\documentclass[11pt,reqno]{amsart} \input{preamble} \title[Torsion over number fields of degree $10$] {Torsion of elliptic curves over number fields of degree $10$} \author{Filip Najman} \address{University of Zagreb Faculty of Science, Department of Mathematics, Bijeni\v cka cesta 30, 10000 Zagreb, Croatia} \email{fnajman@math.hr} \thanks{The author was supported by the Croatian Science Foundation under the project no.\ IP-2022-10-5008, by the project ``Implementation of cutting-edge research and its application as part of the Scientific Center of Excellence for Quantum and Complex Systems, and Representations of Lie Algebras'', PK.1.1.10.0004, co-financed by the European Union through the European Regional Development Fund -- Competitiveness and Cohesion Programme 2021--2027, and by the European Union -- NextGenerationEU through the National Recovery and Resilience Plan 2021--2026, via an institutional grant of the University of Zagreb Faculty of Science, IK IA 1.1.3, Impact4Math.} \subjclass[2020]{11G05, 11G18, 14G05} \keywords{elliptic curves, torsion, number fields, modular curves, sporadic points} \setlength{\emergencystretch}{3em} \begin{document} \begin{abstract} We determine all the groups that appear as the torsion group of an elliptic curve over a number field of degree $10$. There are $69$ such groups. For $4$ of them, namely $\tg{2}{26}$, $\tg{3}{15}$, $\tg{3}{18}$ and $\tg{6}{12}$, we also determine all the elliptic curves over number fields of degree $10$ that realize them, and there are only finitely many. These four groups were not known to occur over number fields of degree $10$. The proofs combine the global method of Derickx, Hecke sieves, formal immersion criteria at the prime $2$, and Riemann-Roch computations on modular curves and their quotients over finite fields. \end{abstract} \date{\today} \maketitle \input{sections/01_intro} \input{sections/02_notation} \input{sections/03_occurrences} \input{sections/04_groups} \input{sections/05_global} \input{sections/06_mxn} \input{sections/07_2x2n} \input{sections/08_sieve} \input{sections/08b_sieve} \input{sections/09_formal} \input{sections/10_further} \input{sections/10b_further} \input{sections/11_sporadic} \input{sections/12_proof} \input{sections/13_computations} \bibliographystyle{amsalpha} \bibliography{refs} \end{document}