Abstract
The formulas for local root numbers of abelian varieties of dimension one are known. In this paper we treat the simplest unknown case in dimension two by considering a curve of genus 2 defined over a 5-adic field such that the inertia acts on the first \(\ell \)-adic cohomology group through the largest possible finite quotient, isomorphic to \(C_5\rtimes C_8\). We give a few criteria to identify such curves and prove a formula for their local root numbers in terms of invariants associated to a Weierstrass equation.
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Notes
The formula is stated for the \(\epsilon _0\)-factor of \(\chi \), which is equal to the \(\epsilon \)-factor when \(\chi \) is ramified.
References
Abbes, A., Saito, T.: Local Fourier transform and epsilon factors. Compos. Math. 146(6), 1507–1551 (2010). https://doi.org/10.1112/S0010437X09004631
Berndt, B.C., Evans, R.J., Williams, K.S.: Gauss and Jacobi Sums (Canadian Mathematical Society Series of Monographs and Advanced Texts), pp. xii+583. Wiley, New York (1998)
Bisatt, M.: Explicit root numbers of abelian varieties. Trans. Am. Math. Soc. 372(11), 7889–7920 (2019). https://doi.org/10.1090/tran/7926
Bisatt, M.: Root number of the jacobian of y\(^2 = x^p\) + a, (2021). ar**v: 2102.05720 [math.NT]
Brumer, A., Kramer, K., Sabitova, M.: Explicit determination of root numbers of abelian varieties. Trans. Am. Math. Soc. 370(4), 2589–2604 (2018). https://doi.org/10.1090/tran/7116
Bosch, S., Lütkebohmert, W., Raynaud, M.: Néron Models (Ergeb. Math. Grenzgeb. (3)), vol. 21, pp. x+325. Springer, Berlin (1990) https://doi.org/10.1007/978-3-642-51438-8
Chai, C.-L.: Néron models for semiabelian varieties: Congruence and change of base field. Asian J. Math. 4(4), 715–736 (2000). https://doi.org/10.4310/AJM.2000.v4.n4.a1
Coppola, N.: Wild galois representations: A family of hyperelliptic curves with large inertia image (2020). ar**v:2001.08287 [math.NT]
Dokchitser, T., Dokchitser, V.: Root numbers of elliptic curves in residue characteristic 2. Bull. Lond. Math. Soc. 40(3), 516–524 (2008). https://doi.org/10.1112/blms/bdn034
Deligne, P. Les constantes des équations fonctionnelles des fonctions L. In: Modular Functions of One Variable, II (Proc. Internat. Summer School, Univ. Antwerp, Antwerp,: ser. Lecture Notes in Math., vol. 349, pp. 501–597. Springer, Berlin (1972)
Dokchitser, T.: GroupNames. (Feb. 2020), [Online]. http://groupnames.org
Hasse, H.: Theorie der relativ-zyklischen algebraischen Funktionenkörper, insbesondere bei endlichem Konstantenkörper. J. Reine Angew. Math. 172, 37–54 (1935). https://doi.org/10.1515/crll.1935.172.37
Homma, M.: Automorphisms of prime order of curves. Manuscripta Math. 33(1), 99–109 (1980/81). https://doi.org/10.1007/BF01298341
Kobayashi, S.: The local root number of elliptic curves with wild ramification. Math. Ann. 323(3), 609–623 (2002). https://doi.org/10.1007/s002080200318
Kraus, A.: Sur le défaut de semi-stabilité des courbes elliptiques á réduction additive. Manuscripta Math. 69(4), 353–385 (1990). https://doi.org/10.1007/BF02567933
Liu, Q.: Courbes stables de genre 2 et leur schéma de modules. Math. Ann. 295(2), 201–222 (1993). https://doi.org/10.1007/BF01444884
Liu, Q.: Conducteur et discriminant minimal de courbes de genre 2. Compos. Math. 94(1), 51–79 (1994)
