.We perform a calculation of the -M1M2, with M1,M2 either pseudoscalar or vector mesons using the basic weak interaction and angular momentum algebra to relate the different processes. The formalism also leads to a different interpretation of the role played by G-parity in these decays. We also observe that, while PPp-wave production is compatible with chiral perturbation theory and experiment, VP and VVp-wave production is clearly incompatible with experiment and we develop the formalism also in this case, producing the VP or VV pairs in s-wave. We compare our results with experiment and other theoretical approaches for rates and invariant mass distributions and make predictions for unmeasured decays. We show the value of these reactions, particularly if the M1M2 mass distribution is measured, as a tool to learn about the meson-meson interaction and the nature of some resonances, coupling to two mesons, which are produced in such decays.

We study the B+J/K+ reaction, and show that it is driven by the presence of two resonances, the X(3940) and X(3930), that are of molecular nature and couple most strongly to D*D*, but also to J/. Because of that, in the J/ mass distribution we find a peak related to the excitation of the resonances and a cusp with large strength at the D*D* threshold.

We study the amplitudes of the -VP decay for the different polarizations of the vector meson V, using a formalism where the mapping from the quark degrees of freedom to the meson ones is done with the P-3(0) model. We extend the formalism to a case, with the operator -5, that can account for different models beyond the Standard Model and study in detail the -K*0K- reaction for the different polarizations of the K*0. The results are shown in terms of the parameter that differs for each model. We find that is very different for each of the third components of the vector spin, M=3D+/- 1,0, and in particular the magnitude |M=3D-1 is very sensitive to the parameter, which makes the investigation of this magnitude very useful to test different models beyond the Standard Model.

We use a recent formalism of the weak hadronic reactions that maps the transition matrix elements at the quark level into hadronic matrix elements, evaluated with an elaborate angular momentum algebra that allows finally to write the weak matrix elements in terms of easy analytical formulas. In particular they appear explicitly for the different spin third components of the vector mesons involved. We extend the formalism to a general case, with the operator parameter, which suggest to use this magnitude to test different models beyond the standard model. We show that our formalism implies the heavy quark limit and compare our results with calculations that include higher order corrections in heavy quark effective theory. We find very similar results for both approaches in normalized distributions, which are practically identical at the end point of M-inv((nu l)) =3D m(B) - m(D)*

Considering the mixing of scalar mesons, the Omega Omega and Xi* Omega systems are dynamically investigated within the framework of the chiral SU(3) quark model by solving the resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a good description of the energies of the baryon ground states, the binding energy of deuteron, and the experimental data of the nucleon-nucleon (NN) and nucleon-hyperon (NY) scattering processes. Two different mixing cases, one is the ideal mixing and another is 19 degrees mixing, are discussed. The results show that no matter what kind of mixing is adopted, the OO and Xi* Omega systems are still bound states. It is also shown that they are deeply bound if 19 degrees mixing is adopted.

The mixing of scalar mesons is introduced into the baryon-baryon system in the chiral SU(3) quark model to further dynamically investigate the Di-omega state by using the same parameters as those in reasonably describing the experimental hyperon-nucleon and nucleon-nucleon scattering data. Two different mixings of scalar mesons, the ideal mixing and 19deg mixing, are discussed, and compared with no mixing. The results show that it is still deeply bound state if 19deg mixing is adopted, the same as those of no mixing. However, for ideal mixing, the binding energy is reduced quite a lot, yet it is still a bound state.

By introducing the mixing of scalar mesons in the chiral SU(3) quark model, we dynamically investigate the baryon-baryon interaction. The hyperon-nucleon and nucleon-nucleon interactions are studied by solving the resonating group method (RGM) equation in a coupled-channel calculation. In our present work, the experimental lightest pseudoscalar pi, K, eta, eta' mesons correspond exactly to the chiral nonet pseudoscalar fields pi, K, eta, eta' in the chiral SU(3) quark model. The eta, eta' mesons are considered as the mixing of singlet and octet mesons, and the mixing angle theta(ps) is taken to be -23 degrees. For scalar nonet mesons, we suppose that there exists a correspondence between the experimental lightest scalar f(0)(600), kappa, a(0)(980), f(0)(980) mesons and the theoretical scalar nonet sigma, kappa, sigma', epsilon fields in the chiral SU(3) quark model. For scalar mesons, we consider two different mixing cases: one is the ideal mixing and another is the theta(s) = 19 degrees mixing. The masses of the sigma' and epsilon mesons are taken to be 980MeV, which are just the masses of the experimental a(0)(980), f(0)(980) mesons. The mass of the sigma meson is an adjustable parameter and is decided by fitting the binding energy of the deuteron, the masses of 560MeV and 644MeV are obtained for the ideal mixing and the theta(s) = 19 degrees mixing, respectively. We find that, in order to reasonably describe the YN interactions, the mass of the. meson is near 780 MeV for the ideal mixing. However, we must enhance the mass of the kappa meson for the theta(s) - 19 degrees mixing, the 1050MeV is favorably used in the present work. The experimental sigma and kappa scalar mesons are very strange, both have larger widths. Hence, no matter what kind of mixing is considered, all the masses of scalar mesons we used in the present work seem to be consistent with the present PDG information.

We study the B-c(-) -> pi(-) J/omega and B-c(-) -> pi(-) D* (D) over bar* reactions and show that they are related by the presence of two resonances, the X(3940) and X(3930), that are of molecular nature and couple most strongly to D* (D) over bar*, but also to J/psi omega. Because of that, in the J/psi omega mass distribution we find a cusp with large strength at the D* (D) over bar* threshold and predict the ratio of strengths between the peak of the cusp and the maximum of the D* (D) over bar* distribution close to D* (D) over bar* threshold, which are distinct features of the molecular nature of these two resonances.

The hyperon-nucleon scattering processes and some dibaryon states are studied both in the chiral SU(3) quark model and in the extended chiral SU(3) quark model by solving the resonating group method (RGM) equation. We find that the short-range interaction could be described either by the one-gluon exchange or by the vector meson exchange for baryon-baryon system.

We give the comparisons between the chiral SU(3) quark model and the extended chiral SU(3) quark model. The results show that the phase shifts of NN scattering are very similar. However, the short range mechanisms of nucleon-nucleon interaction are totally different. In the chiral SU(3) quark model, the short range interaction is dominantly from OGE, and in the extended chiral SU(3) quark model, it is dominantly from vector meson exchanges.

We investigate the KD and eta D-s system in a finite volume and study the properties of the D-s*0(2317) resonance, which is generated in this coupled channel system. We calculate the energy levels in a cubic box and considering them as synthetic lattice data we solve the inverse problem of determining the bound states and phase shifts in the infinite volume. We observe that it is possible to obtain accurate KD phase shifts and the position of the D-s*0(2317) state from the synthetic lattice data considered and that a careful analysis of the finite volume data can shed some light on the nature of the D-s*0(2317) resonance as a KD molecule or otherwise.