1. H. P. Dürr andH. Pilkuhn:Nuovo Cimento,40 A, 899 (1965).
2. Here and in the following the vertex functionV aec is denoted by the invariant functionV j (t), the spherical harmonic describing the polarization of the resonance c being omitted. The variablet is the square of the momentum transfer,t=(c−a) 2. Bya, b, … we also mean the four-momenta of the particles a, b, … The metric isg 00=1,g ii =−1 (i=1, 2, 3),g μν=0 (μ≠ν), and the units are ℏ=c=1.a c is the momentum of a in the c rest frame anda c=|a c|;m a,m b, … are the masses of the particles a, b, …;s c=(a+e)2 is the square of the effective mass of the resonance c, ands=(a+b)2 is the square of the total c.m. energy.
3. SeeJ. D. Jackson:Rev. Mod. Phys.,37, 484 (1965).
4. K. Dietz andH. Pilkuhn:Nuovo Cimento,37, 1561 (1965).
5. J. M. Blatt andV. F. Weisskopf:Theoretical Nuclear Physics (New York, 1952), p. 361.