skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Can CMB data constrain the inflationary field range?

Abstract

We study to what extent the spectral index n{sub s} and the tensor-to-scalar ratio r determine the field excursion Δφ during inflation. We analyse the possible degeneracy of Δ φ by comparing three broad classes of inflationary models, with different dependence on the number of e-foldings N, to benchmark models of chaotic inflation with monomial potentials. The classes discussed cover a large set of inflationary single field models. We find that the field range is not uniquely determined for any value of (n{sub s}, r); one can have the same predictions as chaotic inflation and a very different Δ φ. Intriguingly, we find that the field range cannot exceed an upper bound that appears in different classes of models. Finally, Δ φ can even become sub-Planckian, but this requires to go beyond the single-field slow-roll paradigm.

Authors:
 [1]; ; ;  [2]
  1. Instituto de Física Teórica IFT-UAM-CSIC, Universidad Autónoma de Madrid, C/ Nicolás Cabrera 13-15, Cantoblanco, 28049 Madrid (Spain)
  2. Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)
Publication Date:
OSTI Identifier:
22375901
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 09; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICAL METHODS AND COMPUTING; BENCHMARKS; CHAOS THEORY; COSMOLOGICAL INFLATION; DATA; TENSORS

Citation Formats

Garcia-Bellido, Juan, Roest, Diederik, Scalisi, Marco, and Zavala, Ivonne, E-mail: juan.garciabellido@uam.es, E-mail: d.roest@rug.nl, E-mail: m.scalisi@rug.nl, E-mail: e.i.zavala@rug.nl. Can CMB data constrain the inflationary field range?. United States: N. p., 2014. Web. doi:10.1088/1475-7516/2014/09/006.
Garcia-Bellido, Juan, Roest, Diederik, Scalisi, Marco, & Zavala, Ivonne, E-mail: juan.garciabellido@uam.es, E-mail: d.roest@rug.nl, E-mail: m.scalisi@rug.nl, E-mail: e.i.zavala@rug.nl. Can CMB data constrain the inflationary field range?. United States. doi:10.1088/1475-7516/2014/09/006.
Garcia-Bellido, Juan, Roest, Diederik, Scalisi, Marco, and Zavala, Ivonne, E-mail: juan.garciabellido@uam.es, E-mail: d.roest@rug.nl, E-mail: m.scalisi@rug.nl, E-mail: e.i.zavala@rug.nl. Mon . "Can CMB data constrain the inflationary field range?". United States. doi:10.1088/1475-7516/2014/09/006.
@article{osti_22375901,
title = {Can CMB data constrain the inflationary field range?},
author = {Garcia-Bellido, Juan and Roest, Diederik and Scalisi, Marco and Zavala, Ivonne, E-mail: juan.garciabellido@uam.es, E-mail: d.roest@rug.nl, E-mail: m.scalisi@rug.nl, E-mail: e.i.zavala@rug.nl},
abstractNote = {We study to what extent the spectral index n{sub s} and the tensor-to-scalar ratio r determine the field excursion Δφ during inflation. We analyse the possible degeneracy of Δ φ by comparing three broad classes of inflationary models, with different dependence on the number of e-foldings N, to benchmark models of chaotic inflation with monomial potentials. The classes discussed cover a large set of inflationary single field models. We find that the field range is not uniquely determined for any value of (n{sub s}, r); one can have the same predictions as chaotic inflation and a very different Δ φ. Intriguingly, we find that the field range cannot exceed an upper bound that appears in different classes of models. Finally, Δ φ can even become sub-Planckian, but this requires to go beyond the single-field slow-roll paradigm.},
doi = {10.1088/1475-7516/2014/09/006},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 09,
volume = 2014,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}
  • We study how the next generation of Cosmic Microwave Background (CMB) measurement missions (such as EPIC, LiteBIRD, PRISM and COrE) will be able to constrain the inflationary landscape in the hardest to disambiguate situation in which inflation is simply described by single-field slow-roll scenarios. Considering the proposed PRISM and LiteBIRD satellite designs, we simulate mock data corresponding to five different fiducial models having values of the tensor-to-scalar ratio ranging from 10{sup -1} down to 10{sup -7}. We then compute the Bayesian evidences and complexities of all Encyclopædia Inflationaris models in order to assess the constraining power of PRISM alone andmore » LiteBIRD complemented with the Planck 2013 data. Within slow-roll inflation, both designs have comparable constraining power and can rule out about three quarters of the inflationary scenarios, compared to one third for Planck 2013 data alone. However, we also show that PRISM can constrain the scalar running and has the capability to detect a violation of slow roll at second order. Finally, our results suggest that describing an inflationary model by its potential shape only, without specifying a reheating temperature, will no longer be possible given the accuracy level reached by the future CMB missions.« less
