Tricritical behavior in two dimensions. II. Universal quantities from theεexpansion

The tricirical exponents ${\eta }_t$ and ${\phi }_t$ are calculated through order ${\epsilon }^3$ and ${\epsilon }^2$, respectively, in the isotropic $n$-component model, where $\epsilon =3-d$. The estimate for ${\eta }_t$, in two dimensions for the Ising case, is 0.027; the series for ${\phi }_t$ is quite ill behaved, producing a negative estimate at this order. Beginning at this order in $\epsilon$, the spherical-model limit fails to exist. A scaling function for the spin-spin correlation function, appropriate for nonexceptional paths of approach to the tricritical point in the disordered phase, is calculated through ${\epsilon }^2$; its large momentum expansion is shown to involve the crossover exponent. These results are generalized to points where $\theta$ coexisting phases become critical.