Waleed MustafaCIIT-SP15-RPH-008/LHRDr. Shabana NisarLHR TP 69402026-02-072017https://repository.cuilahore.edu.pk/handle/123456789/1199This thesis consists of the study of the D-meson decays using flavor symmetry. The research involves SU(3) symmetry analysis of the flavor diagrams to relate D-meson decays in the Cabibbo suppressed sector. Feynman Diagrams have been considered that express amplitudes for different decay modes in terms of Tree, Annihilation, Color suppressed and Exchange amplitudes. The decay rates have been then compared to the observational values to see if SU(3) symmetry approach can be used to describe the Cabibbo suppressed D-meson decays. Similar analysis has been done for the Cabibbo favored decays as well. In both cases, especially in singly Cabibbo-suppressed decays, SU(3) flavor symmetry breaking has been observedenDepartment of PhysicsSP15PhysicsD meson decaysFlavor symmetryExchange amplitudesDr. Shabana NisarThesis