Photoproduction Of Hadrons And Productions Of Charmed Mesons

During the past few decades, great strides have been made in hadron spectroscopy, due to the progress of experiment and theory. Especially, the research of hadron spectroscopy has reached a new stage since more and more charmonium-like/bottomonium-like states referred to XYZ particle have been observed in experiment. However, there are still many challenges and problems in the studies of hadron spectroscopy. For example, some exotic states cannot be explained within the classical quark model. The new theoretical model is needed and necessary. Besides, since the low energy processed which are completely governed by non-perturbative QCD, we can only use the phenomenological model to study and explain the relevant physics in this energy region. However, it is known that the phenomenological results are highly dependent on the model, which causes the large uncertainty of physics. In experiment, due to lack of high precise experimental data, it is difficult to clarify the relevant physics problems. In this thesis, combined with the relevant experiment, the detailed reaction process and hadron production will be explored and discussed, which is helpful to have a more comprehensive understanding of the non-perturbative physics.The main contents of this thesis include:(i) We construct a model to repair local gauge invariance broken by Reggeization of t-channel meson exchanges in single-meson photoproduction off a baryon. Our model is consistent with the underlying field-theoretical foundations, while the construction principle is based on the underlying generalized Ward-Takahashi identities which validity ensure local gauge invariance. And then we apply our model to the γnâ†'K+Σ*(1385)- reaction. The cross sections for the γnâ†'K+Σ*(1385)-reaction are calculated and compared with experimental results from the CLAS and LEPS Collaborations. The theoretical approach provides a good description of the main features of the data. Besides, Inspired by the preliminary experimental data by the CLAS Collaboration, the K*0Λ photoproduction off a neutron is studied based on the Regge model and the Feynman model. The discrepancy between two models is found small in the energy range of CLAS data and predicted to become obvious at energies higher than 3 GeV.(ii) Photoproduction of the charm onium-like state Zc (4200) and the charmed baryon A*c (2940) is investigated with an effective Lagrangian approach and the Regge trajectories applying to the COMPASS experiment. Combining the experimental data from COMPASS and our theoretical model we estimate the upper limit of ΓZc(4200)>J/φπ to be of about 37 MeV. Moreover, the pos- sibility to produce Λ*c(2940) at COMPASS is discussed. It seems one can try to search for this hadron in the missing mass spectrum since the l-channel is dominating for the Λ*c(2940) photo-production.(iii) By assuming the Z(4430) as a tetraquark state, we study the production of neutral Z0(4430) by antiproton-proton annihilation. It is found that there exists an obvious peak for the production of signal near the Z(4430) threshold. Moreover, we explore the discovery po-tential of the hidden charm pentaquark candidate N*(4261) production via Ï€-p scattering, while the production of hidden charm baryon Λ*c-c(4209) via K-p scattering is studied. The numerical results indicate that it is effective way to search for the hidden charm pentaquark candidate by meson-nucleon scattering.(iv) the role of the Δ* resonances in the process of pp â†' nK+Σ- are systematically inves-tigated with the effective Lagrangian approach and the isobar model. We find that a P31 state, either Δ*(1750) or Δ*(1910), is favored by the data while the P33 state, namely Δ*(1920), has small contribution. Besides, either sub-threshold S31 Δ* (1620) resonance or strong nΣ final state interaction or both have possible contribution at near threshold region, depending on the measured cross sections. We demonstrate the invariant mass distributions and the Dalitz Plots in order to investigate whether it is possible to distinguish the controversial KΣ production mechanism in these observables.The theoretical calculations obtained by us may not only shed light on the further experiment of searching for the relevant states, but enable us to have a better understanding of the interaction mechanism of the photoproduction and other processes. Besides, it should be noted that more precise experimental datas are necessary for clarifying the roles of resonances and the theoretical model. Thus the relevant experiment measurement is encouraged.