We study the prospect of probing electroweak baryogenesis driven by an extra bottom Yukawa coupling $ρ_{bb}$ in a general two Higgs doublet model via electric dipole moment (EDM) measurements and at the collider experiments. The parameter space receives meaningful constraints from 125 GeV Higgs $h$ boson signal strength measurements as well as several heavy Higgs boson searches at the Large Hadron Collider (LHC). In addition, we show that the asymmetry of the CP asymmetry of inclusive $B\to X_s γ$ decay would provide complementary probe. A discovery is possible at the LHC via $bg\to bA \to b Z h$ process if $|ρ_{bb}|\sim 0.15$ and $250~\mbox{GeV}\lesssim m_A \lesssim 350$ GeV, where $A$ is CP odd scalar. For $m_A> 2 m_t$ threshold, where $m_t$ is the top quark mass, one may also discover $bg\to bA \to b t \bar t$ at the high luminosity LHC run if an extra top Yukawa coupling $|ρ_{tt}|\sim0.5$, though it may suffer from systematic uncertainties. For completeness we study $gg\to t \bar t A \to t \bar t b \bar b $ but find it not promising.
We perform a study on the predictions of electric-dipole moments (EDMs) of neutron, Mercury (Hg), Thallium (Tl), deuteron, and Radium (Ra) in the framework of next-to-minimal supersymmetric standard model (NMSSM) with CP-violating parameters in the superpotential and soft-supersymmetry-breaking sector. We confine to the case in which only the physical tree-level CP phase $(ϕ'_λ- ϕ'_κ)$, associated with the couplings of the singlet terms in the superpotential and with the vacuum-expectation-values (VEVs), takes on a nonzero value. We found that the one-loop contributions from neutralinos are mo…
It is conventional wisdom that successful electroweak baryogenesis in the Minimal Supersymmetric extension of the Standard Model (MSSM) is in tension with the non-observation of electric dipole moments (EDMs), since the level of CP-violation responsible for electroweak baryogenesis is believed to generate unavoidably large EDMs. We show that CP-violation in the bino-Higgsino sector of the MSSM can account for successful electroweak baryogenesis without inducing large EDMs. This observation weakens the correlation between electroweak baryogenesis and EDMs, and makes the bino-driven electroweak …
Baryon asymmetry of the universe is generated in the supersymmetric standard model (SSM) through the charge transport mechanism mediated by top squarks. Necessary CP violation originates from a complex phase contained in mass-squared matrices of squarks and sleptons. This complex phase also gives contributions to the electric dipole moments (EDMs) of the neutron and the electron. The amount of induced baryon asymmetry is consistent with its observed value within reasonable ranges of SSM parameters. The EDMs are predicted to be slightly smaller than their experimental upper limits.
We study the simplest generic extension of the Standard Model which allows for conventional electroweak baryogenesis, through the addition of dimension six operators in the Higgs sector. At least one such operator is required to be CP-odd, and we study the constraints on such a minimal setup, and related scenarios with minimal flavor violation, from the null results of searches for electric dipole moments (EDMs), utilizing the full set of two-loop contributions to the EDMs. The results indicate that the current bounds are stringent, particularly that of the recently updated neutron EDM, but fa…
The predicted Standard Model (SM) electric dipole moments (EDMs) of electrons and quarks are tiny, providing an important window to observe new physics. Theories beyond the SM typically allow relatively large EDMs. The EDMs depend on the relative phases of terms in the effective Lagrangian of the extended theory, which are generally unknown. Underlying theories, such as string/M-theories compactified to four dimensions, could predict the phases and thus EDMs in the resulting supersymmetric (SUSY) theory. Earlier one of us, with collaborators, made such a prediction and found, unexpectedly, tha…
We consider a scenario in which an extra bottom Yukawa coupling can drive electroweak baryogenesis in the general two-Higgs doublet model. It is found that the new bottom Yukawa coupling with $\mathcal{O}(0.1)$ in magnitude can generate the sufficient baryon asymmetry without conflicting existing data. We point out that future measurements of the bottom Yukawa coupling at High-Luminosity Large Hadron Collider and International Linear Collider, together with the CP asymmetry of $B\to X_sγ$ at SuperKEKB provide exquisite probes for this scenario.
