حالت شاخه اي و مرتبه دوم ساختار پنگوين گليوني در واپاشيهاي مزون B

Tree-Level And Second Order Gluon Penguin Structure in B Meson Decays

Introduction: Weak decays of heavy quarks test the Standard Model and can be used to determine its parameters, including the weak mixing angles of the CKM matrix. In addition, the study of heavy quark decay provides important insight into the least well understood sector of the strong interaction. Decays of the b quark play a unique role for physics of the CKM matrix. This is also an important place to test our understanding of interplay between strong and weak interaction. Higher order decays of the b quark are also a sensitive window for physics beyond the Standard Model. In the Standard Model, flavor-changing neutral currents are forbidden, for example, there is no direct coupling between the b quark and the s or d quarks. Effective flavor-changing neutral currents are induced by penguin diagrams, where a quark emits and reabsorbs a W, thus changing flavors twice. Penguin decays have become increasingly appreciated in recent years. These loop diagrams with their interesting combination of CKM matrix elements give insight into the Standard Models. Aim: Obtaining the second order approximation part of gluon penguin in various b quark and B Meson decays. Materials and Methods: In this research, we are going to study weak interaction, Quark and Standard Models. According to Effective Hamiltonian Theory, we deduced various two and three body of B meson decays from various decays of b Quark Models Results: The amplitude of decays of tree level and gluon penguin structure in Quark Model up to the first and second orders approximation calculated. We calculated the amplitude of tree level plus gluon penguin on lowest order of the strong coupling constant as = 0.2 for first order of the decay processes b ^ qiqkqj + qkqlqj and for second order of the decay processes b ^ qiqkqj + qkqiq-j (qoqp). Also the decay rates of various decays of b quark up to the first and second orders approximation of the tree level plus penguin structure calculated. Conclusion: Comparing of theoretical and experimental values of decay rates and branching ratios, we consider that, the decay rate of the second order decays are much smaller than the first ones and the tree level dominated. Finally we compared the branching ratios of various decays of B meson, theoretically and experimentally and saw that the second order of gluon penguin term in b quark decays is small.