WikipediA article "History of Quantum Field Theory" says the following.
“… Of great importance are the studies of Soviet physicists, Viktor Ambartsumian and Dmitri Ivanenko, in particular the Ambarzumian - Ivanenko hypothesis of creation of massive particles (published in 1930) which is the cornerstone of the contemporary quantum field theory. The idea is that not only the quanta of the electromagnetic field, photons, but also other particles (including particles having nonzero rest mass) may be born and disappear as a result of their interaction with other particles. This idea of Ambartsumian and Ivanenko formed the basis of modern quantum field theory and theory of elementary particles.”
V. Ambarzumian, D. Iwanenko, Les électrons inobservables et les rayons, Compt. Rend. Acad Sci. Paris 190 (1930) 582.