Date of Original Version
© 2013 World Scientific Publishing Company
Abstract or Description
We argue that a plausible operational definition for an initial state of the universe is the initial quantum state of the curvature perturbations generated during inflation. We provide a parametrization of this state and generalize the standard in–in formalism to incorporate the structures in this state into the computation of correlators of the perturbations. Measurements of these correlators using both the cosmic microwave background as well as large scale structure probe different structures in the initial state, as they give rise to bi- and tri-spectra peaked on different shapes of triangles and quadrilaterals in momentum space. In essence, the shapes implied by the correlators feed directly into information about the shape of the initial state and what physics could have preceded inflation to set this state up.
International Journal of Modern Physics D, 22, 1341015.