We study general aspects of the CP-violating effects on the baryon asymmetry of the Universe (BAU) and electric dipole moments (EDMs) in models extended by an extra Higgs doublet and a singlet, together with electroweak-interacting fermions. In particular, the emphasis is on the structure of the CP-violating interactions and dependences of the BAU and EDMs on masses of the relevant particles. In a concrete mode, we investigate a relationship between the BAU and the electron EDM for a typical parameter set. As long as the BAU-related CP violation predominantly exists, the electron EDM has a str…
We study electroweak baryogenesis driven by the top quark in a general two Higgs doublet model with flavor-changing Yukawa couplings, keeping the Higgs potential $CP$ invariant. With Higgs sector couplings and the additional top Yukawa coupling $ρ_{tt}$ all of $\mathcal{O}$(1), one naturally has sizable $CP$ violation that fuels the cosmic baryon asymmetry. Even if $ρ_{tt}$ vanishes, the favor-changing coupling $ρ_{tc}$ can still lead to successful baryogenesis. Phenomenological consequences such as $t\to ch$, $τ\to μγ$, electron electric dipole moment, $h\toγγ$, and $hhh$ coupling are discuss…
We demonstrate that in effective theories arising from a class of N=1 fluxless compactifications of M-theory on a G2 manifold with low energy supersymmetry, CP-violating phases do not appear in the soft-breaking Lagrangian except via the Yukawas appearing in the trilinear parameters. Such a mechanism may be present in other string compactifications as well; we describe properties sufficient for this to occur. CP violation is generated via the Yukawas since the soft trilinear matrices are generically not proportional to the Yukawa matrices. Within the framework considered, the estimated theoret…
The origin of the matter-antimatter asymmetry in the Universe is a fundamental question of physics. Electroweak baryogenesis is a compelling scenario for explaining it but it requires beyond the Standard Model sources of the CP symmetry violation. The simplest possibility is CP violation in the third generation fermion Higgs couplings, widely investigated theoretically and searched for experimentally. It has been found that the experimental bounds on the CP violation in the quark Yukawa couplings exclude their significant role in the electroweak baryogenesis, but it can be still played by the …
CP violation in the Higgs couplings to fermions is an intriguing, but not yet extensively explored possibility. We use inclusive and differential LHC Higgs boson measurements to fit the CP structure of the Higgs Yukawa couplings. Starting with simple effective models featuring CP violation in a single Higgs-fermion coupling, we probe well-motivated models with up to nine free parameters. We also investigate the complementarity of LHC constraints with the electron electric dipole moment bound, taking into account the possibility of a modified electron Yukawa coupling, and assess to which extent…
We analyze the quantum transport equations for supersymmetric electroweak baryogenesis including previously neglected bottom and tau Yukawa interactions and show that they imply the presence of a previously unrecognized dependence of the cosmic baryon asymmetry on the spectrum of third generation quark and lepton superpartners. For fixed values of the CP-violating phases in the supersymmetric theory, the baryon asymmetry can vary in both magnitude and sign as a result of the squark and slepton mass dependence. For light, right-handed top and bottom quark superpartners, the baryon number creati…
We study top-assisted di-Higgs production via $cg \to tH \to thh$, where $h$ is the 125 GeV scalar boson, and $H$ is the $CP$-even heavy Higgs. The context is the two Higgs doublet model without a $Z_2$ symmetry, where the extra Yukawa coupling $ρ_{tc}$ generates $tH$ production, with the extra top Yukawa $ρ_{tt} \simeq 0$ to avoid $gg \to H$ constraints. We find that discovery is possible for $m_H$ around 300 GeV or so at the LHC, but would need finite $h$-$H$ mixing angle $\cosγ$ to allow for finite $λ_{Hhh}$ coupling, and $ρ_{tc}$ also needs to be not too small. A sizable $ρ_{tc}$ could dri…
