Electroweak phase transition in Georgi–Machacek model

The Georgi–Machacek model extends the standard model Higgs sector by adding two isospin triplet scalar fields and imposing global SU(2)R symmetry on them. A feature of the model is that the triplets can acquire a large vacuum expectation value without conflicting with the current experimental bound on the ρ parameter. We investigate the electroweak phase transition in the Georgi–Machacek model by evaluating the finite-temperature effective potential of the Higgs sector. The electroweak phase transition can be sufficiently strong in a large parameter space when the triplets acquire a vacuum expectation value of O(10)GeV, opening a possibility to realize successful electroweak baryogenesis.