Propagating waves in an extremal black string
  We investigate the black string in the context of the string theories. It is shown that the graviton is the only propagating mode in the (2+1)--dimensional extremal black string background. Both the dilation and axion turn out to be non-propagating modes. 
H.W. Lee, Y.S. Myung (Inje University), Jin Young Kim (Dongseo   University) and D.K. Park (Kyungnam University)