Abstract. In this research, the e ective Hamiltonian theory is described and applied to the calculation
of current-current (Q1;2) and QCD penguin (Q3; ;6) decay rates. The channels of charm quark decay in
the quark levels are: c ! dud, c ! dus, c ! sud and c ! sus where the channel c ! sud is dominant.
The total decay rates of the hadronic of charm quark in the e ective Hamiltonian theory are calculated.
The decay rates of D meson decays according to Spectator Quark Model (SQM) are investigated for the
calculation of D meson decays. It is intended to make the transition from decay rates at the quark level to
D meson decay rates for two body hadronic decays, D ! h1h2. By means of that, the modes of nonleptonic
D ! PV , D ! PP, D ! V V decays where V and P are light vector with JP = 0???? and pseudoscalar
with JP = 1???? mesons are analyzed, respectively. So, the total decay rates of the hadronic of charm quark
in the e ective Hamiltonian theory, according to Colour Favoured (C-F) and Colour Suppressed (C-S) are
obtained. Then the amplitude of the Colour Favoured and Colour Suppressed (F-S) processes are added
and their decay rates are obtained. Using the spectator model, the branching ratio of some D meson
decays are derived as well.
)