Abstract
We introduce and study (strict) Schottky G-bundles over a compact Riemann surface X, where G is a connected reductive algebraic group. Strict Schottky representations are shown to be related to branes in the moduli space of G-Higgs bundles over X, and we prove that all Schottky G-bundles have trivial topological type. Generalizing the Schottky moduli map introduced in Florentino (Manuscr Math 105:69–83, 2001) to the setting of principal bundles, we prove its local surjectivity at the good and unitary locus. Finally, we prove that the Schottky map is surjective onto the space of flat bundles for two special classes: when G is an abelian group over an arbitrary X, and the case of a general G-bundle over an elliptic curve.
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Notes
Interestingly, the consideration of the Schottky uniformization problem for vector bundles over Mumford curves, in the framework of p-adic analysis, has furnished stronger results. (see [11]).
We are using a left action both on Y and on G; this was chosen (other options would be equivalent) for a standard use of Fox calculus in Sect. 8.
For a general real Lie group, the analogous pairing defines a smooth (\(C^{\infty }\)) symplectic structure, see [20].
Note that the case \(X=\mathbb {P}^{1}\) (\(g=0\)) is irrelevant, as \(\pi _{1}\) is trivial and so are Schottky representations.
References
Anchouche, B., Biswas, I.: Einstein–Hermitian connections on polystable principal bundles over a compact Kahler manifold. Am. J. Math. 123(2), 207–228 (2001)
Atiyah, M.: Vector bundles over an elliptic curve. Proc. Lond. Math. Soc. 7, 414–452 (1957)
Auerbach, H.: Sur les groupes linéaires bornés (III). Stud. Math. 5(1), 43–45 (1934)
Azad, H., Biswas, I.: On holomorphic principal bundles over a compact Riemann surface admitting a flat connection, II. Bull. Lond. Math. Soc. 35, 440–444 (2003)
Baraglia, D., Schaposnik, L.: Higgs bundles and \((A, B, A)\)-branes. Commun. Math. Phys. 331(3), 1271–1300 (2014)
Baranovsky, V., Ginzburg, V.: Conjugacy classes in loop groups and \(G\)-bundles on elliptic curves. Int. Math. Res. Not. 15, 733–751 (1996)
Beauville, A.: Vector bundles on curves and generalized theta functions: recent results and open problems. In: Clemens, H., Kollár, J. (eds.) Current Topics in Complex Algebraic Geometry. Mathematical Sciences Research Institute Publications, vol. 28. Cambridge University Press, Cambridge (1995)
Bers, L.: Automorphic forms for Schottky groups. Adv. Math. 16, 332–361 (1975)
Biswas, I., Hoffmann, N.: A Torelli theorem for moduli spaces of principal bundles over a curve. Ann. Inst. Fourier 62(1), 87–106 (2012)
Brown, K.: Cohomology of Groups. Graduate Texts in Mathematics, vol. 87. Springer, New York (1994)
Faltings, G.: Semistable vector bundles on Mumford curves. Invent. Math. 74(2), 199–212 (1983)
Florentino, C.: Schottky uniformization and vector bundles over Riemann surface. Manuscr. Math. 105, 69–83 (2001)
Florentino, C., Casimiro, A.: Stability of affine G-varieties and irreducibility in reductive groups. Int. J. Math. 23(8), 30 (2012)
Florentino, C., Ludsteck, T.: Unipotent Schottky bundles on Riemann surfaces and complex tori. Int. J. Math. 25(6), 23 (2014)
Florentino, C., Mourão, J., Nunes, J.P.: Coherent state transforms and vector bundles on elliptic curves. J. Funct. Anal. 204(2), 355–398 (2003)
Florentino, C., Mourão, J., Nunes, J.P.: Coherent state transforms and theta functions. Tr. Mat. Inst. Steklova 246, 283–302 (2004)
Ford, L.: Automorphic Functions, 2nd edn. Chelsea Publishing Co., New York (1951)
Friedman, R., Morgan, J., Witten, E.: Principal \(G\)-bundles over elliptic curves. Math. Res. Lett. 5(1–2), 97–118 (1998)
