Abstract
To any finite quadratic module, that is, a finite abelian group together with a non-degenerate quadratic form, it is possible to associate a representation of \(\mathrm{Mp}_{2}(\mathbb Z )\), the metaplectic cover of the modular group. This representation is usually referred to as a Weil representation and our main result is a general explicit formula for its matrix coefficients. This result completes earlier work by Scheithauer in the case when the representation factors through \(\mathrm{SL}_{2}(\mathbb Z )\). Furthermore, our formula is given in a such a way that it is easy to implement efficiently on a computer.
Similar content being viewed by others
References
Berndt, B.C., Evans, R.J., Williams, K.S.: Gauss and Jacobi Sums. Canadian Mathematical Society Series of Monographs and Advanced Texts. Wiley, New York (1998)
Borcherds, R.E.: Reflection groups of Lorentzian lattices. Duke Math. J. 104(2), 319–366 (2000). doi:10.1215/S0012-7094-00-10424-3
Bruinier, J.H., Strömberg, F.: Computation of harmonic weak Maass forms. Exp. Math. 21(2), 117–131 (2011)
Cassels, J.W.S.: Rational Quadratic Forms. London Mathematical Society Monographs, vol. 13. Academic Press Inc., London (1978)
Conway, J.H., Sloane, N.J.A.: On the classification of integral quadratic forms. In: Conway, J.H., Sloane, N.J.A. (eds.) Sphere Packings, Lattices and Groups, pp. 352–405. Die Grundlehren der mathematischen Wissenschaften, vol. 290, Springer, New York (1999)
Ebeling, W.: Lattices and Codes. Friedrich Vieweg & Sohn, Braunschweig (1994)
Eichler, M.: Introduction to the Theory of Algebraic Numbers and Functions. Pure and Applied Mathematics, vol. 23. Academic Press, New York (1966)
Gelbart, S.: Weil’s Representation and the Spectrum of the Metaplectic Group. Lecture Notes in Mathematics, vol. 530. Springer, Berlin (1976)
Kloosterman, H.D.: The behaviour of general theta functions under the modular group and the characters of binary modular congruence groups. I, II. Ann. Math. (2) 47, 317–375, 376–447 (1946)
Kubota, T.: Topological covering of SL(2) over a local field. J. Math. Soc. Jpn. 19, 114–121 (1967)
Maass, H.: Lectures on Modular Functions of One Complex Variable, 2nd edn. Tata Institute of Fundamental Research Lectures on Mathematics and Physics, vol. 29. Tata Institute of Fundamental Research, Bombay (1983)
Milnor, J., Husemoller, D.: Symmetric Bilinear Forms. Ergebnisse der Mathematik und ihrer Grenzgebiete, Band 73. Springer, New York (1973)
Pfetzer, W.: Die Wirkung der Modulsubstitutionen auf mehrafache Thetareihen zu quadratischen Formen ungerader Variablenzahl. Arch. Math. 4, 448–454 (1953)
Ryan, N., Skoruppa, N., Strömberg, F.: Numerical computation of a certain Dirichlet series attached to Siegel modular forms of degree two. Math. Comput. 81(280), 2361–2376 (2012)
Scheithauer, N.R.: The Weil representation of \({\rm SL}_2({\mathbb{Z}})\) and some applications. Int. Math. Res. Not. 8, 1488–1545 (2009)
Schoeneberg, B.: Das Verhalten von mehrfachen Thetareihen bei Modulsubstitutionen. Math. Ann. 116(1), 511–523 (1939)
Shimura, G.: On modular forms of half integral weight. Ann. Math. 97, 440–481 (1973)
Shintani, T.: On construction of holomorphic cusp forms of half integral weight. Nagoya Math. J. 58, 83–126 (1975)
Skoruppa, N.-P.: Finite quadratic modules, Weil representations and vector valued modular forms. (2013, preprint)
Skoruppa, N.P.: Über den Zusammenhang zwischen Jacobiformen und Modulformen halbganzen Gewichts. Bonner Math. Schriften, no. 159. University of Bonn, Bonn (1985)
Stein, W., et al.: Sage mathematics software (Version 5.3). The Sage Development Team (2012). http://www.sagemath.org
Weil, A.: Sur certains groupes d’opérateurs unitaires. Acta Math. 111, 143–211 (1964)
Acknowledgments
I would like to thank Nils Scheithauer for clarifying details of [15], Nils-Peter Skoruppa for sharing thoughts about Weil representations in general, and the manuscript [19], in particular. I would also like to thank Stephan Ehlen for his extensive assistance with proof reading the manuscript and in simplifying Theorem 4.1.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Strömberg, F. Weil representations associated with finite quadratic modules. Math. Z. 275, 509–527 (2013). https://doi.org/10.1007/s00209-013-1145-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00209-013-1145-x