Gaussian periods and Shanks' cubic polynomials. II
We give a linear relation between a cubic Gaussian period and a root of Shanks' cubic polynomial in wildly ramified cases.
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arXiv subjects
Miho Aoki
Publications and source records attributed to Miho Aoki.
Galois module structure of algebraic integers of cyclic cubic fields
We determine the Galois module structure of the ring of integers for all cubic fields using roots of the generic cyclic cubic polynomial $f_n(X)=X^3-nX^2-(n+3)X-1$. Let $L_n=\mathbb Q(\rho_n)$ be a cyclic cubic field with Galois group $G:={\rm Gal}(L_n/\mathbb Q)$, where $\rho_n$ is a root of $f_n (X)$, and ${\mathcal O}_{L_n}$ the ring of integers of $L_n$. We explicitly give the generator of the free module ${\mathcal O}_{L_n}$ of rank $1$ over the associated order ${\mathcal A}_{L_n/\mathbb Q}:= \{ x\in \mathbb Q [G] \, |\, x\, {\mathcal O}_{L_n} \subset {\mathcal O}_{L_n} \}$ by using the roots of $f_n(X)$.
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Galois module structure of algebraic integers of the simplest cubic field
Let $L_n$ be a simplest cubic field with Galois group $G=\rm{Gal} (L_n/\mathbb Q)$. The associated order is denoted as ${\cal A}_{L_n/\mathbb Q}:= \{ x\in {\mathbb Q} [G] \, |\, x \cdot \cal{O}_{L_n} \subset {\cal O}_{L_n } \}$, where ${\cal O}_{L_n}$ is the ring of integers of $L_n$. Leopoldt showed that $\cal{O}_{L_n} \simeq {\cal A}_{L_n/\mathbb Q}$ as ${\cal A}_{L_n/\mathbb Q}$-modules. In this paper, we give a generator of the ${\cal A}_{L_n/\mathbb Q}$-module ${\cal O}_{L_n}$ explicitly using the roots of Shanks' cubic polynomial. If $L_n/\mathbb Q$ is tamely ramified, then we have ${\cal A}_{L_n/\mathbb Q}=\mathbb Z [G]$, and the conjugates form a normal integral basis, which has been obtained explicitly in the previous work of Hashimoto and the second author.
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Normal integral bases of Lehmer's cyclic quintic fields
Let $K_n$ be a tamely ramified cyclic quintic field generated by a root of Emma Lehmer's parametric polynomial. We give all normal integral bases for $K_n$ only by the roots of the polynomial, which is a generalization of the work of Lehmer in the case that $n^4+5n^3+15n^2+25n+25$ is prime number, and Spearman-Willliams in the case that $n^4+5n^3+15n^2+25n+25$ is square-free.
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Chebyshev's Bias against Splitting and Principal Primes in Global Fields
Reasons for the emergence of Chebyshev's bias were investigated. The Deep Riemann Hypothesis (DRH) enables us to reveal that the bias is a natural phenomenon for achieving a well-balanced disposition of the whole sequence of primes, in the sense that the Euler product converges at the center. By means of a weighted counting function of primes, the authors succeed in expressing magnitudes of the deflection by a certain asymptotic formula under the assumption of DRH, which provides a new formulation of Chebyshev's bias. For any Galois extension of global fields and for any element $\sigma$ in the Galois group, we have established a criterion of the bias of primes whose Frobenius elements are equal to $\sigma$ under the assumption of DRH. As an application we have obtained a bias toward non-splitting and non-principle primes in abelian extensions under DRH. In positive characteristic cases, DRH is known, and all these results hold unconditionally.
