The first part of the thesis deals with the relations among meson-baryon scattering amplitudes detained under various collinear symmetries. The auxiliary group and its role in constructing relativistic field theories that incorporate internal symmetries is developed in the introductory chapter following Feldmann and Matthews. The collinear groups, in particular S(U(3)U(3)) is discussed in detail. Various predictions among the mesonbaryon scattering amplitudes are worked out under this group and also under SU(6)w and compared with experimental data. These processes are also considered under the collinear groups SU(4)w and S(U(2)U(2))I.Y. These smaller groups are used to compare the effects of symmetry-breaking in SU(3) and SU(4). The second part examines the decomposition of the unitary irreducible representations of SL(2,c) restricted to U(1)^T(2) and SU(l,l). Integral representations for unitary matrices that allow to pass from one set of basis vectors to another (labelled by the corresponding Casimir operators of the subgroups SU(2), SU(1,1) and U(1)^T(2)) are derived using the theory of Induced Representation.