Hartle-Hawking wave function and large-scale power suppression of CMB
  In this presentation, we first describe the Hartle-Hawking wave function in
the Euclidean path integral approach. After we introduce perturbations to the
background instanton solution, following the formalism developed by
Halliwell-Hawking and Laflamme, one can obtain the scale-invariant power
spectrum for small-scales. We further emphasize that the Hartle-Hawking wave
function can explain the large-scale power suppression by choosing suitable
potential parameters, where this will be a possible window to confirm or
falsify models of quantum cosmology. Finally, we further comment on possible
future applications, e.g., Euclidean wormholes, which can result in distinct
signatures to the power spectrum.
