Uniqueness of Lorentzian Hopf tori (Q763053)

The setting of this work is provided by a \textit{Lorentzian Killing submersion}, a notion introduced by the author in correspondence with the similar Riemannian concept. In such a manifold two smooth functions, \(k\) and \(\tau \), are introduced. The main result of the paper states that if \(\tau \) is constant and \(k+4\tau ^2\neq 0\) then every Lorentzian flat torus is a Hopf torus.