Multicritical behavior of the two-field Ginzburg-Landau model coupled to a gauge field

In this paper, we study the multicritical behavior of the Ginzburg-Landau model in a O(n₁)⊕O(n₂)-symmetric version containing (n₁/2+n₂/2)-complex order parameters coupled to a gauge field. We develop the RG analysis at a one-loop approximation in the context of the ?-expansion approach. The beta functions are obtained, and in the case of equal couplings between the two scalar fields and the gauge field and n₁=n₂=n/2, the infrared stability of the fixed points is discussed. It is found that the charged infrared-stable fixed point exists for n>393.2. Calculations of the relevant critical exponents are also carried out.