2,446 research outputs found
QCD thermodynamics with nonzero chemical potential at and effects from heavy quarks
We extend our work on QCD thermodynamics with 2+1 quark flavors at nonzero
chemical potential to finer lattices with . We study the equation of
state and other thermodynamic quantities, such as quark number densities and
susceptibilities, and compare them with our previous results at . We
also calculate the effects of the addition of the charm and bottom quarks on
the equation of state at zero and nonzero chemical potential. These effects are
important for cosmological studies of the early Universe.Comment: 27 pages, 17 figures. Some small text and figure change
String Breaking in Non-Abelian Gauge Theories with Fundamental Matter Fields
We present clear numerical evidence for string breaking in three-dimensional
SU(2) gauge theory with fundamental bosonic matter through a mixing analysis
between Wilson loops and meson operators representing bound states of a static
source and a dynamical scalar. The breaking scale is calculated in the
continuum limit. In units of the lightest glueball we find . The implications of our results for QCD are discussed.Comment: 4 pages, 2 figures; equations (4)-(6) corrected, numerical results
and conclusions unchange
Dimensional Reduction, Hard Thermal Loops and the Renormalization Group
We study the realization of dimensional reduction and the validity of the
hard thermal loop expansion for lambda phi^4 theory at finite temperature,
using an environmentally friendly finite-temperature renormalization group with
a fiducial temperature as flow parameter. The one-loop renormalization group
allows for a consistent description of the system at low and high temperatures,
and in particular of the phase transition. The main results are that
dimensional reduction applies, apart from a range of temperatures around the
phase transition, at high temperatures (compared to the zero temperature mass)
only for sufficiently small coupling constants, while the HTL expansion is
valid below (and rather far from) the phase transition, and, again, at high
temperatures only in the case of sufficiently small coupling constants. We
emphasize that close to the critical temperature, physics is completely
dominated by thermal fluctuations that are not resummed in the hard thermal
loop approach and where universal quantities are independent of the parameters
of the fundamental four-dimensional theory.Comment: 20 pages, 13 eps figures, uses epsfig and pstrick
Quark Matter and Nuclear Collisions: A Brief History of Strong Interaction Thermodynamics
The past fifty years have seen the emergence of a new field of research in
physics, the study of matter at extreme temperatures and densities. The theory
of strong interactions, quantum chromodynamics (QCD), predicts that in this
limit, matter will become a plasma of deconfined quarks and gluons -- the
medium which made up the early universe in the first 10 microseconds after the
big bang. High energy nuclear collisions are expected to produce short-lived
bubbles of such a medium in the laboratory. I survey the merger of statistical
QCD and nuclear collision studies for the analysis of strongly interacting
matter in theory and experiment.Comment: 24 pages, 14 figures Opening Talk at the 5th Berkeley School on
Collective Dynamics in High Energy Collisions, LBNL Berkeley/California, May
14 - 18, 201
Meson Correlation Function and Screening Mass in Thermal QCD
Analytical results for the spatial dependence of the correlation functions
for all meson excitations in perturbative Quantum Chromodynamics, the lowest
order, are calculated. The meson screening mass is obtained as a large distance
limit of the correlation function. Our analysis leads to a better understanding
of the excitations of Quark Gluon Plasma at sufficiently large temperatures and
may be of relevance for future numerical calculations with fully interacting
Quantum Chromodynamics.Comment: 11 page
Real-time Chern-Simons term for hypermagnetic fields
If non-vanishing chemical potentials are assigned to chiral fermions, then a
Chern-Simons term is induced for the corresponding gauge fields. In thermal
equilibrium anomalous processes adjust the chemical potentials such that the
coefficient of the Chern-Simons term vanishes, but it has been argued that
there are non-equilibrium epochs in cosmology where this is not the case and
that, consequently, certain fermionic number densities and large-scale
(hypermagnetic) field strengths get coupled to each other. We generalise the
Chern-Simons term to a real-time situation relevant for dynamical
considerations, by deriving the anomalous Hard Thermal Loop effective action
for the hypermagnetic fields, write down the corresponding equations of motion,
and discuss some exponentially growing solutions thereof.Comment: 13 page
Layered Higgs Phase as a Possible Field Localisation on a Brane
So far it has been found by using lattice techniques that in the anisotropic
five--dimensional Abelian Higgs model, a layered Higgs phase exists in addition
to the expected five--dimensional one. The exploration of the phase diagram has
shown that the two Higgs phases are separated by a phase transition from the
confining phase. This transition is known to be first order. In this paper we
explore the possibility of finding a second order transition point in the
critical line which separates the first order phase transition from the
crossover region. This is shown to be the case only for the four--dimensional
Higgs layered phase whilst the phase transition to the five--dimensional broken
phase remains first order. The layered phase serves as the possible realisation
of four--dimensional spacetime dynamics which is embedded in a
five--dimensional spacetime. These results are due to gauge and scalar field
localisation by confining interactions along the extra fifth direction.Comment: 1+15 pages, 12 figure
Design of the Spitzer Space Telescope Heritage Archive
It is predicted that Spitzer Space Telescope’s cryogen will run out in April 2009, and the final reprocessing for the cryogenic mission is scheduled to end in April 2011, at which time the Spitzer archive will be transferred to the NASA/IPAC Infrared Science Archive (IRSA) for long-term curation. The Spitzer Science Center (SSC) and IRSA are collaborating to design and deploy the Spitzer Heritage Archive (SHA), which will supersede the current Spitzer archive. It will initially contain the raw and final reprocessed cryogenic science products, and will eventually incorporate the final products from the Warm mission. The SHA will be accompanied by tools deemed necessary to extract the full science content of the archive and by comprehensive documentation
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