Theory of the Landau critical point. II. Low-temperature renormalization group and1Nexpansion

An isolated critical point on a line of first-order transitions (Landau point) is studied by means of the low-temperature renormalization group and $\frac{1}{N}$ expansion. Critical exponents are computed in dimension $d=3\mathrm{}$, using polynomials fitting the first two terms of the expansion about $d=2\mathrm{}$ and the previously calculated first three terms of the $\epsilon$ expansion about $d=4\mathrm{}$. The results are ${\lambda }_3=1.081\mathrm{}$ and ${\lambda }_6=-1.617\mathrm{}$. The conclusions for the shape of the phase diagram are drawn from these values.