Related papers: A 2 Loop 2PPI Analysis of $\lambda\phi^4$ at Finit…
We use an optimised hopping parameter expansion for the free energy (linear delta expansion) to study the phase transitions at finite temperature and finite charge density in a global U(1) scalar Higgs sector on the lattice at large lattice…
We calculate the one loop effective potential for a 5D SU(2) gauge field theory at finite temperature $T=1/\beta$ and radius R=1/M. This calculation is performed, for the first time, in the case of background fields with two constant…
To study the convergence of the loop expansion at the high-temperature electroweak phase transition, we calculate the 2-loop effective potential of the 3d SU(2)-Higgs model in a general covariant gauge. We find that the loop expansion…
The two-particle irreducible (2PI) effective action theories are employed to study the strongly fluctuating electron systems, under the formalism of the two-dimensional Hubbard model. We obtain the corresponding quantum 2PI effective action…
In a previous paper we derived a relation between the operator product coefficients and anomalous dimensions. We explore this relation in the $(\phi^4)_4$ theory and compute the coefficient functions in the products of $\phi^2$ and $\phi^4$…
We study conformal field theories with finite group symmetries with spontaneous symmetry breaking (SSB) phases that persist at all temperatures. We work with two $\lambda \phi^4$ theories coupled through their mass terms. The two $\lambda…
We develop a systematic method for solving the 3-loop $\Phi$-derivable approximation to the thermodynamics of the massless $\phi^4$ field theory. The method involves expanding sum-integrals in powers of $g^2$ and m/T, where g is the…
By the concurrent use of two different resummation methods, the composite operator formalism and the Dyson-Schwinger equation, we re-examinate the behavior at finite temperature of the O(N)-symmetric $\lambda\phi^{4}$ model in a generic…
We investigate the critical behaviour of the $N$-component Euclidean $\lambda \phi^4$ model at leading order in $\frac{1}{N}$-expansion. We consider it in three situations: confined between two parallel planes a distance $L$ apart from one…
In this work we provide a numerical method to obtain the Bloch-Nordsieck spectral function at finite temperature in the framework of the 2PI approximation. We find that the 2PI results nicely agree with the exact one, provided we perform a…
We consider the large order behavior of the perturbative expansion of the scalar $\varphi^4$ field theory in terms of a perturbative expansion around an instanton solution. We have computed the series of the free energy up to two-loop order…
The renormalization of effective potentials for the noncommutative scalar field theory at high temperature are investigated to the two-loop approximation. The Feynman diagrams in evaluating the effective potential may be classified into two…
The Symmetry Improved Two-Particle-Irreducible (SI2PI) formalism is a powerful tool to calculate the effective potential beyond perturbation theory, whereby infinite sets of selective loop-graph topologies can be resummed in a systematic…
We investigate QCD at finite temperature in the quark composites approach, which is based on the use of quark composites with hadronic quantum numbers as fundamental variables. We find that chiral symmetry restoration and quark…
The chiral Abelian Higgs model is studied at finite temperature. By integrating out the heavy modes, we make a three-dimensional effective theory for the static modes. It is demonstrated that the plasma masses are correctly reproduced to…
Condsidering a massive self-interacting phi ^6 scalar field coupled arbitrarily to a (2+1) dimensional Bianchi type-I spacetime, we evaluate the one-loop effective potential. It is found that phi ^6 potential can be regularized in (2+1)…
The high-temperature limit of the 2-loop effective potential for the Higgs field is calculated from an effective 3d theory, in a general covariant gauge. It is shown explicitly that a gauge-independent result can be extracted for the…
We introduce the 2PPI expansion which sums the bubble graphs to all orders. We show that this expansion can be renormalised with the usual counterterms in a mass independent scheme. We discuss its application to the O(N) linear sigma model.
We describe in detail, in the context of the simple scalar $\phi^4$ theory, the prescription for resummation of daisy and superdaisy diagrams in the effective potential using the solution of the gap equations in the infrared limit. We find…
Gauge theories broken by a single Higgs field are known to have first-order phase transitions in temperature if $\lambda/g^2 \ll 1$, where $g$ is the gauge coupling and $\lambda$ the Higgs self-coupling. If the theory is extended from one…