Liu, Q.: Modéles minimaux des courbes de genre deux. J. Reine Angew. Math. 453, 137–164 (1994). https://doi.org/10.1515/crll.1994.453.137
Liu, Q.: Modéles entiers des courbes hyperelliptiques sur un corps de valuation discréte. Trans. Am. Math. Soc. 348(11), 4577–4610 (1996). https://doi.org/10.1090/S0002-9947-96-01684-4
Liu, Q.: Algebraic Geometry and Arithmetic Curves (Oxford Graduate Texts in Mathematics), vol. 6, pp. xvi+576. Oxford University Press, Oxford (2002)
The LMFDB Collaboration: The L-functions and modular forms database. http://www.lmfdb.org (2021)
Liu, Q., Tong, J.: Néron models of algebraic curves. Trans. Am. Math. Soc. 368(10), 7019–7043 (2016). https://doi.org/10.1090/tran/6642
Mumford, D.: Tata Lectures on Theta. II (Progress in Mathematics), vol. 43, pp. xiv+272. Birkhäuser Boston, Inc., Boston (1984). https://doi.org/10.1007/978-0-8176-4578-6
Neukirch, J. Algebraic Number Theory (Grundlehren Math. Wiss.), vol. 322, pp. xviii+571. Springer, Berlin (1999). https://doi.org/10.1007/978-3-662-03983-0
Namikawa, Y., Ueno, K.: The complete classification of fibres in pencils of curves of genus two. Manuscripta Math. 9, 143–186 (1973). https://doi.org/10.1007/BF01297652
Rohrlich, D. E.: Elliptic Curves and the Weil–Deligne Group, in Elliptic Curves and Related Topics, ser. CRM Proc. Lecture Notes, vol. 4, pp. 125–157. Amer. Math. Soc., Providence (1994)
Rohrlich, D.E.: Galois theory, elliptic curves, and root numbers. Compositio Math. 100(3), 311–349 (1996)
Roquette, P.: Abschätzung der Automorphismenanzahl von Funktionenkörpern bei Primzahlcharakteristik. Math. Z. 117, 157–163 (1970). https://doi.org/10.1007/BF01109838
Sabitova, M.: Root numbers of abelian varieties. Trans. Am. Math. Soc. 359(9), 4259–4284 (2007). https://doi.org/10.1090/S0002-9947-07-04148-7
Serre, J.-P.: Rigidité du foncteur de jacobi d’échelon n \(\geqslant \) 3, Appendix to A. Grothendieck, Techniques de construction en géométrie analytique, X. Construction de l’espace de Teichmüller, Séminaire Henri Cartan, 1960/61, no. 17
Serre, J.-P.: Local Fields (Graduate Texts in Mathematics). Springer, New York (1977)
Serre, J.-P., Tate, J.: Good reduction of abelian varieties. Ann. Math. 2(88), 492–517 (1968)
Stichtenoth, H.: Algebraic Function Fields and Codes (Graduate Texts in Mathematics), Second, vol. 254, pp. xiv+355. Springer, Berlin (2009)
Silverberg, A., Zarhin, Y.G.: Inertia groups and abelian surfaces. J. Number Theory 110(1), 178–198 (2005). https://doi.org/10.1016/j.jnt.2004.05.015
Yelton, J.: Images of 2-adic representations associated to hyperelliptic Jacobians. J. Number Theory 151, 7–17 (2015). https://doi.org/10.1016/j.jnt.2014.10.020
Acknowledgements
I thank my doctoral thesis advisors Adriano Marmora and Rutger Noot as well as Kȩstutis Česnavičius and Takeshi Saito for their remarks and suggestions concerning the manuscript. I also thank Jeff Yelton for answering my questions about his results on the splitting fields of the 4-torsion of Jacobians. The study presented in this paper constitutes a part of my thesis.
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Melninkas, L. Root Numbers of 5-adic Curves of Genus Two Having Maximal Ramification. Milan J. Math. 91, 255–279 (2023). https://doi.org/10.1007/s00032-023-00380-7
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DOI: https://doi.org/10.1007/s00032-023-00380-7