Inflation and the scale dependent spectral index: prospects and strategies

By Peter Adshead, R. Easther, J. Pritchard, Abraham Loeb. 2010

168 citations recorded by the source corpus.

We consider the running of the spectral index as a probe of both inflation itself, and of the overall evolution of the very early universe. Surveying a collection of simple single field inflationary models, we confirm that the magnitude of the running is relatively consistent, unlike the tensor amplitude, which varies by orders of magnitude. Given this target, we confirm that the running is potentially detectable by future large scale structure or 21 cm observations, but that only the most futuristic measurements can distinguish between these models on the basis of their running. For any specified inflationary scenario, the combination of the running index and unknown post-inflationary expansion history induces a theoretical uncertainty in the predicted value of the spectral index. This effect can easily dominate the statistical uncertainty with which Planck and its successors are expected to measure the spectral index. More positively, upcoming cosmological experiments thus provide an intriguing probe of physics between TeV and GUT scales by constraining the reheating history associated with any specified inflationary model, opening a window into the ``primordial dark age'' that follows the end of inflation.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/253a9b645c54645530f87cb46e6b3b430fd0c837

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Citations in the corpus

Cosmological Moduli and the Post-Inflationary Universe: A Critical Review (2015, background): “The resulting fractional uncertainties ∆r/r, ∆ns/|ns−1| in these observables can be substantial [148, 150].”
Exploring cosmic origins with CORE: Inflation (2016, background): “The forecast uncertainties reported in Tables 5 and 8 show that none of the configurations alone will allow precise measurements of running down to the level of dns/d ln k ∼ (ns−1)(2)/2, but the CORE configurations will certainly be more powerful when combined with future large scale structure or 21”
Standard Model—axion—seesaw—Higgs portal inflation. Five problems of particle physics and cosmology solved in one stroke (2016, background): “Besides, the model generically predicts a small negative running of the scalar spectral index, of the order of |α| ∼ 10−4 − 10−3, which may be probed in the future by 21cm line observations [118,119].”
Non-Gaussianity and the induced gravitational wave background (2021, background): “[97]), a number of scenarios can enhance the curvature power spectrum on small scales.”
Inflation and String Theory (2014, background): “Current bounds on αs are still two orders of magnitude larger than this target, but future galaxy surveys may allow such a measurement [157] (see also [158]).”