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 $T\simeq3\;T_c$. 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 $T \sim 2-3\,T_c$, which are temperatures accessible by current and forthcoming heavy-ion collision experiments.Comment: 27 pages, 11 figures; corresponds with published version in JHE