  We evaluate dominant two-loop corrections to the triple Higgs coupling and
strength of a first-order electroweak phase transition in the inert Higgs
doublet model. It is found that sunset diagrams can predominantly enhance the
former and reduce the latter. As a result, the triple Higgs coupling normalized
by the standard model value at two-loop level is more enhanced than the
corresponding one-loop value.

High Energy Physics - Phenomenology