Non Bunch Davies group coherent states, and their quantum signatures in   CMB observables
  We approach the problem of finding generalized states for matter fields in a de Sitter universe, moving from a group theoretical point of view. This has profound consequences for cosmological perturbations during inflation, and for other CMB observables. In a systematic derivation, we find all the allowed generalities that such a state may have, within the requirements of coherent states. Furthermore, we show their relation to the more familiar excited initial states, often used in inflation. 
Pietro Dona and Antonino Marciano
gr-qc astro-ph.CO hep-th