Speaker: Matthias Burkardt (New Mexcio State University) 

Title: What is orbital angular momentum?

Abstract:
While the total angular momentum of an isolated system is 
uniquely defined, ambiguities arise when decomposing the 
total angular momentum of an interacting multi-constituent 
system into contributions from various constituents. 
Moreover, in a gauge theory, switching the gauge may result 
in shuffling angular momentum between matter and gauge 
degrees of freedom. I will discuss some of  the resulting 
subtleties in defining these quantities and implications 
on the nucleon's spin budget(s).