  The mechanism of "cold electroweak baryogenesis" has been so far unpopular
because its proposal has relied on the ad-hoc assumption of a period of hybrid
inflation at the electroweak scale with the Higgs acting as the waterfall
field. We argue here that cold baryogenesis can be naturally realized without
the need to introduce any slow-roll potential. Our point is that composite
Higgs models where electroweak symmetry breaking arises via a strongly
first-order phase transition provide a well-motivated framework for cold
baryogenesis. In this case, reheating proceeds by bubble collisions and we
argue that this can induce changes in Chern-Simons number, which in the
presence of new sources of CP violation commonly lead to baryogenesis. We
illustrate this mechanism using as a source of CP violation an effective
dimension-six operator which is free from EDM constraints, another advantage of
cold baryogenesis compared to the standard theory of electroweak baryogenesis.
Our results are general as they do not rely on any particular UV completion but
only on a stage of supercooling ended by a first-order phase transition in the
evolution of the universe, which can be natural if there is nearly conformal
dynamics at the TeV scale. Besides, baryon-number violation originates from the
Standard Model only.
