Index, Prime Ideal Factorization in simplest Quartic Fields and counting their discriminants

Abstract

We consider the simplest quartic number fields ${\mathbb{K}}_m$ defined by the irreducible quartic polynomials $$x^4-m{x}^3-6x^2+mx+1,$$ where $m$ runs over the positive rational integers such that the odd part of $m^2+16$ is squarefree. In this paper, we study the common index divisor $I({\mathbb{K}}_m)$ and determine explicitly the prime ideal decomposition for any prime number in any simplest quartic number fields ${\mathbb{K}}_m$. On the other hand, we establish an asymptotic formula for the number of simplest quartic fields with discriminant $\le x$ and given index.