Effect of Long-Range Interactions on the Multicritical Behavior of   Homogeneous Systems
  A field-theoretic approach is applied to describe behavior of homogeneous three-dimensional systems with long-range interactions defined by two order parameters at bicritical and tetracritical points. Renormalization- group equations are analyzed in the two-loop approximation by using the Pade-Borel summation technique. The fixed points corresponding to various types of multicritical behavior are determined. It is shown that effects due to long-range interactions can be responsible for a change from bicritical to tetracritical behavior. 
S.V.Belim