  The overview is given of the results obtained recently in the course of
renormalization-group (RG) study of two-dimensional (2D) models. RG functions
of the two-dimensional n-vector \lambda \phi^4 Euclidean field theory are
written down up to the five-loop terms and perturbative series are resummed by
the Pade-Borel-Leroy techniques. An account for the five-loop term is shown to
shift the Wilson fixed point only briefly, leaving it outside the segment
formed by the results of the lattice calculations. This is argued to reflect
the influence of the non-analytical contribution to the \beta-function. The
evaluation of the critical exponents for n = 1, n = 0 and n = -1 in the
five-loop approximation and comparison of the results with known exact values
confirm the conclusion that non-analytical contributions are visible in two
dimensions. The estimates obtained on the base of pseudo-\epsilon expansions
originating from the 5-loop 2D RG series are also discussed.

Statistical Mechanics;High Energy Physics - Lattice;High Energy Physics - Phenomenology;High Energy Physics - Theory