  We introduce a class of particle models in one dimension involving exchange
interactions that have scattering properties satisfying the Yang-Baxter
consistency condition. A subclass of these models exhibits reflectionless
scattering, in which particles are "transparent" to each other, generalizing a
property hitherto only known for the exchange Calogero model. The
thermodynamics of these systems can be derived using the asymptotic
Bethe-ansatz method.
