  A non-vanishing vacuum expectation value for an antisymmetric tensor field
leads to the violation of Lorentz invariance on the brane. This violation is
controlled by the $\theta_{\mu \nu}$ parameter, which has a dimension of
inverse mass squared. We assume that the zeroth order term in theta-expansion
represents the Standard Model and study the effects induced by linear terms in
theta_{\mu\nu}. Low-energy precision experiments place the limit on the
possible size of this background at the level of $1/\sqrt{\theta} > 5 \times
10^{14}$ GeV. This poses certain difficulty for the TeV-range string scale
models, in which the antisymmetric field has to acquire a relatively large mass
to ensure that $\theta_{\mu \nu}=0$ and avoid cosmological moduli problem.
