Topics of Higher Order Electroweak Processes and Nonleptonic Weak Processes in Standard Model.

This thesis is devoted to the calculation of higher order electroweak processes and nonleptonic weak interaction processes in the framework of the standard model. Primarily to standardize the notation, the thesis begins with a brief discussion of the Feynman rules and the dimensional regularization in a general renormalizable gauge for a spontaneously broken gauge theory. A typical process where higher order corrections are significant is the s(--->)d(gamma) transition. Amplitude including QCD radiative corrections for this process is calculated using a free quark model, which is then used to compute hyperon weak radiative decays. Explicit evaluation of the transition amplitude of the (SIGMA)(--->)P(gamma) mode is given. The quark fields are expanded in terms of MIT bag modes, so as to be consistent with quark confinement. We rederive the traditional baryon-pole model result and discover some evidence for a (V + A) weak hadronic current. The thesis also contains a phenomenological Lagrangian model for charmed meson decays. The model consists of a SU(,L)(3) x SU(,R)(3) nonlinear chiral Lagrangian with gauge fields. The charmed meson triplet (D('0), D('-), F('-)) is incorporated into the Lagrangian following the general framework proposed by Coleman, Wess and Zumino. The model can describe many body decay processes as well as two body decay processes. It also gives a unified description of pseudo-scalar, vector and axial vector meson decay modes of the charmed mesons. The model gives a one-parameter prediction of all two body and three body decay data. We predict the life time ratio (tau)(D)/(tau)(D('0)) = 3.75 and branching ratio of D('0) decay modes, namely B(,r)(D('0)( --->)K('0)(pi)('0))/B(,r)(D('0)(--->)K('-)(pi)('+)) = 1.04. These are in good agreement with experimental results. Several results of the flavor symmetry model, e.g. the sum rule for the D meson decay amplitudes, are rederived in the model. Dalitz plots of three body decay processes are also constructed and compared with data.