Thermal operator representation of finite temperature graphs. II

F. T. Brandt, Ashok Das, Olivier Espinosa, J. Frenkel, Silvana Perez
2006 Physical Review D  
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
more » ... rature 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.
doi:10.1103/physrevd.73.065010 fatcat:gossmpni2zf2dlbflb53lxtk6m