  The lack of correlations at the long-wavelength scales of the cosmic
microwave background spectrum is a long-standing puzzle and it persists in the
latest Planck data. By considering the Hartle-Hawking no-boundary wave function
as the initial condition of the inflationary universe, we propose that the
power suppression can be the consequence of a massive inflaton, whose initial
vacuum is the Euclidean instanton in a compact manifold. We calculate the
primordial power spectrum of the perturbations, and find that as long as the
scalar field is moderately massive, the power spectrum is suppressed at the
long-wavelength scales.
