The multicritical point at which both a 3-component and a 2-component order
parameters order simultaneously in 3 dimensions is shown to have the critical
behavior of the decoupled fixed point, with separate n=3 and n=2 behavior. This
contradicts both the extrapolation of the epsilon-expansion at leading order,
which yields the biconical point, and recent Monte Carlo simulations, which
gave isotropic SO(5) behavior. Thus, this tetracritical point carries no
information on the relevance of the so-called SO(5) theory of high-T
superconductivity.Comment: 1 pag