SU(2)R and its axion in cosmology: A common origin for inflation, cold sterile neutrinos, and baryogenesis

We introduce an axion-inflation model embedded in the left-right symmetric extension of the Standard Model in which ${W}_{R}$ is coupled to the axion. This model merges three milestones of modern cosmology, i.e., inflation, cold dark matter, and baryon asymmetry. Thus, it can naturally explain the observed coincidences among cosmological parameters, i.e., ${\ensuremath{\eta}}_{\mathsf{B}}\ensuremath{\approx}{P}_{\ensuremath{\zeta}}$ and ${\mathrm{\ensuremath{\Omega}}}_{\mathrm{DM}}\ensuremath{\simeq}5{\mathrm{\ensuremath{\Omega}}}_{\mathsf{B}}$. The source of asymmetry is spontaneous $CP$ violation in the physics of inflation, and the lightest right-handed neutrino is the cold dark matter candidate with mass ${m}_{{N}_{1}}\ensuremath{\sim}1\text{ }\text{ }\mathrm{GeV}$. The introduced mechanism does not rely on the largeness of the unconstrained $CP$-violating phases in the neutrino sector or fine-tuned masses for the heaviest right-handed neutrinos. It has two unknown fundamental scales, i.e., scale of inflation ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{inf}}=\sqrt{H{M}_{\mathrm{Pl}}}$ and left-right symmetry breaking ${\mathrm{\ensuremath{\Lambda}}}_{F}$. Sufficient matter asymmetry demands that ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{inf}}\ensuremath{\approx}{\mathrm{\ensuremath{\Lambda}}}_{F}$. Baryon asymmetry and dark matter today are remnants of a pure quantum effect (chiral anomaly) in inflation, which, thanks to flavor effects, has been memorized by cosmic evolution.