  • We develop a method to constrain non-isotropic features of Cosmic Microwave Background (CMB) polarization, of a type expected to arise in some models describing quantum gravity effects on light propagation. We describe the expected signatures of this kind of anomalous light propagation on CMB photons, showing that it will produce a non-isotropic birefringence effect, i.e. a rotation of the CMB polarization direction whose observed amount depends in a peculiar way on the observation direction. We also show that the sensitivity levels expected for CMB polarization studies by the Planck satellite are sufficient for testing these effects if, as assumed inmore » the quantum-gravity literature, their magnitude is set by the minute Planck length.« less
  • The hypothesis of the self-induced collapse of the inflaton wave function was proposed as responsible for the emergence of inhomogeneity and anisotropy at all scales. This proposal was studied within an almost de Sitter space-time approximation for the background, which led to a perfect scale-invariant power spectrum, and also for a quasi-de Sitter background, which allows to distinguish departures from the standard approach due to the inclusion of the collapse hypothesis. In this work we perform a Bayesian model comparison for two different choices of the self-induced collapse in a full quasi-de Sitter expansion scenario. In particular, we analyze themore » possibility of detecting the imprint of these collapse schemes at low multipoles of the anisotropy temperature power spectrum of the Cosmic Microwave Background (CMB) using the most recent data provided by the Planck Collaboration. Our results show that one of the two collapse schemes analyzed provides the same Bayesian evidence of the minimal standard cosmological model ΛCDM, while the other scenario is weakly disfavoured with respect to the standard cosmology.« less
  • Here, the discovery of extraterrestrial neutrinos in the ~30 TeV–PeV energy range by IceCube provides new constraints on high energy astrophysics. An important background to the signal are the prompt neutrinos which originate from the decay of charm hadrons produced by high energy cosmic-ray particles interacting in the Earth’s atmosphere. It is conventional to use the calculations of charm hadroproduction using gluon splitting g → c¯c alone. However, QCD predicts an additional “intrinsic" component of the heavy quark distribution which arises from diagrams where heavy quarks are multiply connected to the proton’s valence quarks. We estimate the prompt neutrino spectrummore » due to intrinsic charm. We find that the atmospheric prompt neutrino flux from intrinsic charm is comparable to those calculated using QCD computations not including intrinsic charm, once we normalize the intrinsic charm differential cross sections to the ISR and the LEBC-MPS collaboration data. In the future, IceCube will constrain the intrinsic charm content of the proton and will contribute to one of the major questions in high energy physics phenomenology.« less
    Cited by 1
  • We update constraints on the Hubble function H({phi}) during inflation, using the most recent cosmic microwave background (CMB) and large scale structure (LSS) data. Our main focus is on a comparison between various commonly used methods of calculating the primordial power spectrum via analytical approximations and the results obtained by integrating the exact equations numerically. In each case, we impose naive, minimally restrictive priors on the duration of inflation. We find that the choice of priors has an impact on the results: the bounds on inflationary parameters can vary by up to a factor of two. Nevertheless, it should bemore » noted that, within the region allowed by the minimal prior of the exact method, the accuracy of the approximations is sufficient for current data. We caution, however, that a careless minimal implementation of the approximative methods allows models for which the assumptions behind the analytical approximations fail, and recommend using the exact numerical method for a self-consistent analysis of cosmological data.« less