{ "id": "1409.7829", "version": "v1", "published": "2014-09-27T18:53:07.000Z", "updated": "2014-09-27T18:53:07.000Z", "title": "Discriminants of simplest 3^n-tic extensions", "authors": [ "T. Alden Gassert" ], "categories": [ "math.NT" ], "abstract": "Let $\\ell>2$ be a positive integer, $\\zeta_\\ell$ a primitive $\\ell$-th root of unity, and $K$ a number field containing $\\zeta_\\ell+\\zeta_\\ell^{-1}$ but not $\\zeta_\\ell$. In a recent paper, Chonoles et. al. study iterated towers of number fields over $K$ generated by the generalized Rikuna polynomial, $r_n(x,t;\\ell) \\in K(t)[x]$. They note that when $K = \\mathbb{Q}$, $t \\in \\{0,1\\}$, and $\\ell=3$, the only ramified prime in the resulting tower is 3, and they ask under what conditions is the number of ramified primes small. In this paper, we apply a theorem of Gu\\`ardia, Montes, and Nart to derive a formula for the discriminant of $\\mathbb{Q}(\\theta)$ where $\\theta$ is a root of $r_n(x,t;3)$, answering the question of Chonoles et. al. in the case $K = \\mathbb{Q}$, $\\ell=3$, and $t \\in \\mathbb{Z}$. In the latter half of the paper, we identify some cases where the dynamics of $r_n(x,t;\\ell)$ over finite fields yields an explicit description of the decomposition of primes in these iterated extensions.", "revisions": [ { "version": "v1", "updated": "2014-09-27T18:53:07.000Z" } ], "analyses": { "keywords": [ "discriminant", "number field", "finite fields yields", "generalized rikuna polynomial", "study iterated towers" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2014arXiv1409.7829G" } } }