Field Theory with Fourth-order Differential Equations

We introduce a new class of higgs type complex-valued scalar fields $U$ with Feynman propagator $\sim 1/p^4$ and consider the matching to the traditional fields with propagator $\sim 1/p^2$ in the viewpoint of effective potentials at tree level. With some particular postulations on the convergence and the causality, there are a wealth of potential forms generated by the fields $U$, such as the linear, logarithmic, and Coulomb potentials, which might serve as sources of effects such as the confinement, dark energy, dark matter, electromagnetism and gravitation. Moreover, in some limit cases, we get some deductions, such as: a nonlinear Klein-Gordon equation, a linear QED, a mass spectrum with generation structure and a seesaw mechanism on gauge symmetry and flavor symmetry; and, the propagator $\sim 1/p^4$ would provide a possible way to construct a renormalizable gravitation theory and to solve the non-perturbative problems.