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Stability of vector bundles and reduction mod p
Abstract
Let E be a vector bundle on a normal complex projective variety. We prove that slope stability of mathopSym2E and Zariski density of the reductions of E modulo p that are not strongly geometrically stable imply that the bundle E is projectively unitary flat. This generalizes Shepherd--Barron's result from rank $2$ to arbitrary rank. We also show that if E has rank ≤ 3 we can replace stability of mathopSym2E by stability of E but we cannot do so if E has rank $4$. We also generalize these results to reflexive sheaves on some mildly singular normal complex projective varieties.
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BibTeX
@misc{langer2026stability,
title = {{Stability of vector bundles and reduction mod $p$}},
author = {Adrian Langer},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.14276},
eprint = {2610.14276},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.14276},
}
RIS
TY - UNPB
TI - Stability of vector bundles and reduction mod p
AU - Adrian Langer
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2610.14276
UR - https://arxiv.org/abs/2610.14276
AB - Let E be a vector bundle on a normal complex projective variety. We prove that slope stability of mathopSym^2E and Zariski density of the reductions of E modulo p that are not strongly geometrically stable imply that the bundle E is projectively unitary flat. This generalizes Shepherd--Barron's result from rank $2$ to arbitrary rank. We also show that if E has rank ≤ 3 we can replace stability of mathopSym^2E by stability of E but we cannot do so if E has rank $4$. We also generalize these results to reflexive sheaves on some mildly singular normal complex projective varieties.
ER -