A new insight into the phase transition in the early Universe with two Higgs doublets

Abstract

We study the electroweak phase transition in the alignment limit of the CP-conserving two-Higgs-doublet model (2HDM) of Type I and Type II. The effective potential is evaluated at one-loop, where the thermal potential includes Daisy corrections and is reliably approximated by means of a sum of Bessel functions. Both 1-stage and 2-stage electroweak phase transitions are shown to be possible, depending on the pattern of the vacuum development as the Universe cools down. For the 1-stage case focused on in this paper, we analyze the properties of phase transition and discover that the field value of the electroweak symmetry breaking vacuum at the critical temperature at which the first order phase transition occurs is largely correlated with the vacuum depth of the 1-loop potential at zero temperature.We demonstrate that a strong first order electroweak phase transition (SFOEWPT) in the 2HDM is achievable and establish benchmark scenarios leading to different testable signatures at colliders. In addition, we verify that an enhanced triple Higgs coupling (including loop corrections) is a typical feature of the SFOPT driven by the additional doublet. As a result, SFOEWPT might be able to be probed at the LHC and future lepton colliders through Higgs pair production.

The electroweak phase transition: a collider target

“…In both cases (mass and precision), a wide range of EWPT studies involving specific model realizations are consistent with the general arguments provided below. These realizations include Higgs portal models with gauge singlets -either real [13, or complex [64][65][66][67][68] -or with electroweak multiplets [14,16,[69][70][71][72][73][74][75]; the two Higgs doublet model (2HDM) [11,[76][77][78][79][80][81][82][83][84][85][86][87][88]; the minimal supersymmetric SM (MSSM) [89][90][91][92][93][94][95][96][97][98] and its extensions with gauge singlet superfields [99][100][101][102][103][104][105][106][107]<...>…”

Gravitational wave and collider searches for electroweak symmetry breaking patterns

“…We note that, as in the 2HDM case, to ensure the photon is massless, we do not expect the violation of the U(1) electromagnetic symmetry during the EWPT process and assume the classical values for the charged scaler fields to be zero [15,[28][29][30]. Furthermore, we avoid all other possible alternative minima (see Ref.…”

“…For previous studies of multistep phase transition and related vacuum structure at zero temperature, we refer to Refs. [9,[12][13][14][15][16][17][18][19][20]. In this work, we use the Georgi-Machacek model to reveal that, the extra EWSB contribution can induce one-step or two-step SFOEWPT depending on the vacuum structure that has been studied previously by us in Ref [21].…”

Singlet-doublet fermionic dark matter and gravitational waves in a two-Higgs-doublet extension of the Standard Model

“…Such choices of the tan β is in agreement with the the DM phenomenology. As discussed in[64,104], SFOPT can take place in Type-I 2HDM even if the masses of the three extra Higgs bosons are degenerate ∼ 350 GeV. Such scenario leads to potentially testable premise through the A → Hh decay channel at colliders.…”

“…The strength of the phase transition depends on the ratio of the VEVs v c = √ < v 1 > 2 + < v 2 > 2 , measured at the critical temperature, to the critical temperature T c at which two degenerate minima exist. If the condition ξ = v c /T c > 1 is satisfied then the strong first-order phase transition (SFOPT) is said to be occured[64].The BPs in Tab. V are chosen in such a way that they not only satisfy constraints from the DM sector, but obeys the condition for SFOPT as well.…”