Higgs Boson Exchange Research Articles

Electric dipole moment of the electron and of the neutron.

It is shown that if Higgs-boson exchange mediates CP violation a significant electric dipole moment for the electron can result. Analogous effects can contribute to the neutron's electric dipole moment at a level competitive with Weinberg's three-gluon operator.

Ultraheavy quarkonium and its production in multi-TeV hadron colliders

Based on the standard model with two Higgs-doublets, we study physics of ultraheavy quarkonia which are composed of superheavy (such as 4-th generation) quarks. Owing to the strong Higgs-boson exchange force over the gluon exchange force, the situation of the mass levels of such quarkonia becomes drastically different from the ordinary qaurkonia like\(c\bar c\) or\(b\bar b\). The hyperfine splitting becomes larger than the fine splitting. The production rate of such quarkonia increases largely in multi-TeV colliders. Feasibility for observing such quarkonia is discussed.

Comments on the neutron electric dipole moment in the Weinberg model of CP-violation

The calculation of neutron EDM due to the exchange of neutral Higgs bosons is reconsidered. We find that, contrary to previous claims, both the scalar and the pseudoscalar Higgs nucleon couplings are not dominated by the heavy-quark contributions. The relevant pseudoscalar coupling is calculated by using the recent EMC data on the nucleon matrix element of the axial vector current; the scalar coupling incorporates the information contained in the πN sigma-term. The need for a proper treatment of the strange quark operators between the nucleon states is emphasized.

Production of ultraheavy leptonium and/or quarkonium ate + e ? colliders in TeV regions

The production cross section of the ultraheavy leptonium and quarkonium with the mass around 1 TeV which have the contribution of the Higgs-boson exchange is calculated in TeV regions ate+e− colliders. In some kinematical regions, we find that the Drell ratio for a bound state production shows a prominent resonance structure.

Production of ultraheavyS-state bound statesη Q (0− +) andψ(1−−) in multi-TeV collider energies

We study the Higgs-boson exchange interaction in ultraheavys-state bound statesηQ(0− +) and ψ(1−−) composed of ultraheavy quarksQ. Owing to the strong Higgs-ultraheavy quark interaction, the production of such bound states is hugely enhanced in multi-TeV collider energies over the case of bound states via gluon exchange alone.

Larger Higgs-boson-exchange terms in the neutron electric dipole moment.

The neutron electric dipole moment (${d}_{n}$) due to Higgs-boson exchange is reconsidered, now without assuming that Higgs-boson exchange is solely responsible for ${K}_{L}^{0}$\ensuremath{\rightarrow}2\ensuremath{\pi}. The dominant contribution to ${d}_{n}$ arises from a three-gluon operator, produced in integrating out top quarks and neutral Higgs bosons. The estimated results together with current experimental bounds on ${d}_{n}$ show, even for the largest plausible Higgs-boson masses, that CP is not maximally violated in neutral-Higgs-boson exchange.

CP violation in models with chiral color.

We study /ital CP/ violation in a chiral color model with exotic fermions transforming as singlets of the weak-isospin group SU(2)/sub /ital L//. The Higgs sector consists of a nonet of chiral color and the usual doublet of SU(2)/sub /ital L///times/U(1)/sub /ital Y//. In the limit in which the mixings between the third generation with the first two generations are small, /ital CP/-violating interactions are dominated by the exchange of neutral Higgs bosons. The /ital CP/-violating parameters /epsilon/ and /epsilon//prime///epsilon/ for the kaon system are easily accommodated. The neutron electric dipole moment is generated at the one-loop level and is /similar to/10/sup /minus/25/--10/sup /minus/26/e cm.

Energetic neutrinos from supersymmetric dark matter

We investigate the effect of Higgs-boson exchange on the capture of dark-matter neutralinos by the sun and the earth. If the Higgs boson is lighter than about 30 GeV, we predict a large enhancement of the flux of energetic neutrinos coming from annihilations of the trapped neutralinos. We study the expected neutrino energy spectrum and the rates for neutrino-generated events in underground detectors.

Flavor-changing decays of toponium

We consider flavor-changing decays of toponium V t= 3S 1(t t)→b s+ bs due to t-channel W exchange in the standard model. A new expression for V t→b b′+ bb′ (where b′ is a heavy fourth-generation Q=− 1 3 quark) is derived and its consequences discussed. We also consider the possible effects of the t-channel exchange of both charged Higgs bosons and the diquarks/leptoquarks found in some superstring-inspired E 6 models for flavor-changing toponium decays.

RADIATIVE CORRECTIONS TO $e^ + e^ - \to \bar tt$ IN ELECTROWEAK THEORY

The 0(α) radiative corrections to [Formula: see text] are calculated in the standard SU(2)×U(1) theory keeping the top quark mass. The contribution of the hard photon emission is included with suitable experimental cuts. We found that the 1-loop vertex diagrams for the top quark give rise to a fairly large correction in the order of 5% to the differential cross-section. Effects of the Higgs boson exchange are also discussed.

CP violation through Higgs-boson exchange in left-right-symmetric models.

A chiral electroweak model which accounts for spontaneous CP breaking is proposed. Under the requirement of realistic quark mixing matrices and as a result of a detailed study of the Higgs potential, CP-violating relative phases among the vacuum expectation values of the scalars coupled to the fermions are seen to emerge. The strong CP problem is solved without any restrictive assumptions. The phenomenological implications of the neutral-kaon system are analyzed, and a new physics in the Higgs sector is proposed to render \ensuremath{\Vert}\ensuremath{\Delta}scrS\ensuremath{\Vert}=2 enhanced interactions consistent with a not too high value of parity-breaking scale.

