2025/09/11 by Beaufort, Louis-Brahim
#37D30 #37D40 #57R22 #Differential Geometry (math.DG) #Dynamical Systems (math.DS) #FOS: Mathematics
paper · doi:10.48550/arxiv.2509.09500
Let M be a closed, negatively curved Riemannian manifold of dimension n ≠ 4, 8 with strictly 1/4-pinched sectional curvature. We prove, that if the frame flow is ergodic and the sum of its unstable and stable bundles together with its flow direction is C2, then M is homothetic to a real hyperbolic manifold. This extends to higher dimensions a previous result of Kanai in dimension 3. The proof generalises to isometric extensions of geodesic flows to a principal bundle P with compact structure group and yields the following alternative : either P is flat, or M is hyperbolic.