The quadratic character of 1+\sqrt{2} and an elliptic curve

$L$-series values for sextic twists of elliptic curves over $\mathbb{Q}[\sqrt{-3}]$

We prove a new formula for the central value of the $L$-function $L(E_{D, α}, 1)$ corresponding to the family of sextic twists over $\mathbb{Q}[\sqrt{-3}]$ of elliptic curves $E_{D, α}: y^2=x^3+16D^2α^3$ for $D$ an integer and $α\in \mathbb{Q}[\sqrt{-3}]$. The formula generalizes the result of cubic twists over $\mathbb{Q}$ of Rodriguez-Villegas and Zagier for a prime $D \equiv 1 (9)$ and of Rosu for general $D$. For $α$ prime and all integers $D$, we also show that the expected value from the Birch and Swinnerton-Dyer conjecture of the order of the Tate-Shafarevich group is an integer square …

Complete classification of torsion of elliptic curves over quadratic cyclotomic fields

In a previous paper, the author examined the possible torsions of an elliptic curve over the quadratic fields $\mathbb Q(i)$ and $\mathbb Q(\sqrt{-3})$. Although all the possible torsions were found if the elliptic curve has rational coefficients, we were unable to eliminate some possibilities for the torsion if the elliptic curve has coefficients that are not rational. In this note, by finding all the points of two hyperelliptic curves over $\mathbb Q(i)$ and $\mathbb Q(\sqrt{-3})$, we solve this problem completely and thus obtain a classification of all possible torsions of elliptic curves o…

On the $p$-part of the Birch-Swinnerton-Dyer conjecture for elliptic curves with complex multiplication by the ring of integers of $\mathbb{Q}(\sqrt{-3})$

We study infinite families of quadratic and cubic twists of the elliptic curve $E = X_0(27)$. For the family of quadratic twists, we establish a lower bound for the $2$-adic valuation of the algebraic part of the value of the complex $L$-series at $s=1$, and, for the family of cubic twists, we establish a lower bound for the $3$-adic valuation of the algebraic part of the same $L$-value. We show that our lower bounds are precisely those predicted by the celebrated conjecture of Birch and Swinnerton-Dyer.

Class fields generated by coordinates of elliptic curves

Let $K$ be an imaginary quadratic field different from $\mathbb{Q}(\sqrt{-1})$ and $\mathbb{Q}(\sqrt{-3})$. For a nontrivial integral ideal $\mathfrak{m}$ of $K$, let $K_\mathfrak{m}$ be the ray class field modulo $\mathfrak{m}$. By using some inequalities on special values of modular functions, we show that a single $x$-coordinate of a certain elliptic curve generates $K_\mathfrak{m}$ over $K$.

Growth of torsion of elliptic curves with full 2-torsion over quadratic cyclotomic fields

Let $K = \mathbb{Q}(\sqrt{-3})$ or $\mathbb{Q}(\sqrt{-1})$ and let $C_n$ denote the cyclic group of order $n$. We study how the torsion part of an elliptic curve over $K$ grows in a quadratic extension of $K$. In the case $E(K)[2] \approx C_2 \oplus C_2$ we determine how a given torsion structure can grow in a quadratic extension and the maximum number of quadratic extensions in which it grows. We also classify the torsion structures which occur as the quadratic twist of a given torsion structure.

Torsion of elliptic curves over quadratic cyclotomic fields

In this paper we study the possible torsions of elliptic curves over $\mathbb Q(i)$ and $\mathbb Q(\sqrt {-3})$.

椭圆曲线在固定二次域上的循环同源

Cyclic isogenies of elliptic curves over fixed quadratic fields

本文基于Mazur的工作，开发程序确定二次域上椭圆曲线的循环同源，并在一般化黎曼假设下确定19个二次域的同源结构。

Studying Hilbert's 10th problem via explicit elliptic curves

N.García-Fritz and H.Pasten showed that Hilbert's 10th problem is unsolvable in the ring of integers of number fields of the form $\mathbb{Q}(\sqrt[3]{p},\sqrt{-q})$ for positive proportions of primes $p$ and $q$. We improve their proportions and extend their results to the case of number fields of the form $\mathbb{Q}(\sqrt[3]{p},\sqrt{Dq})$, where $D$ belongs to an explicit family of positive square-free integers. We achieve this by using multiple elliptic curves, and replace their Iwasawa theory arguments by a more direct method.

Growth of torsion of elliptic curves with odd-order torsion over quadratic cyclotomic fields

Let $K = \mathbb{Q}(\sqrt{-3})$ or $\mathbb{Q}(\sqrt{-1})$ and let $C_n$ denote the cyclic group of order $n$. We study how the torsion part of an elliptic curve over $K$ grows in a quadratic extension of $K$. In the case $E(K)[2] \approx C_1$ we investigate how a given torsion structure can grow in a quadratic extension and the maximum number of extensions in which it grows. We also study the torsion structures which occur as the quadratic twist of a given torsion structure. In order to achieve this we examine $N$-isogenies defined over $K$ for $N=15,20,21,24,27,30,35$.

