p-adic Rigidity and Supercongruences at Rank Two Attractors
Abstract
We study a p-adic rigidity phenomenon suggested by rank two attractors. Near an ordinary special fiber of a Calabi--Yau family, the excellent Frobenius of Beukers and Vlasenko acts on the parameter disk. Achinger--Zdanowicz construct a canonical W2-lift of the Frobenius twist, while Brantner--Taelman construct a canonical formal lift. We conjecture that the Dwork and Achinger--Zdanowicz first-order obstruction maps agree and that the fixed points of the excellent Frobenius are precisely the parameters of the Brantner--Taelman canonical formal lifts. Our main theorem gives a cohomological criterion in arbitrary dimension. Under its hypotheses, a Frobenius-stable rank two factor of the p-adic cohomology containing the holomorphic class forces that class to span a Cartier-stable line and gives supercongruences modulo p2s for every sā„1. Moreover, if the hypotheses of the Beukers--Vlasenko excellent lift theorem hold, then the excellent Frobenius fixes the corresponding parameter. We apply the criterion to the Hulek--Verrill A4 family at t*=ā1/7, a parameter predicted to be a rank two attractor. Assuming Dummigan's Conjecture~1.1, we prove that the excellent Frobenius fixes t*, the supercongruences hold, and the fiber with parameter t*bmod p2 is the Achinger--Zdanowicz canonical lift at every prime where the required Dwork ordinarity conditions are satisfied. A CM fiber of the mirror quartic K3 pencil gives a second application. We also prove that the q-power map on a split formal torus has the unit section as its unique periodic point in the identity residue disk over every finite extension of W(š½q)[1/p], where q is the cardinality of the residue field.
Related
- Second derivatives of p-adic L-functions and the Shafarevich--Tate group of rank-two CM elliptic curves
- On cube and Cremona rigidity for higher-rank lattices
- Finite-rank rigidity and Nash-curve discreteness for correlation potentials
- Weak rank rigidity for groups with a navigable path system
- q-Analogues of some supercongruences related to Van Hamme's (E.2) and (F.2) supercongruences
BibTeX
@misc{fu2026padic,
title = {{p-adic Rigidity and Supercongruences at Rank Two Attractors}},
author = {Yu Fu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.36045},
eprint = {2609.36045},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.36045},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - p-adic Rigidity and Supercongruences at Rank Two Attractors
AU - Yu Fu
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2609.36045
UR - https://arxiv.org/abs/2609.36045
AB - We study a p-adic rigidity phenomenon suggested by rank two attractors. Near an ordinary special fiber of a Calabi--Yau family, the excellent Frobenius of Beukers and Vlasenko acts on the parameter disk. Achinger--Zdanowicz construct a canonical W_2-lift of the Frobenius twist, while Brantner--Taelman construct a canonical formal lift. We conjecture that the Dwork and Achinger--Zdanowicz first-order obstruction maps agree and that the fixed points of the excellent Frobenius are precisely the parameters of the Brantner--Taelman canonical formal lifts. Our main theorem gives a cohomological criterion in arbitrary dimension. Under its hypotheses, a Frobenius-stable rank two factor of the p-adic cohomology containing the holomorphic class forces that class to span a Cartier-stable line and gives supercongruences modulo p^2s for every sā„1. Moreover, if the hypotheses of the Beukers--Vlasenko excellent lift theorem hold, then the excellent Frobenius fixes the corresponding parameter. We apply the criterion to the Hulek--Verrill A_4 family at t_*=ā1/7, a parameter predicted to be a rank two attractor. Assuming Dummigan's Conjecture~1.1, we prove that the excellent Frobenius fixes t_*, the supercongruences hold, and the fiber with parameter t_*bmod p^2 is the Achinger--Zdanowicz canonical lift at every prime where the required Dwork ordinarity conditions are satisfied. A CM fiber of the mirror quartic K3 pencil gives a second application. We also prove that the q-power map on a split formal torus has the unit section as its unique periodic point in the identity residue disk over every finite extension of W(š½_q)[1/p], where q is the cardinality of the residue field.
ER -