Probing String Theory with Modulated Cosmological Fluctuations

By Lev Kofman. 2003

341 citations recorded by the source corpus.

Superstring theory, models with extra dimensions and other SUSY models generically predict that the coupling constants are in fact vacuum expectation values of fields like the dilaton, moduli etc. Assuming some of these fields are light during inflation, we get generation of small classical inhomogeneities in these fields from inflation. Consequently, coupling constants inherit small inhomogeneities at scales much larger than the causal horizon in the early universe. After the moduli get pinned down to their minima, the spatial variations of coupling constants in the late time universe will be erased. However, inhomogeneities in coupling constants in the very early universe would generate modulated large scale fluctuations in all relic species that are produced due to interactions and freezing out. Moreover (p)reheating of the inflaton field results in modulated curvature fluctuations. Even if the standard inflaton fluctuations are suppressed, in this picture we may have pure curvature cosmological fluctuations entirely generated by the modulated spatial variations of the coupling constants during preheating.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/818dc42d1e7a44fda8987d0257b977a513e27cad

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In Astronomy and Astrophysics

1. Xingang Chen
2. D. Baumann
3. L. Senatore
4. M. Zaldarriaga
5. Yi Wang
6. K. Koyama
7. D. Green
8. C. Byrnes

In Nuclear and High Energy Physics

1. Xingang Chen
2. D. Baumann
3. L. Senatore
4. K. Koyama
5. Liam McAllister
6. Lavinia Heisenberg
7. Yi Wang
8. C. Byrnes

Citations in the corpus

• Inflation, Cosmic Perturbations and Non-Gaussianities (2013, background): “This scenario is known as the modulated reheating [117, 189, 190].”
• Primordial Non-Gaussianities from Inflation Models (2010, background): “In modulated reheating [154, 155] or preheating [156–161] scenarios, the role of isocurvatons are played by the massless fields which control the couplings during the reheating or preheating.”
• Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “Other models generating local non-Gaussianities are the so called modulated reheating models, in which one light field modulates the decay of the inflaton field [443, 687].”
• DBI in the sky (2004, neutral): “ar X”
• Varying Constants, Gravitation and Cosmology (2010, background): “More speculative, is the effect that such fluctuations can have during preheating after inflation since the decay rate of the inflaton in particles may fluctuate on large scales [293, 294].”
• Planck 2018 results. IX. Constraints on primordial non-Gaussianity (2019, methodology): “…in the decay rate or interactions of the inflaton field, as realized in modulated (p)reheating and modulated hybrid inflationary models (Kofman 2003; Dvali et al. 2004a,b; Bernardeau et al. 2004; Zaldarriaga 2004; Lyth 2005; Salem 2005; Lyth & Riotto 2006; Kolb et al. 2006; Cicoli et…”
• Hilltop inflation (2005, background): “Alternatively, it may happen during preheating [12], or during a reheating process (modulated decay [13]) or during the run-up to some reheating not caused by the inflaton decay (the curvaton mechanism [14]).”
• Inflation and String Theory (2014, background): “A more dramatic example of the effect of multiple fields arises if the inflaton contribution to the scalar perturbations is negligible in comparison to the perturbations arising from a curvaton [131], or through modulated reheating [172, 256].”
• New Ekpyrotic Cosmology (2007, neutral): “In the inflationary context, the idea of using a spectator field to generate a scale-invariant spectrum of entropy perturbations, later to be imprinted on the adiabatic mode, was also considered in the curvaton [30] and modulon scenarios [31].”
• Suppressing the lower multipoles in the CMB anisotropies (2003, background): “We would like to mention also, that there is a new possibility of modulated cosmological perturbations from inflation [44, 45], where one may use a different type of tuning to get desirable spectra from inflation, while leaving the inflaton potential unchanged.”