Impact of new particles on the ratio of Electromagnetic form factors

We consider the electromagnetic form factors ratio in the Rosenbluth and polarization methods. We explore the impact of adding new particles as the mediators in the electron-proton scattering on these ratios. Consequently, we find some bound on the scalar coupling as ${\alpha }_{sc}\sim {10}^{-5}$ for $m_{sc}\sim 5MeV-2GeV$ and ${\alpha }_{sc}\sim {10}^{-4}-{10}^{-3}$ for $m_{sc}\sim 2-10GeV$. Meanwhile, the vector coupling is bounded as ${\alpha }_v\sim {10}^{-5}$ for $m_v\sim 5MeV-1.1GeV$ and ${\alpha }_v\sim {10}^{-4}-{10}^{-3}$ for $m_v\sim 1.2-10GeV$. These constraints are in complete agreement with those which is found from other independent experiments.