Local Factors, Reciprocity and Vinberg Monoids

This article addresses the problem of existence of local factors, i.e., the root numbers and L-functions attached to representations of reductive groups over local fields and irreducible finite dimensional representations of their L-groups, as well as their equality with those of Artin factors through the local Langlands correspondence. We conclude the paper with a survey of the theory of monoids of Braverman-Kazhdan, Ngo and Vinberg in generalizing the method of Godement and Jacquet to arbitrary setting and their connections with Langlands-Shahidi method.