The degeneracy problem in non-canonical inflation

Damien Easson, Brian A. Powell

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


While attempting to connect inflationary theories to observational physics, a potential difficulty is the degeneracy problem: a single set of observables maps to a range of different inflaton potentials. Two important classes of models affected by the degeneracy problem are canonical and non-canonical models, the latter marked by the presence of a non-standard kinetic term that generates observables beyond the scalar and tensor two-point functions on CMB scales. The degeneracy problem is manifest when these distinguishing observables go undetected. We quantify the size of the resulting degeneracy in this case by studying the most well-motivated non-canonical theory having Dirac-Born-Infeld Lagrangian. Beyond the scalar and tensor two-point functions on CMB scales, we then consider the possible detection of equilateral non-Gaussianity at Planck-precision and a measurement of primordial gravitational waves from prospective space-based laser interferometers. The former detection breaks the degeneracy with canonical inflation but results in poor reconstruction prospects, while the latter measurement enables a determination of nT which, while not breaking the degeneracy, can be shown to greatly improve the non-canonical reconstruction.

Original languageEnglish (US)
Article number028
JournalJournal of Cosmology and Astroparticle Physics
Issue number3
StatePublished - Mar 2013


  • CMBR theory
  • gravitational waves and CMBR polarization
  • ination
  • non-gaussianity

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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