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Pre - Inflationary Clues from String Theory ?
High Energy Physics - Theory · Submitted 6 Feb 2014
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim A first look at WMAP9 raw data shows that, while the chi^2 fits for the low-l CMB angular power spectrum are clearly compatible with an almost scale invariant behavior, they display nonetheless an eye-catching preference for this type of setting within a perturbative string regime.
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The abstract, sentence by sentence
"Brane supersymmetry breaking" occurs in String Theory when the only available combinations of D-branes and orientifolds are not mutually BPS and yet do not introduce tree-level tachyon instabilities. It is characterized by the emergence of a steep exponential potential, and thus by the absence of maximally symmetric vacua. The corresponding low-energy supergravity admits intriguing spatially-flat cosmological solutions where a scalar field is forced to climb up toward the steep potential after an initial singularity, and additional milder terms can inject an inflationary phase during the ensuing descent. We show that, in the resulting power spectra of scalar perturbations, an infrared suppression is typically followed by a pre-inflationary peak that reflects the end of the climbing phase and can lie well apart from the approximately scale invariant profile. A first look at WMAP9 raw data shows that, while the chi^2 fits for the low-l CMB angular power spectrum are clearly compatible with an almost scale invariant behavior, they display nonetheless an eye-catching preference for this type of setting within a perturbative string regime.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | "Brane supersymmetry breaking" occurs in String Theory when the only available combinations of D-branes and orientifolds are not mutually BPS and yet do not introduce tree-level tachyon instabilities. | background 1.00 | 0.06 | 0.03 | asserted 1.00 |
| s1 | It is characterized by the emergence of a steep exponential potential, and thus by the absence of maximally symmetric vacua. | background 0.97 | 0.13 | 0.04 | asserted 1.00 |
| s2 | The corresponding low-energy supergravity admits intriguing spatially-flat cosmological solutions where a scalar field is forced to climb up toward the steep potential after an initial singularity, and additional milder terms can inject an inflationary phase during the ensuing descent. | background 0.68 | 0.17 | 0.09 | asserted 0.94 |
| s3 | We show that, in the resulting power spectra of scalar perturbations, an infrared suppression is typically followed by a pre-inflationary peak that reflects the end of the climbing phase and can lie well apart from the approximately scale invariant profile. | result 0.99 | 0.91 | 0.42 | asserted 0.93 |
| s4 | A first look at WMAP9 raw data shows that, while the chi^2 fits for the low-l CMB angular power spectrum are clearly compatible with an almost scale invariant behavior, they display nonetheless an eye-catching preference for this type of setting within a perturbative string regime. | result 0.89 | 0.91 | 0.51 | asserted 0.53 |
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The paper
Original abstract
"Brane supersymmetry breaking" occurs in String Theory when the only available combinations of D-branes and orientifolds are not mutually BPS and yet do not introduce tree-level tachyon instabilities. It is characterized by the emergence of a steep exponential potential, and thus by the absence of maximally symmetric vacua. The corresponding low-energy supergravity admits intriguing spatially-flat cosmological solutions where a scalar field is forced to climb up toward the steep potential after an initial singularity, and additional milder terms can inject an inflationary phase during the ensuing descent. We show that, in the resulting power spectra of scalar perturbations, an infrared suppression is typically followed by a pre-inflationary peak that reflects the end of the climbing phase and can lie well apart from the approximately scale invariant profile. A first look at WMAP9 raw data shows that, while the chi^2 fits for the low-l CMB angular power spectrum are clearly compatible with an almost scale invariant behavior, they display nonetheless an eye-catching preference for this type of setting within a perturbative string regime.
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References
How the literature uses it
21 arXiv papers cite this in 58 sentences
Papers citing it · 40 sentences without a confident label
Builds on it 2 papers
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The present work is meant to complement the analysis in [ref] with a scrutiny of new effects introduced by the gaussian bump.
A String-Inspired Model for the Low-$\ell$ CMB · Introduction · 0.95
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The same mechanism of gravitinos production discussed in Section III could also be implemented in string-inspired climbing scalar pre-inflationary models [ref] .
Dark Matter and Inflation in $R+\zeta R^{2}$ Supergravity · Conclusions and discussions · 0.92
Uses its method or tool 1 paper
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In order to compare these power spectra with the low–$ℓ$ CMB, in [ref] we followed a simple procedure guided by the order parameter
Low-$\ell$ CMB from String-Scale SUSY Breaking? · Introduction · 0.82
Compares with it 3 papers
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We came to it from a different perspective in [ref] , and the work in [ref] differs from previous or other present approaches in three respects: the well–motivated parametrization in eqs.
