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Observing the structure of the landscape with the CMB experiments
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
2010 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, no 4, 002- p.Article in journal (Refereed) Published
Abstract [en]

Assuming that inflation happened through a series of tunneling in the string theory landscape, it is argued that one can determine the structure of vacua using precise measurements of the scalar spectral index and tensor perturbations at large scales. It is shown that for a vacuum structure where the energy gap between the minima is constant, i.e. epsilon(i) = im(f)(4), one obtains the scalar spectral index, n(s), to be similar or equal to 0.9687, for the modes that exit the horizon 60 e-folds before the end of inflation. Alternatively, for a vacuum structure in which the energy gap increases linearly with the vacuum index, i.e. epsilon(i) = i(2)/2m(f)(4), n(s) turns out to be. 0.9614. Both these two models are motivated within the string theory landscape using flux-compactification and their predictions for scalar spectral index are compatible with WMAP results. For both these two models, the results for the scalar spectral index turn out to be independent of m(f). Nonetheless, assuming that inflation started at Planckian energies and that there had been successful thermalization at each step, one can constrain m(f) < 2.6069 x 10(-5)m(P) and m(f) < 6.5396 x 10(-7)m(P) in these two models, respectively. Violation of the single-field consistency relation between the tensor and scalar spectra is another prediction of chain inflation models. This corresponds to having a smaller tensor/scalar ratio at large scales in comparison with the slow-roll counterparts. Similar to slow-roll inflation, it is argued that one can reconstruct the vacuum structure using the CMB experiments.

Place, publisher, year, edition, pages
2010. no 4, 002- p.
Keyword [en]
inflation, string theory and cosmology, cosmological phase transitions
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-136567DOI: 10.1088/1475-7516/2010/04/002ISI: 000277684600031OAI: oai:DiVA.org:uu-136567DiVA: diva2:377309
Available from: 2010-12-14 Created: 2010-12-13 Last updated: 2010-12-14Bibliographically approved

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