Electroweak Phase Transition and Gravitational Waves in the Type-II
  Seesaw Model
  The type-II seesaw model is a possible candidate for simultaneously
explaining non-vanishing neutrino masses and the observed baryon asymmetry of
the Universe. In this work, we study in detail the pattern of phase transition
and the gravitational wave production of this model. We find a strong
first-order electroweak phase transition generically prefers positive Higgs
portal couplings and a light triplet below $\sim550$ GeV. In addition, we find
the gravitational wave yield generated during the phase transition would be at
the edge of BBO sensitivity and could be further examined by Ultimate-DECIGO.
