SLOW RELAXATION IN A MODEL WITH MANY CONSERVATION-LAWS - DEPOSITION AND EVAPORATION OF TRIMERS ON A LINE

We study the slow decay of the steady-state autocorrelation function C(t) in a stochastic model of deposition and evaporation of trimers on a line with infinitely many conservation laws and sectors. Simulations show that C(t) decays as different powers of t, or as exp(-t(1/2)), depending on the sector. We explain this diversity by relating the problem to diffusion of hard core particles with conserved spin labels. The model embodies a matrix generalization of the Kardar-Parisi-Zhang model of interface roughening. In the sector which includes the empty line, the dynamical exponent z is 2.55 +/- 0.15.