@article{articlee7479d5d, title = {Thermal operator representation of finite temperature graphs. II.}, author = {Brandt, Fernando Tadeu Caldeira and Das, Ashok and Espinosa, Olivier and Frenkel, Josif and Perez, Silvana}, year = {2006}, doi = {10.1103/physrevd.73.065010}, journal = {Physical Review D} }