Bound states in the three dimensional phi⁴ model

We discuss the spectrum of the three dimensional phi^4 theory in the broken symmetry phase. In this phase the effective potential between the elementary quanta of the model is attractive and bound states of two or more of them may exist. We give theoretical and numerical evidence for the existence of these bound states. Looking in particular at the Ising model realization of the phi^4 theory we show, by using duality, that these bound states are in one-to-one correspondence with the glueball states of the gauge Ising model. We discuss some interesting consequences of this identification.