arXiv subjects

Somphoach Saichaemchan

Publications and source records attributed to Somphoach Saichaemchan.

2 recordsLinked to original sources

arXiv2018

Palatini NMDC gravity: cosmological scalar field phase portraits in exponential potential

We consider cosmological scalar field evolving under exponential potential of the Non-minimal Derivative Coupling (NMDC) gravity model in Palatini formalism. Slow-roll regime is assumed. GR and metric formalism NMDC cases are compared in this study. Phase portraits show that Palatini NMDC effect restricts acceleration phase into smaller region in the phase space. NMDC effect of the Palatini case suppresses expansion rate than that of the GR while the metric NMDC enhances rate of expansion of the GR case.

gr-qc↗

arXiv2017

Non-minimal derivative coupling in Palatini cosmology: acceleration in chaotic inflation potential

NMDC-Palatini cosmology in slow-roll regime is of our interests. We present flat FLRW cosmological NMDC-Palatini field equations and acceleration condition. Late time trajectory is approximated. Chaotic inflation potential is considered here as it is viable in a range of positive coupling constant as constrained by CMB results. Phase portraits show that the NMDC-Palatini gives new saddle-point solutions. In $V \propto ϕ^2$ potential, the NMDC-Palatini effect enlarges the acceleration-allowed region from that of GR case.

gr-qc↗