Factorization of measures and applications to the weak Goldfeld conjecture

Abstract

Extending Gross's result, we prove that a certain factorizaton of measures holds for all $p$ and any finite even Dirichlet character $\chi$ of any conductor, rather than only for split $p$ and $\chi$ with conductor a power of $p$. Using this generalization, we find lower bounds on the proportion of imaginary quadratic fields $K$ for which (under certain assumptions on the elliptic curve) a chosen quadratic twist of an elliptic curve $E$ over $K$ has rank $1$. We also find lower and upper bounds for the proportion of quadratic twists with rank $1$ when we vary $D$, the factor we twist by, under the assumption that $\omega$ (the prime factor counting function) is sufficiently close to a Gaussian distribution, as described by Erd\"os-Kac. We apply similar methods to cubic twists, and then derive analogous lower bounds for the proportion of imaginary quadratic fields for which a sextic twist has rank $1$. Lastly, for elliptic curves over $\mathbb{Q}$ satisfying certain assumptions, we find positive lower bounds on the proportion of quadratic twists (over $\mathbb{Q}$) which have rank $0$ and rank $1$, which yields examples of elliptic curves satisfying the weak Goldfeld conjecture.