REVIEW
False Vacuum Inflation with Einstein Gravity
Astrophysics · Submitted 10 Jan 1994 · 66 references
Pith's verdict: The standard reference for hybrid inflation phenomenology; the parameter-space map and the corrected n ≲ 1.14 are the durable contributions, and the prompt-transition argument in §3.2 is the one place where the abstract outruns the body.
T0 · AI review
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Referee report
The paper
The paper claims
A two-field false-vacuum inflation model can produce a slightly blue primordial spectrum and can be embedded naturally in supergravity from orbifold compactification of superstrings.
The reading
What carries the argument
The load-bearing mechanism is the false-vacuum trajectory: while $�phi^2>�lambda M^2/�lambda'$, the $�psi$ field is pinned at $�psi=0$ and its constant energy density $V_0=�lambda M^4/4$ dominates the potential, so $H$ is nearly constant and the inflaton rolls slowly. The instability at $�phi_{�rm inst}$ converts the false-vacuum energy into the true vacuum and ends inflation. The spectral prediction comes from the standard slow-roll formula $n-1=2�eta-6�epsilon$ evaluated 60 e-foldings before the end, with $�eta=m_{�rm Pl}^2 V''/(8�pi V)$; in the vacuum-dominated limit $�eta$ is independent of $�phi$ and fixed by COBE, which is why $n$ is slightly above $1$. The supergravity part uses the orbifold Kähler potential $K=-�ln Y-�sum_i�ln X_i$ with $X_i=T_i+�bar T_i-�sum_�alpha|�phi_{�alpha i}|^2$; the cancellation of the $X_3$ factor in the $F$-term potential keeps the inflaton mass below $H$ and makes $n$ depend on the one-loop coefficient $�delta_{GS3}$.
Extended reading notes
Core claim
The central claim is that false-vacuum-dominated two-field inflation is a viable and distinctive model. With the potential $V(�phi,�psi)=�frac14�lambda(�psi^2-M^2)^2+�frac12 m^2�phi^2+�frac12�lambda'�phi^2�psi^2$, inflation proceeds along $�psi=0$ until $�phi$ drops below $�phi_{�rm inst}^2=�lambda M^2/�lambda'$; the resulting instability ends inflation. In the vacuum-dominated regime the slow-roll parameters satisfy $�epsilon�ll�eta$, so the spectral index is $n-1=2�eta_{60}-6�epsilon_{60}>0$, with $�eta$ fixed by the COBE normalization; for unit couplings $n$ runs from essentially $1$ to about $1.14$, not the larger values previously suggested. The same potential can be realized in orbifold-compactified supergravity, where the $X_3$ factor that would generate an $O(H)$ mass for the inflaton cancels for one modulus direction and $n=1+�delta_{GS3}/(2�pi^2�langle S+�bar S�rangle)$, for example $n=1.06$ for $�delta_{GS3}=5$ and $�langle S+�bar S�rangle=4$. The inflationary energy scale can be as low as $10^{11}$ GeV, but reheating is prompt, so the reheat temperature is not far below that, and topological defects are almost inevitable.
Load-bearing premise
The load-bearing premise is that the phase transition ends inflation within about a Hubble time of $�phi=�phi_{�rm inst}$, which the authors establish by a contradiction argument that assumes slow roll continues for one Hubble time and that spatial gradients of both fields are negligible, without following the actual dynamics or the resulting defect statistics.
Editorial extensions
If this is right
- The false-vacuum-dominated branch predicts a spectral index between $1$ and about $1.14$ for couplings of order unity, a blue tilt that differs from the red tilt typical of ordinary chaotic inflation.
- The inflationary energy scale can be anywhere from $10^{16}$ down to $10^{11}$ GeV, but prompt reheating keeps the reheat temperature from falling far below $10^{11}$ GeV, which constrains gravitino production.
- Topological defects — domain walls, strings, monopoles, or textures depending on the symmetry — form when the false vacuum decays, and at the upper energy scale they can contribute significantly to the microwave background and large-scale structure.
- The model can be realized in global supersymmetry through an axion-like global $U(1)$ false vacuum, and in orbifold supergravity the spectral index is tied to the one-loop coefficient and the dilaton expectation.
- A first-order version with bubble nucleation is subject to big-bubble constraints and generally requires $M�gtrsim 10^{13}$ GeV for unit couplings unless the couplings are tuned.
