A Tachyonic Scalar Field with Mutually Interacting Components

We investigate the tachyonic cosmological potential V(?) in two different cases of the quasi-exponential expansion of universe and discuss various forms of interaction between the two components—matter and the cosmological constant—of the tachyonic scalar field, which lead to the viable solutions of their respective energy densities. The distinction among the interaction forms is shown to appear in the O _m (x) diagnostic. Further, the role of the high- and low-redshift observations of the Hubble parameter is discussed to determine the proportionality constants and hence the correct form of matter–cosmological constant interaction.