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,...

An expression of the XXZ model is given from which the Ising, isotropic XY and Heisenberg models may be more properly obtained by varying only one anisotropy parameter. The ground state and spin configuration of the antiferromagnetic quasi-classical s = 12XXZ chain in a magnetic field of...