1,198 research outputs found
Z(3)-symmetric effective theory for pure gauge QCD at high temperature
We review the construction and basic properties of a three-dimensional
effective field theory for high-temperature SU(3) Yang-Mills theory, which
respects its center symmetry and was introduced in hep-ph/0604100. We explain
why the phase diagram of the new theory is expected to closely resemble the one
of the full theory and argue that this implies that it is applicable down to
considerably lower temperatures than the usual non-Z(3)-symmetric 3d effective
theory EQCD.Comment: 4 pages, 1 figure; to appear in the proceedings of Strong and
Electroweak Matter 200
Z(3)-symmetric effective theory for SU(3) Yang-Mills theory at high temperature
A three-dimensional effective theory for high temperature SU(3) gauge theory,
which maintains the Z(3) center symmetry of the full theory, is constructed.
Such a Z(3) invariant effective theory should be applicable to a wider
temperature range than the usual effective theory, known as EQCD, which fails
to respect the center symmetry. This center-symmetric effective theory can
reproduce domain wall and phase transition properties that are not accessible
in EQCD. After identifying a convenient class of Z(3) invariant effective
theories, we constrain the coefficients of the various terms in the Lagrangian
using leading-order matching to EQCD at high temperature, plus matching of
domain wall properties in the full theory. We sketch the expected structure of
the phase diagram of the effective theory and briefly discuss the prospects of
numerical simulations and the addition of quarks.Comment: 30 pages, 5 figures, v2 with minor correction
The N_f^3 g^6 term in the pressure of hot QCD
We determine the first independent part of the g^6 coefficient in the weak
coupling expansion of the QCD pressure at high temperatures, the one
proportional to the maximal power of the number of quark flavors N_f. In
addition to introducing and developing computational methods that can be used
in evaluating other parts of the expansion, our calculation provides a result
that becomes dominant in the limit of large N_f and a fixed effective coupling
g_{eff}^2 = g^2 N_f/2.Comment: 9 pages, 2 figures, revtex, v2: minor modifications and additional
reference
Hyperfine Splitting and the Zeeman Effect in Holographic Heavy-Light Mesons
We inspect the mass spectrum of heavy-light mesons in deformed N=2 super
Yang-Mills theory using the AdS/CFT correspondence. We demonstrate how some of
the degeneracies of the supersymmetric meson spectrum can be removed upon
breaking the supersymmetry, thus leading to the emergence of hyperfine
structure. The explicit SUSY breaking scenarios we consider involve on one hand
tilting one of the two fundamental D7 branes inside the internal R^6 space, and
on the other hand applying an external magnetic field on the (untilted) branes.
The latter scenario leads to the well-known Zeeman effect, which we inspect for
both weak and strong magnetic fields.Comment: 5 pages, 1 figur
Pressure of the standard model
We review the computation of the thermodynamic pressure of the entire minimal
standard model to three loop order, performed in hep-ph/0510375 and
hep-ph/0512177.Comment: 4 pages, 3 figures, to appear in the proceedings of Strong and
Electroweak Matter 200
Four-loop pressure of massless O(N) scalar field theory
Inspired by the corresponding problem in QCD, we determine the pressure of
massless O(N) scalar field theory up to order g^6 in the weak-coupling
expansion, where g^2 denotes the quartic coupling constant. This necessitates
the computation of all 4-loop vacuum graphs at a finite temperature: by making
use of methods developed by Arnold and Zhai at 3-loop level, we demonstrate
that this task is manageable at least if one restricts to computing the
logarithmic terms analytically, while handling the ``constant'' 4-loop
contributions numerically. We also inspect the numerical convergence of the
weak-coupling expansion after the inclusion of the new terms. Finally, we point
out that while the present computation introduces strategies that should be
helpful for the full 4-loop computation on the QCD-side, it also highlights the
need to develop novel computational techniques, in order to be able to complete
this formidable task in a systematic fashion.Comment: 34 page
Norm inequalities for vector functions
We study vector functions of into itself, which are of the
form where is a
continuous function and call these radial functions. In the case when for some we find upper bounds for the distance of
image points under such a radial function. Some of our results refine recent
results of L. Maligranda and S. Dragomir. In particular, we study
quasiconformal mappings of this simple type and obtain norm inequalities for
such mappings.Comment: 19 page
Perturbative QCD at non-zero chemical potential: Comparison with the large-Nf limit and apparent convergence
The perturbative three-loop result for the thermodynamic potential of QCD at
finite temperature and chemical potential as obtained in the framework of
dimensional reduction is compared with the exact result in the limit of large
flavor number. The apparent convergence of the former as well as possibilities
for optimization are investigated. Corresponding optimized results for full QCD
are given for the case of two massless quark flavors.Comment: REVTEX4, 4 pages, 3 color figures. v2: fig. 3 now includes also
lattice data for two-flavor QCD at nonzero chemical potentia
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