Eur. Phys. J. C (2013) 73: 2331
https://doi.org/10.1140/epjc/s10052-013-2331-z

Regular Article - Theoretical Physics

Stability of curvature perturbation with new covariant form for energy-momentum transfer in dark sector

¹ Institute of Modern Physics, Northwest University, Xian, 710069, P.R. China
² Faculty of Science, Ningbo University, Ningbo, 315211, P.R. China

^* e-mail: ddscy@163.com
^** e-mail: cysun@mails.ucas.ac.cn

Received: 22 December 2012
Published online: 28 February 2013

Abstract

It was found that the model with interaction between cold dark matter (CDM) and dark energy (DE) proportional to the energy density of CDM ρ _m and constant equation of state of DE w _d suffered from instabilities of the density perturbations on the super-Hubble scales. Here we suggest a new covariant model for the energy-momentum transfer between CDM and DE. Then using the covariant model, we analyze the evolution of density perturbations on the super-Hubble scale. We find that the instabilities can be avoided in the model with constant w _d and interaction proportional to ρ _m . Furthermore, we analyze the dominant non-adiabatic mode in the radiation era and find that the mode grows regularly.