CONSERVATION-LAWS AND INTEGRABILITY OF A ONE-DIMENSIONAL MODEL OF DIFFUSING DIMERS

We study a model of assisted diffusion of hard-core particles on a lin e. Our model is a special case of a multispecies exclusion process, bu t the lung-time decay of correlation functions can be qualitatively di fferent from that of the simple exclusion process, depending on initia l conditions. This behavior is a consequence of the existence of an in finity of conserved quantities. The configuration space breaks up into an exponentially large number of disconnected sectors whose number an d sizes are determined. The decays of autocorrelation functions in dif ferent sectors follow from ail exact mapping to a model of the diffusi on of hard-core random walkers with conserved spins. These are also ve rified numerically. Within each sector the model is reducible to the H eisenberg model and hence is fully integrable. We discuss additional s ymmetries of the equivalent quantum Hamiltonian which relate observabl es in different sectors. We also discuss some implications of the exis tence of an infinity of conservation laws for a hydrodynamic descripti on.