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Normal integral bases and Gaussian periods in the simplest cubic fields
We give all normal integral bases for the simplest cubic field $L_n$ generated by the roots of Shanks' cubic polynomial when these bases exist, that is, $L_n/\mathbb Q$ is tamely ramified. Furthermore, as an application of the result, we give an explicit relation between the roots of Shanks' cubic polynomial and the Gaussian periods of $L_n$ in the case $L_n/\mathbb Q$ is tamely ramified, which is a generalization of the work of Lehmer, Ch\^{a}telet and Lazarus in the case that the conductor of $L_n$ is equal to $n^2+3n+9$.
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On values of the higher derivatives of the Barnes zeta function at non-positive integers
Let $x$ be a complex number which has a positive real part, and $w_1,\ldots,w_N$ be positive rational numbers. We show that $w^s ζ_N (s, x \ |\ w_1,\ldots, w_N)$ can be expressed as a finite linear combination of the Hurwitz zeta functions over $\mathbb Q(x)$, where $ζ_N (s,x \ |\ w_1,\ldots, w_N)$ is the Barnes zeta function and $w$ is a positive rational number explicitly determined by $w_1,\ldots, w_N$. Furthermore, we give generalizations of Kummer's formula on the gamma function and Koyama-Kurokawa's formulae on the multiple gamma functions, and an explicit formula for the values at non-positive integers for higher order derivatives of the Barnes zeta function in the case that $x$ is a positive rational number, involving the generalized Stieltjes constants and the values at positive integers of the Riemann zeta function. Our formulae also makes it possible to calculate an approximation in the case that $w_1, \ldots, w_N$ and $x$ are positive real numbers.
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Several properties of hypergeometric Bernoulli numbers
In this paper, we give the determinant expressions of the hypergeometric Bernoulli numbers, and some relations between the hypergeometric and the classical Bernoulli numbers which include Kummer's congruences. By applying Trudi's formula, we have some different expressions and inversion relations. We also determine explicit forms of convergents of the generating function of the hypergeometric Bernoulli numbers, from which several identities for hypergeometric Bernoulli numbers are given.
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On the Laxton Group
We redefine a multiplicative group structure on the set of equivalence classes of rational sequences satisfying a fixed linear recurrence of degree two, which was defined by R. R. Laxton in his paper "On groups of linear recurrences I" published in Duke Math. 36, 721--736 (1969). In the article, he also defined some natural subgroups of the group, and determined the structures of their quotient groups. However, he did not study the whole group itself. Nothing has been known about the structure of Laxton's whole group and its interpretation. The aims of this paper are to redefine Laxton's group in a natural way and determine the structure of the whole group itself, which clarifies Laxton's results on the quotient groups. According to our formulation by algebraic number theory method, we can simplify the proof of Laxton's results. Our definition also gives a natural interpretation of Laxton's results, and makes us possible to use the group to show various properties of such sequences.
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A family of pairs of imaginary cyclic fields of degree $(p-1)/2$ with both class numbers divisible by $p$
We construct a new infinite family of pairs of imaginary cyclic fields of degree $(p-1)/2$ explicitly with both class numbers divisible by a given prime number $p$. For the proof, we use the fundamental unit of $\mathbb Q(\sqrt{p})$, certain units which are roots of a parametric quartic polynomial, the Kummer theory, the Gauss sums and the Jacobi sums, linear recurrence sequences, a consequence of the Weil conjecture and a result of Lenstra which is a generalization of Artin conjecture on primitive roots. Our result is based on the famous Scholz' results on pairs of quadratic fields $\mathbb Q(\sqrt{D})$ and $\mathbb Q (\sqrt{-3D})$.
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Remarks on hypergeometric Cauchy numbers
Hypergeometric numbers can be recognized as one of the most natural extensions of the classical Cauchy numbers in terms of determinants, though many kinds of generalizations of the Cauchy numbers have been considered by many authors. In addition, there are some relations between the hypergeometric Cauchy numbers and the classical Cauchy numbers. In this paper, we give the determinant expressions of hypergeometric Cauchy numbers and their generalizations, and show some interesting expressions of hypergeometric Cauchy numbers.
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