Euler factors at bad primes (reviewed)

For an abelian variety $A$ over $\Q$, the local factor that appears in the Euler product of its L-function at a bad prime $p$ depends on the type of reduction $A$ has at $p$. In general, the degree of the Euler factor at a bad prime will be less than the degree of the L-function (which is $2g$, where $g$ is the dimension of the abelian variety).