De Sitter solutions in Einstein-Gauss-Bonnet gravity

Vernov, Sergey; Pozdeeva, Ekaterina

doi:10.48550/arxiv.2104.11111

Cited by 2 publications

(2 citation statements)

References 62 publications

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“…; see our definition of the variables (11). It is also convenient to define the following parameters:…”

Section: Ultra-slow-roll Near the Fixed Pointmentioning

confidence: 99%

CMB from a Gauss-Bonnet-induced de Sitter fixed point

Kawai,

Kim

2021

Preprint

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In gravitational effective theories including higher curvature terms, cosmological solutions can have nontrivial de Sitter fixed points. We study phenomenological implications of such points, focusing on a theory in which a massive scalar field is nonminimally coupled to the Euler density.We first analyze the phase portrait of the dynamical system, and show that the fixed point can be a sink or a saddle, depending on the strength of the coupling. Then we compute the perturbation spectra generated in the vicinity of the fixed point in order to investigate whether the fixed point may be considered as cosmic inflation. We find parameter regions that are consistent with the cosmological data, given that the anisotropies in the cosmic microwave background are seeded by the fluctuations generated near the fixed point. Future observation may be used to further constrain the coupling function of this model. We also comment briefly on the swampland conjecture.

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“…; see our definition of the variables (11). It is also convenient to define the following parameters:…”

Section: Ultra-slow-roll Near the Fixed Pointmentioning

confidence: 99%

CMB from a Gauss-Bonnet-induced de Sitter fixed point

Kawai,

Kim

2021

Preprint

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“…The idea of an "effective potential" has been advocated as a useful concept in the nonminimal curvature coupling case [76][77][78][79], where it also turns out to be an invariant quantity under conformal transformations [80] and thus rules the dynamics in a frameindependent way. (Curiously, it can be also extended to theories with an additional coupling to a Gauss-Bonnet term [81,82]). In the torsion coupling case, the "effective potential" was introduced in Refence [52] to explain the existence and stability of de Sitter fixed points, and it was noted how these points correspond to the "balanced solutions" of Reference [48].…”

Section: Effective Mass Effective Potential Fixed Point Condition Sta...mentioning

confidence: 99%

Global Portraits of Nonminimal Teleparallel Inflation

Järv

Lember

2021

Universe

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We construct global phase portraits of inflationary dynamics in teleparallel gravity models with a scalar field nonminimally coupled to torsion scalar. The adopted set of variables can clearly distinguish between different asymptotic states as fixed points, including the kinetic and inflationary regimes. The key role in the description of inflation is played by the heteroclinic orbits that run from the asymptotic saddle points to the late time attractor point and are approximated by nonminimal slow roll conditions. To seek the asymptotic fixed points, we outline a heuristic method in terms of the “effective potential” and “effective mass”, which can be applied for any nonminimally coupled theories. As particular examples, we study positive quadratic nonminimal couplings with quadratic and quartic potentials and note how the portraits differ qualitatively from the known scalar-curvature counterparts. For quadratic models, inflation can only occur at small nonminimal coupling to torsion, as for larger coupling, the asymptotic de Sitter saddle point disappears from the physical phase space. Teleparallel models with quartic potentials are not viable for inflation at all, since for small nonminimal coupling, the asymptotic saddle point exhibits weaker than exponential expansion, and for larger coupling, it also disappears.

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De Sitter solutions in Einstein-Gauss-Bonnet gravity

Cited by 2 publications

References 62 publications

CMB from a Gauss-Bonnet-induced de Sitter fixed point

CMB from a Gauss-Bonnet-induced de Sitter fixed point

Global Portraits of Nonminimal Teleparallel Inflation

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