The Cosmological Constant as a Ghost of Inflaton
  The cosmological constant (term) is the simplest way, presently known, to illustrate the accelerating expansion of the universe. However, because of/despite its simple appearance, there is much confusion surrounding its essence. Theorists have been asking questions for years: Is there a mechanism to explain this term? Is it really a constant or a variable? Moreover, it seems that we have created a huge gulf separating the theories of inflation and accelerating expansion. Can we eliminate such an uncomfortable discontinuity?   Abstract In this paper, we will journey to see the growth of the universe from the very beginning of inflation. To simplify our discussion, we will briefly "turn off" the effects of real and dark matter and shall use inflaton (a classical scalar field) dynamics with a time-varying inflaton potential V(phi,t) as the screen to watch this process. Relying on these conditions, we propose a non-traditional method of obtaining the solution of scale factor R(t), which is only dependent on phi'(t)^2, and discover that the term R"(t)/R(t) will be a constant after kinetic inflaton phi'(t) is at rest. This result can be regarded as the effective cosmological constant phenomenally. Moreover, we will also "rebuild" V(phi,t), realize its evolutionary process and then, according to the relationship between V(phi,t) and phi'(t)^2, it will be possible to smoothly describe the whole evolution of the universe from the epoch of inflation. Therefore, the implications of our findings will mean that the gulf between theories will disappear. Lastly, we will also see how the formula could provide a framework for solving the old and new cosmological constant problems as well as much more besides. 
Yu-Chung Chen
gr-qc hep-th