Benjamin Delarue

Formerly known as Benjamin Küster

Principal Investigator of the project Resonances for non-compact locally symmetric spaces in the SPP 2026 Geometry at Infinity

Member of the Spectral analysis group in the Institute of Mathematics at Paderborn University, Germany

Contact details available here

Google scholar ResearchGate

Photo courtesy of the Oberwolfach Archives, taken during the Workshop Anosov3 which I co-organized

Research interests


  1. Singular cohomology of symplectic quotients by circle actions and Kirwan surjectivity. Preprint. With Maximilian Schmitt and Pablo Ramacher.
  2. A Riemann-Roch formula for singular reductions by circle actions. Preprint. With Louis Ioos and Pablo Ramacher.
  3. Resonances and weighted zeta functions for obstacle scattering via smooth models. Ann. Henri Poincaré 25 (2024), 1607–1656. With Philipp Schütte and Tobias Weich.
  4. The Ruelle zeta function at zero for nearly hyperbolic 3-manifolds. Invent. Math. 229 (2022), 303–394. With Mihajlo Cekić, Semyon Dyatlov, and Gabriel Paternain.
  5. Asymptotic expansion of generalized Witten integrals for Hamiltonian circle actions. J. Symplectic Geom. (6) 19 (2021), 1281–1337. With Pablo Ramacher.
  6. Spectral Theory of the Frame Flow on Hyperbolic 3-Manifolds. Ann. Henri Poincaré 22 (2021), 3565–3617. With Colin Guillarmou, appendix by Charles Hadfield.
  7. Pollicott-Ruelle resonant states and Betti numbers. Commun. Math. Phys. 378 (2020), 917–941. With Tobias Weich.
  8. Quantum-Classical Correspondence on Associated Vector Bundles Over Locally Symmetric Spaces. Int. Math. Res. Not. (11) 2021 (2019), 8225–8296. With Tobias Weich.
  9. On the semiclassical functional calculus for h-dependent functions. Ann. Glob. Anal. Geom. (1) 52 (2017), 57–97.
  10. Quantum ergodicity and symmetry reduction. J. Funct. Anal. (1) 273 (2017), 41-124. With Pablo Ramacher.
  11. Discontinuity of the Fuglede-Kadison determinant on a group von Neumann algebra. Commun. Math. (2) 22 (2014), 141-149.


Geometrie für Lehramtsstudierende (Geometry for students of Education), Paderborn University, 2024

Analysis für Informatiker (Analysis for computer scientists), Paderborn University, 2021/22

Symplektische Geometrie und Hamiltonsche Dynamik (Symplectic geometry and Hamiltonian dynamics), Paderborn University, 2017/18

SPP 2026 Geometry at Infinity

My project

SPP 2026 homepage

Selected talks

Brief introduction to Anosov representations, Study group on Patterson-Sullivan Theory, Paderborn 2024

The Ruelle zeta function at zero for nearly hyperbolic 3-manifolds, Online seminar organized by Colin Guillarmou, Nguyen Viet Dang, Frederic Naud, and Gabriel Rivière, January 2021

The frame flow on hyperbolic 3-manifolds, 56th Seminar Sophus Lie, Paderborn, February 2020

Quantum-classical correspondence for resonances on vector bundles, Séminaire Problèmes Spectraux en Physique Mathématique, Institut Henri Poincaré, Paris, January 2019



Selected memories from conferences and workshops

A documentation of the harsh working conditions of a mathematician
  1. Porquerolles, France
    Plage du Langoustier   Georges du Loup   Coastline nearby
  2. MSRI, Berkeley, United States
    Lobby   Sunset behind the Golden Gate   Night view
  3. CIRM, Marseille, France
    Parc national des Calanques   High up on the route to Cassis   Between the rocks
  4. Peyresq, French Alps
    Morning view   Housing   Remains of snow at higher altitude
  5. Oberwolfach, Germany
    Black Forest   Fresh snow