Baryogenesis at the electroweak scale depends on divers but identifiable details of bubble wall dynamics and the particle physics. We show that inclusion of the dynamics of relative phase in two-Higgs-doublet model (2HDM) enhances the adiabatic order of the mechanism proposed by McLerran-Shaposhnikov-Turok-Voloshin where the scalar-scalar-vector triangle diagram with top quark in the loop gives rise to a significant contribution to the effective chemical potential biasing the Chern-Simons number. We also show that in 2HDM with less stringent constraints on Yukawa couplings than those imposed b…
The electric dipole moments (EDMs) of charged leptons are significantly suppressed in standard model. It has been found previously that they are even more severely suppressed in seesaw type models by powers of tiny neutrino masses as far as a leptonic CP source is concerned. We investigate whether a Majorana-type Yukawa coupling between charged leptons and a doubly charged scalar can contribute significantly to their EDMs. An observable EDM would then help unravel the Majorana nature of neutrinos by a lepton number conserving quantity. We find that the EDMs are indeed parametrically large, of …
We derive the contributions to the quantum transport equations for electroweak baryogenesis due to decays and inverse decays induced by tri-scalar and Yukawa interactions. In the Minimal Supersymmetric Standard Model (MSSM), these contributions give rise to couplings between Higgs and fermion supermultiplet densities, thereby communicating the effects of CP-violation in the Higgs sector to the baryon sector. We show that the decay and inverse decay-induced contributions that arise at zeroth order in the strong coupling, α_s, can be substantially larger than the O(α_s) terms that are generated …
In the context of the supersymmetrized seesaw mechanism embedded in the Minimal Supersymmetric Standard Model (MSSM), complex neutrino Yukawa couplings can induce Electric Dipole Moments (EDMs) for the charged leptons, providing an additional route to seesaw parameters. However, the complex neutrino Yukawa matrix is not the only possible source of CP violation. Even in the framework of Constrained MSSM (CMSSM), there are additional sources, usually attributed to the phases of the trilinear soft supersymmetry breaking couplings and the mu-term, which contribute not only to the electron EDM but …
CP-violating contributions to Higgs--fermion couplings are absent in the standard model of particle physics (SM), but are motivated by models of electroweak baryogenesis. Here, we employ the framework of the SM effective theory (SMEFT) to parameterise deviations from SM Yukawa couplings. We present the leading contributions of the relevant operators to the fermionic electric dipole moments (EDMs). We obtain constraints on the SMEFT Wilson coefficients from the combination of LHC data and experimental bounds on the electron, neutron, and mercury EDMs, and for the first time, we perform a combin…
Electroweak baryogenesis can be driven by the top quark in a general two Higgs doublet model with extra Yukawa couplings. Higgs quartics provide the first order phase transition, while extra top Yukawa coupling $ρ_{tt}$ can fuel the cosmic baryon asymmetry through the $λ_t\,{\rm Im}\,ρ_{tt}$ product, with flavor-changing $ρ_{tc}$ coupling as backup. The impressive ACME 2018 bound on the electron electric dipole moment calls for an extra electron coupling $ρ_{ee}$ for exquisite cancellation among dangerous diagrams, broadening the baryogenesis solution space. The mechanism suggests that extra Y…
It has been recently shown that the electroweak baryogenesis mechanism is feasible in Standard Model extensions containing extra fermions with large Yukawa couplings. We show here that the lightest of these fermionic fields can naturally be a good candidate for cold dark matter. We find regions in the parameter space where the thermal relic abundance of this particle is compatible with the dark matter density of the Universe as determined by the WMAP experiment. We study direct and indirect dark matter detection for this model and compare with current experimental limits and prospects for upco…
We calculate the contribution to the baryon asymmetry of the Universe (BAU) from a $\mathcal{CP}$-violating source of the light quarks (charm, strange, down, up) and the electron, resulting from a dimension-six effective field theory term. We derive relevant bounds from the electric dipole moments of the electron and neutron to estimate the maximal contribution from each single flavor modification. Current bounds show that the charm quark can generate at most $\mathcal{O}(1\%)$ of the BAU, while the lighter quarks and the electron contribute at much lower levels.