Spontaneous CP violation in the SU(2) L × U(1) Y model with two Higgs doublets

Spontaneous CP violation can occur in the SU(2) L × U(1) Y model if there are two Higgs doublets. This model is analyzed accepting standard constraints on the Higgs masses. CP violation occurs both as the result of Higgs boson exchange and the usual KM mechanism of gauge boson exchange. The main contribution to ε comes from superweak Higgs boson exchange. The value of ε′/ε is found to be between 10 −3 and 10 −5 arising both from the Higgs boson exchange and the KM mechanism. The neutron electric dipole moment is found to be of order 10 −26 e · cm arising mainly from the charged Higgs boson exchange. As a special feature of this model the muon longitudinal polarization in the decay K L → g ̄ mμ is found between the order of unity and 10 −2 arising from the flavor changing neutral Higgs boson exchange.

Hard gamma emission from b-decay and the Higgs boson doublet model

The possible contribution to b→ s + γ decay of the charged physical Higgs boson is discussed in models with two Higgs boson doublets. It is shown that the extra charged Higgs boson exchange in the one-loop level significantly enhance the b→ s+ γ decay over the standard theory which has one Higgs boson doublet. The possible detection of hard gamma from b→ s+ γ decay through ϒ‴ in the e +e − annihilation experiments will give rigorous restrictions on the possibility of two Higgs boson doublet models The b→ s+ γ decay is also briefly discussed.

CP violation in a left-right symmetric Higgs boson exchange theory

The CP violation parameter ϵ′ ϵ is calculated through charged Higgs boson exchange in a left-right symmetric theory. We renormalize the vertex functions involved in the K 0 → π +π − amplitude. An estimation gives the predicted value of ϵ′ ϵ equal to −0.038, which is much larger in magnitude than the experimental value, −0.003±0.015.

Reanalysis of Higgs-boson-exchange models of CP violation.

We reexamine the value of \ensuremath{\epsilon}'/\ensuremath{\epsilon} in models where CP violation is due to the exchange of charged Higgs bosons. Previous work has been flawed by incorrect treatment of the chiral properties of weak amplitudes. We use the effective-chiral-Lagrangian framework to clear up these aspects. The resultant value of \ensuremath{\epsilon}'/\ensuremath{\epsilon} is estimated to be in the neighborhood of \ensuremath{\epsilon}'/\ensuremath{\epsilon}=-0.006, although this estimate could be off by a factor of two or three in either direction. This value is consistent with the present experimental bounds.

New standard-model test for future colliders.

We point out that for $W$-pair production from ${e}^{+}{e}^{\ensuremath{-}}$ or $q\overline{q}$ beams, the correlation between the decay planes of the $W'\mathrm{s}$ is numerically negligible (at tree level) in the standard model. This occurs for the production of $\mathrm{WW}$ via intermediate fermions or gauge bosons and independently for $\mathrm{WW}$ produced via Higgs-boson exchange, and is not restricted to two-body diagrams. In general, the correlation need not vanish, and so a nonzero correlation would be a clear signal of physics beyond the standard model. Definition of the $W$-decay plane should be fairly straightforward from the decay $W\ensuremath{\rightarrow}f\overline{f}$ and, hence, the correlation measurement is experimentally feasible.

Electric Dipole Moment of Neutrons in a Left-Right Symmetric Higgs Boson Exchange Theory

The electric dipole moment of neutrons is considered through the charged Higgs boson exchange in a left-right symmetric theory. We show that it is related with the CP-nonconserving Higgs boson propagators. Estimation gives 1.8×10-23e·cm in comparison with the experimental value, (0.4±1.1)×10-24e·cm.

CP Violation in a Left-Right Symmetric Theory

Recently Sanda and DeshpandeJ) have shown that the Weinberg model 2 ) for two quark doublets of CP nonconservation through charged Higgs boson exchange and based on natural flavor conservation gives an unacceptably large value for the CP violation parameter E' / E, so that the model can probably be ruled out. Therefore it seems to' compel one to accept the KobayashiMaskawa mixing matrix for three quark doublets ) as a powerful candidate responsible for CP nonconservation. This mixing matrix is complex and contains a CP violation phase in itself, and hence the source of CP violation is hidden behind this assumed phase. On the other hand, the Weinberg model reduces the CP violation exclusively to the Higgs sector, allowing for the possibility that CP is a spontaneously broken symmetry. We keep this property, but we analyze, in this paper, the CP violation by the quark-Higgs-boson-interaction') of a left-right symmetric theory of the gauge group, G = SU(2hx SU(2)RX SU(3)color. We use a left-right symmetric interaction Lagrangian between Higgs bosons and quarks')

Effective lagrangian for ΔS = 1 and ΔS = 2 transition in the Higgs boson exchange model of CP violation

Using standard renormalization group technique, strong interaction corrections to ΔS = 1 and ΔS = 2 transitions are calculated in the Higgs-boson exchange model of CP violation. It is shown that the box diagram contribution to the ratio ϵ′ ϵ is not modified in any significant way with respect to lowest order calculation.

Consistency of models with CP violation predominantly in the ΔS = 1 Hamiltonian

It is emphasized that models with small or vanishing CP violation in the ΔS = 2 “superweak“ sector can be compatible with experiment provided there is “direct” ΔS = 1 CP violation and “soft” contribution of ΔMK. Such models must possess the following special features: (1) ϵ′ϵ negative and close to the experimental lower bound of −0.018; (2) a large negative “soft” contribution to ΔMK such that ReMsoft12 ⩽ −1.7 ReMexp12, consistent with some current algebra estimat es. The Higgs-boson exchange model of Weinberg is an example of this class of model. The standard KM model can be another.