[en] A brief report on some aspects of mesonic physics in few body experiments performed at LNS (Saclay, France) is presented. Due to its large branching ratio (BR) to ηN, this hadronic excitation in few body systems is connected to η-meson production, in particular near thresholds in various channels. Another important point of the production of particles near their thresholds is the specific kinematical condition - S-wave production - emphasizing the possible production of resonances or new states of matter. The last part of this short review is concerned with rare events observed in particular reactions, even if these observations lead to surprisingly higher cross sections than expected. (K.A.) 24 refs., 9 figs., 1 tab

[en] Taking advantage of the selectivity of different few body reactions, several experiments are in progress at the French National Laboratory (LNS) with the aim to bring new insight into Hadron Structure. Two programs are here developed: the first one concerns the monopole excitation of the proton to the P11 (1440) resonance. The second one studies the meson production near threshold and in particular the K anti K threshold energy domain where K anti K molecules are expected

[en] An experimental search for strange S=-1 dibaryons, performed at Saturne National Laboratory by means of pp - K⁺X is described. The experimental status and the theoretical previsions are presented first. A presentation of our preliminary results is then given, with a discussion on further developments

[en] Three-body mechanisms in hadron collisions, and the role of the A = 3 system are reviewed, and the excitation functions of the proton deuteron system in interactions at energies up to 2.9 GeV are discussed. Meson productions at large angles reveal structures due to the mesonic degrees of freedom in the interaction of the proton with the deuteron, exciting n^* isobars in intermediate states. Propagation in the nuclei does not seem to change the properties of these isobars. The meson double scattering mechanism provides a way to understand coherent meson production in pd capture. It is difficult to say whether this coherent process corresponds to eigenstates of the A = 3 system. The sharing of the momentum transfer between the three nucleons renders impossible the observation of high momentum components in coherent proton captures. The possible contribution of the electromagnetic probe in hadron physics with a multi GeV electron accelerator is mentioned

[en] Meson production near threshold is a spectroscopic tool in the studies of meson structure. Some interesting features of meson production near threshold in few body reactions are emphasized. In particular, the region of KK-bar thresholds studied in pd→³He X at LNS could be an excellent tool to bring new information about the a₀ (983) and f₀ (975) meson structure dilemma. (author) 11 refs., 5 figs

[en] A new p-p → K⁺X experiment has been performed at the Saturn National Laboratory to study through final state interaction λ-p and σ-N in a large range of momentum transfer and missing mass. After some recalls on recent searches on strange dibaryons we present here preliminary calculations of the p-p → K⁺ (λ)p differential cross section done within the one kaon exchange mechanism with (λ)-p final state interaction

[en] The total cross section for η-production near threshold in deuteron-deuteron interactions has been recently measured at four different energies, from 0.7 to 3.7 MeV above threshold. Low energy η-α scattering parameters are extracted. With a low energy η-A scattering model, the evolution of scattering length with A is studied for 1≤A≤4. Assuming a dominant π⁰-η mixing reaction mechanism, a prediction for the differential cross section in the isospin-forbidden reaction dd → απ⁰ is given. (author). 12 refs., 3 figs., 1 tab

No abstract available

[en] The SATURNE synchrotron was used in a pp→ K⁺X experiment with high resolution to study λp and σN final interactions in a large range of momentum transfer and missing mass. Results at an incident proton energy of 2.3 GeV in the mass region for X: 2055 < M_X< 2180 GeV and for kaon emission angles of 8 and 10 deg are presented

[en] The production of π⁰ and eta⁰ mesons in the reactions pd→π⁰tau and pd→eta⁰tau has been studied at very backward angles for kinetic proton energies Tsub(p) ranging from 0.92 to 2.6 GeV. The excitation functions at phisub(π) = phisub(eta) = 180⁰ display large structures which might be related to baryonic (Δ and N*) excitations in the intermediate state