In the frame of the scalar theory λφ4, we explore the occurrence of thermal renormalons, i. e. temperature dependent singularities in the Borel plane. Using Thermofield Dynamics, we found in fact a series of singularities of this kind, which are located to the right of the well known zero temperature pole, being therefore of a subleading character in the ambiguity of the Borel sum.

We establish the Schlieder and the Borchers property for thermal field theories. In addition, we provide some information on the commutation and localization properties of projection operators.

The application of generalized Kramers-Kronig relations, the so-called Leontovich relations, to thermal field theory is discussed. Medium effects contained in the full, thermal propagators can easily be taken into account by this method. As examples the collisional energy loss of a charged particle in a relativistic plasma and the radiation of energetic photons from a quark-gluon plasma are con...

Two problems in thermal field theory François Gelis Brookhaven National Laboratory, Nuclear Theory, Bldg 510A, Upton, NY-11973, USA Abstract. In this talk, I review recent progress made in two areas of thermal field theory. In particular, I discuss various approaches for the calculation of the quark gluon plasma thermodynamical properties, and the problem of its photon production rate.

A new thermal field-flow fractionation (ThFFF) method has been developed for the separation and analysis of polyacrylates and acrylic-styrene copolymers. This important class of polymers is commonly used as pressure sensitive adhesives, in coatings and paintings, and as the basis for polyelectrolyte materials. The structure and chemical composition of these polymers play a vital role in the end...

We present a new grid of LTE model atmospheres for weakly magnetic (B <∼ 10 10 G) neutron stars, using opacity and equation of state data from the OPAL project and employing a fully frequency and angle dependent radiation transfer. We discuss the differences to earlier models, including a comparison with a detailed NLTE calculation. As a first application of the new synthetic spectra, we re-ana...

We analyze the effect of a finite volume on the thermodynamic potentials of a relativistic quantum field theory defined on a hypertorus at vanishing chemical potential. Using the symmetries of the Euclidean partition function, we interpret the thermodynamic observables as the expectation value of the energy-momentum tensor in the same theory living on a β×L2 volume. In the case where the screen...

Standard entropy calculations in quantum field theory, when applied to a subsystem of definite volume, exhibit area-dependent UV divergences that make a thermodynamic interpretation troublesome. Such divergences cannot be reabsorbed by local counterterms although, with a rather unusual procedure, they can be subtracted from the final result. A key issue here is which set of quantum degrees of f...

We have built a high-resolution optical coherence tomography (OCT) system, based on a Linnik-type interference microscope, illuminated by a white-light thermal lamp. The extremely short coherence length of the illumination source and the large aperture of the objectives permit resolution close to 1 microm in three dimensions. A parallel detection scheme with a CCD camera provides cross-section ...