Critical exponents of O(N) models in fractional dimensions

We compute critical exponents of O(N) models in fractional dimensions between d = 2 and 4, and for continuous values of the number of field components N, in this way completing the RG classification of universality classes for these models. These curves represent nonperturbative approximation to the exact results, they respect all the qualitative features expected from such quantities conciliating previously known perturbative results in three dimensions with exact results in two dimensions and giving a strong indication of what could be the exact behavior of such curves. We also report critical exponents for some multicritical universality classes in the cases N >= 2 and N = 0. Finally, in the large-N limit our critical exponents correctly approach those of the spherical model, allowing us to set N similar to 100 as the threshold for the quantitative validity of leading order large-N estimates.