Hott, M.Metikas, G.2014-05-202014-05-202002-04-15Physical Review D. College Pk: American Physical Soc, v. 65, n. 8, 7 p., 2002.0556-2821http://hdl.handle.net/11449/36270We show that for the pion-nucleon theory the thermal bubble graph is analytic at the origin of the momentum-frequency space, although the internal propagators in the loop have the same mass. This means that, for this theory, the thermal effective potential is uniquely defined. We then examine how a slight modification of the interaction term results in a theory for which the thermal bubble graph displays the usual nonanalyticity at the origin and the thermal effective potential is not uniquely defined.7engArtigo10.1103/PhysRevD.65.085043WOS:000175147000055Acesso abertoWOS000175147000055.pdf