Study on early inflationary phase using a new form of non-canonical scalar field model
We study the inflationary phase of the early universe as modeled by a non-canonical scalar field. The homogeneous scalar field equation is derived from a Lagrangian density containing a new form of non-canonical kinetic term and a general potential function. The Lie symmetry is studied and a one par...
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Published in | General relativity and gravitation Vol. 53; no. 3 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
New York
Springer US
01.03.2021
Springer Nature B.V |
Subjects | |
Online Access | Get full text |
ISSN | 0001-7701 1572-9532 |
DOI | 10.1007/s10714-021-02794-3 |
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Summary: | We study the inflationary phase of the early universe as modeled by a non-canonical scalar field. The homogeneous scalar field equation is derived from a Lagrangian density containing a new form of non-canonical kinetic term and a general potential function. The Lie symmetry is studied and a one parameter Lie point symmetry for the homogeneous scalar field equation is found. We use Lie symmetry generator to construct the exact analytical group invariant closed-form solution of the homogeneous scalar field equation without applying any slow-roll approximation from invariant curve condition. The solution thus obtained is seen to be consistent with the Friedmann equations subject to constraint conditions on the potential parameter
λ
. In this scenario, we obtain the values for various inflationary parameters and make useful checks on the observational constraints on the parameters from Planck data by imposing a set of bounds on the parameter
λ
of the potential. The results for scalar spectral index (
n
S
) and tensor-to-scalar ratio (
r
) presented in the
(
n
S
,
r
)
plane in the background of Planck2015 and Planck2018 data are in good agreement with cosmological observations. We find
r
∼
10
-
3
, the targeted value of
r
that will be detected by the future CMB observation such as LiteBIRD. Interestingly, most significant primordial non-Gaussianity is also achieved. For theoretical completeness of our non-canonical model, we obtain the allowed parameter space in which the ghosts and Laplacian instabilities are absent. We apply the formulas for slow-roll parameter to explain exit from the inflationary phase using the general potential. We also treat the non-canonical scalar field model equation by the dynamical system theory to provide useful checks on the stability of the critical points and show that the group invariant non-canonical inflationary solution is stable attractor in the phase space. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 |
ISSN: | 0001-7701 1572-9532 |
DOI: | 10.1007/s10714-021-02794-3 |