Robustness of inflation to kinetic inhomogeneities

We investigate the effects of large inhomogeneities in both the inflaton field and its momentum. We find that in general, large kinetic perturbations reduce the number of e-folds of inflation. In particular, we observe that inflationary models with sub-Planckian characteristic scales are not robust even to kinetic energy densities that are sub-dominant to the potential energy density, unless the initial field configuration is sufficiently far from the minimum. This strengthens the results of our previous work. In inflationary models with super-Planckian characteristic scales, despite a reduction in the number of e-folds, inflation is robust even when the potential energy density is initially sub-dominant. For the cases we study, the robustness of inflation strongly depends on whether the inflaton field is driven into the reheating phase by the inhomogeneous scalar dynamics.

Note:

8 pages, 5 figures, 1 appendix. Comments welcome!

gravity
inflation
initial conditions and eternal universe
physics of the early universe
energy: density
potential: energy
inflation: model
energy: kinetic
inflaton
reheating

References(99)

Figures(7)

[1]

The Inflationary Universe: A Possible Solution to the Horizon and Flatness Problems

Alan H. Guth
(
- SLAC
)

- Phys.Rev.D 23 (1981) 347-356,
- Adv.Ser.Astrophys.Cosmol. 3 (1987) 139-148 (reprint)
•
DOI:
- 10.1103/PhysRevD.23.347

[2]

A New Type of Isotropic Cosmological Models Without Singularity

Alexei A. Starobinsky
(
- Cambridge U. and
- Landau Inst.
)

- Phys.Lett.B 91 (1980) 99-102,
- Adv.Ser.Astrophys.Cosmol. 3 (1987) 130-133,
•
DOI:
- 10.1016/0370-2693(80)90670-X

[3]

A New Inflationary Universe Scenario: A Possible Solution of the Horizon, Flatness, Homogeneity, Isotropy and Primordial Monopole Problems

Andrei D. Linde
(
- Lebedev Inst.
)

- Phys.Lett.B 108 (1982) 389-393,
- In *Moscow 1981, Proceedings, Quantum Gravity*, 185-195 and Moscow Inst. Phys. Acad. Sci. - 81-229 (81,REC.DEC.) 15p,
- Adv.Ser.Astrophys.Cosmol. 3 (1987) 149-153 (reprint)
•
DOI:
- 10.1016/0370-2693(82)91219-9

[4]

Cosmology for Grand Unified Theories with Radiatively Induced Symmetry Breaking

- Phys.Rev.Lett. 48 (1982) 1220-1223,
- Adv.Ser.Astrophys.Cosmol. 3 (1987) 158-161 (reprint)
•
DOI:
- 10.1103/PhysRevLett.48.1220

[5]

Chaotic Inflation

Andrei D. Linde
(
- Lebedev Inst.
)

- Phys.Lett.B 129 (1983) 177-181,
- Reprinted in *Abbott, L.F. (ed.), Pi, S.Y. (ed.): Inflationary cosmology*, 37-41
•
DOI:
- 10.1016/0370-2693(83)90837-7

[6]

Planck 2018 results. X. Constraints on inflation

Planck

Collaboration

•

Y. Akrami
(
- Leiden U. and
- Inst. Theor. Astrophys., Oslo
)

et al.

- Astron.Astrophys. 641 (2020) A10
•
e-Print:
- 1807.06211
•
DOI:
- 10.1051/0004-6361/201833887

[7]

On the Initial State and Consistency Relations

Lasha Berezhiani
(
- Pennsylvania U.
)
,
Justin Khoury
(
- Pennsylvania U.
)

- JCAP 09 (2014) 018
•
e-Print:
- 1406.2689
•
DOI:
- 10.1088/1475-7516/2014/09/018

[8]

How Likely are Constituent Quanta to Initiate Inflation?

Lasha Berezhiani
(
- Pennsylvania U.
)
,
Mark Trodden
(
- Pennsylvania U.
)

- Phys.Lett.B 749 (2015) 425-430
•
e-Print:
- 1504.01730
•
DOI:
- 10.1016/j.physletb.2015.08.007

[9]

A relativistic gas of inflatons as an initial state for inflation

- Phys.Lett.B 840 (2023) 137852
•
e-Print:
- 2211.06222
•
DOI:
- 10.1016/j.physletb.2023.137852

[10]

Cosmological Event Horizons, Thermodynamics, and Particle Creation

G.W. Gibbons
(
- Cambridge U.
)
,
S.W. Hawking
(
- Cambridge U.
)

- Phys.Rev.D 15 (1977) 2738-2751
•
DOI:
- 10.1103/PhysRevD.15.2738

[11]

Supercooled Phase Transitions in the Very Early Universe

S.W. Hawking
(
- Cambridge U.
)
,
I.G. Moss
(
- Cambridge U.
)

- Phys.Lett.B 110 (1982) 35-38,
- Adv.Ser.Astrophys.Cosmol. 3 (1987) 154-157
•
DOI:
- 10.1016/0370-2693(82)90946-7

[12]

Asymptotic behavior of homogeneous cosmological models in the presence of a positive cosmological constant

Robert M. Wald
(
- Chicago U., EFI
)

- Phys.Rev.D 28 (1983) 2118-2120
•
DOI:
- 10.1103/PhysRevD.28.2118

[13]

Isotropization of arbitrary cosmological expansion given an effective cosmological constant

Alexei A. Starobinsky
(
- Landau Inst.
)

- JETP Lett. 37 (1983) 66-69

[14]

Inhomogeneous cosmologies with cosmological constant

John D. Barrow
(
- Sussex U.
)
,
J. Stein-Schabes
(
- Sussex U.
)

- Phys.Lett.A 103 (1984) 315-317
•
DOI:
- 10.1016/0375-9601(84)90467-5

[15]

On the Realization of New Inflation

Andreas Albrecht
(
- Santa Barbara, KITP and
- Texas U.
)
,
Robert H. Brandenberger
(
- Santa Barbara, KITP
)

- Phys.Rev.D 31 (1985) 1225
•
DOI:
- 10.1103/PhysRevD.31.1225

[16]

Closed universes: their future evolution and final state*

J.D. Barrow
,
F.J. Tipler

- Mon.Not.Roy.Astron.Soc. 216 (1985) 395-402
•
DOI:
- 10.1093/mnras/216.2.395

[17]

A Natural Measure on the Set of All Universes

- Nucl.Phys.B 281 (1987) 736
•
DOI:
- 10.1016/0550-3213(87)90425-1

[18]

Is Inflation Natural?

Lars Gerhard Jensen
(
- Fermilab
)
,
Jaime A. Stein-Schabes
(
- Fermilab
)

- Phys.Rev.D 35 (1987) 1146
•
DOI:
- 10.1103/PhysRevD.35.1146

[19]

How probable is inflation?

S.W. Hawking
(
- Cambridge U.
)
,
Don N. Page
(
- Penn State U.
)

- Nucl.Phys.B 298 (1988) 789-809
•
DOI:
- 10.1016/0550-3213(88)90008-9

[20]

Difficulties with inflationary cosmology

R. Penrose
(
- Oxford U. and
- Syracuse U.
)

- Annals N.Y.Acad.Sci. 571 (1989) 249-264,
- In *Dallas 1988, Proceedings, Relativistic astrophysics* 249-264. (see HIGH ENERGY PHYSICS INDEX 30 (1992) No.9903)
•
DOI:
- 10.1111/j.1749-6632.1989.tb50513.x