  The naive low energy effective action of the tachyon and the U(1) gauge field
obtained from string field theory does not correspond to the world volume
action of unstable branes in bosonic string theory. We show that there exists a
field redefinition which relates the gauge field and the tachyon of the string
field theory action to the fields in the world volume action of unstable
branes. We identify a string gauge symmetry which corresponds to the U(1) gauge
transformation. This is done to the first non-linear order in the fields. We
examine the vector fluctuations at the tachyon condensate till level (4,8).
