# Drell-Yan process and factorization scale

What is the most relevant choice for the factorization scale of the Drell-Yan process? Can it be the invariant mass at the reaction threshold?

This is all under the premise of resummation and is the thing to do because an all order expansion (which is by no means achievable currently) will be void of all such artifacts ($\mu_R^2$, $\mu_F^2$ etc) arising in the choice of mathematical regularisation/factorisation framework.
There is a work here https://arxiv.org/abs/hep-ph/0703156v1 in which the authors find $\mu_F \sim Q/2$, where $Q$ is a final state invariant mass, to be an optimal choice of factorisation scale in the Drell-Yan process you mention.