Abstract:

The J-invariant is a motivic invariant defined by the Chow ring of a linear algebraic group G.
In the case of a symplectic group G corresponding to a pair (A, \sigma), A a central simple algebra,
\sigma a symplectic involution on A, the J-invariant only contains information about the index of A.
Introducing conormed Chow rings allows us to construct a finer motivic invariant that contains also
information about the involution \sigma.