  We consider bulk tachyon condensations in a non-linear sigma model whose low
energy effective theory contains a nontrivial scalar potential. We argue that
one would typically encounter a strong coupling background along a RG flow
corresponding to a bulk tachyon condensation, beyond which the RG analysis
would not be reliable. In a range of the flow in which the string coupling
constant is small, we can show that the tachyon condensation actually decreases
the central charge of the sigma model.
