Standard Model-Axion-Seesaw-Higgs Portal Inflation. Five problems of
  particle physics and cosmology solved in one stroke
  We present a minimal extension of the Standard Model (SM) providing a
consistent picture of particle physics from the electroweak scale to the Planck
scale and of cosmology from inflation until today. Three right-handed neutrinos
$N_i$, a new color triplet $Q$ and a complex SM-singlet scalar $\sigma$, whose
vacuum expectation value $v_\sigma \sim 10^{11}$ GeV breaks lepton number and a
Peccei-Quinn symmetry simultaneously, are added to the SM. At low energies, the
model reduces to the SM, augmented by seesaw generated neutrino masses and
mixing, plus the axion. The latter solves the strong CP problem and accounts
for the cold dark matter in the Universe. The inflaton is comprised by a
mixture of $\sigma$ and the SM Higgs, and reheating of the Universe after
inflation proceeds via the Higgs portal. Baryogenesis occurs via thermal
leptogenesis. Thus, five fundamental problems of particle physics and cosmology
are solved at one stroke in this unified Standard Model - Axion - seesaw -
Higgs portal inflation (SMASH) model. It can be probed decisively by upcoming
cosmic microwave background and axion dark matter experiments.
