Running of the Running and Entropy Perturbations During Inflation

Abstract

In single field slow-roll inflation, one expects that the spectral index $n_s-1$ is first order in slow-roll parameters. Similarly, its running ${\alpha }_s=d{n}_s/d\log k$ and the running of the running ${\beta }_s=d{\alpha }_s/d\log k$ are second and third order and therefore expected to be progressively smaller, and usually negative. Hence, such models of inflation are in considerable tension with a recent analysis hinting that ${\beta }_s$ may actually be positive, and larger than ${\alpha }_s$. Motivated by this, in this work we ask the question of what kinds of inflationary models may be useful in achieving such a hierarchy of runnings, particularly focusing on two--field models of inflation in which the late-time transfer of power from isocurvature to curvature modes allows for a much more diverse range of phenomenology. We calculate the runnings due to this effect and briefly apply our results to assessing the feasibility of finding $|{\beta }_s|\gtrsim |{\alpha }_s|$ in some specific models.

6 pages, 2 figures. Fixes typos present in published version. Corrected numerical parameters in example. General results remain unchanged

References in corpus (7)

• A Joint Analysis of BICEP2/Keck Array and Planck Data
• Primordial perturbations and non-Gaussianities in DBI and general multi-field inflation
• Curvature and isocurvature perturbations in two-field inflation
• Energy Transfer in Multi Field Inflation and Cosmological Perturbations
• Power Spectra beyond the Slow Roll Approximation in Theories with Non-Canonical Kinetic Terms
• Effect of transitions in the Planck mass during inflation on primordial power spectra
• Ambiguity in running spectral index with an extra light field during inflation

Cited by in corpus (14)

• Warm inflation dissipative effects: predictions and constraints from the Planck data
• Frame Covariant Nonminimal Multifield Inflation
• Imprint of entanglement entropy in the power spectrum of inflationary fluctuations
• Study of the Inflationary Spectrum in the Presence of Quantum Gravity Corrections
• Running and running of the running of the scalar spectral index in warm inflation
• Tracking the Multifield Dynamics with Cosmological Data: A Monte Carlo approach
• Conformal GUT inflation, proton lifetime and non-thermal leptogenesis
• Non-Gaussianity in multi-sound-speed disformally coupled inflation
• Adiabatic and isocurvature perturbations in extended theories with kinetic couplings
• Inflation and Scale-invariant $R^2$-Gravity
• On signatures of spontaneous collapse dynamics modified single field inflation
• Non-standard hierarchies of the runnings of the spectral index in inflation
• The running of featureful primordial power spectra
• Quantum Gravity Corrections to the inflationary spectrum in a Bohmian approach