Capital accumulation, learning, and endogenous growth

I develop a growth model with three sectors of production (final goods, int ermediate goods, and R&D), each with a different technology using three inp uts (labor, capital, and knowledge), and combining elements from three stra nds of the literature (neoclassical growth, and AK and R&D endogenous growt h). The paper suggests not only that capital accumulation and innovation ar e complementary processes, neither of which would take place in the long ru n without the other, but also that this process can be self-sustaining eith er through Hicks-neutral knowledge spillovers without capital accumulation, or through Harrod-neutral knowledge spillovers with capital accumulation.