Unraveling the Structure of Hadrons with Effective Field Theories of QCD

Effective Field theory is a powerful framework based on controlled expansions for problems with a natural separation of energy scales. This technique is particularly important for QCD, the theory of strong interactions, due to the vast diversity of phenomena that it describes. Stewart and collaborators have invented a new class of effective theories that can be used in processes with energetic hadrons. These Soft-Collinear Effective Theories provide a unified framework for describing hadronic processes which involve hard probes or the release of a large amount of energy. Many interesting issues about hadronic physics can be addressed with the soft-collinear effective theory. Examples include the size and shape of hadronic form factors, the universality of hadronic distribution functions for a plethora of processes, and the importance of subleading corrections at intermediate energy scales. Effective field theories allow these issues to be addressed using only the underlying symmetries and scales in QCD. Understanding these issues also has a direct impact on other areas of physics, such as on devising clean methods for the measurement of CP violation in the decay of B-mesons. Current progress on the soft-collinear effective theory and related methods is discussed in this report