QCD-Electroweak First-Order Phase Transition in a Supercooled Universe
  If the electroweak sector of the standard model is described by classically
conformal dynamics, the early Universe evolution can be substantially altered.
It is already known that---contrarily to the standard model case---a first
order electroweak phase transition may occur. Here we show that, depending on
the model parameters, a dramatically different scenario may happen: A
first-order, six massless quark QCD phase transition occurs first, which then
triggers the electroweak symmetry breaking. We derive the necessary conditions
for this dynamics to occur, using the specific example of the classically
conformal B-L model. In particular, relatively light weakly coupled particles
are predicted, with implications for collider searches. This scenario is also
potentially rich in cosmological consequences, such as renewed possibilities
for electroweak baryogenesis, altered dark matter production, and gravitational
wave production, as we briefly comment upon.
