Finite temperature symmetry restoration in the U_L(3)xU_R(3) linear   sigma model from a large-n approximation
  A recently proposed approximate large-n ground state solution of the U_L(n)xU_R(n) symmetric linear sigma model is investigated at finite temperature. We study the coupled evaporation of two condensates corresponding to the symmetry breaking pattern U_L(3)xU_R(3) -> U_V(2), realized by the ground state in certain parts of the coupling space. The region of the fluctuation induced first order transitions and its second order boundary is mapped out. The existence of a tricritical point is conjectured. 
G. Fejos, A. Patkos
hep-ph