2-particle asymptotic completeness and bound states in weakly coupled quantum field theories

Rigorous results on poles of the 2- and 4-point functions, which yield 2-particle asymptotic completeness and give information on the presence or absence of 2-particle bound states and resonances, are presented for weakly coupled even and non-even-field theories with mass gap in space-time dimension d = 2,3 (and for related hypothetical theories in dimension 4). Methods used are more convenient and more general than those used previously (with more limited results) for P(φ)2 theories. (orig.)