Spacetime structure of 5D hypercylindrical vacuum solutions with tension

We investigate geometrical properties of 5D cylindrical vacuum solutions with a transverse spherical symmetry. The metric is uniform along the fifth direction and characterized by tension and mass densities. The solutions are classified by the tension-to-mass ratio. One particular example is the well-known Schwarzschild black string which has a curvature singularity enclosed by a horizon. We focus mainly on geometry of other solutions which possess a naked singularity. The light signal emitted by an object approaching the singularity reaches a distant observer with finite time, but is infinitely red-shifted.Comment: revtex4, 5 pages, 2 figures. To appear in the proceedings of the 10th Asia Pacific Physics Conference (APPC10), Pohang, Korea, 21-24 Aug. 2007. Submitted to J. Korean Phys. Soc. Penrose diagram has been adde