Mass spectrum of the diproton system produced in the reaction pn->pp pi(-)

The shape of the mass spectrum of the pp system produced near the threshold of the reaction pn-->pp pi(-) at initial proton momentum p(lab) similar or equal to 2 GeV/s is discussed. It is shown that the shape of the spectrum becomes universal when the diproton system is produced with a large momentum transfer. All effects of the Coulomb and strong interactions in the final state are taken into account exactly for the model ''Coulomb+separable Yamaguchi potential.'' The solution presented for the amplitude of the reaction gives a good description of the experimentally observed shape of the spectrum near the peak (chi(2)/d.f. = 0.654). (C) 1996 American Institute of Physics.