We use the factorized tree graphs of the generalized Veneziano model to construct, through the tree theorem, all graphs with one closed loop. While unitary in the sense of perturbation theory, the loops contain a new "particle counting" divergence related to the very large number of daughters in the trees.

• Received 6 June 1969

DOI:https://doi.org/10.1103/PhysRev.185.1910