Mikroprimstellen für p-adische Zahlkörper
Micro primes were introduced by J. Neukirch in the context of abstract class field theory. A generalization of decomposition groups of primes of global fields led him to a purely group theoretical definition of micro primes as certain equivalence classes of Frobenius elements. Applied to the case of Galois groups of local or global fields this theory yields a description of special conjugacy classes. The main problem already posed by J. Neukirch is to understand the number theoretical meaning
... eoretical meaning of micro primes, that is to describe them in terms of the base field. J. Mehlig and E.-W. Zink established a bijection between micro primes and norm compatible sequences of prime elements in field towers. These towers arise as fixed point fields for the sequence of derived subgroups of the inertia group. So one has to study micro primes for the corresponding factor groups of the absolute Galois group and then to form a projective limit. In the first step, a bijection between relative micro primes and conjugacy classes of prime elements has been obtained. The main result of this project is a complete answer to the problem of J. Neukirch for the second step. One has to introduce norm maps between Lubin-Tate power series of different height and the projective limit has to be taken with respect to these norm maps. For this purpose results from class field theory are transferred to an ""almost abelian"" case. In the end micro primes can be described as Galois orbits of norm compatible sequences of normic Lubin-Tate power series. The coefficients of all the Lubin-Tate power series are in finite unramified extensions of the base field. Therefore one can define a field of coefficients for a given norm compatible sequence of normic Lubin-Tate power series. The degree of that field respectively the length of the Galois orbit is at the same time the degree of the corresponding micro prime.