2,181 research outputs found
Three loop HTL perturbation theory at finite temperature and chemical potential
In this proceedings contribution we present a recent three-loop
hard-thermal-loop perturbation theory (HTLpt) calculation of the thermodynamic
potential for a finite temperature and chemical potential system of quarks and
gluons. We compare the resulting pressure, trace anomaly, and
diagonal/off-diagonal quark susceptibilities with lattice data. We show that
there is good agreement between the three-loop HTLpt analytic result and
available lattice data.Comment: 4 pages, 4 figure
QED Thermodynamics at Intermediate Coupling
We discuss reorganizing finite temperature perturbation theory using
hard-thermal-loop (HTL) perturbation theory in order to improve the convergence
of successive perturbative approximations to the free energy of a gauge theory.
We briefly review the history of the technique and present new results for the
three-loop HTL-improved approximation for the free energy of QED. We show that
the hard-thermal-loop perturbation reorganization improves the convergence of
the successive approximations to the QED free energy at intermediate coupling,
e ~ 2. The reorganization is gauge invariant by construction, and due to
cancellation among various contributions, one can obtain a completely analytic
result for the resummed thermodynamic potential at three loops.Comment: 8 pages, 3 figures, Proceedings contribution to "Three Days of Strong
Interactions", Wroclaw (Poland), July 200
The QCD trace anomaly
In this brief report we compare the predictions of a recent
next-to-next-to-leading order hard-thermal-loop perturbation theory (HTLpt)
calculation of the QCD trace anomaly to available lattice data. We focus on the
trace anomaly scaled by T^2 in two cases: N_f=0 and N_f=3. When using the
canonical value of mu = 2 pi T for the renormalization scale, we find that for
Yang-Mills theory (N_f=0) agreement between HTLpt and lattice data for the
T^2-scaled trace anomaly begins at temperatures on the order of 8 T_c while
when including quarks (N_f=3) agreement begins already at temperatures above 2
T_c. In both cases we find that at very high temperatures the T^2-scaled trace
anomaly increases with temperature in accordance with the predictions of HTLpt.Comment: 12 pages, 4 figures; v3 published versio
Hard-thermal-loop QCD Thermodynamics
Naively resummed perturbative approximations to the thermodynamic functions
of QCD do not converge at phenomenologically relevant temperatures. Here we
review recent results of a three-loop hard-thermal-loop perturbation theory
calculation of the thermodynamic functions of a quark-gluon plasma for general
N_c and N_f. We show comparisons of our recent results with lattice data from
both the hotQCD and Wuppertal-Budapest groups. We demonstrate that the
three-loop hard-thermal-loop perturbation result for QCD thermodynamics agrees
with lattice data down to temperatures T ~ 2 T_c.Comment: 8 pages, 2 figures; Talk given at the Symposium on "High Energy
Strong Interactions", Aug. 9-13, 2010, Yukawa Institute for Theoretical
Physics, Kyoto, Japan; submitted to Prog. Theor. Phys. Supp
Gluon Thermodynamics at Intermediate Coupling
We calculate the thermodynamic functions of Yang-Mills theory to three-loop
order using the hard-thermal-loop perturbation theory reorganization of finite
temperature quantum field theory. We show that at three-loop order
hard-thermal-loop perturbation theory is compatible with lattice results for
the pressure, energy density, and entropy down to temperatures T ~ 2 - 3 T_c.Comment: 4 pages, 3 figures; v2 - published version
NNLO hard-thermal-loop thermodynamics for QCD
We calculate the thermodynamic functions of a quark-gluon plasma for general
N_c and N_f to three-loop order using hard-thermal-loop perturbation theory. At
this order, all the ultraviolet divergences can be absorbed into
renormalizations of the vacuum, the HTL mass parameters, and the strong
coupling constant.We show that at three loops, the results for the pressure and
trace anomaly are in very good agreement with recent lattice data down to
temperatures T~2T_c.Comment: 8 pages, 2 fig
Three-loop HTL gluon thermodynamics at intermediate coupling
We calculate the thermodynamic functions of pure-glue QCD to three-loop order
using the hard-thermal-loop perturbation theory (HTLpt) reorganization of
finite temperature quantum field theory. We show that at three-loop order
hard-thermal-loop perturbation theory is compatible with lattice results for
the pressure, energy density, and entropy down to temperatures .
Our results suggest that HTLpt provides a systematic framework that can used to
calculate static and dynamic quantities for temperatures relevant at LHC.Comment: 24 pages, 13 figs. 2nd version: improved discussion and fixing typos.
Published in JHE
Three-loop HTL Free Energy for QED
We calculate the free energy of a hot gas of electrons and photons to three
loops using the hard-thermal-loop perturbation theory reorganization of
finite-temperature perturbation theory. We calculate the free energy through
three loops by expanding in a power series in m_D/T, m_f/T, and e^2, where m_D
and m_f are thermal masses and e is the coupling constant. We demonstrate that
the hard-thermal-loop perturbation reorganization improves the convergence of
the successive approximations to the QED free energy at large coupling, e ~ 2.
The reorganization is gauge invariant by construction, and due to cancellation
among various contributions, we obtain a completely analytic result for the
resummed thermodynamic potential at three loops. Finally, we compare our result
with similar calculations that use the Phi-derivable approach.Comment: 23 pages, 10 figures; v3 - typos corrected, additional discussions of
systematics added; corresponds with published versio
Three-loop HTL QCD thermodynamics
The hard-thermal-loop perturbation theory (HTLpt) framework is used to
calculate the thermodynamic functions of a quark-gluon plasma to three-loop
order. This is the highest order accessible by finite temperature perturbation
theory applied to a non-Abelian gauge theory before the high-temperature
infrared catastrophe. All ultraviolet divergences are eliminated by
renormalization of the vacuum, the HTL mass parameters, and the strong coupling
constant. After choosing a prescription for the mass parameters, the three-loop
results for the pressure and trace anomaly are found to be in very good
agreement with recent lattice data down to , which are
temperatures accessible by current and forthcoming heavy-ion collision
experiments.Comment: 27 pages, 11 figures; corresponds with published version in JHE
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