The objective of this work is to find the error in kinetic energy of particle-antiparticle and law of conservation of energy in Pair-production Phenomena, theoretically. When photon of suitable energy incidence or enter on nucleus field of heavy nucleus, whose energy are suitable or sufficient for pair production phenomena. The energy of incidence photon or photon goes to produce particle-antiparticle in nucleus field and these particle-antiparticle goes on several phenomena with coulomb force in nucleus field. This several phenomena cause the change in kinetic energy of particle- antiparticle which causes change in law of conservation, before and after pair-production. In this work, we are introducing the role of potential energy (Coulomb force) between the pair production constituent and charge particle produce by nucleus (Proton into Neutron, Neutron into Proton), which play important role to change the speed of particle-antiparticle, from point of formation (within nucleus field) and away from the point of formation ( out of nucleus field). Since, Pair- production produce Particle-antiparticle having positive and negative charge, and also inside the nucleus there is existence of proton (positive charge), pion (positve, negative and neutral charge). The presence of these charge causes attraction and repulsion of the particle- antiparticle in nucleus field and effect the speed of particle-antiparticle after formation. In this paper, we have developed a mathematical model or relation that the velocity of Particle- antiparticle at formation point or on nucleus field is less than the velocity of particle-antiparticle away from point of formation or out of nucleus field that mean velocity of Particle-antiparticle is inversely proportional to the distance of particle-antiparticle from nucleus or nucleus field.

Keywords : Pair-Production, Pion, Particle-Antiparticle, Photon, Nucleus Field etc.