The momentum spectra of protons, produced at 0 ~ as a result of fragmentation of relativistic deuterons on nuclei, are analyzed. Possible causes of the existing discrepancy of the data on the 0 ~ proton spectrum from the 1H(d,p)X reaction at 9.1 GeV/c with results of the impulse approximation calculations are considered. It is shown that taking into account the finite angular resolution of the experimental setup and the corresponding renormalization of the experimental data, on the one hand, and also the inclusion of the additional (to stripping) contribution of protons from the scattering of deuteron nucleons by target protons, on the other, make it possible to match these data with the results of calculations within the framework of the relativistic impulse approximation using the deuteron wave function for the Paris potential. In the literature various hypotheses have been put forward to explain the above-mentioned salient feature in the proton spectra at 0 ~ Among them are assumption about the presence of admixture of a six-quark component in the deuteron wave function [2,6], about the contribution of processes with the production of intermediate pions and with their subsequent absorption or rescattering by a spectator nucleon [7,8], about the different restrictions on the phase space near the kinematic boundary of the proton spectrum for the elastic and inelastic reaction channels E9], and about the contribution of processes of multiple nucleon scattering [10].
PACSAnother problem, associated with the data on the fragmentation of relativistic deuterons into protons at 0 ~ consists in that the invariant differential cross sections for the 1H(d,p(O~ reaction at 5.75 and 9.1GeV/c, plotted as function of the proton momentum in the deuteron rest frame, contrary to expectations, differ by the absolute value: for matching the spectra with each other the data at 5.75 GeV/c should be multiplied by a factor of 1.4 [6]. The fact that the data of [5] and 1-6] are inconsistent with each other was also pointed out in [10].In the present paper we consider two effects which could account for the anomalous behaviour of the momentum proton spectrum in the 1H(d, p)X reaction at 0 ~ at 9.1 GeV/c. The first effect is of methodical character and is associated with the finite angular resolution of the experimental setup, which should be taken into account when comparing the results of calculations with the experimental data. The second is due to the presence, apart from direct fragmentation, of the processes of scattering of deuteron nucleons by the target proton.
.We shall consider the process of fragmentation of a deuteron on a nucleus in the impulse approximation. A deviation from the impulse approximation due to rescatterins or final state interaction in the kinematical condi-