Reading between the lines
- Because most working inflation models predict $n<1$, a precise measurement of the sign of the tilt is a cleaner discriminator for this branch than the amplitude of the ripples alone.
- If the orbifold relation $n=1+�delta_{GS3}/(2�pi^2�langle S+�bar S�rangle)$ is taken seriously, the spectral index becomes a direct probe of the one-loop coefficient and the dilaton expectation during inflation, so a measured $n$ would constrain string compactification parameters.
- The paper leaves the defect statistics of the vacuum-dominated transition unresolved; a numerical simulation of the reheating transition could turn the defect abundance into either a confirmation or an exclusion channel for the high-scale end of the model.
Original abstract
We investigate chaotic inflation models with two scalar fields, such that one field (the inflaton) rolls while the other is trapped in a false vacuum state. The false vacuum becomes unstable when the inflaton field falls below some critical value, and a first or second order transition to the true vacuum ensues. Particular attention is paid to Linde's second-order `Hybrid Inflation'; with the false vacuum dominating, inflation differs from the usual true vacuum case both in its cosmology and in its relation to particle physics. The spectral index of the adiabatic density perturbation can be very close to 1, or it can be around ten percent higher. The energy scale at the end of inflation can be anywhere between $10^{16}$\,GeV and $10^{11}$\,GeV, though reheating is prompt so the reheat temperature can't be far below $10^{11}\,$GeV. Topological defects are almost inevitably produced at the end of inflation, and if the inflationary energy scale is near its upper limit they can have significant effects. Because false vacuum inflation occurs with the inflaton field far below the Planck scale, it is easier to implement in the context of supergravity than standard chaotic inflation. That the inflaton mass is small compared with the inflationary Hubble parameter is still a problem for generic supergravity theories, but remarkably this can be avoided in a natural way for a class of supergravity models which follow from orbifold compactification of superstrings. This opens up the prospect of a truly realistic, superstring
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
We investigate chaotic inflation models with two scalar fields, such that one field (the inflaton) rolls while the other is trapped in a false vacuum state. The false vacuum becomes unstable when the inflaton field falls below some critical value, and a first or second order transition to the true vacuum ensues. Particular attention is paid to Linde's second-order `Hybrid Inflation'; with the false vacuum dominating, inflation differs from the usual true vacuum case both in its cosmology and in its relation to particle physics. The spectral index of the adiabatic density perturbation can be very close to 1, or it can be around ten percent higher. The energy scale at the end of inflation can be anywhere between $10^{16}$\,GeV and $10^{11}$\,GeV, though reheating is prompt so the reheat temperature can't be far below $10^{11}\,$GeV. Topological defects are almost inevitably produced at the end of inflation, and if the inflationary energy scale is near its upper limit they can have significant effects. Because false vacuum inflation occurs with the inflaton field far below the Planck scale, it is easier to implement in the context of supergravity than standard chaotic inflation. That the inflaton mass is small compared with the inflationary Hubble parameter is still a problem for generic supergravity theories, but remarkably this can be avoided in a natural way for a class of supergravity models which follow from orbifold compactification of superstrings. This opens up the prospect of a truly realistic, superstring
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We investigate chaotic inflation models with two scalar fields, such that one field (the inflaton) rolls while the other is trapped in a false vacuum state. | contribution 0.92 | 0.70 | 0.05 | asserted 0.95 |
| s1 | The false vacuum becomes unstable when the inflaton field falls below some critical value, and a first or second order transition to the true vacuum ensues. | method 0.39 | 0.27 | 0.08 | asserted 0.99 |
| s2 | Particular attention is paid to Linde's second-order `Hybrid Inflation'; with the false vacuum dominating, inflation differs from the usual true vacuum case both in its cosmology and in its relation to particle physics. | contribution 0.67 | 0.32 | 0.12 | asserted 0.98 |
| s3 | The spectral index of the adiabatic density perturbation can be very close to 1, or it can be around ten percent higher. | result 1.00 | 0.70 | 0.10 | hedged possibility 0.74 |
| s4 | The energy scale at the end of inflation can be anywhere between $10^{16}$\,GeV and $10^{11}$\,GeV, though reheating is prompt so the reheat temperature can't be far below $10^{11}\,$GeV. | result 1.00 | 0.68 | 0.09 | asserted 0.55 |
| s5 | Topological defects are almost inevitably produced at the end of inflation, and if the inflationary energy scale is near its upper limit they can have significant effects. | result 0.91 | 0.50 | 0.07 | asserted 0.65 |
| s6 | Because false vacuum inflation occurs with the inflaton field far below the Planck scale, it is easier to implement in the context of supergravity than standard chaotic inflation. | interpretation 0.86 | 0.26 | 0.12 | asserted 0.87 |
| s7 | That the inflaton mass is small compared with the inflationary Hubble parameter is still a problem for generic supergravity theories, but remarkably this can be avoided in a natural way for a class of supergravity models which follow from orbifold compactification of superstrings. | contribution 0.32 | 0.41 | 0.14 | asserted 0.85 |
| s8 | This opens up the prospect of a truly realistic, superstring | interpretation 0.85 | 0.12 | 0.12 | hedged possibility 0.74 |
What was examined, and what was not
- arXiv listing abstract v1
- full text
- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
- S sections
- T body sentences
- C citations
- R cross-paper relations
Figures
Figures reproduced from arXiv:astro-ph/9401011 by the authors.