We investigate the impact of the tau and bottom Yukawa couplings on the transport dynamics for electroweak baryogenesis in supersymmetric extensions of the Standard Model. Although it has generally been assumed in the literature that all Yukawa interactions except those involving the top quark are negligible, we find that the tau and bottom Yukawa interaction rates are too fast to be neglected. We identify an illustrative "lepton-mediated electroweak baryogenesis" scenario in which the baryon asymmetry is induced mainly through the presence of a left-handed leptonic charge. We derive analytic …
We explore the implications of the Standard Model effective field theory (SMEFT) with dimension-six terms involving the Higgs boson and third-generation fermion fields on the rate of Higgs boson production and decay into fermions, on the electric dipole moments (EDMs) of the electron, and on the baryon asymmetry of the Universe. We study the consequences of allowing these additional terms for each flavor separately and for combinations of two flavors. We find that a complex $τ$ Yukawa coupling can account for the observed baryon asymmetry $Y_B^{\rm obs}$ within current LHC and EDM bounds. A co…
Electroweak Baryogenesis, given a first order phase transition, does not work in the standard model because the quark Yukawa matrices are too hierarchical. On the other hand, the neutrino mass matrix is apparently not hierarchical. In models with neutrino mass generation at low scales, the neutrino Yukawa couplings lead to large CP-violation in the reflection probability of heavy leptons by the expanding Higgs bubble wall, and can generate the observed baryon asymmetry of the universe. The mechanism predicts new vector-like leptons below the TeV scale and sizable mu -> e processes.
We study the complementarity between the Large Hadron Collider (LHC) and future lepton colliders in probing electroweak baryogenesis induced by an additional bottom Yukawa coupling $ρ_{bb}$. The context is general two Higgs doublet model (g2HDM) where such additional bottom Yukawa coupling can account for the observed baryon asymmetry of the Universe if $\mbox{Im}(ρ_{bb}) \gtrsim 0.058$. We find that LHC would probe the nominal $\mbox{Im}(ρ_{bb})$ required for baryogenesis to some extent via $bg \to bA \to bZh$ process if $300~\mbox{GeV}\lesssim m_A \lesssim 450$ GeV, where $A$ is the CP-odd s…
We show that the CKM matrix can be the source of CP violation for electroweak baryogenesis if Yukawa couplings vary at the same time as the Higgs acquires its vacuum expectation value. This offers new avenues for explaining the baryon asymmetry of the universe. These ideas apply if the mechanism explaining the flavour structure of the Standard Model is connected to electroweak symmetry breaking. We compute the resulting baryon asymmetry for various low-scale flavour models and different configurations of the Yukawa coupling variation across the bubble wall, and show that it can naturally be of…
We investigate if the CP violation necessary for successful electroweak baryogenesis may be sourced by the neutrino Yukawa couplings. In particular, we consider an electroweak scale Seesaw realisation with sizeable Yukawas where the new neutrino singlets form (pseudo)-Dirac pairs. We find that flavour effects critically impact the final asymmetry obtained and that, taking them into account, the observed value may be obtained in some regions of the parameter space. This source of CP violation naturally avoids the strong constraints from electric dipole moments and links the origin of the baryon…
We investigate the feasibility of electroweak baryogenesis in a two-Higgs doublet model with lepton flavor violation. By scrutinizing the heavy Higgs boson mass spectrum, regions satisfying both strong first-order electroweak phase transition and the muon $g-2$ anomaly are identified. We also estimate the baryon number density by exploiting extra Yukawa couplings in the $μ$-$τ$ sector. It is found that a CP-violating source term can be enhanced by the $μ$-$τ$ flavor-violating coupling together with the extra $τ$ coupling. With $\mathcal{O}(1)$ Yukawa couplings and CP-violating phases, the obse…
We derive strong contraints on the Yukawa couplings and the vacuum expectation value in the singlet majoron model, taking into account the possibility of a small gravitationally induced mass for the majoron. If the present baryon asymmetry was created earlier than at the electroweak phase transition, then to preserve it from the combined effects of lepton number violating interactions and electroweak sphalerons, we find that stringent constraints on the Yukawa couplings, $h < 10^{-7}$, and the majoron scale, $v_s < v_{EW}$, must be satisfied. We also carefully rederive baryogenesis bounds on n…
We propose a new seesaw model in an extra-dimensional setup where only right-handed neutrinos are bulk fields. In the model, localizations of an extra-dimensional wave function and brane Majorana mass of the right-handed neutrinos can be different among each generation of the right-handed neutrinos. The setup can lead to different suppression factor dependences of effective right-handed neutrino masses and neutrino Yukawa couplings for each generation. It is shown that the resultant mass spectra of the right-handed neutrinos and neutrino Yukawa couplings are favored in models of neutrino dark …
The observation of $t\bar th(125)$ production at the Large Hadron Collider (LHC) is the first direct measurement of the top Yukawa coupling. It opens the window on an extra top Yukawa coupling, $ρ_{tt}$, from a second Higgs doublet, without a $Z_2$ symmetry to forbid flavor changing neutral Higgs couplings. We show that $t\bar th$ and Higgs property measurements at the High Luminosity LHC can constrain the ${\rm Re}\,ρ_{tt}$--${\rm Im}\,ρ_{tt}$ parameter space that could drive electroweak baryogenesis, but the $Γ_h$ width measurement must be considerably improved beyond current projections.
