Products, patents and productivity persistence: A DSGE model of endogenous growth

This paper builds a dynamic stochastic general equilibrium (DSGE) model of endogenous growth that is capable of generating substantial degrees of endogenous persistence in productivity.  When products go out of patent protection, the rush of entry into their production destroys incentives for process improvements.  Consequently, old production processes are enshrined in industries producing non-protected products, resulting in aggregate productivity persistence.  Our model also generates sizeable delayed movements in productivity in response to preference shocks, providing a form of endogenous news shock.  Finally, if we calibrate our model to match a high aggregate mark-up then we can replicate the negative response of hours to a positive technology shock, even without the inclusion of any frictions.