Related papers: Finite Temperature Retarded and Advanced Fields
It is shown that the perturbative expansions of the correlation functions of a relativistic quantum field theory at finite temperature are uniquely determined by the equations of motion and standard axiomatic requirements, including the KMS…
We have shown recently that the resummation of soft photon contributions leads to a non-exponential decay of the fermion excitations in hot QED plasmas. The retarded propagator of a massless fermion was found to behave as $S_R(t >> 1/gT)…
The symmetry group of the staggered Fermion transfer matrix in a spatial direction is constructed at finite temperature. Hadron-like operators carrying irreducible representations of this group are written down from the breaking of the zero…
The temperature dependence of the anomalous sector of the effective action of fermions coupled to external gauge and pseudo-scalar fields is computed at leading order in an expansion in the number of Lorentz indices in two and four…
We use a generalised real-time path formalism with properly regularised propagators based on Le Bellac and Mabilat \cite{belmab} and calculate the effective potential and the higher order derivative terms of the effective action in the case…
For a given diagrammatic approximation in many-body perturbation theory it is not guaranteed that positive observables, such as the density or the spectral function, retain their positivity. For zero-temperature systems we developed a…
Using an exact expression for the bi-spinor of parallel transport, we construct the Feynman propagator for Dirac fermions in the vacuum state on anti-de Sitter space-time. We compute the vacuum expectation value of the stress-energy tensor…
We address the modification of open heavy-flavor mesons in a hot medium of light mesons within an effective theory approach consistent with chiral and heavy-quark spin-flavor symmetries and the use of the imaginary time formalism to…
The aim of the article is to construct the S-matrix interpretation of the perturbation theory for the Wigner functions generating functional at a finite temperature. The temperature is introduced in the theory by the way typical for the…
We construct the retarded Green function and the Hadamard function in the Lorentzian (d+1)-dimensional anti-de Sitter spacetime for the Poincar\'e coordinate by performing the mode integration directly. We explore the structure of…
A finite-temperature many-body perturbation theory is presented that expands in power series the electronic grand potential, chemical potential, internal energy, and entropy on an equal footing. Sum-over-states and sum-over-orbitals…
In momentum space the Feynman propagator $D_{F}(k)$ at non-zero temperature is defined by a simple dispersion relation with the familiar property of being an even function of $k^{0}$ and analytic for Re$(k^{0})^{2}>0$. The coordinate space…
We study temperature dependence of diagonal conductivity at half filled Landau level by means of the theory of composite fermions in the weakly disordered regime $(k_{F}l>>1)$. At low temperatures we find the leading $\log T$ correction…
The two-point Green function of the massive scalar $(3+1)$-quantum field theory with $\lambda\phi^4$ interaction at finite temperature is evaluated up to the 2nd order of perturbation theory. The averaging on the vacuum fluctuations is…
The finite-temperature transport properties of FeRh compounds are investigated by first-principles Density Functional Theory-based calculations. The focus is on the behavior of the longitudinal resistivity with rising temperature, which…
In this Comment we show that the temperature-dependent effective Hamiltonian derived by Reslen {\it et al} [Europhys. Lett., {\bf 69} (2005) 8] or that one by Liberti and Zaffino [arXiv:cond-mat/0503742] for the Dicke model cannot be…
Complex-valued Feynman integrals in the imaginary time formalism and zero-temperature limit suffer from particular types of infrared divergences that can not be regulated by integration dimension alone. Related problems leading to…
When an ordered spin system of a given dimensionality undergoes a second order phase transition the dependence of the order parameter i.e. magnetization on temperature can be well-described by thermal excitations of elementary collective…
We discuss the thermal behaviour of the pion vector form factors and calculate them in one-loop Chiral Perturbation Theory. The perturbative result is used to analyze the $T$-dependent electromagnetic pion charge radius, obtaining a rough…
We develop a finite-temperature perturbation theory for quasi-one-dimensional quantum spin systems, in the manner suggested by H.J. Schulz (1996) and use this formalism to study their dynamical response. The corrections to the random-phase…