Local Constants for Galois Representations - Some Explicit Results

Abstract

We can associate local constant to every continuous finite dimensional complex representation of the absolute Galois group $G_F$ of a non-archimedean local field $F/\mathbb{Q}_p$ by Deligne and Langlands. To give explicit formula of local constant of a representation, we need to compute $\lambda$-functions explicitly. In this thesis we compute $\lambda_{K/F}$ explicitly, where $K/F$ is a finite degree Galois extension of a non-archimedean local field $F$, except when $K/F$ is a wildly ramified quadratic extension with $F\ne\mathbb{Q}_2$. Then by using this $\lambda$-function computation, in general, we give an invariant formula of local constant of finite dimensional Heisenberg representations of the absolute Galois group $G_F$ of a non-archimedean local field $F$. But for explicit invariant formula of local constant for a Heisenberg representation, we should have information about the dimension of a Heisenberg representation and the arithmetic description of the determinant of a Heisenberg representation. In this thesis, we give explicit arithmetic description of the determinant of Heisenberg representation. We also construct all Heisenberg representations of dimensions prime to $p$, and study their various properties. By using $\lambda$-function computation and arithmetic description of the determinant of Heisenberg representations, we give an invariant formula of local constant for a Heisenberg representation of dimension prime to $p$.