Renormalized g-log (g) double expansion for the invariant φ⁴-trajectory in three dimensions

We study the invariant unstable manifold of the trivial renormalization group fixed point tangent to the $\phi^{4}$-vertex in three dimensions. We parametrize it by a running $\phi^{4}$-coupling with linear step $\beta$-function. It is shown to have a renormalized double expansion in the running coupling and its logarithm.