A generalized Rubin formula for Hecke characters
Matteo Longo, Stefano Vigni, Shilun Wang
TL;DR
The paper extends Rubin's Katz $p$-adic $L$-function results from CM elliptic curves to self-dual algebraic Hecke characters of imaginary quadratic fields, by adapting the Bertolini–Darmon–Prasanna framework of generalized Heegner cycles and a $p$-adic Gross–Zagier formula to infinity types $(1+ obreak ext{ell},- ext{ell})$ with $ ext{ell} obreak \ge0$. It builds a motivic framework using generalized Kuga–Sato motives, along with Deligne–Scholl and theta-factorized pieces, to realize the Hecke characters in both de Rham and étale cohomologies and to construct canonical cycle classes whose $p$-adic logarithms control Katz and BDP $p$-adic $L$-values. A central result is a generalized Rubin formula: under $ mathscr{L}_{p,rak c}( chi^ ext{*}) eq 0$, the $p$-adic $L$-value $ mathscr{L}_{p,rak c}( chi^ ext{*})$ is congruent to ${oldsymbol{ extOmega}_p( chi^*)}^{-1}igl( ext{log}_{ chi}(oldsymbol{z}_ chi)igr)^2$ modulo the appropriate coefficient field, where $oldsymbol{z}_ chi$ is a Bloch–Kato Selmer-class associated to $ chi$. The work ties this congruence to a $p$-adic Gross–Zagier framework, validates the conjectural links with the Bloch–Kato conjecture, and paves the way for understanding derivatives $L'( chi,1)$ in a $p$-adic context through generalized factorization and reciprocity laws. Overall, it broadens Rubin-type phenomena to a larger class of self-dual Hecke characters via a robust motivic and $p$-adic analytic apparatus with potential arithmetic applications.
Abstract
The goal of this paper is to generalize Rubin's theorem on values of Katz's $p$-adic $L$-function outside the range of interpolation from the case of Hecke characters of CM elliptic curves to more general self-dual algebraic Hecke characters. We follow the approach by Bertolini-Darmon-Prasanna, based on generalized Heegner cycles, which we extend from characters of imaginary quadratic fields of infinity type $(1,0)$ to characters of infinity type $(1+\ell,-\ell)$ for an integer $\ell\geq0$.
