Prospects for Primordial Gravitational Waves in String Inflation
| Autor: | Ivonne Zavala, Susha L. Parameswaran |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
High Energy Physics - Theory
Cosmology and Nongalactic Astrophysics (astro-ph.CO) media_common.quotation_subject FOS: Physical sciences General Relativity and Quantum Cosmology (gr-qc) Astrophysics::Cosmology and Extragalactic Astrophysics String theory 01 natural sciences String (physics) Upper and lower bounds General Relativity and Quantum Cosmology Moduli Theoretical physics High Energy Physics - Phenomenology (hep-ph) 0103 physical sciences Effective field theory 010306 general physics Mathematical Physics media_common Physics Inflation (cosmology) 010308 nuclear & particles physics Gravitational wave Astronomy and Astrophysics Universe High Energy Physics - Phenomenology High Energy Physics - Theory (hep-th) Space and Planetary Science Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | International Journal of Modern Physics D |
| Popis: | Assuming that the early universe had (i) a description using perturbative string theory and its field theory limit (ii) an epoch of slow-roll inflation within a four-dimensional effective field theory and a hierarchy of scales $M_{inf} < m_{kk} < m_s \lesssim M_{pl}$ that keeps the latter under control, we derive an upper bound on the amplitude of primordial gravitational waves. The bound is very sensitive to mild changes in numerical coefficients and the expansion parameters. For example, allowing couplings and mass-squared hierarchies $\lesssim 0.2$, implies $r \lesssim 0.05$, but asking more safely for hierarchies $\lesssim 0.1$, the bound becomes $r \lesssim 10^{-6}$. Moreover, large volumes -- typically used in string models to keep backreaction and moduli stabilisation under control -- drive $r$ down. Consequently, any detection of inflationary gravitational waves would present an interesting but difficult challenge for string theory. Received Honourable Mention in the 2016 Gravity Research Foundation Awards for Essays on Gravitation; submitted to IJMPD Special issue with some revisions and clarifications, 3 pages + refs; v2 further clarifications |
| Databáze: | OpenAIRE |
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