Tubular D-branes in Salam-Sezgin Model

We study DBI-type effective theory of an unstable D3-brane in the background manifold R^{1,1} x M_2 where M_2 is an arbitrary two-dimensional manifold. We obtain an exact tubular D2-brane solution of arbitrary cross sectional shape by employing 1/cosh tachyon potential. When M_2=S^2, the solution is embedded in the background geometry R^{1,3} x S^2 of Salam-Sezgin model. This tachyon potential shows a unique property that an array of tachyon soliton solutions has a fixed period which is independent of integration constants of the equations of motion. The thin BPS limit of the configurations leads to supertubes of arbitrary cross sectional shapes.