  The present matter content of our universe may be governed by a $U(1)_{B-L}$
symmetry -- the simplest gauge completion of the seesaw mechanism which
produces small neutrino masses. The matter parity results as a residual gauge
symmetry, implying dark matter stability. The Higgs field that breaks the $B-L$
charge inflates the early universe successfully and then decays to right-handed
neutrinos, which reheats the universe and generates both normal matter and dark
matter manifestly.
