On the Chow Ring of the Stack of truncated Barsotti-Tate Groups
  We determine the Chow ring of the stack of truncated displays and more generally the Chow ring of the stack of G-zips. We also investigate the pull-back morphism of the truncated display functor. From this we can determine the Chow ring of the stack of truncated Barsotti-Tate groups over a field of characteristic p up to p-torsion. 
Dennis Brokemper
math.AG