Static and rotating black strings in dynamical Chern-Simons modified gravity

Four-dimensional homogeneous static and rotating black strings in dynamical Chern-Simons modified gravity, with and without torsion, are presented. Each solution is supported by a scalar field that depends linearly on the coordinate that span the string. The solutions are locally AdS3xR and they represent the continuation of the Banados-Teitelboim-Zanelli black hole. Moreover, they belong to the so-called Chern-Simons sector of the space of solutions of the theory, since the Cotton tensor contributes nontrivially to the field equations. The case with nonvanishing torsion is studied within the first-order formalism of gravity, and it considers nonminimal couplings of the scalar fields to three topological invariants: Nieh-Yan, Pontryagin and Gauss-Bonnet terms, which are studied separately. These nonminimal couplings generate torsion in vacuum, in contrast to Einstein-Cartan theory. In all cases, torsion contributes to an effective cosmological constant that, in particular cases, can be set to zero by a proper choice of the parameters.