Low-$\ell$ CMB from String-Scale SUSY Breaking? · Introduction · 0.85
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The end result is similar to what occurred close to the exponential wall in [ref] and in [ref] .
A String-Inspired Model for the Low-$\ell$ CMB · Comparison with the low–$ℓ$ CMB · 0.97
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Actually, similar shapes of the power spectrum have also been obtained in Ref. [ref] .
Pre-inflationary primordial perturbations · The bounce inflation · 0.97
Cites it as support 1 paper
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In conclusion, the considerations in [ref] , inspired by String Theory, and in particular by the supersymmetry breaking mechanism of [ref] and the related cosmological dynamics of [ref] , provided the original motivation for the present analysis.
Observational Hints of a Pre--Inflationary Scale? · Introduction · 1.00
Cites it as background 10 papers
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with $γ< 1$, which were examined in detail in [ref] .
String Theory clues for the low-$\ell$ CMB ? · Introduction · 0.83
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The string–inspired models of [ref] rest on the energy scale of string excitations, which determines the scalar potential and lies typically a few orders of magnitude below the Planck scale.
Observational Hints of a Pre--Inflationary Scale? · Introduction · 0.82
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After the WMAP1 data were released, some studies have been done in Refs. [ref] , [ref] , [ref] , [ref] , [ref] , [ref] , [ref] along this line, and also recently [ref] , [ref] , [ref] , [ref] , [ref] , [ref] , [ref] , [ref] ; see Ref. [ref] for a review.
Pre-inflationary primordial perturbations · Introduction · 0.83
What it cites · 85 sentences without a confident label
Contests 1 paper
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The ensuing analysis refines and corrects to some extent the results in [ref] , and hopefully it can also convey an overall picture of the potential imprints of BSB on the CMB power spectrum of scalar perturbations.
CMB Imprints of a Pre-Inflationary Climbing Phase · Climbing Scalars and String Theory · contest 0.86
Uses the method or tool of 1 paper
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All these results were obtained, as in [ref] , starting from a Bunch–Davies–like vacuum, setting initial conditions close to the singularity (at $τ=0.01$, in terms of parametric time) as we have explained and working in terms of the parametric time $τ$ in the gauge of eq.
CMB Imprints of a Pre-Inflationary Climbing Phase · A New Look at the Power Spectra of Climbing Scalars · 0.97
Uses data or values from 2 papers
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The lack of power in large–angle correlations that both WMAP9 [ref] and PLANCK [ref] apparently see, if their data are taken at face value despite cosmic variance, could thus seemingly translate into an indication that our instruments are capturing some glimpses of an initial singularity.
Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results · A New Look at the Power Spectra of Climbing Scalars · 0.84
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The lack of power in large–angle correlations that both WMAP9 [ref] and PLANCK [ref] apparently see, if their data are taken at face value despite cosmic variance, could thus seemingly translate into an indication that our instruments are capturing some glimpses of an initial singularity.
Planck 2013 results. I. Overview of products and scientific results · A New Look at the Power Spectra of Climbing Scalars · 0.84
Compares with 1 paper
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[ref], which are also along the lines of [ref] .
The pre-inflationary and inflationary fast-roll eras and their signatures in the low CMB multipoles · A New Look at the Power Spectra of Climbing Scalars · 0.90
Cites as support 1 paper
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[ref] find a key motivation in String Theory, in a link between string scale and supersymmetry breaking scale that manifests itself in a class of orientifold models [ref] .
Open strings and their symmetry groups · Climbing Scalars and String Theory · 0.96
Cites as background 12 papers
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The first, drawn from String Theory [ref] , is the existence of a class of orientifold vacua [ref] with “brane supersymmetry breaking” [ref] .
Open strings and their symmetry groups · Conclusions · 0.86
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The first, drawn from String Theory [ref] , is the existence of a class of orientifold vacua [ref] with “brane supersymmetry breaking” [ref] .
Anomaly Cancellations in the Type I D9-anti-D9 System and the USp(32) String Theory · Conclusions · 0.86
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The solution has a long history [ref] , but its main lesson was appreciated only recently [ref] .
Brane solutions in strings with broken supersymmetry and dilaton tadpoles · Introduction · 0.92
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