NN annihilation at the open charm threshold

We discuss the pp annihilation into a pair of charmed D mesons not far from the threshold of the reaction. An interesting interference pattern in the differential cross section is predicted to arise from the existence of both t-channel charmed-baryon exchange and s-channel charmonium resonance amplitudes. We argue that the experimental study of this process would provide new and valuable information about the unknown pp and cND couplings. These are important to know to solve the long-standing puzzle of the heavy flavor contents of baryons and to test the semilocal duality.