Is it Possible to Find a Probable Solution for the Problem of Divergence in QFT?

There are some fundamental questions in quantum physics and quantum field theory which can not be answered considering the positive energy states, alone. Negative energy states show up in many places in physics and could help us to provide an answer to some 'awkward' questions of physics. In recent years much research has been done on extending classical mechanics, quantum mechanics and quantum field theory into the complex domain. On the other hand, applying negative energy states in QFT and performing the field quantization results in a theory without ultraviolet and infrared divergences and it seems as if evaluating divergent integrals of QED space leads to convergent values. Due to Dirac, 'negative energies and probabilities should not be considered as nonsense...', so that comparison of different approaches and reviving quantum theories that were thought to be dead may be helpful in leading us toward a general formalism and finding an appropriate answer to the problem of divergence in QFT.