CP violation in $t\rightarrow W^+b$ decays in two-Higgs doublet model

Abstract

Due to the large mass of top quark, CP violation in the top-quark decay is sensitive to the interactions mediated by Higgs bosons. We consider CP violation in t → W + b decay by calculating consistently in unitary gauge the CP-violating up-down asymmetry of the leptons from W boson decays in t → W + b, defined by Grzadkowski and Gunion, in the two-Higgs doublet model with CP-violating neutral sector. The asymmetry is shown to be at most of the order of (1 − 3) × 10 −4 for tan β = 1.0, where tan β is the ratio of vacuum expectation values for the two neutral Higgs bosons.1

The top-quark decay vertex in standard model extensions

“…With the empirical constraint that m H + > m t , only the diagrams Fig. 1 In [51,[73][74][75] the form factor Img R was analyzed, with which our results are in accord. The couplings Im f L , Im g R are too small to cause observable CP-violating effects, i.e.…”

CPviolation in the semileptonic top-quark decay in the two-Higgs-doublet model

“…2 and 3, the values of A t are comparably smoothly connected among the three regions of tan β, though the solutions for the mass and eigenvector of Higgs mass matrix are obtained in the extreme region of tan β. The tan β-dependence is nearly one order lower than the previous solutions [9], where only one generate neutral Higgs boson is adopted as an approximation. The reason why the magnitude of A t is reduced in the new calculation is that some cancellation has occurred in the evaluation of Im f R 2 of Eqs.…”

“…We investigate CP violation in t → W + b decays [9] by the lepton distribution up-down asymmetry from W decay defined by Grzadkowski and Gunion [8]. We introduce the up-down asymmetry with respect to t → W + b decay plane in the top-quark laboratory frame for e + e − → t t defined in Ref.…”

“…The two-Higgs doublet model of type II [5] with the CP-violating neutral sector [6] was used in the study of electric dipole moment of neutron [7], and then the idea was applied to t → W + b decay [8]. Lately, we considered consistently in unitary guage the CP violating up-down asymmetry of the leptons from W boson decays in t → W + b [9], which was defined by Grzadkowski and Gunion [8]. Though only one!…”

ObservingCP-violating Higgs signals with heavy Majorana neutrinos

“…A number of studies have discussed the detection of the CP -phase of the Higgs boson using, for instance, angular observables sensitive to CP -violation in the HZZ and HW + W − couplings [17][18][19][20][21][22][23][24][25][26][27] as well as in the decays of the top quark in the process h → tt → bbW + W − [17,[28][29][30][31][32][33][34][35][36][37][38][39]. The results in the latter case can apply equally well to other heavy fermions coupling to the Higgs boson and decaying via the W -boson.…”