arXiv subjects

Emmanuel Petitgirard

Publications and source records attributed to Emmanuel Petitgirard.

4 recordsLinked to original sources

arXiv2003

Two-loop HTL Thermodynamics with Quarks

We calculate the quark contribution to the free energy of a hot quark-gluon plasma to two-loop order using hard-thermal-loop (HTL) perturbation theory. All ultraviolet divergences can be absorbed into renormalizations of the vacuum energy and the HTL quark and gluon mass parameters. The quark and gluon HTL mass parameters are determined self-consistently by a variational prescription. Combining the quark contribution with the two-loop HTL perturbation theory free energy for pure-glue we obtain the total two-loop QCD free energy. Comparisons are made with lattice estimates of the free energy for N_f=2 and with exact numerical results obtained in the large-N_f limit.

hep-ph↗

arXiv2002

HTL Perturbation Theory to Two Loops

We calculate the pressure for pure-glue QCD at high temperature to two-loop order using hard-thermal-loop (HTL) perturbation theory. At this order, all the ultraviolet divergences can be absorbed into renormalizations of the vacuum energy density and the HTL mass parameter. We determine the HTL mass parameter by a variational prescription. The resulting predictions for the pressure fail to agree with results from lattice gauge theory at temperatures for which they are available.

hep-ph↗

arXiv2001

Solution to the 3-Loop $Φ$-Derivable Approximation for Massless Scalar Thermodynamics

We develop a systematic method for solving the 3-loop $Φ$-derivable approximation to the thermodynamics of the massless $ϕ^4$ field theory. The method involves expanding sum-integrals in powers of $g^2$ and m/T, where g is the coupling constant, m is a variational mass parameter, and T is the temperature. The problem is reduced to one with the single variational parameter m by solving the variational equations order-by-order in $g^2$ and m/T. At the variational point, there are ultraviolet divergences of order $g^6$ that cannot be removed by any renormalization of the coupling constant. We define a finite thermodynamic potential by truncating at $5^{th}$ order in g and m/T. The associated thermodynamic functions seem to be perturbatively stable and insensitive to variations in the renormalization scale.

hep-ph↗

arXiv2001

Solution to the 3-loop $Φ$-derivable Approximation for Scalar Thermodynamics

We solve the 3-loop $Φ$-derivable approximation to the thermodynamics of the massless $ϕ^4$ field theory by reducing it to a 1-parameter variational problem. The thermodynamic potential is expanded in powers of $g^2$ and $m/T$, where $g$ is the coupling constant, $m$ is a variational mass parameter, and $T$ is the temperature. There are ultraviolet divergences beginning at 6th order in $g$ that cannot be removed by renormalization. However the finite thermodynamic potential obtained by truncating after terms of 5th order in $g$ and $m/T$ defines a stable approximation to the thermodynamic functions.

hep-ph↗