Warm tachyon inflation and swampland criteria *

Mohammadi, Abolhassan; Golanbari, T.; Sheikhahmadi, Haidar; Sayar, K.; Akhtari, L.; Rasheed, Mariwan A.; Saaidi, Kh.

doi:10.1088/1674-1137/44/9/095101

“…It's also worth noting that in both GR and non-GR based cosmologies, the warm inflation paradigm has been shown to be very compatible with the swampland criterion even for single field models [36][37][38][39][40] The recently proposed "Trans Planckian Censorship Conjecture" (TCC) [41] is another swampland conjecture that has sparked a lot of interest in inflationary cosmology . Models with tachyonic scalar fields as the inflaton can also be consistent with the conjectures [42,43]. Single field GR based inflationary models can only be compatible with the TCC if they are extremely fine tuned [44], which is ironic given that inflation was invented to solve the fine tuning problem of traditional big bang cosmology.…”

Section: Introductionmentioning

confidence: 73%

Lorentz violating inflation and the Swampland

Trivedi

2021

Preprint

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The swampland conjectures from String theory have had very interesting implications for cosmology and particularly for Inflation. It has been shown that the single field inflationary models in a GR based cosmology are in unavoidable tensions with these conjectures, while these single field models can still be consistent in certain non-trivial inflationary regimes. So it becomes interesting to see whether there is a way to overcome the issues of the swampland and single field inflation in an essentially GR based cosmology. We show that this can indeed be the case and for this, we consider a certain type of Lorentz violating inflationary scenario. We work out the swampland bounds for Lorentz violating inflationary models after which show that inflationary models which would have had otherwise serious tensions with these conjectures in a usual GR based scenario, can be very tranquil with the criterion in this regime. For this we take examples of Higgs inflation, radion gauge inflation and Spontaenous symmetry breaking inflation and show that the bounds imposed by the swampland on the Lorentz violating parameter can be easily satisfied in these models.

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“…In an isotropic background, i.e. λ = 1, and when α tends to zero, the first slow-roll parameter goes back to the usual warm inflation relation [138,174,175]. To examine the validity of a theoretical model, one basic approach is to compare its predictions with the observations.…”

Section: Evolution Equations For Non-comoving Warm Inflationmentioning

confidence: 99%

“…In the following we will consider models in which the dissipation coefficient is introduced phenomenologically via an ansatz of the form = 0 T ζ /φ ζ −1 , where 0 and ζ are constants [103,119,137,175]. Then the function G(Q), depending on the different values of the parameter ζ , can be approximated by [103,119] ζ = 1 −→ G(Q) 1 + 0.127Q 4.330 + 4.981Q 1.946 , ζ = 3 −→ G(Q) 1 + 0.0185Q 2.315 + 0.335Q 1.364…”

Section: Strong Dissipative Regimementioning

confidence: 99%

“…Currently one of the main dark energy scenarios is based on the so-called quintessence [20][21][22][23][24], where dark energy corresponds to a scalar particle φ. For other proposals for dark energy, in which the dynamical equation of state is realized by a scalar field, one can refer to k-essence [25][26][27], tachyon [28,29,175], phantom [30][31][32], quintom [33][34][35], chameleon [36][37][38][39][40][41], and Chaplygin gas [42,43] models, which have also been investigated. Modifying gravity at galactic or astrophysical scales, or considering extra-dimensional cosmological models, can also lead to an explanation of the late acceleration of the Universe [44][45][46][47][48][49][50][51].…”

Section: Introductionmentioning

confidence: 99%

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Warm inflation with non-comoving scalar field and radiation fluid

Harkó

¹

,

Sheikhahmadi

²

2021

Self Cite

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We consider a warm inflationary scenario in which the two major fluid components of the early Universe, the scalar field and the radiation fluid, evolve with distinct four-velocities. This cosmological configuration is equivalent to a single anisotropic fluid, expanding with a four-velocity that is a combination of the two fluid four-velocities. Due to the presence of anisotropies the overall cosmological evolution is also anisotropic. We obtain the gravitational field equations of the non-comoving scalar field–radiation mixture for a Bianchi Type I geometry. By assuming the decay of the scalar field, accompanied by a corresponding radiation generation, we formulate the basic equations of the warm inflationary model in the presence of two non-comoving components. By adopting the slow-roll approximation the theoretical predictions of the warm inflationary scenario with non-comoving scalar field and radiation fluid are compared in detail with the observational data obtained by the Planck satellite in both weak dissipation and strong dissipation limits, and constraints on the free parameters of the model are obtained. The functional forms of the scalar field potentials compatible with the non-comoving nature of warm inflation are also obtained.

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“…Hence the action of the gravitational theory becomes 4 x, leading to socalled quintessence models [20][21][22][23][24][25]. Other dark constituent models are k-essence models [26][27][28], tachyon field models [28,29], models considering phantom fields [30][31][32], or quintom field models [33][34][35], respectively. In [25] it was pointed out that quintessence always lower H 0 relative to the CDM model, thus making the Hubble tension worse.…”

Section: Introductionmentioning

confidence: 99%

Generalizing the coupling between geometry and matter: $$f\left( R,L_m,T\right) $$ gravity

Haghani

¹

,

Harkó

²

2021

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We generalize and unify the $$f\left( R,T\right) $$ f R , T and $$f\left( R,L_m\right) $$ f R , L m type gravity models by assuming that the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar R, of the trace of the energy–momentum tensor T, and of the matter Lagrangian $$L_m$$ L m , so that $$ L_{grav}=f\left( R,L_m,T\right) $$ L grav = f R , L m , T . We obtain the gravitational field equations in the metric formalism, the equations of motion for test particles, and the energy and momentum balance equations, which follow from the covariant divergence of the energy–momentum tensor. Generally, the motion is non-geodesic, and takes place in the presence of an extra force orthogonal to the four-velocity. The Newtonian limit of the equations of motion is also investigated, and the expression of the extra acceleration is obtained for small velocities and weak gravitational fields. The generalized Poisson equation is also obtained in the Newtonian limit, and the Dolgov–Kawasaki instability is also investigated. The cosmological implications of the theory are investigated for a homogeneous, isotropic and flat Universe for two particular choices of the Lagrangian density $$f\left( R,L_m,T\right) $$ f R , L m , T of the gravitational field, with a multiplicative and additive algebraic structure in the matter couplings, respectively, and for two choices of the matter Lagrangian, by using both analytical and numerical methods.

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Warm tachyon inflation and swampland criteria *

Cited by 37 publications

References 141 publications

Lorentz violating inflation and the Swampland

Lorentz violating inflation and the Swampland

Warm inflation with non-comoving scalar field and radiation fluid

Generalizing the coupling between geometry and matter: $$f\left( R,L_m,T\right) $$ gravity

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