  We study the effects of asymptotically anti-de Sitter wormholes in low-energy
field theory and give a general prescription for obtaining the local effective
interaction terms induced by them. The choice of vacuum for the matter fields
selects a basis of the Hilbert space of anti-de Sitter wormholes whose elements
can be interpreted as states containing a given number of particles. This
interpretation is subject to the same kind of ambiguity in the definition of
particle as that arising from quantum field theory in curved spacetime.
