3 papers
math.DG2026
Curvature of Lie Groupoids with Source-Fibre Metric and Riemannian Lie Algebroids
René Langøen
Classical curvature formulas for Lie groups and Riemannian submersions are recast in terms of Lie groupoids with right-invariant source-fibre metrics and Riemannian Lie algebroids.…
math.DG2025
Curvature of Measure-Preserving Diffeomorphism Groups of Non-Orientable Surfaces
Boris Khesin, René Langøen, Irina Markina
We study curvatures of the groups of measure-preserving diffeomorphisms of non-orientable compact surfaces. For the cases of the Klein bottle and the real projective plane we compu…
math-ph2024
Stokes graphs of the Rabi problem with real parameters
René Langøen, Irina Markina, Alexander Yu. Solynin
The goal of this paper is to study the geometry of the Stokes graphs associated with the problem, which was introduced by Isidor Rabi in 1937 to model reactions of atoms to the har…