Rank of elliptic curves and class groups of real quadratic fields
Kalyan Banerjee
TL;DR
The paper addresses the problem of connecting the positive Mordell-Weil rank of an elliptic curve $E$ given by $y^2=x^3+ax+b$ to nontrivial elements in the class groups of real quadratic fields $K=\mathbb{Q}(\sqrt{p^3+ap+b})$ via specialization from a rank generator. It develops the spreading technique of a rank point to a Weil divisor on the integral model $E_{\mathbb{Z}}$ and leverages Chow/Hilbert schemes to produce nonprincipal class elements in $\mathrm{Cl}(K)$ for infinitely many primes $p$, with Siegel's theorem ensuring infinitude. The work highlights a novel use of Weil divisors rather than Cartier divisors, enabling a functorial, motivic link from the elliptic curve to class groups and extending to singular varieties. Overall, it provides a constructive bridge between elliptic-curve arithmetic and class groups of real quadratic fields, offering a framework to realize large class groups from elliptic data and potential generalizations to higher dimensions.
Abstract
In this paper, we are going to prove the relation between rank of elliptic curves and the non-triviality of class groups of infinitely many real quadratic fields.
