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The total cross section for ω production in the pp → ppω reaction has been measured at five c.m. excess energies from 3.8 to 30 MeV. The energy dependence is easily understood in terms of a strong protonproton final state interaction combined with a smearing over the width of the state. The ratio of near-threshold φ and ω production is consistent with the predictions of a one-pion-exchange model and the degree of violation of the OZI rule is similar to that found in the π − p → nω/φ reactions.

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The reaction pp ! pp 1 N has been studied at three energies (T p 1520, 1805, and 2100 MeV) and six angles from 0 ± up to 17 ± (laboratory). Several narrow states have been observed in missing mass spectra at 1004, 1044, and 1094 MeV. Their widths are typically 1 order of magnitude smaller than the widths of N ‫ء‬ or D. Possible biases are discussed. These masses are in good agreement with those calculated within a simple phenomenological mass formula based on color magnetic interaction between two colored quark clusters. [S0031-9007(97)

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MeV (and possibly 1339 MeV). Some of them were also observed at the same masses in the missing mass spectra of the d p → p p X reaction although with a weaker signature. Many checks were performed to make sure that these structures were not produced by experimental artifacts. Several narrow small amplitude peaks, were also extracted using already published photo-nucleon cross sections. The small widths of all these results, and the stability of the observed structures, regardless of the experiment, were used to conclude that they are genuine baryons which and not merely the consequence of dynamical rescatterings. These baryons cannot be associated with classical q 3 quark configurations. We associate them with two colored cluster quark configurations.1 with real hadrons and not with final state rescatterings. There is no room for new low mass mesons within the many quark models for mesons, that consider only qq configurations, given the excellent agreement between observation and calculations [7]. Once again there is no room in the mass range M≤1.5 GeV for new baryons within the many quark models for baryons, if we consider only qqq configurations. The classical baryonic spectrum, which corresponds to broad resonances, is rather well understood. This is not the case for the narrow structures observed.An interpretation was tentatively proposed to explain these narrow and exotic hadrons, associating them with two colored quark clusters. It was shown in the already quoted references that such an attempt allows to reproduce the masses with models using a very small number of adjusted parameters (from zero to two), depending on the hadronic species in question. In these models, where the exotic hadron arises from a partial deconfinement, we would expect small narrow amplitude signatures throughout the complete hadronic spectra. This paper presents the analysis and the results obtained in order to check this idea in low mass baryons. Preliminary results concerning the three first exotic baryons have previously been published [3]. This paper is constructed in the following way: in Sec II we will describe the detector performances, and the data processing; in Sec. III the various normalizations applied in order to get the cross sections will be described; the simulation used to make some of these normalizations and to test the complete experimental device will be discussed in Sec. IV whereas the various checks performed in order to underline our confidence in the genuine reality of the observed structures are presented in Section V. In Section VI the results of our two experiments are presented, namely: -the p p → p π + X reaction, studied at three incident energies: T p =1.52 GeV, 1.805 GeV, and 2.1 GeV and several forward angles. Narrow baryons were looked for in the missing mass M X and in the invariant mass M pπ + ; -the missing mass of the d p → p p X reaction was studied at two incident deuteron energies: T d =1.722GeV and 2.1 GeV.We compare the masses of our structures to the masses of small structures which can ...

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