García-Prada, Oscar, Oliveira, André: Connectedness of Higgs bundle moduli for complex reductive Lie groups. Asian J. Math. 21(5), 791–810 (2017)
Goldman, W.: The symplectic nature of fundamental groups of surfaces. Adv. Math. 54(2), 200–225 (1984)
Goldman, W.: Topological components of spaces of representations. Invent. Math. 93(3), 557–607 (1988)
Gunning, R.: Lectures on Vector Bundles Over Riemann Surfaces. University of Tokyo Press, Tokyo (1967)
Kapustin, A., Witten, E.: Electric-magnetic duality and the geometric Langlands program. Commun. Number Theory Phys. 1(1), 1–236 (2007)
Lawton, Sean, Ramras, Daniel: Covering spaces of character varieties. N. Y. J. Math. 21, 383–416 (2015). With an appendix by Nan-Kuo Ho and Chiu-Chu Melissa Liu
Li, J.: The space of surface group representations. Manuscr. Math. 78(3), 223–243 (1993)
Lubotzky, A., Magid, A.: Varieties of representations of finitely generated groups. Mem. Am. Math. Soc. 58(336), 2205–2213 (1985)
Martin, B.: Restrictions of representations of surface group to a pair of free subgroups. J. Algebra 225(1), 231–249 (2000)
Maskit, B.: A characterization of Schottky groups. J. Anal. Math. 19, 227–230 (1967)
Narasimhan, M., Seshadri, C.: Holomorphic vector bundles on a compact Riemann surface. Math. Ann. 155, 69–80 (1964)
Narasimhan, M., Seshadri, C.: Stable unitary vector bundles on compact Riemann surface. Ann. Math. (2) 82(3), 540–567 (1965)
Newstead, P.: Introduction to Moduli Problems and Orbitspaces. Tata Institute of Fundamental Research Lectures on Mathematics and Physics, vol. 51. Tata Institute of FundamentalResearch, Bombay; Narosa Publishing House, New Delhi, Bombay (1978)
Ramanathan, A.: Stable principal bundles on a compact Riemann surface. Math. Ann. 213, 129–152 (1975)
Ramanathan, A.: Moduli for principal bundles over algebraic curves: ii. Proc. Indian Acad. Sci. Math. Sci. 106(4), 421–449 (1996)
Sikora, A.: Character varieties. Trans. Am. Math. Soc. 364(10), 5173–5208 (2012)
Simpson, C.: Moduli of representations of the fundamental group of a smooth projective variety. I. Inst. Hautes Études Sci. Publ. Math 79, 47–129 (1994)
Tu, L.: Semistable bundles over an elliptic curve. Adv. Math. 98(1), 1–26 (1993)
Tyurin, A.: Quantization, Classical and Quantum Field Theory and Theta Functions. CRM Monograph Series, vol. 21. American Mathematical Society, Providence, RI (2003)
Weil, A.: Généralization des fonctions abéliennes. J. Math Pure Appl. 17, 47–87 (1938)
Acknowledgements
We thank I. Biswas, E. Franco, P. B. Gothen, C. Meneses-Torres and A. Oliveira for several useful discussions on Schottky bundles and related subjects, and the referees for clarifying comments. The last author thanks the organizers of the Simons Center for Geometry and Physics workshop on Higgs bundles, and L. Schaposnik and D. Baraglia for details on their construction of (A,B,A) branes.
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This work was partially supported by the Projects PTDC/MAT/120411/2010, PTDC/MAT-GEO/0675/2012 and EXCL/MAT-GEO/0222/2012, UID/MAT/00297/2013, FCT, Portugal, and by the USA NSF Grants DMS 1107452, 1107263, 1107367 “RNMS: GEometric structures And Representation varieties” (the GEAR Network).
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Casimiro, A.C., Ferreira, S. & Florentino, C. Principal Schottky bundles over Riemann surfaces. Geom Dedicata 201, 379–409 (2019). https://doi.org/10.1007/s10711-018-0398-2
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DOI: https://doi.org/10.1007/s10711-018-0398-2
Keywords
- Representations of the fundamental group
- Character varieties
- Principal bundles
- Moduli spaces
- Riemann surfaces
- Schottky bundles
- Uniformization