Effective critical exponents in two-dimensional systems from conformal field theory

Thermal and field perturbations away from the renormalization-group fixed point are considered in 2D conformal field theory. General expressions for the effective critical exponents ν, α and δ are obtained in terms of the central charge, third moment of energy and spin correlation, temperature and external field. Apparent spin dependence expressions for the effective critical exponents are given for a high-spin system with only one fixed point. These expression may be described as critical behavior and crossover phenomena for 2D systems away from the critical points.