TY - JOUR

T1 - Cosmological dynamics of D-BIonic and DBI scalar field and coincidence problem of dark energy

AU - Panpanich, Sirachak

AU - Maeda, Kei Ichi

AU - Mizuno, Shuntaro

N1 - Funding Information:
S.P. is supported by the Japanese Government (Monbukagakusho) Scholarship. This work was supported in part by Grants-in-Aid from the Scientific Research Fund of the Japan Society for the Promotion of Science, Grants No. 16K05362 (K.M.) and No. 16K17709 (S.M.).

PY - 2017

Y1 - 2017

N2 - We study the cosmological dynamics of a D-BIonic and Dirac-Born-Infeld scalar field, which is coupled to matter fluid. For the exponential potential and the exponential couplings, we find a new analytic scaling solution yielding the accelerated expansion of the Universe. Since it is shown to be an attractor for some range of the coupling parameters, the density parameter of matter fluid can be the observed value, as in the coupled quintessence with a canonical scalar field. Contrary to the usual coupled quintessence, where the value of the matter coupling giving the observed density parameter is too large to satisfy the observational constraint from the cosmic microwave background, we show that the D-BIonic theory can give a similar solution with a much smaller value of matter coupling. As a result, together with the fact that the D-BIonic theory has a screening mechanism, the D-BIonic theory can solve the so-called coincidence problem as well as the dark energy problem.

AB - We study the cosmological dynamics of a D-BIonic and Dirac-Born-Infeld scalar field, which is coupled to matter fluid. For the exponential potential and the exponential couplings, we find a new analytic scaling solution yielding the accelerated expansion of the Universe. Since it is shown to be an attractor for some range of the coupling parameters, the density parameter of matter fluid can be the observed value, as in the coupled quintessence with a canonical scalar field. Contrary to the usual coupled quintessence, where the value of the matter coupling giving the observed density parameter is too large to satisfy the observational constraint from the cosmic microwave background, we show that the D-BIonic theory can give a similar solution with a much smaller value of matter coupling. As a result, together with the fact that the D-BIonic theory has a screening mechanism, the D-BIonic theory can solve the so-called coincidence problem as well as the dark energy problem.

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U2 - 10.1103/PhysRevD.95.103520

DO - 10.1103/PhysRevD.95.103520

M3 - Article

AN - SCOPUS:85020190191

VL - 95

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 10

M1 - 103520

ER -