Abstract
We describe spatio-temporal correlations and heterogeneities in a kineticallyconstrained glassy model, the Kob-Andersen model. The kinetic constraints ofthe model alone induce the existence of dynamic correlation lengths, thatincrease as the density $\rho$ increases, in a way compatible with adouble-exponential law. We characterize in detail the trapping time correlationlength, the cooperativity length, and the distribution of persistent clustersof particles. This last quantity is related to the typical size of blockedclusters that slow down the dynamics for a given density.