TY - JOUR
T1 - Viable cosmology in bimetric theory
AU - Felice, Antonio De
AU - Gümrüküoǧlu, A. Emir
AU - Mukohyama, Shinji
AU - Tanahashi, Norihiro
AU - Tanaka, Takahiro
PY - 2014/6/1
Y1 - 2014/6/1
N2 - We study cosmological perturbations in bimetric theory with two fluids each of which is coupled to one of the two metrics. Focusing on a healthy branch of background solutions, we clarify the stability of the cosmological perturbations. For this purpose, we extend the condition for the absence of the so-called Higuchi ghost, and show that the condition is guaranteed to be satisfied on the healthy branch. We also calculate the squared propagation speeds of perturbations and derive the conditions for the absence of the gradient instability. To avoid the gradient instability, we find that the model parameters are weakly constrained.
AB - We study cosmological perturbations in bimetric theory with two fluids each of which is coupled to one of the two metrics. Focusing on a healthy branch of background solutions, we clarify the stability of the cosmological perturbations. For this purpose, we extend the condition for the absence of the so-called Higuchi ghost, and show that the condition is guaranteed to be satisfied on the healthy branch. We also calculate the squared propagation speeds of perturbations and derive the conditions for the absence of the gradient instability. To avoid the gradient instability, we find that the model parameters are weakly constrained.
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U2 - 10.1088/1475-7516/2014/06/037
DO - 10.1088/1475-7516/2014/06/037
M3 - Article
AN - SCOPUS:84902583382
SN - 1475-7516
VL - 2014
JO - Journal of Cosmology and Astroparticle Physics
JF - Journal of Cosmology and Astroparticle Physics
IS - 6
M1 - 037
ER -