Spinons in magnetic chains of arbitrary spins at finite temperatures

The thermodynamics of solvable isotropic chains with arbitrary spins is addressed by the recently developed quantum transfer matrix (QTM) approach. The set of nonlinear equations which exactly characterizes the free energy is derived by respecting the physical excitations at T = 0, spinons and RSOS kinks. We argue the implication of the present formulation for a spinon character formula of the level- WZWN model.