https://neckpinch.com/authors/amadou-sy/New arXiv papers by Amadou Sy, from Neckpinch Tue, 03 Nov 2026 08:41:12 GMT https://neckpinch.com/papers/2610.11705/arxiv:2610.11705Thu, 08 Oct 2026 00:00:00 GMTAmadou Sy, Ameth Ndiaye, Ghodratallah Fasihi-Ramandi — We study Killing vector fields, Ricci solitons and hyperbolic Ricci solitons on the hyperbolic strip Sₐ=\(x,y)∈ℝ²:0<y<a\ endowed with the metric g_Sₐ=(π²)/(a²sin²(πy/a))(dx²+dy²), and on its unit tangent bundle T¹Sₐ endowed with the Sasaki metric g^S. On the strip, we show that the Gauss curvature is constant equal to −1, that the Lie algebra of Killing fields is isomorphic to sl(2,ℝ), that every Ricci soliton is trivial (Killing potential, λ=−1), and that a 2-Killing field which is conformal, or which is the potential of a hyperbolic Ricci soliton with λ≠0, is a Killing field. On the unit tangent bundle, we prove that the Lie algebra of Killing fields of (T¹Sₐ,g^S) is four-dimensional and isomorphic to sl(2,ℝ)⊕ℝ, that g^S is not Einstein but is η-Einstein with constant coefficients, Ric^S=−3/2 g^S+2 η⊗η, and that (T¹Sₐ,g^S) admits no Ricci soliton. For hyperbolic Ricci solitons we prove non-existence for Killing, left-invariant, and θ-invariant potentials with conformal projection, and we reduce the general θ-invariant case to a system of equations on the strip; the classification for an arbitrary potential is left open. Finally, we show that the η-Ricci solitons of g^S have a Killing potential and λ=3/2, μ=−2, and that the η-hyperbolic Ricci solitons obtained in the same classes of potentials are the trivial ones, with a Killing potential, μ=−3/2 and ν=2.Ricci solitonsAlmost & η-Ricci solitons4-manifoldsSasakian & contact geometry