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Thermal Operator Representation of Finite Temperature Graphs II

Fernando T. Brandt·Ashok Das·Olivier Espinosa·Josif Frenkel·Silvana Perez
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Abstract

Using the mixed space representation, we extend our earlier analysis to the case of Dirac and gauge fields and show that in the absence of a chemical potential, the finite temperature Feynman diagrams can be related to the corresponding zero temperature graphs through a thermal operator. At non-zero chemical potential we show explicitly in the case of the fermion self-energy that such a factorization is violated because of the presence of a singular contact term. Such a temperature dependent term which arises only at finite density and has a quadratic mass singularity cannot be related, through a regular thermal operator, to the fermion self-energy at zero temperature which is infrared finite. Furthermore, we show that the thermal radiative corrections at finite density have a screening effect for the chemical potential leading to a finite renormalization of the potential.

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Fernando T. Brandt, Ashok Das, Olivier Espinosa, Josif Frenkel, Silvana Perez. 2006-02-09. Thermal Operator Representation of Finite Temperature Graphs II. https://doi.org/10.1103/physrevd.73.065010

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