With the assistance of a complex singlet, and an effective operator involving CP violations, the dark matter relic abundance and baryon asymmetry of the universe have been addressed simultaneously. We studied the electroweak baryogenesis mechanism systematically. The electroweak phase transition analysis indicates that the strong first order phase transition takes place by onestep or two-step type due to the dynamics of the energy gap between the electroweak vacuum and the vacuum of the complex singlet. The relation between the magnitude of baryon asymmetry of the universe and the phase transition type and strength has been explored in the framework of electroweak baryogenesis.1 Which should be the strong first-order EWPT to protect the generated baryon asymmetry from washout and suppress the sphaleron after the process is ended.

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.

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We study the strong first order electroweak phase transition (SFOEWPT) with the SO(6)/SO(5) composite Higgs model, whose scalar sector contains one Higgs doublet and one real singlet. Six benchmark models are built with fermion embeddings in 1, 6, and 15 of SO(6). We show that SFOEWPT cannot be triggered under the minimal Higgs potential hypothesis, which assumes the scalar potential is dominated by the form factors from the lightest composite resonances. To get a SFOEWPT, the contributions from local operators induced by physics above the cutoff scale are needed. We take the 6 + 6 model as an example to investigate the gravitational waves prediction and the related collider phenomenology. arXiv:1909.02014v2 [hep-ph] 5 Dec 2019 6 Which has been proved to be gauge-independent in Refs. [53,54]. 7 We briefly comment on the other two possible SFOEWPT mechanisms. The first one is the "one-step"

We present a class of cancellation mechanisms to suppress the total contributions of Barr-Zee diagrams to the electron electric dipole moment (eEDM). This class of mechanisms are of particular significance after the new eEDM upper limit, which strongly constrains the allowed magnitude of CP-violation in Higgs couplings and hence the feasibility of electroweak baryogenesis (EWBG), were released by the ACME collaboration in 2013. We point out: if both the CP-odd Higgs-photonphoton (Z boson) and the CP-odd Higgs-electron-positron couplings are turned on, a cancellation may occur either between the contributions of a CP-mixing Higgs boson, with the other Higgs bosons being decoupled, or between the contributions of a CP-even and a CP-odd Higgs bosons. With the assistance of the cancellation mechanisms, a large CP-phase in Higgs couplings with viable electroweak baryogenesis (EWBG) is still allowed. The reopened parameter regions would be probed by the future neutron, mercury EDM measurements, and direct measurements of Higgs CP-properties at the LHC and future colliders. INTRODUCTIONThe baryon asymmetry in the Universe (BAU) nowadays, i.e., [1,2] n b s ≈ (0.7 − 0.9) × 10 −10 = 0has puzzled people for more than half a century. Here s is entropy density of the Universe. Among various dynamical mechanisms to solve this puzzle, electroweak baryogenesis (EWBG) falls in the most popular class, due to its potential testability at the Large Hadron Collider and in the other experiments. A generic feature of the EWBG is that the CP phases employed to generate the cosmic baryon asymmetry need to enter the couplings between the Higgs sector and particles which either exist in the Standard Model (SM) or are introduced in new physics, no matter the CP-phases are flavor-diagonal, offdiagonal [3], or flavor-decoupled. Otherwise, these CPphases are decoupled from electroweak phase transition (EWPT) and the EWBG will never be implemented. The measurement of the Higgs CP-properties therefore provides important information to solve the BAU puzzle. Motivated by this, the CP-properties of the Higgs boson discovered in 2012 [4] have been extensively studied by both theorists [5][6][7][8][9] and experimental groups [11] since its discovery [4], by using a method of direct measurements at the LHC. Given the limited statistics, however, the sensitivity of the LHC at this stage is still low. On the other hand, fast progress has been made in indirect measurements. Using the polar molecule thorium monoxide (ThO), the ACME collaboration reported an upper limit on the eEDM recently [12] [56]at 90% confidence level, an order of magnitude stronger than the previous best limit. This limit severely constrains the allowed magnitude of CP-phases in the Higgs couplings [6-9] via Barr-Zee diagrams, causing a tension between the observation and the CP-phase required for successfully implementing EWBG (e.g., see [10] where the expected projection of the eEDM bounds to the EWBG in the MSSM was studied.) [57].In this letter we point out that in these studi...

We consider an anomaly-free U (1) model with favorable couplings to heavy flavors in the Standard Model(SM), as motivated by B-meson anomalies at LHCb. Taking the, we can explain the B-meson anomalies without invoking extra charged fermions or flavor violation beyond the SM. We show that there is a viable parameter space with a small x that is compatible with other meson decays, tau lepton and neutrino experiments as well as the LHC dimuon searches. We briefly discuss the prospects of discovering the Z gauge boson at the LHC in the proposed model.

In this work, we make the first study of electroweak baryogenesis (EWBG) based on the LHC data in the CP-violating next-to-minimal supersymmetric model (NMSSM) where a strongly first order electroweak phase transition (EWPT) is obtained in the general complex Higgs potential. With representative benchmark points which pass the current LEP and LHC constraints, we demonstrate the structure of EWPT for those points and how a strongly first order EWPT is obtained in the complex NMSSM where the resulting gravitational wave production properties are found to be within the reaches of future space-based interferometers like BBO and Ultimate-DECIGO. We further calculate the generated baryon asymmetries where the CP violating sources are (1): higgsino-singlino dominated, (2): higgsino-gaugino dominated or (3): from both sources. It is shown that all three representing scenarios could evade the strong constraints set by various electric dipole moments (EDM) searches where cancellations among the EDM contributions occur at the tree level (higgsino-singlino dominated) or loop level (higgsino-gaugino dominated). The 125 GeV SM like Higgs can be either the second lightest neutral Higgs H2 or the third lightest neutral Higgs H3. Finally, we comment on the future direct and indirect probe of CPV in the Higgs sector from the collider and EDM experiments.

In this paper, we construct two component dark matter model and revisit fine-tuning, unitarity and vacuum stability problem in this framework. Through Higgs-portal interactions, the additional scalar and vector singlet field can interact with the SM particles. The parameter space of the model are severely constraint by observed relic density and direct detection experiments. We found that, unlike the SM, the fine-tuning problem is relaxed due to the modified Veltman condition. The vacuum stability problem is addressed, the additional contributions from two DM singlets to the β function make the Higgs quartic coupling λ(µ) be positive up to Planck scale in some parameter space. 1 The simplest solution to the problem is to suppose V C SM = 0 [2], the conventional Veltman condition is realized. It is obvious that this condition could not be satisfied in the SM at low scale, since the top-quark's contribution is larger than the others in this case, giving rise to negative contribution to V C SM .