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Paper   IPM / Physic / 13275
School of Physics
  Title:   Non-Bunch-Davis Initial State Reconciles Chaotic Models with BICEP and Planck
1.  A. Ashoorioon
2.  K. Dimopoulos
3.  M.M. Sheikh-Jabbari
4.  G. Shiu
  Status:   Published
  Journal: Phys. Lett. B
  Vol.:  737
  Year:  2014
  Pages:   98
  Supported by:  IPM
The BICEP2 experiment [arXiv:1403.3985] has announced a signal for primordial gravity waves with tensor-to-scalar ratio r=0.2+0.07−0.05. This result may be reconciled with the Planck experiment [arXiv:1303.5082] if there is a considerable tilt of r, Tr, with a positive sign, Tr=dlnr/dlnk ∼ 0.16 corresponding to a blue tilt for the tensor modes of order nT ≅ 0.12. Simple slow-roll models fail to provide this tilt. In this note we show that a non-Bunch-Davis initial state for perturbations not only provides a match between large field chaotic models (like m2ϕ2) with the Planck result [arXiv:1306.4914], but also naturally accommodates the running of the tilt needed to explain the BICEP2 result.

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