  We consider the mechanism of spontaneous symmetry breaking of a bulk vector
field to study signatures of bulk dimensions invisible to the standard model
confined to the brane. By assigning a non-vanishing vacuum expectation value to
the vector field, a direction is singled out in the bulk vacuum, thus breaking
the bulk Lorentz symmetry. We present the condition for induced Lorentz
symmetry on the brane, as phenomenologically required, noting that it is
related to the value of the observed cosmological constant.
