Large tensor spectrum of BICEP2 in the natural SUSY hybrid model

Abstract

The large tensor spectrum recently observed by the BICEP2 Collaboration requires a super-Planckian field variation of the inflaton in the single-field inflationary scenario. The required slow-roll parameter ε\approx 0.01 would restrict the e-folding number to around 7 in (sub-)Planckian inflationary models. To overcome such problems, we consider a two-field scenario based on the natural assisted supersymmetric (SUSY) hybrid model ("natural SUSY hybrid inflation" [1]), which combines the SUSY hybrid and the natural inflation models. The axionic inflaton field from the natural inflation sector can admit the right values for the tensor spectrum as well as a spectral index of 0.96 with a decay constant smaller than the Planck scale, f \lesssim M_P. On the other hand, the vacuum energy of 2 x 10^{16} GeV with 50 e-folds is provided by the inflaton coming from the SUSY hybrid sector, avoiding the eta problem. These are achieved by introducing both the U(1)_R and a shift symmetry, and employing the minimal Kahler potential.

14 pages, 2 eps figures, version to appear in Phys. Rev. D

References in corpus (10)

• Non-Gaussianities in two-field inflation
• Multi-brid inflation and non-Gaussianity
• More hilltop inflation models
• Large non-Gaussianity from multi-brid inflation
• Multi-Natural Inflation in Supergravity and BICEP2
• BICEP2 implications for single-field slow-roll inflation revisited
• Observable Gravity Waves from Supersymmetric Hybrid Inflation II
• Observable Gravity Waves From Supersymmetric Hybrid Inflation
• Kaehler Potentials for Hilltop F-term Hybrid Inflation
• Primordial gravitational wave of BICEP2 from dynamical double hybrid inflation

Cited by in corpus (6)

• Chaotic Inflation in Supergravity after Planck and BICEP2
• Axion monodromy inflation with multi-natural modulations
• Modified Lyth bound and implications of BICEP2 results
• Dynamical breaking of shift-symmetry in supergravity-based inflation
• False vacuum energy dominated inflation with large $r$ and the importance of ${\kappa }_s$
• Light Scalars and the Cosmos: Nambu-Goldstone and Otherwise