4,150 research outputs found
Modified Fragmentation Function and Jet Quenching at RHIC
Medium modification of jet fragmentation functions and parton energy loss in
cold and hot matter are reviewed. The predicted nuclear modification of the jet
fragmentation function agrees well with the recent HERMES data with a resultant
energy loss dE/dx approximately 0.5 GeV/fm. From the the recent PHENIX data of
high p_T pi_0 spectra in central Au+Au collisions at sqrt(s)=130 GeV, one
extracts an energy loss for a 10 GeV parton that is equivalent to dE/dx=7.3
GeV/fm in a static medium with the same gluon density as in the initial stage
of the collision at tau_0=0.2 fm/c. Constraints on jet quenching by the central
rapidity density of charged hadrons is also discussed.Comment: Invited talk at International Symposium on Statistical QCD,
Bielefeld, Germany, 26-30 Aug 2001; 11 pages with 6 postscript figure
Jet Tomography of Quark Gluon Plasma
Recent experimental measurements of high hadron spectra and jet
correlation at RHIC are analyzed within a parton model which incoporates
initial jet production and final propagation in heavy-ion collisions. The
suppresion of single hadron spectra, back-to-back correlation, their centrality
dependence and azimuthal anisotropy point to a dense matter with an initial
parton density about 30 times of that in a cold heavy nucleus.Comment: 7 pages in RevTex, 4 figures. Invited talk at Confinement
2003-International Symposium on ``Color Confinement and Hadrons in Quantum
Chromodynamics", RIKEN, Japan, July 21-24, 2003 and XXIV Brazilian Meeting of
Particle and Field Physics, Caxambu, Brazil, Oct. 1-3, 200
Hard Probes in High-energy Heavy-ion Collisions
Hard QCD processes in ultrarelativistic heavy-ion collisions become
increasingly relevant and they can be used as probes of the dense matter formed
during the violent scatterings. We will discuss how one can use these hard
probes to study the properties of the dense matter and the associated
phenomenologies. In particular, we study the effect of jet quenching due to
medium-induced energy loss on inclusive particle distributions and
investigate how one can improve the measurement of parton energy loss in direct
photon eventsComment: Talk given at the International School on Physics of the Quark Gluon
Plasma, Hiroshima, June 3-6, 1997 and the 5th International Workshop on
Relativistic Aspects of Nuclear Physics, Rio de Janeiro, August 27-29. 17
pages with 9 ps figure
Monte Carlo Models: Quo Vadimus?
Coherence, multiple scattering and the interplay between soft and hard
processes are discussed. These physics phenomena are essential for
understanding the nuclear dependences of rapidity density and spectra in
high-energy heavy-ion collisions. The RHIC data have shown the onset of hard
processes and indications of high spectra suppression due to parton
energy loss. Within the pQCD parton model, the combination of azimuthal
anisotropy () and hadron spectra suppression at large can help one
to determine the initial gluon density in heavy-ion collisions at RHIC.Comment: 10 Pages with 8 figures, Plenary talk at 15th International
Conference on Ultrarelativistic Nucleus-Nucleus Collisions (QM2001), Stony
Brook, New York, 15-20 Jan 200
Particle Production in High-energy Heavy-ion Collisions
Particle production mechanisms in high-energy heavy-ion collisions are
reviewed in connection with recent experimental data from RHIC. Implications on
mini-jet production, parton saturation and jet quenching are discussed.Comment: 14 pages, 5 figures in eps, talk given at XXXI International
Symposium on Multiparticle Dynamics, Sept 1-7, 2001, Datong China. URL
http://ismd31.ccnu.edu.cn
Rapidity Asymmetry in High-energy Collisions
In contrast to the recent prediction of high hadron suppression within
the parton saturation model, it is shown that multiple parton scattering
suffered by the projectile will enhance high hadron spectra in
collisions relative to a superposition of binary collisions at RHIC. A
stronger enhancement in the forward rapidity region of the projectile is also
predicted, resulting in a unique rapidity asymmetry of the hadron spectra at
high . The shape of the rapidity asymmetry should be reversed for low
hadrons that are dominated by soft and coherent interactions which
suppress hadron spectra in the projectile rapidity region. The phenomenon at
the LHC energies is shown to be qualitatively different because of parton
shadowing.Comment: 13 pages in RevTex, 5 figures. The numerical data files of the
figures can be downloaded from
http://www-hpc.lbl.gov/datacode_files/hadrons.ht
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