Explicit reciprocity laws for diagonal classes: higher level cases
Luca Marannino
TL;DR
The paper proposes a generalized framework for p-adic explicit reciprocity laws of diagonal classes in triple products of modular forms, allowing a $p$-ordinary form $f$ and either supercuspidal or ramified principal-series partners $g,h$ at $p$. It develops étale and syntomic formalisms, tying diagonal Galois cohomology classes to $p$-adic periods via a Bloch-Kato logarithm evaluated on a distinguished de Rham class, and provides a concrete formula relating this period to a traced product of $g$ and $h$ with a Serre derivative. The main results are fully established in weight $(2,2,2)$ and are conditional in general balanced weights due to current limitations in cohomology with semistable coefficients, with a clear path outlined through forthcoming syntomic-coefficient theories. The work connects to $p$-adic $L$-functions and diagonal-class constructions, suggesting applications to anticyclotomic Iwasawa theory and the study of diagonal interactions at inert primes, thereby enriching the arithmetic of triple product p-adic phenomena.
Abstract
We generalize the $p$-adic explicit reciprocity laws for balanced diagonal classes by Darmon-Rotger and Bertolini-Seveso-Venerucci to the case of geometric balanced triples $(f,g,h)$ of modular eigenforms where $f$ is a $p$-ordinary newform, while $g$ and $h$ are allowed to be (both) supercuspidal at $p$ or (both) ramified principal series at $p$.
