A strong electroweak phase transition in the 2HDM after LHC8

The nature of the electroweak phase transition in two-Higgs-doublet models is revisited in light of the recent LHC results. A scan over an extensive region of their parameter space is performed, showing that a strongly first-order phase transition favours a light neutral scalar with SM-like properties, together with a heavy pseudo-scalar (m(A0) greater than or similar to 400GeV) and a mass hierarchy in the scalar sector, m(H+/-) less than or similar to m(H0) < m(A0). We also investigate the h(0) -> gamma gamma decay channel and find that an enhancement in the branching ratio is allowed, and in some cases even preferred, when a strongly first-order phase transition is required.