We analyze the correlations between electric dipole moments (EDMs) of the neutron and heavy atoms and CP violation in B_{s,d} mixing in two Higgs doublet models respecting the Minimal Flavour Violation hypothesis, with flavour-blind CP-violating (CPV) phases. In particular, we consider the case of flavour-blind CPV phases from i) the Yukawa interactions and ii) the Higgs potential. We show that in both cases the upper bounds on the above EDMs do not forbid sizable non-standard CPV effects in B_s mixing. However, if a large CPV phase in B_s mixing will be confirmed, this will imply EDMs very cl…
We demonstrate how probes of CP-violating observables in Higgs di-tau decays at prospective future lepton colliders could provide a test of weak scale baryogenesis with significant discovery potential. Measurements at the Circular Electron Positron Collider, for example, could exclude a CP phase larger than $2.9^\circ$ ($5.6^\circ$) at 68% (95%) C.L. assuming the Standard Model value for magnitude of the tau lepton Yukawa coupling. Conversely, this sensitivity would allow for a $5\,σ$ discovery for 82% of the CP phase range $[0,2π)$. The reaches of the Future Circular Collider - ee and Interna…
Negative searches for permanent electric dipole moments (EDMs) heavily constrain models of baryogenesis utilising various higher dimensional charge and parity violating (CPV) operators. Using effective field theory, we create a model independent connection between these EDM constraints and the baryon asymmetry of the universe (BAU) produced during a strongly first order electroweak phase transition. The thermal aspects of the high scale physics driving the phase transition are paramaterised by the usual kink solution for the bubble wall profile. We find that operators involving derivatives of …
We present a comprehensive study of the electroweak phase transition in composite Higgs models, where the Higgs arises from a new, strongly-coupled sector which confines near the TeV scale. This work extends our study in Ref. [1]. We describe the confinement phase transition in terms of the dilaton, the pseudo-Nambu-Goldstone boson of broken conformal invariance of the composite Higgs sector. From the analysis of the joint Higgs-dilaton potential we conclude that in this scenario the electroweak phase transition can naturally be first-order, allowing for electroweak baryogenesis. We then exten…
The cosmological evolution of standard model Yukawa couplings may have major implications for baryogenesis. In particular, as highlighted recently, the CKM matrix alone could be the source of CP-violation during electroweak baryogenesis provided that the Yukawa couplings were large and varied during the electroweak phase transition. We provide a natural realisation of this idea in the context of Randall-Sundrum models and show that the geometrical warped approach to the fermion mass hierarchy may naturally display the desired cosmological dynamics. The key ingredient is the coupling of the Gol…
In supersymmetric theories the radiative corrections due to heavy states could leave their footprints in the flavour structure of the supersymmetry breaking masses. We investigate whether present and future searches for the muon and electron EDMs could be sensitive to the CP violation and flavour misalignment induced on slepton masses by the radiative corrections due to the right-handed neutrinos of the seesaw model and to the heavy Higgs triplets of SU(5) GUT. When this is the case, limits on the relevant combination of neutrino Yukawa couplings are obtained. Explicit analytical expressions a…
Unitarity constraints on anomalous top-Higgs couplings are examined. We also compare the unitarity constraints with the constraints from electroweak baryogenesis and electric dipole moments derived earlier.
