguistic knowledge, speed of processing, and metacognitive knowledge
Measurements of high identified particles and in GeV Au+Au collisions by PHENIX
The and of pions, kaons and protons have been measured by
PHENIX in 200 GeV Au+Au collisions up to 6 GeV/c and 4 GeV/c,
respectively. The of all these identified particles have been found to
scale with the number of constituent quarks and all these particles have a
similar / ratio which is close to 0.9. The scaling behavior
of is studied at high- and a deviations from the universal scaling
is observed for transverse kinetic energy () higher than 1 GeV.Comment: 4 pages, 3 figures, proceedings of 20th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008),
Jaipur, India, 04-10 Feb 200
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