Quadratic Twists of Elliptic Curves

In this paper, we show that Tian's induction method can be generalised to study the Birch-Swinnerton-Dyer conjecture for the quadratic twists, both with global root number $+1$ and with global root number $-1$, of certain elliptic curves $E$ defined over $\mathbb Q$. In particular, for the curve $E = X_0(49)$ we prove the following results. Let $q_1, \ldots, q_r$ be distinct primes which are congruent to $1$ modulo $4$ and inert in the field $F = \mathbb Q(\sqrt{-7})$, and let $E^{(R)}$ be the twist of $E$ by the quadratic extension $\mathbb Q(\sqrt{R})/\mathbb Q$, where $R=q_1\ldots q_r$. The…

Elliptic Curves with Everywhere Good Reduction

We consider the question of which quadratic fields have elliptic curves with everywhere good reduction. By revisiting work of Setzer, we expand on congruence conditions that determine the real and imaginary quadratic fields with elliptic curves of everywhere good reduction and rational $j$-invariant. Using this, we determine the density of such real and imaginary quadratic fields. If $R(X)$ (respectively $I(X)$) denotes the number of real (respectively imaginary) quadratic fields $K=\mathbb{Q}[\sqrt{m}]$ such that $|Δ_K| < X$ and for which there exists an elliptic curve $E/K$ with rational $j$…

On the elliptic curve $ y^{2} = x (x^2 + p)$ over some certain imaginary quadratic fields

In this paper, we will talk about the titled elliptic curve defined over imaginary quadratic fields such as $\mathbb{Q}(\sqrt{-q})$, where $q$ is congruent to 3 modulo 8 and $(p,q)=1$.

L-series and their 2-adic and 3-adic valuations at s=1 attached to CM elliptic curves

$L-$series attached to two classical families of elliptic curves with complex multiplications are studied over number fields, formulae for their special values at $s=1, $ bound of the values, and criterion of reaching the bound are given. Let $ E_1: y^{2}=x^{3}-D_1 x $ be elliptic curves over the Gaussian field $K=\Q(\sqrt{-1}), $ with $ D_1 =π_{1} ... π_{n} $ or $ D_1 =π_{1} ^{2}... π_{r} ^{2} π_{r+1} ... π_{n}$, where $π_{1}, ..., π_{n}$ are distinct primes in $K$. A formula for special values of Hecke $L-$series attached to such curves expressed by Weierstrass $\wp-$function are given; a lo…

Three cubes in arithmetic progression over quadratic fields

We study the problem of the existence of arithmetic progressions of three cubes over quadratic number fields Q(sqrt(D)), where D is a squarefree integer. For this purpose, we give a characterization in terms of Q(sqrt(D))-rational points on the elliptic curve E:y^2=x^3-27. We compute the torsion subgroup of the Mordell-Weil group of this elliptic curve over Q(sqrt(D)) and we give partial answers to the finiteness of the free part of E(Q(sqrt(D))). This last task will be translated to compute if the rank of the quadratic D-twist of the modular curve X_0(36) is zero or not.

Generating functions for power moments of elliptic curves over $\mathbb{F}_p$

Seminal works by Birch and Ihara gave formulas for the $m$th power moments of the traces of Frobenius endomorphisms of elliptic curves over $\mathbb{F}_{p}$ for primes $p \geq 5$. Recent works by Kaplan and Petrow generalized these results to the setting of elliptic curves that contain a subgroup isomorphic to a fixed finite abelian group $A$. We revisit these formulas and determine a simple expression for the zeta function $Z_p(A; t)$, the generating function for these $m$th power moments. In particular, we find that \[ Z_p(A;t) = \frac{\widehat{Z}_p(A; t)}{\displaystyle \prod_{a \in \textrm{…

Why is the Class Number of $\Q(\sqrt[3]{11})$ even?

In this article we will describe a surprising observation that occurred in the construction of quadratic unramified extensions of a family of pure cubic number fields. Attempting to find an explanation will lead us on a magical mystery tour through the land of pure cubic number fields, Hilbert class fields, and elliptic curves.

椭圆曲线在二次域扩张下的塔特-沙法列维奇群行为

Behaviors of the Tate--Shafarevich group of elliptic curves under quadratic field extensions

研究椭圆曲线在二次扩张下的塔特-沙法列维奇群行为，证明在特定条件下该群的阶数可无限增长，且对特定形式的椭圆曲线，证明其2-部分阶数的上限及某些情况下的非零性。

Elliptic curves with good reduction away from 2: III

We list the elliptic curves defined over $Q(\sqrt 5)$ with good reduction away from 2. There are 368 isomorphism classes. We give a global minimal model for each class.

Torsion groups of elliptic curves over quadratic cyclotomic fields in elementary abelian 2-extensions

Let K denote the quadratic field $\mathbb{Q}(\sqrt{d})$ where d=$-1$ or $-3$. Let E be an elliptic curve defined over K. In this paper, we analyze the torsion subgroups of E in the maximal elementary abelian $2$-extension of $K$.

模曲线与不良约减

Modular curves and bad reduction

研究证明在不同假设下，所有模曲线上的点对应的椭圆曲线在特定素数处有不良约减，例如定义在有理数域上的椭圆曲线在特定素数处有不良约减。

Class Numbers via 3-Isogenies and Elliptic Surfaces

We show that a character sum attached to a family of 3-isogenies defined on the fibers of a certain elliptic surface over $\mathbb{F}_p$ relates to the class number of the quadratic imaginary number field $\Q(\sqrt{-p})$. In this sense, this provides a higher-dimensional analog of some recent class number formulas associated to 2-isogenies of elliptic curves.

Impossible intersections in a Weierstrass family of elliptic curves

Consider the Weierstrass family of elliptic curves $E_λ:y^2=x^3+λ$ parametrized by nonzero $λ\in\overline{\mathbb{Q}_2}$, and let $P_λ(x)=(x,\sqrt{x^3+λ})\in E_λ$. In this article, given $α,β\in\overline{\mathbb{Q}_2}$ such that $\fracαβ\in\mathbb{Q}$, we provide an explicit description for the set of parameters $λ$ such that $P_λ(α)$ and $P_λ(β)$ are simultaneously torsion for $E_λ$. In particular we prove that the aforementioned set is empty unless $\fracαβ\in\{-2,-\frac{1}{2}\}$. Furthermore, we show that this set is empty even when $\fracαβ\notin\mathbb{Q}$ provided that $α$ and $β$ have d…