Improved ring approximation for the free energy in thermal scalar field theory
Instituto de Física, Universidade de São Paulo - São Paulo, SP 05315-970, Brazil
Received: 16 January 2014
Accepted: 24 February 2014
In a d-dimensional field theory at finite temperature T, with a interaction, we compute the contributions to the free energy in the ring approximation. These are calculated in a consistent manner, by evaluating the thermal self-energy in a similar approximation. The complete result can be expressed in closed form in terms of the Haber and Weldon functions . This result exhibits, to leading order, a non-analyticity in the coupling constant of the form or when d is even or odd, respectively.
PACS: 11.10.Wx – Finite-temperature field theory
© EPLA, 2014