110 research outputs found
Global Flow of Glasma in High Energy Nuclear Collisions
We discuss the energy flow of the classical gluon fields created in
collisions of heavy nuclei at collider energies. We show how the Yang-Mills
analoga of Faraday's Law and Gauss' Law predict the initial gluon flux tubes to
expand or bend. The resulting transverse and longitudinal structure of the
Poynting vector field has a rich phenomenology. Besides the well known radial
and elliptic flow in transverse direction, classical quantum chromodynamics
predicts a rapidity-odd transverse flow that tilts the fireball for non-central
collisions, and it implies a characteristic flow pattern for collisions of
non-symmetric systems . The rapidity-odd transverse flow translates into a
directed particle flow which has been observed at RHIC and LHC. The
global flow fields in heavy ion collisions could be a powerful check for the
validity of classical Yang-Mill dynamics in high energy collisions.Comment: 7 figure
Rapidity Profile of the Initial Energy Density in Heavy-Ion Collisions
The rapidity dependence of the initial energy density in heavy-ion collisions
is calculated from a three-dimensional McLerran-Venugopalan model (3dMVn)
introduced by Lam and Mahlon. This model is infrared safe since global color
neutrality is enforced. In this non-boost-invariant framework, the nuclei have
non-zero thickness in the longitudinal direction. This results in Bjorken-x
dependent unintegrated gluon distribution functions which lead to a
rapidity-dependent initial energy density after the collision. The initial
energy density and its rapidity dependence are important initial conditions for
the quark gluon plasma and its hydrodynamic evolution.Comment: 7 pages, 2 figures. Matches the published versio
Evaluating Results from the Relativistic Heavy Ion Collider with Perturbative QCD and Hydrodynamics
We review the basic concepts of perturbative quantum chromodynamics (QCD) and
relativistic hydrodynamics, and their applications to hadron production in high
energy nuclear collisions. We discuss results from the Relativistic Heavy Ion
Collider (RHIC) in light of these theoretical approaches. Perturbative QCD and
hydrodynamics together explain a large amount of experimental data gathered
during the first decade of RHIC running, although some questions remain open.
We focus primarily on practical aspects of the calculations, covering basic
topics like perturbation theory, initial state nuclear effects, jet quenching
models, ideal hydrodynamics, dissipative corrections, freeze-out and initial
conditions. We conclude by comparing key results from RHIC to calculations.Comment: 78 pages, 45 figures, 3 tables; to be published in Prog. Part. Nucl.
Phys; v2: a few references added, some typos fixe
Hybrid Hadronization
We discuss Hybrid Hadronization, a hadronization model which interpolates
between string fragmentation in dilute parton systems and quark recombination
in dense parton systems. We lay out the basic principles, discuss some details
of the implementation, and show some prelimiary results. Hybrid Hadronization
is realized as a software package which works with PYTHIA 8 and will be
released publicly in the near future.Comment: 4 pages, 2 figures; Contribution to Hard Probes 201
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