$S_4$-quartics with Prescribed Norms

Given a number field $k$ and a finitely generated subgroup $\mathcal{A}\subseteq k^{\ast }$, we study the distribution of $S_4$-quartic extensions of $k$ such that the elements of $\mathcal{A}$ are norms. We show that the density of such extensions is the product of so-called “local masses” at every place of $k$. We give these local masses explicitly in almost all cases and give an algorithm for computing the remaining cases.