Dr. Stephan Ehlen

Professorale Vertretung
Mailing Address
Mathematisches Institut
Universität zu Köln
Weyertal 86-90
50931 Köln
Email: stephan.ehlen [at] math.uni-koeln.de

Office: Gyrhofstr. 8c, 001 (UG)
Phone: 0221 / 470-5559 (Hinweis: Aktuell erreichen Sie mich nur per Email!)

Sprechstunde: nach Vereinbarung (aktuell nur per Telefon oder online/Zoom).

Sommer 2020: Die Lehre startet am 20.4. Infos zur Vorlesung Elliptische Funktionen.

Stephan Ehlen


  • Number Theory
  • Modular Forms, Automorphic Forms


  1. CM values of higher automorphic Green functions on orthogonal groups (with Jan H. Bruinier and T. Yang), submitted (2020), arXiv
  2. On the modular completion of certain generating functions (with K. Bringmann, and Markus Schwagenscheidt), preprint (2018), accepted for publication in IMRN, arXiv
  3. Central L-values of elliptic curves and local polynomials (with P. Guerzhoy, B. Kane, and L. Rolen), 2019 Proc. Lond. Math. Soc. 120 (5), 742-769, arXiv
  4. On two arithmetic theta lifts (with Siddarth Sankaran), 2018, Compositio Mathematica 154 (10), 2090-214, arXiv
  5. Computing Invariants of the Weil representation (with N. P. Skoruppa), in L-Functions and Automorphic Forms (2017, Contributions in Mathematical and Computational Sciences 10, Springer), arXiv
  6. Regularized inner products and errors of modularity (with K. Bringmann and N. Diamantis), 2017, International Mathematics Research Notices, arXiv
  7. Vector valued theta functions associated with binary quadratic forms, Forum Mathematicum 28 (2016), 5, pp. 893-908, arXiv
  8. CM values of regularized theta lifts and harmonic Maass forms of weight one, Duke Math. J., Volume 166, Number 13 (2017), 2447-2519, arXiv
  9. Lattices with many Borcherds products, with J. H. Bruinier and E. Freitag, Math. of. Comp. 85 (2016), 1953-1981 arXiv
  10. Singular moduli of higher level and special cycles, Research in the Mathematical Sciences 2015 2:16, arXiv
  11. Thesis: CM values of regularized theta lifts (2013), tuprints
  12. Twisted Traces of CM values of weak Maass forms (with C. Alfes), J. Number Theory 133 (2013), no. 6. arXivcomputations
  13. On CM values of Borcherds products and harmonic weak Maass forms of weight one, preprint (2012), arXiv
  14. Twisted Borcherds products on Hilbert modular surfaces and the regularized theta lift, Int. J. Number Theory 6 (2010), no. 7, 1473-1489. 


Conferences and Seminars

Research Seminar Darmstadt-Frankfurt: Superstarrheit und Arithmetizität (SS 13), Arakelov-Theorie (WS 12/13), Selbergs 3/16 Theorem (SS 12)