Abstract
The cosmological constant problem is studied in a two component cosmological model. The universe contains a cosmological constant of an arbitrary size and sign and an additional component with an inhomogeneous equation of state. It is shown that, in a proper parameter regime, the expansion of the universe with a large absolute value of the cosmological constant may asymptotically tend to de Sitter space corresponding to a small effective positive cosmological constant. It is argued that such a behavior can be regarded as a solution of the cosmological constant problem in this model. The mechanism behind the relaxation of the cosmological constant is discussed. A connection with modified gravity theories is discussed and an example of a possible realization of the cosmological constant relaxation in f(R) modified gravity is described.
Highlights
Many attempts to solve the cosmological constant (CC) problem have been made during several last decades [5, 6, 7]
The cosmological constant problem is a spot in theoretical physics landscape where the inadequacy of standard theoretical approaches is evident
In this paper we have presented a simple approach based on a cosmological component with an inhomogeneous equation of state
Summary
Many attempts to solve the CC problem have been made during several last decades [5, 6, 7]. The most frequent problem that models of various sorts encounter is the necessity of fine-tuning. Even a very small deviation from these fine-tuned values disrupts the efficiency of the proposed mechanisms. In this paper we propose a dynamical cosmological model with a specific regime in which it is possible to contemplate the resolution of the CC problem. Given the difficulty of the CC problem and its resilience to different attempts of solution, it seems preferable to first concentrate on the very mechanism which could produce the observed value of the effective cosmological constant for a universe with values of Λ comparable to those predicted in QFT
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