Theta series and number fields: theorems and experiments

We construct certain $\theta$-series associated to number fields and prove that for number fields of degree less than equal to 4, these $\theta$-series are number field invariants. We also investigate whether or not the collection of $\theta$-series associated to number fields of the same degree and discriminant are linearly independent. This is known to be true if the degree of the number field is less than or equal to 3. We do not prove in this paper that they are linearly independent in general but we do give computational and heuristic evidence that we would expect them to be.