Gaussian periods and Shanks' cubic polynomials. II
Miho Aoki
TL;DR
The paperAddresses the problem of relating Gaussian periods of a cyclic cubic field to roots of Shanks' cubic polynomials in the wildly ramified setting, extending prior tamely ramified results. It develops a conductor-based parametrization via $n=n_1/n_2$ with $4\mathfrak f=M^2+27N^2$, proves irreducibility and conductor properties for the associated cubic fields $L_n$, and establishes a precise linear relation $n_2^3 \mu(\mathfrak f/9) f_n(X)=P(\mu(\mathfrak f/9)(n_2X-n_1/3))$ that ties Gaussian periods to roots of $f_n$. A key outcome is that all cyclic cubic fields with conductor $\mathfrak f$ arise from suitable $(M,N)$ and that the Gaussian periods $\{\eta_0,\eta_1,\eta_2\}$ correspond (up to the factor $\mu(\mathfrak f/9)$) to the roots of the Shanks polynomial under an explicit affine transformation. The work also analyzes the unit-group structure of the associated order and provides explicit examples, offering a unified framework for understanding period relations across tame and wild ramification with potential computational implications.
Abstract
We give a linear relation between a cubic Gaussian period and a root of Shanks' cubic polynomial in wildly ramified cases.