We investigate the role of leptons in electroweak baryogenesis by studying a relatively simple framework inspired by effective field theory that satisfies all Sakharov conditions. In particular, we study the effectiveness of CP-violating source terms induced by dimension-six Yukawa interactions for quarks and charged leptons. Despite the relatively small Yukawa coupling, CP-violating source terms involving taus are quite effective and can account for the observed matter-antimatter asymmetry. We obtain analytical and numerical expressions for the total baryon asymmetry, the former providing imp…
We investigate if the CP violation necessary for successful electroweak baryogenesis may be sourced by the neutrino Yukawa couplings. In particular, we consider an electroweak scale Seesaw realization with sizable Yukawas where the new neutrino singlets form (pseudo)-Dirac pairs, as in the linear or inverse Seesaw variants. We find that the baryon asymmetry obtained strongly depends on how the neutrino masses vary within the bubble walls. Moreover, we also find that flavour effects critically impact the final asymmetry obtained and that, taking them into account, the observed value may be obta…
We present a complete treatment of the diffusion processes for supersymmetric electroweak baryogenesis that characterizes transport dynamics ahead of the phase transition bubble wall within the symmetric phase. In particular, we generalize existing approaches to distinguish between chemical potentials of particles and their superpartners. This allows us to test the assumption of superequilibrium (equal chemical potentials for particles and sparticles) that has usually been made in earlier studies. We show that in the Minimal Supersymmetric Standard Model, superequilibrium is generically mainta…
The origin of the matter antimatter asymmetry of the universe remains unexplained in the Standard Model of particle physics. The origin of the flavour structure is another major puzzle of the theory. In this article, we report on recent work attempting to link the two themes through the appealing framework of electroweak baryogenesis. We show that Yukawa couplings of Standard Model fermions can be the source of CP-violation for electroweak baryogenesis if they vary at the same time as the Higgs is acquiring its vacuum expectation value, offering new avenues for electroweak baryogenesis. The ad…
The recent discovery of the bottom quark Yukawa coupling ($hbb$) of the 125 GeV scalar motivates one to search for extra bottom Yukawa coupling that may exist in the nature. The two Higgs doublet model without a discrete $Z_2$ symmetry allows the possibility of additional bottom Yukawa coupling $ρ_{bb}$. We show that $ρ_{bb}$ can be searched directly at the LHC via $bg\to b A \to b Z H$ and $gg \to b \bar b A \to b \bar b Z H$ processes, where $A$ and $H$ are the CP-odd and CP-even scalars respectively. We find that the $bg\to b A \to b Z H$ process could be discovered with $\sim300$ fb$^{-1}$…
We study quark and electron EDMs generated by Yukawa couplings in supersymmetric models with different gauge groups, using the EDM properties under flavour transformations. In the MSSM (or if soft terms are mediated below the unification scale) the one loop contributions to the neutron EDM are smaller than in previous computations based on numerical methods, although increasing as tan^3β. A neutron EDM close to the experimental limits can be generated in SU(5), if tanβis large, through the u-quark EDM d_u, proportional to tan^4β. This effect has to be taken into account also in SO(10) with lar…
We study a model with an exotic new sector strongly coupled to the Higgs boson, in which supersymmetry is introduced to protect the quartic coupling from a large running and avoid potential vacuum stability problem. The fermionic components present vector like mass terms, through which the Higgs diphoton decay branching ratio can be tuned. The bosonic components trigger a strongly first order electroweak phase transition. We find a large parameter region of effective Yukawa coupling $y\gtrsim2$ and mass parameters $m_f\sim m_s$ of a few hundred GeV, that can simultaneously accommodate the diph…
We evaluate the baryon number abundance based on the charge transport scenario of top quarks in the CP-violating two Higgs doublet model, in which Yukawa interactions are aligned to avoid dangerous flavor changing neutral currents, and coupling constants of the lightest Higgs boson with the mass $125~\mathrm{GeV}$ coincide with those in the standard model at tree level to satisfy the current LHC data. In this model, the severe constraint from the electric dipole moment of electrons, which are normally difficult to be satisfied, can be avoided by destructive interferences between CP-violating p…
There are theoretical speculations that the top quark may have different properties from that predicted by the standard model. We use an effective Lagrangian technique to model such a non-standard top quark scenario and study its effects on the electroweak baryogenesis, low and high energy physics.
