  We explore the impact of a sudden shift in the mass of a scalar boson field
on long-range forces mediated by this field under the framework of unitarily
inequivalent vacua. Since the search for new long-range forces is an active
experimental area probing physics beyond the Standard Model, the consequence of
a non-trivial vacuum state of a scalar boson on these experiments is
elucidated. We show that while the mass shift affects the one-boson exchange
potential, the Casimir force remains only dependent on the vacuum state.
