A gauged SU(4) flavor symmetric hadronic Lagrangian with empirical hadron masses is constructed to study charmonium absorption and charmed hadron production in hadronic reactions. For the coupling constants, empirical values are used if available. Otherwise, they are determined from known coupling constants using the SU(4) relations. To take into account the finite sizes of hadrons, form factors are introduced at strong interaction vertices with empirical cutoff parameters. For J/ψabsorption by nucleons, we have included both two-and three-body final states and find that with a cutoff parameter of 1 GeV at interaction vertices involving charm hadrons, the cross section is at most 5 mb and is consistent with that extracted from J/ψproduction from both photo-and proton-nucleus reactions. We have also evaluated the cross sections for charmed hadron production from pion and rho meson interactions with nucleons. With the same cutoff parameter of 1 GeV at interaction vertices, we find that these cross sections have values of a few tenths of mb and are dominated bythe s-channel nucleon pole diagram. For charmed hadron production from proton-proton reactions, their cross sections including bothtwo-andthree-body final states are about 1 batcenter-of-mass energyof 11.5 GeV, which is comparable to the measured inclusive cross section in these reactions.Including photon as a U(1) gauge particle, we have extended the model to study charmed hadron production in photon-proton reactions with both two-and three-body final states included. For form factors, an overall one is introduced in each processin order to maintain the gauge invariance of the total amplitude. Fitting the cutoff parameter in the form factor to the measured total cross section for charmed hadron production in photon-proton reactions at a center-of-mass energy of 6 GeV, the ratio of the cross sections for two-body and three-body final states is consistent with available experimental data.This result is further compared with predictions from the leading-order perturbative QCD calculation. Knowledge of the cross sections for charmonium absorption byhadrons and for charmed hadron production in hadronic reactions is essential for understanding charm production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC), where a quark-gluon plasma is expected to be formed during the initial hot dense stage.

GeV photon beams are provided at SPring-8/LEPS facility by backward-Compton scattering (BCS) from Argon laser photon against the 8-GeV electrons inside the SPring-8 storage ring. The energy range of tagged photon by measuring the recoil electron is from 1.5 to 2.4 GeV, and enables us to study the strange meson- and baryon-photoproduction, such as £p(1020), £N(1405) and £N(1520) . In the past 30 years, other than the high-energy £N(1520) photoproduction at NINA/LAMP2 experiment, there is no further study of the £N(1520) photoproduction near the threshold. Based on this exclusive measurement at NINA/LAMP2 experiment, several theoretical calculations predict that the £N(1520) photoproduction near the threshold can be explained by t-channel K* exchange, t-channel K exchange or the contact term together with the t-channel K exchange under the gauge invariance. This experiment was performed at SPring-8/LEPS facility with liquid hydrogen and deuterium targets by a forward spectrometer from 2002 to 2003. The electroproduction experiment with similar c.m. energy region performed by JLab/CLAS is included for comparison. We study three two-track detection modes to reconstruct the £N(1520) resonance and other resonant/non-resonant backgrounds by the invariant mass and missing mass spectra. Utilizing the one-/two-step side-band subtraction methods and Monte Carlo simulation method, we measure the differential cross sections, K^- decay asymmetries in t-channel helicity frame and photon beam asymmetries to understand the production mechanism of £N(1520) . This is the first time, the differential cross sections were measured at low energies and with a deuterium target. A large asymmetry of the production cross sections from protons and neutrons was observed at backward K^{+/0} angles. It can be explained by the dominance of the contact term along with the t-channel K exchange under the satisfaction of gauge invariance. This interpretation was also compatible with the differential cross sections, K^- decay asymmetry, and the photon beam asymmetry measured in the production from protons in the forward K^+ angles. A detector upgrade for the acceptance complement is done by introducing a time projection chamber, the configuration and operation principles except for the physics results will also be discussed in this thesis.

La photoproduction de mésons sur le nucléon donne un accès direct à sa spectroscopie et constitue une voie privilégiée dans l'étude de la structure interne du nucléon. Ce mémoire présente et discute un certain nombre de résultats obtenus avec le dispositif expérimental GRAAL installé à l'ESRF de Grenoble.

A Partial Waves Analysis (PWA) of gamma p to Delta++ X to p pi+ pi- (eta) data taken with the CLAS detector at Jefferson Lab is presented in this work. This reaction is of interest because the Delta++ restricts the isospin of the possible X states, leaving the PWA with a smaller combination of partial waves, making it ideal to look for exotic mesons. It was proposed by Isgur and Paton that photoproduction is a plausible source for the Jpc=1-+ state through flux tube excitation. The pi1(1400) is such a state that has been produced with the use of hadron production but it has yet to be seen in photoproduction. A mass independent amplitude analysis of this channel was performed, followed by a mass dependent fit to extract the resonance parameters. The procedure used an event-based maximum likelihood method to maintain all correlations in the kinematics. The intensity and phase motion is mapped out for the contributing signals without requiring assumptions about the underlying processes. The strength of the PWA is in the analysis of the phase motion, which for resonance behavior is well defined. In the data presented, the eta pi- invariant mass spectrum shows contributions from the a0(980) and a2(1320) partial waves. No pi1 was observed under a clear a2 signal after the angular distributions of the decay products were analyzed using an amplitude analysis. In addition, this dissertation discusses trends in the data, along with the implemented techniques.

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The null result of December 2004 Sub-threshold photoproduction of J/$psi$ experiment has motivated this thesis. This monte-carlo predicts the cross-section for sub-threshold photoproduction process and provides an insight on the cross-section range of these processess. The experiment was also conducted as a calibration run for Omega and Eta mesons for the verification of correctness of experimental procedure. The results from this experiment are compared with the monte-carlo simulation for the number of omega meson events. This is primarily done as the models for photoproduction of omega meson are well tested. The monte-carlo provides satisfactory results for the photoproduction models and with a crude a spectrometer model predicts the number of events which are off by a factor less than two. A refined model from Jefferson lab will eliminate this discrepancy.

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The charged pion production reactions d(gamma,pi⁺n), d(gamma,pi^-p), HD(gamma,pi⁺n)X were studied using linearly polarized gamma-rays with energies in the range from 260 MeV to 370 MeV at the Laser Electron Gamma Source (LEGS). A solid HD target was used in this experiment for the first time. The beam asymmetry data for the d(gamma,pi^-p) reaction significantly add to the previously available data. This gives new input to multipole analysis of pion production. A slight deviation from the beam asymmetry predicted for the free neutron is observed. The cross sections in the d(gamma,pi^-p) channel agree with previous measurements. / Ph. D.