We study electroweak baryogenesis driven by the top quark in two Higgs doublet model that allows flavor-changing neutral Higgs couplings. Taking Higgs sector couplings and the additional top Yukawa coupling $ρ_{tt}$ to be $\mathcal{O}$(1), one naturally has first order electroweak phase transition and sufficient $CP$ violation to fuel the cosmic baryon asymmetry. Even if $ρ_{tt}$ vanishes, the favor-changing coupling $ρ_{tc}$ can still achieve baryogenesis. Phenomenological consequences such as $t\to ch$, $τ\to μγ$, electron electric dipole moment, $h\toγγ$, and $hhh$ coupling are discussed. T…
An axion can make the electroweak phase transition strongly first-order as required for electroweak baryogenesis even if it is weakly coupled to the Higgs sector. This is essentially because the axion periodicity naturally allows the structure of phase transition to be insensitive to the axion decay constant that determines the strength of axion interactions. Furthermore, the axion can serve as a CP phase relevant to electroweak baryogenesis if one introduces an effective axion coupling to the top quark Yukawa operator. Then, for $f$ between about TeV and order $10$~TeV, the observed baryon as…
The framework of Higgs-dependent Yukawa couplings allows one to eliminate small couplings from the Standard Model, which can be tested at the LHC. In this work, I study the conditions for CP violation to occur in such models. I identify a class of weak basis invariants controlling CP violation. The invariant measure of CP violation is found to be more than 10 orders of magnitude greater than that in the Standard Model, which can be sufficient for successful electroweak baryogenesis.
We explore the possibility that the electroweak phase transition happens at a scale much higher than the electroweak scale today. In this context, high scale CP-violating sources for electroweak baryogenesis are not constrained by low-energy experiments. We propose a scenario of high-scale electroweak baryogenesis linked to flavour physics. This scenario allows for a period of enhanced Yukawa couplings during the evolution of the universe, which source time-dependent CP violation. The electroweak symmetry is never restored after the high-scale phase transition due to negative contributions to …
We investigate the possibility that baryogenesis occurs during the weak phase transition in a minimal extension of the Standard Model which contains extra neutral leptons and conserves total lepton number. The necessary CP-violating phases appear in the leptonic Yukawa couplings. We compute the CP-asymmetries in both the neutral and the charged lepton fluxes reflected on the bubble wall. Using present experimental bounds on the mixing angles and Standard Model estimates for the parameters related to the scalar potential, we conclude that it seems unlikely to produce the observed baryon to entr…
After a short review of electroweak scale baryogenesis, we consider the dynamics of chiral fermions coupled to a complex scalar field through the standard Yukawa interaction term at a strongly first order electroweak phase transition. By performing a systematic gradient expansion we can use this simple model to study electroweak scale baryogenesis. We show that the dominant sources for electroweak baryogenesis appear at linear order in the Planck constant h-bar. We provide explicit expressions for the sources both in the flow term and in the collision term of the relevant kinetic Boltzmann equ…
Nonstandard CP violation in the Higgs sector can play an essential role in electroweak baryogenesis. We calculate the full two-loop matching conditions of the standard model, with Higgs Yukawa couplings to light quarks modified to include arbitrary CP-violating phases, onto an effective Lagrangian comprising CP-odd electric and chromoelectric light-quark (up, down, and strange) dipole operators. We find large isospin-breaking contributions of the electroweak diagrams. Using these results, we obtain significant constraints on the phases of the light-quark Yukawas from experimental bounds on the…