References
How the literature uses it
189 arXiv papers cite this in 277 sentences
Papers citing it · 172 sentences without a confident label
Contests it 2 papers
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The `classic' model of hybrid inflation [ref] predicts a blue spectrum of CMB perturbations that is now ruled out by observations [ref] .
On Hybrid Monodromy Inflation (Hic Sunt Dracones) · Introduction · contest 0.85
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The main drawback of hybrid inflationary models was their prediction for the spectral index $n_s ≳1$ [ref] , value excluded by the Planck data [ref] .
Gravitational Waves and Primordial Black Holes from Supersymmetric Hybrid Inflation · Introduction · contest 0.83
Builds on it 2 papers
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We focus on a variation of extended hybrid Inflationary potential [ref] , in which the potential along the rolling direction is replaced with an inflection point inflation potential [ref] V(ϕ,ψ) = V_0+1/2 m^2ϕ^2 - 4 A λ__3/3 ϕ^3 + λ__3^2 ϕ^4+ 1/4λψ^4-1/3γM ψ^3 +1/2 λ^' ϕ^2ψ^2+1/2 αM^2 ψ^2
Examining the end of inflation with primordial black holes mass distribution and gravitational waves · Double field inflation · 0.90
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This is the same as the original hybrid inflation model considered in Refs. [ref] except that we have included the additional field, $σ$, coupled to the waterfall field, as proposed by Lyth [ref] .
Curvaton and the inhomogeneous end of inflation · Hybrid Inflation · 0.99
Uses its method or tool 1 paper
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We shall use the percolation parameter [ref] [equation] to determine the time of the transition.
Curvature perturbations from vacuum transition during inflation · Setup · 0.94
Compares with it 5 papers
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Note that, in our case, the leading SUGRA correction to the inflationary potential for minimal Kähler potential, which corresponds to the second term in the parenthesis of Eq. [ref], is the same as the one found in the first of Ref. [ref] , in the case of standard hybrid inflation and in Ref. [ref] , in the case of shifted and smooth hybrid inflation.
Phenomenology and Cosmology of Supersymmetric Grand Unified Theories · Supergravity corrections · 1.00
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We observe that this result is essentially compatible with the Lyth bound [ref] .]
Higgs Inflation and the Refined dS Conjecture · Introduction · 0.97
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The behavior is also somewhat analogous to hybrid inflation [ref] , although in our case, slow-roll inflation could persist long after the inflaton trajectory changes direction.
QCD Axion Hybrid Inflation · Introduction · 0.96
Cites it as support 1 paper
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In supersymmetric models, generic supergravity correction can spoil the flatness of the inflaton potential during the inflation since it can induce a large mass correction for inflaton field [ref] .
Orbifold GUT inflation · Introduction · 0.96
Cites it as background 80 papers
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Such a process is a crucial element of the hybrid inflationary scenario, introduced by Linde, in which inflation ends through a sudden instability [ref] .
Non-Gaussianity constrains hybrid inflation · Introduction · 0.95
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Supersymmetric hybrid inflation comes in two variants, depending on whether the vacuum energy density during inflation is dominated by a nonzero F term [ref] or D term [ref] .
Unified Model of D-Term Inflation · Introduction · 0.99
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In conventional hybrid inflation [ref] inflation ends abruptly by the waterfall transition.
Curvature perturbation and waterfall dynamics in hybrid inflation · Introduction · 0.91
Discussion
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