Power series expansions of modular forms and $p$-adic interpolation of the square roots of Rankin-Selberg special values

TL;DR

This paper develops a theory of p-adic measures linked to power series expansions of modular forms around CM points, enabling p-adic interpolation of square roots of Rankin-Selberg special values for forms with various nebentypus and level structures.

Contribution

It extends p-adic measure theory to modular forms with arbitrary nebentypus and level divisible by p, and computes Euler factors for p-adic interpolation of special L-values.

Findings

Extended p-adic measures to forms with any nebentypus.

Included cases where p divides the level of the form.

Computed Euler factors for p-adic interpolation of L-values.

Abstract

Let $f$ be a newform of even weight $2\kappa$ for $D^\times$, where $D$ is a possibly split indefinite quaternion algebra over $\mathbb{Q}$. Let $K$ be a quadratic imaginary field splitting $D$ and $p$ an odd prime split in $K$. We extend our theory of $p$-adic measures attached to the power series expansions of $f$ around the Galois orbit of the CM point corresponding to an embedding $K\hookrightarrow D$ to forms with any nebentypus and to $p$ dividing the level of $f$. For the latter we restrict our considerations to CM points corresponding to test objects endowed with an arithmetic $p$-level structure. Also, we restrict these $p$-adic measures to $\mathbb{Z}_p^\times$ and compute the corresponding Euler factor in the formula for the $p$-adic interpolation of the "square roots" of the Rankin-Selberg special values $L(\pi_K\otimes\xi_r,\frac12)$ where $\pi_K$ is the base change to $K$ of the automorphic representation of $\mathrm{GL}_2$ associated, up to Jacquet-Langland correspondence, to $f$ and $\xi_r$ is a compatible family of gr\"ossencharacters of $K$ with infinite type $\xi_{r,\infty}(z)=(z/\bar z)^{\kappa+r}$.