arXiv subjects
Publications and source records attributed to Shuai Zhai.
Given an elliptic curve with Weierstrass equation $y^2=f(x)$, and a positive definite binary quadratic form $Q(u, v)$. We show that there are infinitely many $d$ in the set represented by the quadratic forms in the genus of $Q$ such that the twisted elliptic curve $dy^2=f(x)$ has analytic rank one.
In this paper, we investigate the coefficients of the Taylor expansion of the complex $L$-series of any elliptic curve over $\mathbb{Q}$. We prove that, in the family of quadratic twists by all the discriminants $d$, these coefficients are nonvanishing under GRH when $d$ is sufficiently large. Unconditionally, we obtain a general lower bound for the number of nonvanishing coefficients in the family of quadratic twists, through a series of results from the moments of the central values of the derivatives of quadratic twists of modular $L$-function.
In the present paper, we obtain a general lower bound for the $2$-adic valuation of the algebraic part of the central value of the complex $L$-series for the quadratic twists of any elliptic curve over $\mathbb{Q}$, showing that when the $2$-part of the product of Tamagawa factors grows, the $2$-part of the algebraic central $L$-value grows as well, in accordance with the Birch--Swinnerton-Dyer exact formula. This generalises a result of Coates--Kim--Liang--Zhao to all elliptic curves defined over $\mathbb{Q}$. We also prove the existence of an explicit infinite family of quadratic twists with analytic rank $0$ for a large family of elliptic curves.
Let $f$ be a positive definite integral quadratic form in $d$ variables. In the present paper, we establish a direct link between the genus representation number of $f$ and the order of higher even $K$-groups of the ring of integers of real quadratic fields, provided $f$ is diagonal and $d \equiv 1 \mod 4$, by applying the Siegel mass formula. When $d=3$, we derive an explicit formula of $r_f(n)$ in terms of the class number of the corresponding imaginary quadratic field and the central algebraic values of $L$-functions of quadratic twists of elliptic curves, by exploring a theorem of Waldspurger. Moreover, by the $2$-divisibility results on the algebraic $L$-values of quadratic twist of elliptic curves, we obtain a lower bound for the $2$-adic valuation of $r_f(n)$ for some odd integer $n$. The numerical results show our lower bound is optimal for certain cases. We also apply our main result to the quadratic form $f=x_1^2+\cdots+x^2_d$ to determine the order of the higher $K$-groups numerically.
In the present paper, we generalize the celebrated classical lemma of Birch and Heegner on quadratic twists of elliptic curves over $\mathbb{Q}$. We prove the existence of explicit infinite families of quadratic twists with analytic ranks $0$ and $1$ for a large class of elliptic curves, and use Heegner points to explicitly construct rational points of infinite order on the twists of rank $1$. In addition, we show that these families of quadratic twists satisfy the $2$-part of the Birch and Swinnerton-Dyer conjecture when the original curve does. We also prove a new result in the direction of the Goldfeld conjecture.
In the present paper, we prove, for a large class of elliptic curves defined over $\mathbb{Q}$, the existence of an explicit infinite family of quadratic twists with analytic rank $0$. In addition, we establish the $2$-part of the conjecture of Birch and Swinnerton-Dyer for many of these infinite families of quadratic twists. Recently, Xin Wan has used our results to prove for the first time the full Birch--Swinnerton-Dyer conjecture for some explicit infinite families of elliptic curves defined over $\mathbb{Q}$ without complex multiplication.
In this paper, we show that, by applying some results on modular symbols, for a family of certain elliptic curves defined over $\mathbb Q$, there is a large class of explicit quadratic twists whose complex $L$-series does not vanish at $s=1$, and for which the $2$-part of Birch-Swinnerton-Dyer conjecture holds.
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 $R=q_1\ldots q_r$. Then we show that the complex L-series of $E^{(R)}$ does not vanish at $s=1$, and the full Birch-Swinnerton-Dyer conjecture is true for $E^{(R)}$. Let $l_0$ be a prime number which is congruent to $3$ modulo $4$, and is such that $7$ splits in the field $K = \mathbb Q(\sqrt{-l_0})$. If we assume in addition that all of the primes $q_1, \ldots, q_r$ are inert in $K$ as well as in $F$, then we prove that the complex $L$-series of the twist of $E$ by $\mathbb Q(\sqrt{-l_0R})/\mathbb Q$ always has a simple zero at $s=1$. Similar results are obtained for certain other elliptic curves defined over $\mathbb Q$.