ANTIPROTON PRODUCTION IN PP, DP AND DD COLLISIONS CLOSE TO THRESHOLD

The production of antiprotons in pp collisions is investigated close t o threshold where experimental data about the total cross section are not available. We analyze the latter reaction within the LUND string m odel for inclusive (p) over bar production and within the framework of a one-boson exchange model for the exclusive reaction pp --> ppp (p) over bar. The application of our new results to the analysis of subthr eshold antiproton production in d + p and d + d collisions shows cross sections that are much lower than expected before. Nevertheless, the comparison of experimental (p) over bar differential cross sections fr om d + p and d + d is expected to provide valuable information about a nonnucleonic component in the deuteron wavefunction.