7 research outputs found
CGC, QCD Saturation and RHIC data (Kharzeev-Levin-McLerran-Nardi point of view)
This is the talk given at the Workshop:"Focus on Multiplicitioes", Bari,
Italy, 17-19 June,2004.. In this talk, we are going to discuss ion-ion and
deuteron - nucleus RHIC data and show that they support, if not more, the idea
of the new QCD phase: colour glass condensate with saturated parton density. .Comment: 26 pages with 33 figure
Suppression of High Transverse Momentum Spectra in Au+Au Collisions at RHIC
Au+Au, A GeV measurements at RHIC, obtained with the PHENIX,
STAR, PHOBOS and BRAHMS detectors, have all indicated a suppression of neutral
pion production, relative to an appropriately normalized NN level. For central
collisions and vanishing pseudo-rapidity these experiments exhibit suppression
in charged meson production, especially at medium to large transverse momenta.
In the PHENIX experiment similar behavior has been reported for
spectra.
In a recent work on the simpler D+Au interaction, to be considered perhaps as
a tune-up for Au+Au, we reported on a pre-hadronic cascade mechanism which
explains the mixed observation of moderately reduced suppression at
higher pseudo-rapidity as well as the Cronin enhancement at mid-rapidity. Here
we present the extension of this work to the more massive ion-ion collisions.
Our major thesis is that much of the suppression is generated in a late stage
cascade of colourless pre-hadrons produced after an initial short-lived
coloured phase. We present a pQCD argument to justify this approach and to
estimate the time duration of this initial phase. Of essential
importance is the brevity in time of the coloured phase existence relative to
that of the strongly interacting pre-hadron phase. The split into two phases is
of course not sharp in time, but adequate for treating the suppression of
moderate and high mesons.Comment: 19 pages, 10 figure
High pT hadron spectra at RHIC: an overview
Recent results on high transverse momentum (pT) hadron production in p+p,
d+Au and Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) are
reviewed. Comparison of the nuclear modification factors, and
, demonstrates that the large suppression in central Au+Au
collisions is due to strong final-state effects. Theoretical models which
incorporate jet quenching via gluon Bremsstrahlung in the dense partonic medium
that is expected in central Au+Au collisions at ultra-relativistic energies are
shown to reproduce the shape and magnitude of the observed suppression over the
range of collision energies so far studied at RHIC.Comment: 12 pages, 10 figures, Talk given at Hot Quarks 2004: Workshop for
Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus
Collisions (HQ'04), Taos Valley, New Mexico, 18-24 Jul 2004, to be published
in J. Phys.