Joint Berkeley-Caltech-Stanford Number Theory Seminar

In this talk we will discuss two central problems in algebraic number theory and their interconnections: explicit class field theory (also known as Hilbert's 12th Problem), and the special values of L-functions.  The goal of explicit class field theory is to describe the abelian extensions of a ground number field via analytic means intrinsic to the ground field.  Meanwhile, there is an abundance of conjectures on the special values of L-functions at certain integer points.  Of these, Stark's Conjecture has special relevance toward explicit class field theory.  I will describe my recent proof, joint with Mahesh Kakde, of the Brumer-Stark conjecture away from p=2. This conjecture states the existence of certain canonical elements in CM abelian extensions of totally real fields.  Next I will state a conjectural exact formula for these Brumer-Stark units that has been developed over the last 15 years.  I will conclude with a description of work in progress that aims to prove this conjecture and thereby give a solution to Hilbert's 12th problem.