Degrees of irreducible morphisms in standard components

We study the left degree of an irreducible morphism with X and Yi indecomposable modules in a standard component of the Auslander-Reiten quiver, for 1≤i≤r. Two criteria to determine whether the left degree of these irreducible morphisms is finite or infinite are given, for standard algebras. We also study which of them has left degree two.