Inertial Types of Elliptic Curves Over $\mathbb{Q}_{p^{2}}$
Jose Castro-Moreno, Nuno Freitas
TL;DR
This work delivers a complete, explicit classification of inertial Weil–Deligne types arising from elliptic curves over the unramified quadratic extension $\mathbb Q_{p^2}$ for all primes $p$. It separates the analysis into the tame case $p\ge5$, the $p=3$ case, and the $p=2$ case (including exceptional and triply imprimitive representations), with detailed treatment of quadratic twists and their effect on inertial data. The authors provide exhaustive realizations by constructing elliptic curves over $\mathbb Q_{p^2}$ corresponding to every inertial type, together with explicit base-change towers, character data, and Magma resources. The results have applications to modularity questions, representation theory of $G_{F}$, and Diophantine problems, and extend prior work on inertial types over $\mathbb Q_p$ to the quadratic extension setting. The paper also supplies extensive computational infrastructure (MAGMAFiles) to realize and identify inertial types from given elliptic curves and to study inertia fields explicitly.
Abstract
We provide a complete, explicit description of the inertial Weil-Deligne types arising from elliptic curves over $\mathbb{Q}_{p^{2}}$ for p prime
