Recursion Relation Of Scattering Amplitudes And Its Boundary Contributions

In this dissertation, the author gives a review on new methods which called "the on-shell method" for calculating scattering amplitude. This dissertation mainly talks about the tree-level methods or techniques, especially the BCFW recursion relations and its boundary contributions. For this purpose, we omit the techniques on loop-level. The boundary contributions has become a tough problem in BCFW recursion relations. A large chunk of the thesis was devoted to explaining the derivation, application and significance of the BCFW recursion relations. We also discuss the current research circumstance of the boundary contributions. In the last half of the dissertation, we systematically introduce the approaches to recover the boundary contributions in recent years, and discuss the advantages and disadvantages of them.