12,879 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
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
Algebraic Quantum Theory on Manifolds: A Haag-Kastler Setting for Quantum Geometry
Motivated by the invariance of current representations of quantum gravity
under diffeomorphisms much more general than isometries, the Haag-Kastler
setting is extended to manifolds without metric background structure. First,
the causal structure on a differentiable manifold M of arbitrary dimension
(d+1>2) can be defined in purely topological terms, via cones (C-causality).
Then, the general structure of a net of C*-algebras on a manifold M and its
causal properties required for an algebraic quantum field theory can be
described as an extension of the Haag-Kastler axiomatic framework.
An important application is given with quantum geometry on a spatial slice
within the causally exterior region of a topological horizon H, resulting in a
net of Weyl algebras for states with an infinite number of intersection points
of edges and transversal (d-1)-faces within any neighbourhood of the spatial
boundary S^2.Comment: 15 pages, Latex; v2: several corrections, in particular in def. 1 and
in sec.
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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