MASSIVE INTEGRABLE SOLITON THEORIES

Massive integrable field theories in 1 + 1 dimensions are defined at t he Lagrangian level, whose classical equations of motion are related t o the ''non-abelian'' Toda field equations. They can be thought of as generalizations of the sine-Gordon and complex sine-aordon theories. T he fields of the theories take values in a non-abelian Lie group and i t is argued that the coupling constant is quantized, unlike the situat ion in the sine-Gordon theory, which is a special case since its field takes values in an abelian group. It is further shown that these theo ries correspond to perturbations of certain coset conformal field theo ries. The solitons in the theories will, in general, carry non-abelian charges.