Phases of Brans-Dicke cosmology(II):Matter from NS-NS sector

Lee, Sunggeun; Park, Chanyong; Sin, Sang-Jin

Phases of Brans-Dicke cosmology(II):Matter from NS-NS sector

Authors

Lee, Sunggeun

Park, Chanyong

Sin, Sang-Jin

Description

We study the cosmology of the Brans-Dicke(BD) theory coupled to perfect fluid type matter. In our previous works, the case where matter is coming from the Ramond-Ramond sector of the string theory was studied. Here, we study the case where matter is coming from the NS-NS sector. Exact solutions are found and the cosmology is classified according to the values of $γ$, the parameter of the equation of state and $ω$, Brans-Dicke parameter. We find taht, in string frame, there are solutions without singularity for some ranges of $γ$ and $ω$. In Einstein frame, however, all solutions are singular.
28 pages, 20 eps figures