In this paper, we extend our earlier one loop analysis to two loops and give a simple diagrammatic description for the retarded Greens functions at finite temperature, in terms of forward scattering amplitudes of on-shell thermal particles. We present a simple discussion, which can be easily generalized to any field theory, of the temperature dependent parts of the retarded two and three point ...

We provide an axiomatic framework for Quantum Field Theory at finite temperature which implies the existence of general analyticity properties of the n-point functions; the latter parallel the properties derived from the usual Wightman axioms in the vacuum representation of Quantum Field Theory. Complete results are given for the propagators, including a generalization of the Källén-Lehmann rep...

Within the real-time formalism (RTF) of thermal field theory, we apply the hard thermal loop (HTL) resummation technique to calculating effective two-loop thermodynamic potential in quark-gluon plasma (QGP) and its renormalization. The result with collective effects is obtained, which is valid for an arbitrary number of quark flavors with masses. Keyword: quark-gluon plasma (QGP); finite temper...

We investigate models of opinion formation which are based on the social impact theory. The following approaches are discussed: (i) general mean field theory of social impact, (ii) a social impact model with learning, (iii) a model of a finite group with a strong leader, (iv) a social impact model with dynamically changing social temperature, (v) a model with individuals treated as active Brown...