  We propose a model of inflation driven by the relaxation of an initially
Planckian cosmological constant due to diffusion. The model can generate a
(approximately) scale invariant spectrum of (adiabatic) primordial
perturbations with the correct amplitudes and red tilt without an inflaton. The
inhomogeneities observable in the CMB arise from those associated to the
fundamental Planckian granularity that are imprinted into the standard model
Higgs scalar fluctuations during the inflationary phase. The process admits a
semiclassical interpretation and avoids the trans-Planckian problem of standard
inflationary scenarios based on the role of vacuum fluctuations. The deviations
from scale invariance observed in the CMB are controlled by the self coupling
constant of the Higgs scalar of the standard model of particle physics. The
thermal production of primordial black holes can produce the amount of cold
dark matter required by observations. For natural initial conditions set at the
Planck scale the amplitude and tilt of the power spectrum of perturbations
observed at the CMB depend only on known parameters of the standard model such
as the self coupling of the Higgs scalar and its mass.
