We study gravitational waves from the first-order electroweak phase transition in the SU ( N _ { c } ) gauge theory with N _ { f } / N _ { c } \gg 1 ( “ large N _ { f } QCD ” ) as a candidate for the walking technicolor , which is modeled by the U ( N _ { f } ) \times U ( N _ { f } ) linear sigma model with classical scale symmetry ( without mass term ) , particularly for N _ { f } = 8 ( “ one-family model ” ) .
This model exhibits spontaneous breaking of the scale symmetry as well as the U ( N _ { f } ) \times U ( N _ { f } ) radiatively through the Coleman-Weinberg mechanism \grave { a } la Gildener-Weinberg , thus giving rise to a light pseudo dilaton ( technidilaton ) to be identified with the 125 GeV Higgs .
This model possess a strong first-order electroweak phase transition due to the resultant Coleman-Weinberg type potential .
We estimate the bubble nucleation that exhibits an ultra supercooling and then the signal for a stochastic gravitational wave produced via the strong first-order electroweak phase transition .
We show that the amplitude can be reached to the expected sensitivities of the LISA .