A Brief Introduction to Modern Amplitude Methods

摘要

I provide a basic introduction to modern helicity amplitude methods,including color organization, the spinor helicity formalism, and factorization properties. I also describe the BCFW(on-shell)recursion relation at tree level, and explain how similar ideas - unitarity and on-shell methods - work at the loop level. These notes are based on lectures delivered at the 2012 CERN Summer School and at TASI 2013,and are close to the material Zvi Bern lectured on at TASI 2014.